import ignore from 'ignore';
import AsyncLock from 'async-lock';
import Hash from 'sha.js/sha1.js';
import crc32 from 'crc-32';
import pako from 'pako';

/**
 * @typedef {Object} GitProgressEvent
 * @property {string} phase
 * @property {number} loaded
 * @property {number} total
 */

/**
 * @callback ProgressCallback
 * @param {GitProgressEvent} progress
 * @returns {void | Promise<void>}
 */

/**
 * @typedef {Object} GitHttpRequest
 * @property {string} url - The URL to request
 * @property {string} [method='GET'] - The HTTP method to use
 * @property {Object<string, string>} [headers={}] - Headers to include in the HTTP request
 * @property {Object} [agent] - An HTTP or HTTPS agent that manages connections for the HTTP client (Node.js only)
 * @property {AsyncIterableIterator<Uint8Array>} [body] - An async iterator of Uint8Arrays that make up the body of POST requests
 * @property {ProgressCallback} [onProgress] - Reserved for future use (emitting `GitProgressEvent`s)
 * @property {object} [signal] - Reserved for future use (canceling a request)
 */

/**
 * @typedef {Object} GitHttpResponse
 * @property {string} url - The final URL that was fetched after any redirects
 * @property {string} [method] - The HTTP method that was used
 * @property {Object<string, string>} [headers] - HTTP response headers
 * @property {AsyncIterableIterator<Uint8Array>} [body] - An async iterator of Uint8Arrays that make up the body of the response
 * @property {number} statusCode - The HTTP status code
 * @property {string} statusMessage - The HTTP status message
 */

/**
 * @callback HttpFetch
 * @param {GitHttpRequest} request
 * @returns {Promise<GitHttpResponse>}
 */

/**
 * @typedef {Object} HttpClient
 * @property {HttpFetch} request
 */

/**
 * A git commit object.
 *
 * @typedef {Object} CommitObject
 * @property {string} message Commit message
 * @property {string} tree SHA-1 object id of corresponding file tree
 * @property {string[]} parent an array of zero or more SHA-1 object ids
 * @property {Object} author
 * @property {string} author.name The author's name
 * @property {string} author.email The author's email
 * @property {number} author.timestamp UTC Unix timestamp in seconds
 * @property {number} author.timezoneOffset Timezone difference from UTC in minutes
 * @property {Object} committer
 * @property {string} committer.name The committer's name
 * @property {string} committer.email The committer's email
 * @property {number} committer.timestamp UTC Unix timestamp in seconds
 * @property {number} committer.timezoneOffset Timezone difference from UTC in minutes
 * @property {string} [gpgsig] PGP signature (if present)
 */

/**
 * An entry from a git tree object. Files are called 'blobs' and directories are called 'trees'.
 *
 * @typedef {Object} TreeEntry
 * @property {string} mode the 6 digit hexadecimal mode
 * @property {string} path the name of the file or directory
 * @property {string} oid the SHA-1 object id of the blob or tree
 * @property {'commit'|'blob'|'tree'} type the type of object
 */

/**
 * A git tree object. Trees represent a directory snapshot.
 *
 * @typedef {TreeEntry[]} TreeObject
 */

/**
 * A git annotated tag object.
 *
 * @typedef {Object} TagObject
 * @property {string} object SHA-1 object id of object being tagged
 * @property {'blob' | 'tree' | 'commit' | 'tag'} type the type of the object being tagged
 * @property {string} tag the tag name
 * @property {Object} tagger
 * @property {string} tagger.name the tagger's name
 * @property {string} tagger.email the tagger's email
 * @property {number} tagger.timestamp UTC Unix timestamp in seconds
 * @property {number} tagger.timezoneOffset timezone difference from UTC in minutes
 * @property {string} message tag message
 * @property {string} [gpgsig] PGP signature (if present)
 */

/**
 * @typedef {Object} ReadCommitResult
 * @property {string} oid - SHA-1 object id of this commit
 * @property {CommitObject} commit - the parsed commit object
 * @property {string} payload - PGP signing payload
 */

/**
 * @typedef {Object} ServerRef - This object has the following schema:
 * @property {string} ref - The name of the ref
 * @property {string} oid - The SHA-1 object id the ref points to
 * @property {string} [target] - The target ref pointed to by a symbolic ref
 * @property {string} [peeled] - If the oid is the SHA-1 object id of an annotated tag, this is the SHA-1 object id that the annotated tag points to
 */

/**
 * @typedef Walker
 * @property {Symbol} Symbol('GitWalkerSymbol')
 */

/**
 * Normalized subset of filesystem `stat` data:
 *
 * @typedef {Object} Stat
 * @property {number} ctimeSeconds
 * @property {number} ctimeNanoseconds
 * @property {number} mtimeSeconds
 * @property {number} mtimeNanoseconds
 * @property {number} dev
 * @property {number} ino
 * @property {number} mode
 * @property {number} uid
 * @property {number} gid
 * @property {number} size
 */

/**
 * The `WalkerEntry` is an interface that abstracts computing many common tree / blob stats.
 *
 * @typedef {Object} WalkerEntry
 * @property {function(): Promise<'tree'|'blob'|'special'|'commit'>} type
 * @property {function(): Promise<number>} mode
 * @property {function(): Promise<string>} oid
 * @property {function(): Promise<Uint8Array|void>} content
 * @property {function(): Promise<Stat>} stat
 */

/**
 * @typedef {Object} CallbackFsClient
 * @property {function} readFile - https://nodejs.org/api/fs.html#fs_fs_readfile_path_options_callback
 * @property {function} writeFile - https://nodejs.org/api/fs.html#fs_fs_writefile_file_data_options_callback
 * @property {function} unlink - https://nodejs.org/api/fs.html#fs_fs_unlink_path_callback
 * @property {function} readdir - https://nodejs.org/api/fs.html#fs_fs_readdir_path_options_callback
 * @property {function} mkdir - https://nodejs.org/api/fs.html#fs_fs_mkdir_path_mode_callback
 * @property {function} rmdir - https://nodejs.org/api/fs.html#fs_fs_rmdir_path_callback
 * @property {function} stat - https://nodejs.org/api/fs.html#fs_fs_stat_path_options_callback
 * @property {function} lstat - https://nodejs.org/api/fs.html#fs_fs_lstat_path_options_callback
 * @property {function} [readlink] - https://nodejs.org/api/fs.html#fs_fs_readlink_path_options_callback
 * @property {function} [symlink] - https://nodejs.org/api/fs.html#fs_fs_symlink_target_path_type_callback
 * @property {function} [chmod] - https://nodejs.org/api/fs.html#fs_fs_chmod_path_mode_callback
 */

/**
 * @typedef {Object} PromiseFsClient
 * @property {Object} promises
 * @property {function} promises.readFile - https://nodejs.org/api/fs.html#fs_fspromises_readfile_path_options
 * @property {function} promises.writeFile - https://nodejs.org/api/fs.html#fs_fspromises_writefile_file_data_options
 * @property {function} promises.unlink - https://nodejs.org/api/fs.html#fs_fspromises_unlink_path
 * @property {function} promises.readdir - https://nodejs.org/api/fs.html#fs_fspromises_readdir_path_options
 * @property {function} promises.mkdir - https://nodejs.org/api/fs.html#fs_fspromises_mkdir_path_options
 * @property {function} promises.rmdir - https://nodejs.org/api/fs.html#fs_fspromises_rmdir_path
 * @property {function} promises.stat - https://nodejs.org/api/fs.html#fs_fspromises_stat_path_options
 * @property {function} promises.lstat - https://nodejs.org/api/fs.html#fs_fspromises_lstat_path_options
 * @property {function} [promises.readlink] - https://nodejs.org/api/fs.html#fs_fspromises_readlink_path_options
 * @property {function} [promises.symlink] - https://nodejs.org/api/fs.html#fs_fspromises_symlink_target_path_type
 * @property {function} [promises.chmod] - https://nodejs.org/api/fs.html#fs_fspromises_chmod_path_mode
 */

/**
 * @typedef {CallbackFsClient | PromiseFsClient} FsClient
 */

/**
 * @callback MessageCallback
 * @param {string} message
 * @returns {void | Promise<void>}
 */

/**
 * @typedef {Object} GitAuth
 * @property {string} [username]
 * @property {string} [password]
 * @property {Object<string, string>} [headers]
 * @property {boolean} [cancel] Tells git to throw a `UserCanceledError` (instead of an `HttpError`).
 */

/**
 * @callback AuthCallback
 * @param {string} url
 * @param {GitAuth} auth Might have some values if the URL itself originally contained a username or password.
 * @returns {GitAuth | void | Promise<GitAuth | void>}
 */

/**
 * @callback AuthFailureCallback
 * @param {string} url
 * @param {GitAuth} auth The credentials that failed
 * @returns {GitAuth | void | Promise<GitAuth | void>}
 */

/**
 * @callback AuthSuccessCallback
 * @param {string} url
 * @param {GitAuth} auth
 * @returns {void | Promise<void>}
 */

/**
 * @typedef {Object} SignParams
 * @property {string} payload - a plaintext message
 * @property {string} secretKey - an 'ASCII armor' encoded PGP key (technically can actually contain _multiple_ keys)
 */

/**
 * @callback SignCallback
 * @param {SignParams} args
 * @return {{signature: string} | Promise<{signature: string}>} - an 'ASCII armor' encoded "detached" signature
 */

/**
 * @typedef {Object} MergeDriverParams
 * @property {Array<string>} branches
 * @property {Array<string>} contents
 * @property {string} path
 */

/**
 * @callback MergeDriverCallback
 * @param {MergeDriverParams} args
 * @return {{cleanMerge: boolean, mergedText: string} | Promise<{cleanMerge: boolean, mergedText: string}>}
 */

/**
 * @callback WalkerMap
 * @param {string} filename
 * @param {WalkerEntry[]} entries
 * @returns {Promise<any>}
 */

/**
 * @callback WalkerReduce
 * @param {any} parent
 * @param {any[]} children
 * @returns {Promise<any>}
 */

/**
 * @callback WalkerIterateCallback
 * @param {WalkerEntry[]} entries
 * @returns {Promise<any[]>}
 */

/**
 * @callback WalkerIterate
 * @param {WalkerIterateCallback} walk
 * @param {IterableIterator<WalkerEntry[]>} children
 * @returns {Promise<any[]>}
 */

/**
 * @typedef {Object} RefUpdateStatus
 * @property {boolean} ok
 * @property {string} error
 */

/**
 * @typedef {Object} PushResult
 * @property {boolean} ok
 * @property {?string} error
 * @property {Object<string, RefUpdateStatus>} refs
 * @property {Object<string, string>} [headers]
 */

/**
 * @typedef {0|1} HeadStatus
 */

/**
 * @typedef {0|1|2} WorkdirStatus
 */

/**
 * @typedef {0|1|2|3} StageStatus
 */

/**
 * @typedef {[string, HeadStatus, WorkdirStatus, StageStatus]} StatusRow
 */

/**
 * @typedef {'push' | 'pop' | 'apply' | 'drop' | 'list' | 'clear'} StashOp the type of stash ops
 */

/**
 * @typedef {'equal' | 'modify' | 'add' | 'remove' | 'unknown'} StashChangeType - when compare WORDIR to HEAD, 'remove' could mean 'untracked'
 * @typedef {Object} ClientRef
 * @property {string} ref The name of the ref
 * @property {string} oid The SHA-1 object id the ref points to
 */

/**
 * @typedef {Object} PrePushParams
 * @property {string} remote The expanded name of target remote
 * @property {string} url The URL address of target remote
 * @property {ClientRef} localRef The ref which the client wants to push to the remote
 * @property {ClientRef} remoteRef The ref which is known by the remote
 */

/**
 * @callback PrePushCallback
 * @param {PrePushParams} args
 * @returns {boolean | Promise<boolean>} Returns false if push must be cancelled
 */

/**
 * @typedef {Object} PostCheckoutParams
 * @property {string} previousHead The SHA-1 object id of HEAD before checkout
 * @property {string} newHead The SHA-1 object id of HEAD after checkout
 * @property {'branch' | 'file'} type flag determining whether a branch or a set of files was checked
 */

/**
 * @callback PostCheckoutCallback
 * @param {PostCheckoutParams} args
 * @returns {void | Promise<void>}
 */

// This is straight from parse_unit_factor in config.c of canonical git
const num = val => {
  if (typeof val === 'number') {
    return val
  }

  val = val.toLowerCase();
  let n = parseInt(val);
  if (val.endsWith('k')) n *= 1024;
  if (val.endsWith('m')) n *= 1024 * 1024;
  if (val.endsWith('g')) n *= 1024 * 1024 * 1024;
  return n
};

// This is straight from git_parse_maybe_bool_text in config.c of canonical git
const bool = val => {
  if (typeof val === 'boolean') {
    return val
  }

  val = val.trim().toLowerCase();
  if (val === 'true' || val === 'yes' || val === 'on') return true
  if (val === 'false' || val === 'no' || val === 'off') return false
  throw Error(
    `Expected 'true', 'false', 'yes', 'no', 'on', or 'off', but got ${val}`
  )
};

const schema = {
  core: {
    filemode: bool,
    bare: bool,
    logallrefupdates: bool,
    symlinks: bool,
    ignorecase: bool,
    bigFileThreshold: num,
  },
};

// https://git-scm.com/docs/git-config#_syntax

// section starts with [ and ends with ]
// section is alphanumeric (ASCII) with - and .
// section is case insensitive
// subsection is optional
// subsection is specified after section and one or more spaces
// subsection is specified between double quotes
const SECTION_LINE_REGEX = /^\[([A-Za-z0-9-.]+)(?: "(.*)")?\]$/;
const SECTION_REGEX = /^[A-Za-z0-9-.]+$/;

// variable lines contain a name, and equal sign and then a value
// variable lines can also only contain a name (the implicit value is a boolean true)
// variable name is alphanumeric (ASCII) with -
// variable name starts with an alphabetic character
// variable name is case insensitive
const VARIABLE_LINE_REGEX = /^([A-Za-z][A-Za-z-]*)(?: *= *(.*))?$/;
const VARIABLE_NAME_REGEX = /^[A-Za-z][A-Za-z-]*$/;

// Comments start with either # or ; and extend to the end of line
const VARIABLE_VALUE_COMMENT_REGEX = /^(.*?)( *[#;].*)$/;

const extractSectionLine = line => {
  const matches = SECTION_LINE_REGEX.exec(line);
  if (matches != null) {
    const [section, subsection] = matches.slice(1);
    return [section, subsection]
  }
  return null
};

const extractVariableLine = line => {
  const matches = VARIABLE_LINE_REGEX.exec(line);
  if (matches != null) {
    const [name, rawValue = 'true'] = matches.slice(1);
    const valueWithoutComments = removeComments(rawValue);
    const valueWithoutQuotes = removeQuotes(valueWithoutComments);
    return [name, valueWithoutQuotes]
  }
  return null
};

const removeComments = rawValue => {
  const commentMatches = VARIABLE_VALUE_COMMENT_REGEX.exec(rawValue);
  if (commentMatches == null) {
    return rawValue
  }
  const [valueWithoutComment, comment] = commentMatches.slice(1);
  // if odd number of quotes before and after comment => comment is escaped
  if (
    hasOddNumberOfQuotes(valueWithoutComment) &&
    hasOddNumberOfQuotes(comment)
  ) {
    return `${valueWithoutComment}${comment}`
  }
  return valueWithoutComment
};

const hasOddNumberOfQuotes = text => {
  const numberOfQuotes = (text.match(/(?:^|[^\\])"/g) || []).length;
  return numberOfQuotes % 2 !== 0
};

const removeQuotes = text => {
  return text.split('').reduce((newText, c, idx, text) => {
    const isQuote = c === '"' && text[idx - 1] !== '\\';
    const isEscapeForQuote = c === '\\' && text[idx + 1] === '"';
    if (isQuote || isEscapeForQuote) {
      return newText
    }
    return newText + c
  }, '')
};

const lower = text => {
  return text != null ? text.toLowerCase() : null
};

const getPath = (section, subsection, name) => {
  return [lower(section), subsection, lower(name)]
    .filter(a => a != null)
    .join('.')
};

const normalizePath = path => {
  const pathSegments = path.split('.');
  const section = pathSegments.shift();
  const name = pathSegments.pop();
  const subsection = pathSegments.length ? pathSegments.join('.') : undefined;

  return {
    section,
    subsection,
    name,
    path: getPath(section, subsection, name),
    sectionPath: getPath(section, subsection, null),
    isSection: !!section,
  }
};

const findLastIndex = (array, callback) => {
  return array.reduce((lastIndex, item, index) => {
    return callback(item) ? index : lastIndex
  }, -1)
};

// Note: there are a LOT of edge cases that aren't covered (e.g. keys in sections that also
// have subsections, [include] directives, etc.
class GitConfig {
  constructor(text) {
    let section = null;
    let subsection = null;
    this.parsedConfig = text
      ? text.split('\n').map(line => {
          let name = null;
          let value = null;

          const trimmedLine = line.trim();
          const extractedSection = extractSectionLine(trimmedLine);
          const isSection = extractedSection != null;
          if (isSection) {
            ;[section, subsection] = extractedSection;
          } else {
            const extractedVariable = extractVariableLine(trimmedLine);
            const isVariable = extractedVariable != null;
            if (isVariable) {
              ;[name, value] = extractedVariable;
            }
          }

          const path = getPath(section, subsection, name);
          return { line, isSection, section, subsection, name, value, path }
        })
      : [];
  }

  static from(text) {
    return new GitConfig(text)
  }

  async get(path, getall = false) {
    const normalizedPath = normalizePath(path).path;
    const allValues = this.parsedConfig
      .filter(config => config.path === normalizedPath)
      .map(({ section, name, value }) => {
        const fn = schema[section] && schema[section][name];
        return fn ? fn(value) : value
      });
    return getall ? allValues : allValues.pop()
  }

  async getall(path) {
    return this.get(path, true)
  }

  async getSubsections(section) {
    return this.parsedConfig
      .filter(config => config.isSection && config.section === section)
      .map(config => config.subsection)
  }

  async deleteSection(section, subsection) {
    this.parsedConfig = this.parsedConfig.filter(
      config =>
        !(config.section === section && config.subsection === subsection)
    );
  }

  async append(path, value) {
    return this.set(path, value, true)
  }

  async set(path, value, append = false) {
    const {
      section,
      subsection,
      name,
      path: normalizedPath,
      sectionPath,
      isSection,
    } = normalizePath(path);

    const configIndex = findLastIndex(
      this.parsedConfig,
      config => config.path === normalizedPath
    );
    if (value == null) {
      if (configIndex !== -1) {
        this.parsedConfig.splice(configIndex, 1);
      }
    } else {
      if (configIndex !== -1) {
        const config = this.parsedConfig[configIndex];
        // Name should be overwritten in case the casing changed
        const modifiedConfig = Object.assign({}, config, {
          name,
          value,
          modified: true,
        });
        if (append) {
          this.parsedConfig.splice(configIndex + 1, 0, modifiedConfig);
        } else {
          this.parsedConfig[configIndex] = modifiedConfig;
        }
      } else {
        const sectionIndex = this.parsedConfig.findIndex(
          config => config.path === sectionPath
        );
        const newConfig = {
          section,
          subsection,
          name,
          value,
          modified: true,
          path: normalizedPath,
        };
        if (SECTION_REGEX.test(section) && VARIABLE_NAME_REGEX.test(name)) {
          if (sectionIndex >= 0) {
            // Reuse existing section
            this.parsedConfig.splice(sectionIndex + 1, 0, newConfig);
          } else {
            // Add a new section
            const newSection = {
              isSection,
              section,
              subsection,
              modified: true,
              path: sectionPath,
            };
            this.parsedConfig.push(newSection, newConfig);
          }
        }
      }
    }
  }

  toString() {
    return this.parsedConfig
      .map(({ line, section, subsection, name, value, modified = false }) => {
        if (!modified) {
          return line
        }
        if (name != null && value != null) {
          if (typeof value === 'string' && /[#;]/.test(value)) {
            // A `#` or `;` symbol denotes a comment, so we have to wrap it in double quotes
            return `\t${name} = "${value}"`
          }
          return `\t${name} = ${value}`
        }
        if (subsection != null) {
          return `[${section} "${subsection}"]`
        }
        return `[${section}]`
      })
      .join('\n')
  }
}

/**
 * Manages access to the Git configuration file, providing methods to read and save configurations.
 */
class GitConfigManager {
  /**
   * Reads the Git configuration file from the specified `.git` directory.
   *
   * @param {object} opts - Options for reading the Git configuration.
   * @param {FSClient} opts.fs - A file system implementation.
   * @param {string} opts.gitdir - The path to the `.git` directory.
   * @returns {Promise<GitConfig>} A `GitConfig` object representing the parsed configuration.
   */
  static async get({ fs, gitdir }) {
    // We can improve efficiency later if needed.
    // TODO: read from full list of git config files
    const text = await fs.read(`${gitdir}/config`, { encoding: 'utf8' });
    return GitConfig.from(text)
  }

  /**
   * Saves the provided Git configuration to the specified `.git` directory.
   *
   * @param {object} opts - Options for saving the Git configuration.
   * @param {FSClient} opts.fs - A file system implementation.
   * @param {string} opts.gitdir - The path to the `.git` directory.
   * @param {GitConfig} opts.config - The `GitConfig` object to save.
   * @returns {Promise<void>} Resolves when the configuration has been successfully saved.
   */
  static async save({ fs, gitdir, config }) {
    // We can improve efficiency later if needed.
    // TODO: handle saving to the correct global/user/repo location
    await fs.write(`${gitdir}/config`, config.toString(), {
      encoding: 'utf8',
    });
  }
}

function basename(path) {
  const last = Math.max(path.lastIndexOf('/'), path.lastIndexOf('\\'));
  if (last > -1) {
    path = path.slice(last + 1);
  }
  return path
}

function dirname(path) {
  const last = Math.max(path.lastIndexOf('/'), path.lastIndexOf('\\'));
  if (last === -1) return '.'
  if (last === 0) return '/'
  return path.slice(0, last)
}

/*!
 * This code for `path.join` is directly copied from @zenfs/core/path for bundle size improvements.
 * SPDX-License-Identifier: LGPL-3.0-or-later
 * Copyright (c) James Prevett and other ZenFS contributors.
 */

function normalizeString(path, aar) {
  let res = '';
  let lastSegmentLength = 0;
  let lastSlash = -1;
  let dots = 0;
  let char = '\x00';
  for (let i = 0; i <= path.length; ++i) {
    if (i < path.length) char = path[i];
    else if (char === '/') break
    else char = '/';

    if (char === '/') {
      if (lastSlash === i - 1 || dots === 1) {
        // NOOP
      } else if (dots === 2) {
        if (
          res.length < 2 ||
          lastSegmentLength !== 2 ||
          res.at(-1) !== '.' ||
          res.at(-2) !== '.'
        ) {
          if (res.length > 2) {
            const lastSlashIndex = res.lastIndexOf('/');
            if (lastSlashIndex === -1) {
              res = '';
              lastSegmentLength = 0;
            } else {
              res = res.slice(0, lastSlashIndex);
              lastSegmentLength = res.length - 1 - res.lastIndexOf('/');
            }
            lastSlash = i;
            dots = 0;
            continue
          } else if (res.length !== 0) {
            res = '';
            lastSegmentLength = 0;
            lastSlash = i;
            dots = 0;
            continue
          }
        }
        if (aar) {
          res += res.length > 0 ? '/..' : '..';
          lastSegmentLength = 2;
        }
      } else {
        if (res.length > 0) res += '/' + path.slice(lastSlash + 1, i);
        else res = path.slice(lastSlash + 1, i);
        lastSegmentLength = i - lastSlash - 1;
      }
      lastSlash = i;
      dots = 0;
    } else if (char === '.' && dots !== -1) {
      ++dots;
    } else {
      dots = -1;
    }
  }
  return res
}

function normalize(path) {
  if (!path.length) return '.'

  const isAbsolute = path[0] === '/';
  const trailingSeparator = path.at(-1) === '/';

  path = normalizeString(path, !isAbsolute);

  if (!path.length) {
    if (isAbsolute) return '/'
    return trailingSeparator ? './' : '.'
  }
  if (trailingSeparator) path += '/';

  return isAbsolute ? `/${path}` : path
}

function join(...args) {
  if (args.length === 0) return '.'
  let joined;
  for (let i = 0; i < args.length; ++i) {
    const arg = args[i];
    if (arg.length > 0) {
      if (joined === undefined) joined = arg;
      else joined += '/' + arg;
    }
  }
  if (joined === undefined) return '.'
  return normalize(joined)
}

// I'm putting this in a Manager because I reckon it could benefit
// from a LOT of caching.
class GitIgnoreManager {
  /**
   * Determines whether a given file is ignored based on `.gitignore` rules and exclusion files.
   *
   * @param {Object} args
   * @param {FSClient} args.fs - A file system implementation.
   * @param {string} args.dir - The working directory.
   * @param {string} [args.gitdir=join(dir, '.git')] - [required] The [git directory](dir-vs-gitdir.md) path
   * @param {string} args.filepath - The path of the file to check.
   * @returns {Promise<boolean>} - `true` if the file is ignored, `false` otherwise.
   */
  static async isIgnored({ fs, dir, gitdir = join(dir, '.git'), filepath }) {
    // ALWAYS ignore ".git" folders.
    if (basename(filepath) === '.git') return true
    // '.' is not a valid gitignore entry, so '.' is never ignored
    if (filepath === '.') return false
    // Check and load exclusion rules from project exclude file (.git/info/exclude)
    let excludes = '';
    const excludesFile = join(gitdir, 'info', 'exclude');
    if (await fs.exists(excludesFile)) {
      excludes = await fs.read(excludesFile, 'utf8');
    }
    // Find all the .gitignore files that could affect this file
    const pairs = [
      {
        gitignore: join(dir, '.gitignore'),
        filepath,
      },
    ];
    const pieces = filepath.split('/').filter(Boolean);
    for (let i = 1; i < pieces.length; i++) {
      const folder = pieces.slice(0, i).join('/');
      const file = pieces.slice(i).join('/');
      pairs.push({
        gitignore: join(dir, folder, '.gitignore'),
        filepath: file,
      });
    }
    let ignoredStatus = false;
    for (const p of pairs) {
      let file;
      try {
        file = await fs.read(p.gitignore, 'utf8');
      } catch (err) {
        if (err.code === 'NOENT') continue
      }
      const ign = ignore().add(excludes);
      ign.add(file);
      // If the parent directory is excluded, we are done.
      // "It is not possible to re-include a file if a parent directory of that file is excluded. Git doesn’t list excluded directories for performance reasons, so any patterns on contained files have no effect, no matter where they are defined."
      // source: https://git-scm.com/docs/gitignore
      const parentdir = dirname(p.filepath);
      if (parentdir !== '.' && ign.ignores(parentdir)) return true
      // If the file is currently ignored, test for UNignoring.
      if (ignoredStatus) {
        ignoredStatus = !ign.test(p.filepath).unignored;
      } else {
        ignoredStatus = ign.test(p.filepath).ignored;
      }
    }
    return ignoredStatus
  }
}

class BaseError extends Error {
  constructor(message) {
    super(message);
    // Setting this here allows TS to infer that all git errors have a `caller` property and
    // that its type is string.
    this.caller = '';
  }

  toJSON() {
    // Error objects aren't normally serializable. So we do something about that.
    return {
      code: this.code,
      data: this.data,
      caller: this.caller,
      message: this.message,
      stack: this.stack,
    }
  }

  fromJSON(json) {
    const e = new BaseError(json.message);
    e.code = json.code;
    e.data = json.data;
    e.caller = json.caller;
    e.stack = json.stack;
    return e
  }

  get isIsomorphicGitError() {
    return true
  }
}

class UnmergedPathsError extends BaseError {
  /**
   * @param {Array<string>} filepaths
   */
  constructor(filepaths) {
    super(
      `Modifying the index is not possible because you have unmerged files: ${filepaths.toString}. Fix them up in the work tree, and then use 'git add/rm as appropriate to mark resolution and make a commit.`
    );
    this.code = this.name = UnmergedPathsError.code;
    this.data = { filepaths };
  }
}
/** @type {'UnmergedPathsError'} */
UnmergedPathsError.code = 'UnmergedPathsError';

class InternalError extends BaseError {
  /**
   * @param {string} message
   */
  constructor(message) {
    super(
      `An internal error caused this command to fail.\n\nIf you're not a developer, report the bug to the developers of the application you're using. If this is a bug in isomorphic-git then you should create a proper bug yourselves. The bug should include a minimal reproduction and details about the version and environment.\n\nPlease file a bug report at https://github.com/isomorphic-git/isomorphic-git/issues with this error message: ${message}`
    );
    this.code = this.name = InternalError.code;
    this.data = { message };
  }
}
/** @type {'InternalError'} */
InternalError.code = 'InternalError';

class UnsafeFilepathError extends BaseError {
  /**
   * @param {string} filepath
   */
  constructor(filepath) {
    super(`The filepath "${filepath}" contains unsafe character sequences`);
    this.code = this.name = UnsafeFilepathError.code;
    this.data = { filepath };
  }
}
/** @type {'UnsafeFilepathError'} */
UnsafeFilepathError.code = 'UnsafeFilepathError';

// Modeled after https://github.com/tjfontaine/node-buffercursor
// but with the goal of being much lighter weight.
class BufferCursor {
  constructor(buffer) {
    this.buffer = buffer;
    this._start = 0;
  }

  eof() {
    return this._start >= this.buffer.length
  }

  tell() {
    return this._start
  }

  seek(n) {
    this._start = n;
  }

  slice(n) {
    const r = this.buffer.slice(this._start, this._start + n);
    this._start += n;
    return r
  }

  toString(enc, length) {
    const r = this.buffer.toString(enc, this._start, this._start + length);
    this._start += length;
    return r
  }

  write(value, length, enc) {
    const r = this.buffer.write(value, this._start, length, enc);
    this._start += length;
    return r
  }

  copy(source, start, end) {
    const r = source.copy(this.buffer, this._start, start, end);
    this._start += r;
    return r
  }

  readUInt8() {
    const r = this.buffer.readUInt8(this._start);
    this._start += 1;
    return r
  }

  writeUInt8(value) {
    const r = this.buffer.writeUInt8(value, this._start);
    this._start += 1;
    return r
  }

  readUInt16BE() {
    const r = this.buffer.readUInt16BE(this._start);
    this._start += 2;
    return r
  }

  writeUInt16BE(value) {
    const r = this.buffer.writeUInt16BE(value, this._start);
    this._start += 2;
    return r
  }

  readUInt32BE() {
    const r = this.buffer.readUInt32BE(this._start);
    this._start += 4;
    return r
  }

  writeUInt32BE(value) {
    const r = this.buffer.writeUInt32BE(value, this._start);
    this._start += 4;
    return r
  }
}

function compareStrings(a, b) {
  // https://stackoverflow.com/a/40355107/2168416
  return -(a < b) || +(a > b)
}

function comparePath(a, b) {
  // https://stackoverflow.com/a/40355107/2168416
  return compareStrings(a.path, b.path)
}

/**
 * From https://github.com/git/git/blob/master/Documentation/technical/index-format.txt
 *
 * 32-bit mode, split into (high to low bits)
 *
 *  4-bit object type
 *    valid values in binary are 1000 (regular file), 1010 (symbolic link)
 *    and 1110 (gitlink)
 *
 *  3-bit unused
 *
 *  9-bit unix permission. Only 0755 and 0644 are valid for regular files.
 *  Symbolic links and gitlinks have value 0 in this field.
 */
function normalizeMode(mode) {
  // Note: BrowserFS will use -1 for "unknown"
  // I need to make it non-negative for these bitshifts to work.
  let type = mode > 0 ? mode >> 12 : 0;
  // If it isn't valid, assume it as a "regular file"
  // 0100 = directory
  // 1000 = regular file
  // 1010 = symlink
  // 1110 = gitlink
  if (
    type !== 0b0100 &&
    type !== 0b1000 &&
    type !== 0b1010 &&
    type !== 0b1110
  ) {
    type = 0b1000;
  }
  let permissions = mode & 0o777;
  // Is the file executable? then 755. Else 644.
  if (permissions & 0b001001001) {
    permissions = 0o755;
  } else {
    permissions = 0o644;
  }
  // If it's not a regular file, scrub all permissions
  if (type !== 0b1000) permissions = 0;
  return (type << 12) + permissions
}

const MAX_UINT32 = 2 ** 32;

function SecondsNanoseconds(
  givenSeconds,
  givenNanoseconds,
  milliseconds,
  date
) {
  if (givenSeconds !== undefined && givenNanoseconds !== undefined) {
    return [givenSeconds, givenNanoseconds]
  }
  if (milliseconds === undefined) {
    milliseconds = date.valueOf();
  }
  const seconds = Math.floor(milliseconds / 1000);
  const nanoseconds = (milliseconds - seconds * 1000) * 1000000;
  return [seconds, nanoseconds]
}

function normalizeStats(e) {
  const [ctimeSeconds, ctimeNanoseconds] = SecondsNanoseconds(
    e.ctimeSeconds,
    e.ctimeNanoseconds,
    e.ctimeMs,
    e.ctime
  );
  const [mtimeSeconds, mtimeNanoseconds] = SecondsNanoseconds(
    e.mtimeSeconds,
    e.mtimeNanoseconds,
    e.mtimeMs,
    e.mtime
  );

  return {
    ctimeSeconds: ctimeSeconds % MAX_UINT32,
    ctimeNanoseconds: ctimeNanoseconds % MAX_UINT32,
    mtimeSeconds: mtimeSeconds % MAX_UINT32,
    mtimeNanoseconds: mtimeNanoseconds % MAX_UINT32,
    dev: e.dev % MAX_UINT32,
    ino: e.ino % MAX_UINT32,
    mode: normalizeMode(e.mode % MAX_UINT32),
    uid: e.uid % MAX_UINT32,
    gid: e.gid % MAX_UINT32,
    // size of -1 happens over a BrowserFS HTTP Backend that doesn't serve Content-Length headers
    // (like the Karma webserver) because BrowserFS HTTP Backend uses HTTP HEAD requests to do fs.stat
    size: e.size > -1 ? e.size % MAX_UINT32 : 0,
  }
}

function toHex(buffer) {
  let hex = '';
  for (const byte of new Uint8Array(buffer)) {
    if (byte < 16) hex += '0';
    hex += byte.toString(16);
  }
  return hex
}

/* eslint-env node, browser */

let supportsSubtleSHA1 = null;

async function shasum(buffer) {
  if (supportsSubtleSHA1 === null) {
    supportsSubtleSHA1 = await testSubtleSHA1();
  }
  return supportsSubtleSHA1 ? subtleSHA1(buffer) : shasumSync(buffer)
}

// This is modeled after @dominictarr's "shasum" module,
// but without the 'json-stable-stringify' dependency and
// extra type-casting features.
function shasumSync(buffer) {
  return new Hash().update(buffer).digest('hex')
}

async function subtleSHA1(buffer) {
  const hash = await crypto.subtle.digest('SHA-1', buffer);
  return toHex(hash)
}

async function testSubtleSHA1() {
  // I'm using a rather crude method of progressive enhancement, because
  // some browsers that have crypto.subtle.digest don't actually implement SHA-1.
  try {
    const hash = await subtleSHA1(new Uint8Array([]));
    return hash === 'da39a3ee5e6b4b0d3255bfef95601890afd80709'
  } catch (_) {
    // no bother
  }
  return false
}

// Extract 1-bit assume-valid, 1-bit extended flag, 2-bit merge state flag, 12-bit path length flag
function parseCacheEntryFlags(bits) {
  return {
    assumeValid: Boolean(bits & 0b1000000000000000),
    extended: Boolean(bits & 0b0100000000000000),
    stage: (bits & 0b0011000000000000) >> 12,
    nameLength: bits & 0b0000111111111111,
  }
}

function renderCacheEntryFlags(entry) {
  const flags = entry.flags;
  // 1-bit extended flag (must be zero in version 2)
  flags.extended = false;
  // 12-bit name length if the length is less than 0xFFF; otherwise 0xFFF
  // is stored in this field.
  flags.nameLength = Math.min(Buffer.from(entry.path).length, 0xfff);
  return (
    (flags.assumeValid ? 0b1000000000000000 : 0) +
    (flags.extended ? 0b0100000000000000 : 0) +
    ((flags.stage & 0b11) << 12) +
    (flags.nameLength & 0b111111111111)
  )
}

class GitIndex {
  /*::
   _entries: Map<string, CacheEntry>
   _dirty: boolean // Used to determine if index needs to be saved to filesystem
   */
  constructor(entries, unmergedPaths) {
    this._dirty = false;
    this._unmergedPaths = unmergedPaths || new Set();
    this._entries = entries || new Map();
  }

  _addEntry(entry) {
    if (entry.flags.stage === 0) {
      entry.stages = [entry];
      this._entries.set(entry.path, entry);
      this._unmergedPaths.delete(entry.path);
    } else {
      let existingEntry = this._entries.get(entry.path);
      if (!existingEntry) {
        this._entries.set(entry.path, entry);
        existingEntry = entry;
      }
      existingEntry.stages[entry.flags.stage] = entry;
      this._unmergedPaths.add(entry.path);
    }
  }

  static async from(buffer) {
    if (Buffer.isBuffer(buffer)) {
      return GitIndex.fromBuffer(buffer)
    } else if (buffer === null) {
      return new GitIndex(null)
    } else {
      throw new InternalError('invalid type passed to GitIndex.from')
    }
  }

  static async fromBuffer(buffer) {
    if (buffer.length === 0) {
      throw new InternalError('Index file is empty (.git/index)')
    }

    const index = new GitIndex();
    const reader = new BufferCursor(buffer);
    const magic = reader.toString('utf8', 4);
    if (magic !== 'DIRC') {
      throw new InternalError(`Invalid dircache magic file number: ${magic}`)
    }

    // Verify shasum after we ensured that the file has a magic number
    const shaComputed = await shasum(buffer.slice(0, -20));
    const shaClaimed = buffer.slice(-20).toString('hex');
    if (shaClaimed !== shaComputed) {
      throw new InternalError(
        `Invalid checksum in GitIndex buffer: expected ${shaClaimed} but saw ${shaComputed}`
      )
    }

    const version = reader.readUInt32BE();
    if (version !== 2) {
      throw new InternalError(`Unsupported dircache version: ${version}`)
    }
    const numEntries = reader.readUInt32BE();
    let i = 0;
    while (!reader.eof() && i < numEntries) {
      const entry = {};
      entry.ctimeSeconds = reader.readUInt32BE();
      entry.ctimeNanoseconds = reader.readUInt32BE();
      entry.mtimeSeconds = reader.readUInt32BE();
      entry.mtimeNanoseconds = reader.readUInt32BE();
      entry.dev = reader.readUInt32BE();
      entry.ino = reader.readUInt32BE();
      entry.mode = reader.readUInt32BE();
      entry.uid = reader.readUInt32BE();
      entry.gid = reader.readUInt32BE();
      entry.size = reader.readUInt32BE();
      entry.oid = reader.slice(20).toString('hex');
      const flags = reader.readUInt16BE();
      entry.flags = parseCacheEntryFlags(flags);
      // TODO: handle if (version === 3 && entry.flags.extended)
      const pathlength = buffer.indexOf(0, reader.tell() + 1) - reader.tell();
      if (pathlength < 1) {
        throw new InternalError(`Got a path length of: ${pathlength}`)
      }
      // TODO: handle pathnames larger than 12 bits
      entry.path = reader.toString('utf8', pathlength);

      // Prevent malicious paths like "..\foo"
      if (entry.path.includes('..\\') || entry.path.includes('../')) {
        throw new UnsafeFilepathError(entry.path)
      }

      // The next bit is awkward. We expect 1 to 8 null characters
      // such that the total size of the entry is a multiple of 8 bits.
      // (Hence subtract 12 bytes for the header.)
      let padding = 8 - ((reader.tell() - 12) % 8);
      if (padding === 0) padding = 8;
      while (padding--) {
        const tmp = reader.readUInt8();
        if (tmp !== 0) {
          throw new InternalError(
            `Expected 1-8 null characters but got '${tmp}' after ${entry.path}`
          )
        } else if (reader.eof()) {
          throw new InternalError('Unexpected end of file')
        }
      }
      // end of awkward part
      entry.stages = [];

      index._addEntry(entry);

      i++;
    }
    return index
  }

  get unmergedPaths() {
    return [...this._unmergedPaths]
  }

  get entries() {
    return [...this._entries.values()].sort(comparePath)
  }

  get entriesMap() {
    return this._entries
  }

  get entriesFlat() {
    return [...this.entries].flatMap(entry => {
      return entry.stages.length > 1 ? entry.stages.filter(x => x) : entry
    })
  }

  *[Symbol.iterator]() {
    for (const entry of this.entries) {
      yield entry;
    }
  }

  insert({ filepath, stats, oid, stage = 0 }) {
    if (!stats) {
      stats = {
        ctimeSeconds: 0,
        ctimeNanoseconds: 0,
        mtimeSeconds: 0,
        mtimeNanoseconds: 0,
        dev: 0,
        ino: 0,
        mode: 0,
        uid: 0,
        gid: 0,
        size: 0,
      };
    }
    stats = normalizeStats(stats);
    const bfilepath = Buffer.from(filepath);
    const entry = {
      ctimeSeconds: stats.ctimeSeconds,
      ctimeNanoseconds: stats.ctimeNanoseconds,
      mtimeSeconds: stats.mtimeSeconds,
      mtimeNanoseconds: stats.mtimeNanoseconds,
      dev: stats.dev,
      ino: stats.ino,
      // We provide a fallback value for `mode` here because not all fs
      // implementations assign it, but we use it in GitTree.
      // '100644' is for a "regular non-executable file"
      mode: stats.mode || 0o100644,
      uid: stats.uid,
      gid: stats.gid,
      size: stats.size,
      path: filepath,
      oid,
      flags: {
        assumeValid: false,
        extended: false,
        stage,
        nameLength: bfilepath.length < 0xfff ? bfilepath.length : 0xfff,
      },
      stages: [],
    };

    this._addEntry(entry);

    this._dirty = true;
  }

  delete({ filepath }) {
    if (this._entries.has(filepath)) {
      this._entries.delete(filepath);
    } else {
      for (const key of this._entries.keys()) {
        if (key.startsWith(filepath + '/')) {
          this._entries.delete(key);
        }
      }
    }

    if (this._unmergedPaths.has(filepath)) {
      this._unmergedPaths.delete(filepath);
    }
    this._dirty = true;
  }

  clear() {
    this._entries.clear();
    this._dirty = true;
  }

  has({ filepath }) {
    return this._entries.has(filepath)
  }

  render() {
    return this.entries
      .map(entry => `${entry.mode.toString(8)} ${entry.oid}    ${entry.path}`)
      .join('\n')
  }

  static async _entryToBuffer(entry) {
    const bpath = Buffer.from(entry.path);
    // the fixed length + the filename + at least one null char => align by 8
    const length = Math.ceil((62 + bpath.length + 1) / 8) * 8;
    const written = Buffer.alloc(length);
    const writer = new BufferCursor(written);
    const stat = normalizeStats(entry);
    writer.writeUInt32BE(stat.ctimeSeconds);
    writer.writeUInt32BE(stat.ctimeNanoseconds);
    writer.writeUInt32BE(stat.mtimeSeconds);
    writer.writeUInt32BE(stat.mtimeNanoseconds);
    writer.writeUInt32BE(stat.dev);
    writer.writeUInt32BE(stat.ino);
    writer.writeUInt32BE(stat.mode);
    writer.writeUInt32BE(stat.uid);
    writer.writeUInt32BE(stat.gid);
    writer.writeUInt32BE(stat.size);
    writer.write(entry.oid, 20, 'hex');
    writer.writeUInt16BE(renderCacheEntryFlags(entry));
    writer.write(entry.path, bpath.length, 'utf8');
    return written
  }

  async toObject() {
    const header = Buffer.alloc(12);
    const writer = new BufferCursor(header);
    writer.write('DIRC', 4, 'utf8');
    writer.writeUInt32BE(2);
    writer.writeUInt32BE(this.entriesFlat.length);

    let entryBuffers = [];
    for (const entry of this.entries) {
      entryBuffers.push(GitIndex._entryToBuffer(entry));
      if (entry.stages.length > 1) {
        for (const stage of entry.stages) {
          if (stage && stage !== entry) {
            entryBuffers.push(GitIndex._entryToBuffer(stage));
          }
        }
      }
    }
    entryBuffers = await Promise.all(entryBuffers);

    const body = Buffer.concat(entryBuffers);
    const main = Buffer.concat([header, body]);
    const sum = await shasum(main);
    return Buffer.concat([main, Buffer.from(sum, 'hex')])
  }
}

function compareStats(entry, stats, filemode = true, trustino = true) {
  // Comparison based on the description in Paragraph 4 of
  // https://www.kernel.org/pub/software/scm/git/docs/technical/racy-git.txt
  const e = normalizeStats(entry);
  const s = normalizeStats(stats);
  const staleness =
    (filemode && e.mode !== s.mode) ||
    e.mtimeSeconds !== s.mtimeSeconds ||
    e.ctimeSeconds !== s.ctimeSeconds ||
    e.uid !== s.uid ||
    e.gid !== s.gid ||
    (trustino && e.ino !== s.ino) ||
    e.size !== s.size;
  return staleness
}

// import Lock from '../utils.js'

// const lm = new LockManager()
let lock = null;

const IndexCache = Symbol('IndexCache');

/**
 * Creates a cache object to store GitIndex and file stats.
 * @returns {object} A cache object with `map` and `stats` properties.
 */
function createCache() {
  return {
    map: new Map(),
    stats: new Map(),
  }
}

/**
 * Updates the cached index file by reading the file system and parsing the Git index.
 * @param {FSClient} fs - A file system implementation.
 * @param {string} filepath - The path to the Git index file.
 * @param {object} cache - The cache object to update.
 * @returns {Promise<void>}
 */
async function updateCachedIndexFile(fs, filepath, cache) {
  const [stat, rawIndexFile] = await Promise.all([
    fs.lstat(filepath),
    fs.read(filepath),
  ]);

  const index = await GitIndex.from(rawIndexFile);
  // cache the GitIndex object so we don't need to re-read it every time.
  cache.map.set(filepath, index);
  // Save the stat data for the index so we know whether the cached file is stale (modified by an outside process).
  cache.stats.set(filepath, stat);
}

/**
 * Determines whether the cached index file is stale by comparing file stats.
 * @param {FSClient} fs - A file system implementation.
 * @param {string} filepath - The path to the Git index file.
 * @param {object} cache - The cache object containing file stats.
 * @returns {Promise<boolean>} `true` if the index file is stale, otherwise `false`.
 */
async function isIndexStale(fs, filepath, cache) {
  const savedStats = cache.stats.get(filepath);
  if (savedStats === undefined) return true
  if (savedStats === null) return false

  const currStats = await fs.lstat(filepath);
  if (currStats === null) return false
  return compareStats(savedStats, currStats)
}

class GitIndexManager {
  /**
   * Manages access to the Git index file, ensuring thread-safe operations and caching.
   *
   * @param {object} opts - Options for acquiring the Git index.
   * @param {FSClient} opts.fs - A file system implementation.
   * @param {string} opts.gitdir - The path to the `.git` directory.
   * @param {object} opts.cache - A shared cache object for storing index data.
   * @param {boolean} [opts.allowUnmerged=true] - Whether to allow unmerged paths in the index.
   * @param {function(GitIndex): any} closure - A function to execute with the Git index.
   * @returns {Promise<any>} The result of the closure function.
   * @throws {UnmergedPathsError} If unmerged paths exist and `allowUnmerged` is `false`.
   */
  static async acquire({ fs, gitdir, cache, allowUnmerged = true }, closure) {
    if (!cache[IndexCache]) {
      cache[IndexCache] = createCache();
    }

    const filepath = `${gitdir}/index`;
    if (lock === null) lock = new AsyncLock({ maxPending: Infinity });
    let result;
    let unmergedPaths = [];
    await lock.acquire(filepath, async () => {
      // Acquire a file lock while we're reading the index
      // to make sure other processes aren't writing to it
      // simultaneously, which could result in a corrupted index.
      // const fileLock = await Lock(filepath)
      const theIndexCache = cache[IndexCache];
      if (await isIndexStale(fs, filepath, theIndexCache)) {
        await updateCachedIndexFile(fs, filepath, theIndexCache);
      }
      const index = theIndexCache.map.get(filepath);
      unmergedPaths = index.unmergedPaths;

      if (unmergedPaths.length && !allowUnmerged)
        throw new UnmergedPathsError(unmergedPaths)

      result = await closure(index);
      if (index._dirty) {
        // Acquire a file lock while we're writing the index file
        // let fileLock = await Lock(filepath)
        const buffer = await index.toObject();
        await fs.write(filepath, buffer);
        // Update cached stat value
        theIndexCache.stats.set(filepath, await fs.lstat(filepath));
        index._dirty = false;
      }
    });

    return result
  }
}

class InvalidOidError extends BaseError {
  /**
   * @param {string} value
   */
  constructor(value) {
    super(`Expected a 40-char hex object id but saw "${value}".`);
    this.code = this.name = InvalidOidError.code;
    this.data = { value };
  }
}
/** @type {'InvalidOidError'} */
InvalidOidError.code = 'InvalidOidError';

class NoRefspecError extends BaseError {
  /**
   * @param {string} remote
   */
  constructor(remote) {
    super(`Could not find a fetch refspec for remote "${remote}". Make sure the config file has an entry like the following:
[remote "${remote}"]
\tfetch = +refs/heads/*:refs/remotes/origin/*
`);
    this.code = this.name = NoRefspecError.code;
    this.data = { remote };
  }
}
/** @type {'NoRefspecError'} */
NoRefspecError.code = 'NoRefspecError';

class NotFoundError extends BaseError {
  /**
   * @param {string} what
   */
  constructor(what) {
    super(`Could not find ${what}.`);
    this.code = this.name = NotFoundError.code;
    this.data = { what };
  }
}
/** @type {'NotFoundError'} */
NotFoundError.code = 'NotFoundError';

class GitPackedRefs {
  constructor(text) {
    this.refs = new Map();
    this.parsedConfig = [];
    if (text) {
      let key = null;
      this.parsedConfig = text
        .trim()
        .split('\n')
        .map(line => {
          if (/^\s*#/.test(line)) {
            return { line, comment: true }
          }
          const i = line.indexOf(' ');
          if (line.startsWith('^')) {
            // This is a oid for the commit associated with the annotated tag immediately preceding this line.
            // Trim off the '^'
            const value = line.slice(1);
            // The tagname^{} syntax is based on the output of `git show-ref --tags -d`
            this.refs.set(key + '^{}', value);
            return { line, ref: key, peeled: value }
          } else {
            // This is an oid followed by the ref name
            const value = line.slice(0, i);
            key = line.slice(i + 1);
            this.refs.set(key, value);
            return { line, ref: key, oid: value }
          }
        });
    }
    return this
  }

  static from(text) {
    return new GitPackedRefs(text)
  }

  delete(ref) {
    this.parsedConfig = this.parsedConfig.filter(entry => entry.ref !== ref);
    this.refs.delete(ref);
  }

  toString() {
    return this.parsedConfig.map(({ line }) => line).join('\n') + '\n'
  }
}

class GitRefSpec {
  constructor({ remotePath, localPath, force, matchPrefix }) {
    Object.assign(this, {
      remotePath,
      localPath,
      force,
      matchPrefix,
    });
  }

  static from(refspec) {
    const [forceMatch, remotePath, remoteGlobMatch, localPath, localGlobMatch] =
      refspec.match(/^(\+?)(.*?)(\*?):(.*?)(\*?)$/).slice(1);
    const force = forceMatch === '+';
    const remoteIsGlob = remoteGlobMatch === '*';
    const localIsGlob = localGlobMatch === '*';
    // validate
    // TODO: Make this check more nuanced, and depend on whether this is a fetch refspec or a push refspec
    if (remoteIsGlob !== localIsGlob) {
      throw new InternalError('Invalid refspec')
    }
    return new GitRefSpec({
      remotePath,
      localPath,
      force,
      matchPrefix: remoteIsGlob,
    })
    // TODO: We need to run resolveRef on both paths to expand them to their full name.
  }

  translate(remoteBranch) {
    if (this.matchPrefix) {
      if (remoteBranch.startsWith(this.remotePath)) {
        return this.localPath + remoteBranch.replace(this.remotePath, '')
      }
    } else {
      if (remoteBranch === this.remotePath) return this.localPath
    }
    return null
  }

  reverseTranslate(localBranch) {
    if (this.matchPrefix) {
      if (localBranch.startsWith(this.localPath)) {
        return this.remotePath + localBranch.replace(this.localPath, '')
      }
    } else {
      if (localBranch === this.localPath) return this.remotePath
    }
    return null
  }
}

class GitRefSpecSet {
  constructor(rules = []) {
    this.rules = rules;
  }

  static from(refspecs) {
    const rules = [];
    for (const refspec of refspecs) {
      rules.push(GitRefSpec.from(refspec)); // might throw
    }
    return new GitRefSpecSet(rules)
  }

  add(refspec) {
    const rule = GitRefSpec.from(refspec); // might throw
    this.rules.push(rule);
  }

  translate(remoteRefs) {
    const result = [];
    for (const rule of this.rules) {
      for (const remoteRef of remoteRefs) {
        const localRef = rule.translate(remoteRef);
        if (localRef) {
          result.push([remoteRef, localRef]);
        }
      }
    }
    return result
  }

  translateOne(remoteRef) {
    let result = null;
    for (const rule of this.rules) {
      const localRef = rule.translate(remoteRef);
      if (localRef) {
        result = localRef;
      }
    }
    return result
  }

  localNamespaces() {
    return this.rules
      .filter(rule => rule.matchPrefix)
      .map(rule => rule.localPath.replace(/\/$/, ''))
  }
}

function compareRefNames(a, b) {
  // https://stackoverflow.com/a/40355107/2168416
  const _a = a.replace(/\^\{\}$/, '');
  const _b = b.replace(/\^\{\}$/, '');
  const tmp = -(_a < _b) || +(_a > _b);
  if (tmp === 0) {
    return a.endsWith('^{}') ? 1 : -1
  }
  return tmp
}

// @see https://git-scm.com/docs/git-rev-parse.html#_specifying_revisions
const refpaths = ref => [
  `${ref}`,
  `refs/${ref}`,
  `refs/tags/${ref}`,
  `refs/heads/${ref}`,
  `refs/remotes/${ref}`,
  `refs/remotes/${ref}/HEAD`,
];

// @see https://git-scm.com/docs/gitrepository-layout
const GIT_FILES = ['config', 'description', 'index', 'shallow', 'commondir'];

let lock$1;

async function acquireLock(ref, callback) {
  if (lock$1 === undefined) lock$1 = new AsyncLock();
  return lock$1.acquire(ref, callback)
}

/**
 * A class for managing Git references, including reading, writing, deleting, and resolving refs.
 */
class GitRefManager {
  /**
   * Updates remote refs based on the provided refspecs and options.
   *
   * @param {Object} args
   * @param {FSClient} args.fs - A file system implementation.
   * @param {string} [args.gitdir=join(dir, '.git')] - [required] The [git directory](dir-vs-gitdir.md) path
   * @param {string} args.remote - The name of the remote.
   * @param {Map<string, string>} args.refs - A map of refs to their object IDs.
   * @param {Map<string, string>} args.symrefs - A map of symbolic refs.
   * @param {boolean} args.tags - Whether to fetch tags.
   * @param {string[]} [args.refspecs = undefined] - The refspecs to use.
   * @param {boolean} [args.prune = false] - Whether to prune stale refs.
   * @param {boolean} [args.pruneTags = false] - Whether to prune tags.
   * @returns {Promise<Object>} - An object containing pruned refs.
   */
  static async updateRemoteRefs({
    fs,
    gitdir,
    remote,
    refs,
    symrefs,
    tags,
    refspecs = undefined,
    prune = false,
    pruneTags = false,
  }) {
    // Validate input
    for (const value of refs.values()) {
      if (!value.match(/[0-9a-f]{40}/)) {
        throw new InvalidOidError(value)
      }
    }
    const config = await GitConfigManager.get({ fs, gitdir });
    if (!refspecs) {
      refspecs = await config.getall(`remote.${remote}.fetch`);
      if (refspecs.length === 0) {
        throw new NoRefspecError(remote)
      }
      // There's some interesting behavior with HEAD that doesn't follow the refspec.
      refspecs.unshift(`+HEAD:refs/remotes/${remote}/HEAD`);
    }
    const refspec = GitRefSpecSet.from(refspecs);
    const actualRefsToWrite = new Map();
    // Delete all current tags if the pruneTags argument is true.
    if (pruneTags) {
      const tags = await GitRefManager.listRefs({
        fs,
        gitdir,
        filepath: 'refs/tags',
      });
      await GitRefManager.deleteRefs({
        fs,
        gitdir,
        refs: tags.map(tag => `refs/tags/${tag}`),
      });
    }
    // Add all tags if the fetch tags argument is true.
    if (tags) {
      for (const serverRef of refs.keys()) {
        if (serverRef.startsWith('refs/tags') && !serverRef.endsWith('^{}')) {
          // Git's behavior is to only fetch tags that do not conflict with tags already present.
          if (!(await GitRefManager.exists({ fs, gitdir, ref: serverRef }))) {
            // Always use the object id of the tag itself, and not the peeled object id.
            const oid = refs.get(serverRef);
            actualRefsToWrite.set(serverRef, oid);
          }
        }
      }
    }
    // Combine refs and symrefs giving symrefs priority
    const refTranslations = refspec.translate([...refs.keys()]);
    for (const [serverRef, translatedRef] of refTranslations) {
      const value = refs.get(serverRef);
      actualRefsToWrite.set(translatedRef, value);
    }
    const symrefTranslations = refspec.translate([...symrefs.keys()]);
    for (const [serverRef, translatedRef] of symrefTranslations) {
      const value = symrefs.get(serverRef);
      const symtarget = refspec.translateOne(value);
      if (symtarget) {
        actualRefsToWrite.set(translatedRef, `ref: ${symtarget}`);
      }
    }
    // If `prune` argument is true, clear out the existing local refspec roots
    const pruned = [];
    if (prune) {
      for (const filepath of refspec.localNamespaces()) {
        const refs = (
          await GitRefManager.listRefs({
            fs,
            gitdir,
            filepath,
          })
        ).map(file => `${filepath}/${file}`);
        for (const ref of refs) {
          if (!actualRefsToWrite.has(ref)) {
            pruned.push(ref);
          }
        }
      }
      if (pruned.length > 0) {
        await GitRefManager.deleteRefs({ fs, gitdir, refs: pruned });
      }
    }
    // Update files
    // TODO: For large repos with a history of thousands of pull requests
    // (i.e. gitlab-ce) it would be vastly more efficient to write them
    // to .git/packed-refs.
    // The trick is to make sure we a) don't write a packed ref that is
    // already shadowed by a loose ref and b) don't loose any refs already
    // in packed-refs. Doing this efficiently may be difficult. A
    // solution that might work is
    // a) load the current packed-refs file
    // b) add actualRefsToWrite, overriding the existing values if present
    // c) enumerate all the loose refs currently in .git/refs/remotes/${remote}
    // d) overwrite their value with the new value.
    // Examples of refs we need to avoid writing in loose format for efficieny's sake
    // are .git/refs/remotes/origin/refs/remotes/remote_mirror_3059
    // and .git/refs/remotes/origin/refs/merge-requests
    for (const [key, value] of actualRefsToWrite) {
      await acquireLock(key, async () =>
        fs.write(join(gitdir, key), `${value.trim()}\n`, 'utf8')
      );
    }
    return { pruned }
  }

  /**
   * Writes a ref to the file system.
   *
   * @param {Object} args
   * @param {FSClient} args.fs - A file system implementation.
   * @param {string} [args.gitdir] - [required] The [git directory](dir-vs-gitdir.md) path
   * @param {string} args.ref - The ref to write.
   * @param {string} args.value - The object ID to write.
   * @returns {Promise<void>}
   */
  // TODO: make this less crude?
  static async writeRef({ fs, gitdir, ref, value }) {
    // Validate input
    if (!value.match(/[0-9a-f]{40}/)) {
      throw new InvalidOidError(value)
    }
    await acquireLock(ref, async () =>
      fs.write(join(gitdir, ref), `${value.trim()}\n`, 'utf8')
    );
  }

  /**
   * Writes a symbolic ref to the file system.
   *
   * @param {Object} args
   * @param {FSClient} args.fs - A file system implementation.
   * @param {string} [args.gitdir] - [required] The [git directory](dir-vs-gitdir.md) path
   * @param {string} args.ref - The ref to write.
   * @param {string} args.value - The target ref.
   * @returns {Promise<void>}
   */
  static async writeSymbolicRef({ fs, gitdir, ref, value }) {
    await acquireLock(ref, async () =>
      fs.write(join(gitdir, ref), 'ref: ' + `${value.trim()}\n`, 'utf8')
    );
  }

  /**
   * Deletes a single ref.
   *
   * @param {Object} args
   * @param {FSClient} args.fs - A file system implementation.
   * @param {string} [args.gitdir] - [required] The [git directory](dir-vs-gitdir.md) path
   * @param {string} args.ref - The ref to delete.
   * @returns {Promise<void>}
   */
  static async deleteRef({ fs, gitdir, ref }) {
    return GitRefManager.deleteRefs({ fs, gitdir, refs: [ref] })
  }

  /**
   * Deletes multiple refs.
   *
   * @param {Object} args
   * @param {FSClient} args.fs - A file system implementation.
   * @param {string} [args.gitdir] - [required] The [git directory](dir-vs-gitdir.md) path
   * @param {string[]} args.refs - The refs to delete.
   * @returns {Promise<void>}
   */
  static async deleteRefs({ fs, gitdir, refs }) {
    // Delete regular ref
    await Promise.all(refs.map(ref => fs.rm(join(gitdir, ref))));
    // Delete any packed ref
    let text = await acquireLock('packed-refs', async () =>
      fs.read(`${gitdir}/packed-refs`, { encoding: 'utf8' })
    );
    const packed = GitPackedRefs.from(text);
    const beforeSize = packed.refs.size;
    for (const ref of refs) {
      if (packed.refs.has(ref)) {
        packed.delete(ref);
      }
    }
    if (packed.refs.size < beforeSize) {
      text = packed.toString();
      await acquireLock('packed-refs', async () =>
        fs.write(`${gitdir}/packed-refs`, text, { encoding: 'utf8' })
      );
    }
  }

  /**
   * Resolves a ref to its object ID.
   *
   * @param {Object} args
   * @param {FSClient} args.fs - A file system implementation.
   * @param {string} [args.gitdir] - [required] The [git directory](dir-vs-gitdir.md) path
   * @param {string} args.ref - The ref to resolve.
   * @param {number} [args.depth = undefined] - The maximum depth to resolve symbolic refs.
   * @returns {Promise<string>} - The resolved object ID.
   */
  static async resolve({ fs, gitdir, ref, depth = undefined }) {
    if (depth !== undefined) {
      depth--;
      if (depth === -1) {
        return ref
      }
    }

    // Is it a ref pointer?
    if (ref.startsWith('ref: ')) {
      ref = ref.slice('ref: '.length);
      return GitRefManager.resolve({ fs, gitdir, ref, depth })
    }
    // Is it a complete and valid SHA?
    if (ref.length === 40 && /[0-9a-f]{40}/.test(ref)) {
      return ref
    }
    // We need to alternate between the file system and the packed-refs
    const packedMap = await GitRefManager.packedRefs({ fs, gitdir });
    // Look in all the proper paths, in this order
    const allpaths = refpaths(ref).filter(p => !GIT_FILES.includes(p)); // exclude git system files (#709)

    for (const ref of allpaths) {
      const sha = await acquireLock(
        ref,
        async () =>
          (await fs.read(`${gitdir}/${ref}`, { encoding: 'utf8' })) ||
          packedMap.get(ref)
      );
      if (sha) {
        return GitRefManager.resolve({ fs, gitdir, ref: sha.trim(), depth })
      }
    }
    // Do we give up?
    throw new NotFoundError(ref)
  }

  /**
   * Checks if a ref exists.
   *
   * @param {Object} args
   * @param {FSClient} args.fs - A file system implementation.
   * @param {string} [args.gitdir=join(dir, '.git')] - [required] The [git directory](dir-vs-gitdir.md) path
   * @param {string} args.ref - The ref to check.
   * @returns {Promise<boolean>} - True if the ref exists, false otherwise.
   */
  static async exists({ fs, gitdir, ref }) {
    try {
      await GitRefManager.expand({ fs, gitdir, ref });
      return true
    } catch (err) {
      return false
    }
  }

  /**
   * Expands a ref to its full name.
   *
   * @param {Object} args
   * @param {FSClient} args.fs - A file system implementation.
   * @param {string} [args.gitdir=join(dir, '.git')] - [required] The [git directory](dir-vs-gitdir.md) path
   * @param {string} args.ref - The ref to expand.
   * @returns {Promise<string>} - The full ref name.
   */
  static async expand({ fs, gitdir, ref }) {
    // Is it a complete and valid SHA?
    if (ref.length === 40 && /[0-9a-f]{40}/.test(ref)) {
      return ref
    }
    // We need to alternate between the file system and the packed-refs
    const packedMap = await GitRefManager.packedRefs({ fs, gitdir });
    // Look in all the proper paths, in this order
    const allpaths = refpaths(ref);
    for (const ref of allpaths) {
      const refExists = await acquireLock(ref, async () =>
        fs.exists(`${gitdir}/${ref}`)
      );
      if (refExists) return ref
      if (packedMap.has(ref)) return ref
    }
    // Do we give up?
    throw new NotFoundError(ref)
  }

  /**
   * Expands a ref against a provided map.
   *
   * @param {Object} args
   * @param {string} args.ref - The ref to expand.
   * @param {Map<string, string>} args.map - The map of refs.
   * @returns {Promise<string>} - The expanded ref.
   */
  static async expandAgainstMap({ ref, map }) {
    // Look in all the proper paths, in this order
    const allpaths = refpaths(ref);
    for (const ref of allpaths) {
      if (await map.has(ref)) return ref
    }
    // Do we give up?
    throw new NotFoundError(ref)
  }

  /**
   * Resolves a ref against a provided map.
   *
   * @param {Object} args
   * @param {string} args.ref - The ref to resolve.
   * @param {string} [args.fullref = args.ref] - The full ref name.
   * @param {number} [args.depth = undefined] - The maximum depth to resolve symbolic refs.
   * @param {Map<string, string>} args.map - The map of refs.
   * @returns {Object} - An object containing the full ref and its object ID.
   */
  static resolveAgainstMap({ ref, fullref = ref, depth = undefined, map }) {
    if (depth !== undefined) {
      depth--;
      if (depth === -1) {
        return { fullref, oid: ref }
      }
    }
    // Is it a ref pointer?
    if (ref.startsWith('ref: ')) {
      ref = ref.slice('ref: '.length);
      return GitRefManager.resolveAgainstMap({ ref, fullref, depth, map })
    }
    // Is it a complete and valid SHA?
    if (ref.length === 40 && /[0-9a-f]{40}/.test(ref)) {
      return { fullref, oid: ref }
    }
    // Look in all the proper paths, in this order
    const allpaths = refpaths(ref);
    for (const ref of allpaths) {
      const sha = map.get(ref);
      if (sha) {
        return GitRefManager.resolveAgainstMap({
          ref: sha.trim(),
          fullref: ref,
          depth,
          map,
        })
      }
    }
    // Do we give up?
    throw new NotFoundError(ref)
  }

  /**
   * Reads the packed refs file and returns a map of refs.
   *
   * @param {Object} args
   * @param {FSClient} args.fs - A file system implementation.
   * @param {string} [args.gitdir=join(dir, '.git')] - [required] The [git directory](dir-vs-gitdir.md) path
   * @returns {Promise<Map<string, string>>} - A map of packed refs.
   */
  static async packedRefs({ fs, gitdir }) {
    const text = await acquireLock('packed-refs', async () =>
      fs.read(`${gitdir}/packed-refs`, { encoding: 'utf8' })
    );
    const packed = GitPackedRefs.from(text);
    return packed.refs
  }

  /**
   * Lists all refs matching a given filepath prefix.
   *
   * @param {Object} args
   * @param {FSClient} args.fs - A file system implementation.
   * @param {string} [args.gitdir=join(dir, '.git')] - [required] The [git directory](dir-vs-gitdir.md) path
   * @param {string} args.filepath - The filepath prefix to match.
   * @returns {Promise<string[]>} - A sorted list of refs.
   */
  static async listRefs({ fs, gitdir, filepath }) {
    const packedMap = GitRefManager.packedRefs({ fs, gitdir });
    let files = null;
    try {
      files = await fs.readdirDeep(`${gitdir}/${filepath}`);
      files = files.map(x => x.replace(`${gitdir}/${filepath}/`, ''));
    } catch (err) {
      files = [];
    }

    for (let key of (await packedMap).keys()) {
      // filter by prefix
      if (key.startsWith(filepath)) {
        // remove prefix
        key = key.replace(filepath + '/', '');
        // Don't include duplicates; the loose files have precedence anyway
        if (!files.includes(key)) {
          files.push(key);
        }
      }
    }
    // since we just appended things onto an array, we need to sort them now
    files.sort(compareRefNames);
    return files
  }

  /**
   * Lists all branches, optionally filtered by remote.
   *
   * @param {Object} args
   * @param {FSClient} args.fs - A file system implementation.
   * @param {string} [args.gitdir=join(dir, '.git')] - [required] The [git directory](dir-vs-gitdir.md) path
   * @param {string} [args.remote] - The remote to filter branches by.
   * @returns {Promise<string[]>} - A list of branch names.
   */
  static async listBranches({ fs, gitdir, remote }) {
    if (remote) {
      return GitRefManager.listRefs({
        fs,
        gitdir,
        filepath: `refs/remotes/${remote}`,
      })
    } else {
      return GitRefManager.listRefs({ fs, gitdir, filepath: `refs/heads` })
    }
  }

  /**
   * Lists all tags.
   *
   * @param {Object} args
   * @param {FSClient} args.fs - A file system implementation.
   * @param {string} [args.gitdir=join(dir, '.git')] - [required] The [git directory](dir-vs-gitdir.md) path
   * @returns {Promise<string[]>} - A list of tag names.
   */
  static async listTags({ fs, gitdir }) {
    const tags = await GitRefManager.listRefs({
      fs,
      gitdir,
      filepath: `refs/tags`,
    });
    return tags.filter(x => !x.endsWith('^{}'))
  }
}

class HttpError extends BaseError {
  /**
   * @param {number} statusCode
   * @param {string} statusMessage
   * @param {string} response
   */
  constructor(statusCode, statusMessage, response) {
    super(`HTTP Error: ${statusCode} ${statusMessage}`);
    this.code = this.name = HttpError.code;
    this.data = { statusCode, statusMessage, response };
  }
}
/** @type {'HttpError'} */
HttpError.code = 'HttpError';

class SmartHttpError extends BaseError {
  /**
   * @param {string} preview
   * @param {string} response
   */
  constructor(preview, response) {
    super(
      `Remote did not reply using the "smart" HTTP protocol. Expected "001e# service=git-upload-pack" but received: ${preview}`
    );
    this.code = this.name = SmartHttpError.code;
    this.data = { preview, response };
  }
}
/** @type {'SmartHttpError'} */
SmartHttpError.code = 'SmartHttpError';

class UserCanceledError extends BaseError {
  constructor() {
    super(`The operation was canceled.`);
    this.code = this.name = UserCanceledError.code;
    this.data = {};
  }
}
/** @type {'UserCanceledError'} */
UserCanceledError.code = 'UserCanceledError';

function calculateBasicAuthHeader({ username = '', password = '' }) {
  return `Basic ${Buffer.from(`${username}:${password}`).toString('base64')}`
}

// Convert a value to an Async Iterator
// This will be easier with async generator functions.
function fromValue(value) {
  let queue = [value];
  return {
    next() {
      return Promise.resolve({ done: queue.length === 0, value: queue.pop() })
    },
    return() {
      queue = [];
      return {}
    },
    [Symbol.asyncIterator]() {
      return this
    },
  }
}

function getIterator(iterable) {
  if (iterable[Symbol.asyncIterator]) {
    return iterable[Symbol.asyncIterator]()
  }
  if (iterable[Symbol.iterator]) {
    return iterable[Symbol.iterator]()
  }
  if (iterable.next) {
    return iterable
  }
  return fromValue(iterable)
}

// Currently 'for await' upsets my linters.
async function forAwait(iterable, cb) {
  const iter = getIterator(iterable);
  while (true) {
    const { value, done } = await iter.next();
    if (value) await cb(value);
    if (done) break
  }
  if (iter.return) iter.return();
}

async function collect(iterable) {
  let size = 0;
  const buffers = [];
  // This will be easier once `for await ... of` loops are available.
  await forAwait(iterable, value => {
    buffers.push(value);
    size += value.byteLength;
  });
  const result = new Uint8Array(size);
  let nextIndex = 0;
  for (const buffer of buffers) {
    result.set(buffer, nextIndex);
    nextIndex += buffer.byteLength;
  }
  return result
}

function extractAuthFromUrl(url) {
  // For whatever reason, the `fetch` API does not convert credentials embedded in the URL
  // into Basic Authentication headers automatically. Instead it throws an error!
  // So we must manually parse the URL, rip out the user:password portion if it is present
  // and compute the Authorization header.
  // Note: I tried using new URL(url) but that throws a security exception in Edge. :rolleyes:
  let userpass = url.match(/^https?:\/\/([^/]+)@/);
  // No credentials, return the url unmodified and an empty auth object
  if (userpass == null) return { url, auth: {} }
  userpass = userpass[1];
  const [username, password] = userpass.split(':');
  // Remove credentials from URL
  url = url.replace(`${userpass}@`, '');
  // Has credentials, return the fetch-safe URL and the parsed credentials
  return { url, auth: { username, password } }
}

class EmptyServerResponseError extends BaseError {
  constructor() {
    super(`Empty response from git server.`);
    this.code = this.name = EmptyServerResponseError.code;
    this.data = {};
  }
}
/** @type {'EmptyServerResponseError'} */
EmptyServerResponseError.code = 'EmptyServerResponseError';

class ParseError extends BaseError {
  /**
   * @param {string} expected
   * @param {string} actual
   */
  constructor(expected, actual) {
    super(`Expected "${expected}" but received "${actual}".`);
    this.code = this.name = ParseError.code;
    this.data = { expected, actual };
  }
}
/** @type {'ParseError'} */
ParseError.code = 'ParseError';

// inspired by 'gartal' but lighter-weight and more battle-tested.
class StreamReader {
  constructor(stream) {
    // TODO: fix usage in bundlers before Buffer dependency is removed #1855
    if (typeof Buffer === 'undefined') {
      throw new Error('Missing Buffer dependency')
    }
    this.stream = getIterator(stream);
    this.buffer = null;
    this.cursor = 0;
    this.undoCursor = 0;
    this.started = false;
    this._ended = false;
    this._discardedBytes = 0;
  }

  eof() {
    return this._ended && this.cursor === this.buffer.length
  }

  tell() {
    return this._discardedBytes + this.cursor
  }

  async byte() {
    if (this.eof()) return
    if (!this.started) await this._init();
    if (this.cursor === this.buffer.length) {
      await this._loadnext();
      if (this._ended) return
    }
    this._moveCursor(1);
    return this.buffer[this.undoCursor]
  }

  async chunk() {
    if (this.eof()) return
    if (!this.started) await this._init();
    if (this.cursor === this.buffer.length) {
      await this._loadnext();
      if (this._ended) return
    }
    this._moveCursor(this.buffer.length);
    return this.buffer.slice(this.undoCursor, this.cursor)
  }

  async read(n) {
    if (this.eof()) return
    if (!this.started) await this._init();
    if (this.cursor + n > this.buffer.length) {
      this._trim();
      await this._accumulate(n);
    }
    this._moveCursor(n);
    return this.buffer.slice(this.undoCursor, this.cursor)
  }

  async skip(n) {
    if (this.eof()) return
    if (!this.started) await this._init();
    if (this.cursor + n > this.buffer.length) {
      this._trim();
      await this._accumulate(n);
    }
    this._moveCursor(n);
  }

  async undo() {
    this.cursor = this.undoCursor;
  }

  async _next() {
    this.started = true;
    let { done, value } = await this.stream.next();
    if (done) {
      this._ended = true;
      if (!value) return Buffer.alloc(0)
    }
    if (value) {
      value = Buffer.from(value);
    }
    return value
  }

  _trim() {
    // Throw away parts of the buffer we don't need anymore
    // assert(this.cursor <= this.buffer.length)
    this.buffer = this.buffer.slice(this.undoCursor);
    this.cursor -= this.undoCursor;
    this._discardedBytes += this.undoCursor;
    this.undoCursor = 0;
  }

  _moveCursor(n) {
    this.undoCursor = this.cursor;
    this.cursor += n;
    if (this.cursor > this.buffer.length) {
      this.cursor = this.buffer.length;
    }
  }

  async _accumulate(n) {
    if (this._ended) return
    // Expand the buffer until we have N bytes of data
    // or we've reached the end of the stream
    const buffers = [this.buffer];
    while (this.cursor + n > lengthBuffers(buffers)) {
      const nextbuffer = await this._next();
      if (this._ended) break
      buffers.push(nextbuffer);
    }
    this.buffer = Buffer.concat(buffers);
  }

  async _loadnext() {
    this._discardedBytes += this.buffer.length;
    this.undoCursor = 0;
    this.cursor = 0;
    this.buffer = await this._next();
  }

  async _init() {
    this.buffer = await this._next();
  }
}

// This helper function helps us postpone concatenating buffers, which
// would create intermediate buffer objects,
function lengthBuffers(buffers) {
  return buffers.reduce((acc, buffer) => acc + buffer.length, 0)
}

function padHex(b, n) {
  const s = n.toString(16);
  return '0'.repeat(b - s.length) + s
}

/**
pkt-line Format
---------------

Much (but not all) of the payload is described around pkt-lines.

A pkt-line is a variable length binary string.  The first four bytes
of the line, the pkt-len, indicates the total length of the line,
in hexadecimal.  The pkt-len includes the 4 bytes used to contain
the length's hexadecimal representation.

A pkt-line MAY contain binary data, so implementers MUST ensure
pkt-line parsing/formatting routines are 8-bit clean.

A non-binary line SHOULD BE terminated by an LF, which if present
MUST be included in the total length. Receivers MUST treat pkt-lines
with non-binary data the same whether or not they contain the trailing
LF (stripping the LF if present, and not complaining when it is
missing).

The maximum length of a pkt-line's data component is 65516 bytes.
Implementations MUST NOT send pkt-line whose length exceeds 65520
(65516 bytes of payload + 4 bytes of length data).

Implementations SHOULD NOT send an empty pkt-line ("0004").

A pkt-line with a length field of 0 ("0000"), called a flush-pkt,
is a special case and MUST be handled differently than an empty
pkt-line ("0004").

----
  pkt-line     =  data-pkt / flush-pkt

  data-pkt     =  pkt-len pkt-payload
  pkt-len      =  4*(HEXDIG)
  pkt-payload  =  (pkt-len - 4)*(OCTET)

  flush-pkt    = "0000"
----

Examples (as C-style strings):

----
  pkt-line          actual value
  ---------------------------------
  "0006a\n"         "a\n"
  "0005a"           "a"
  "000bfoobar\n"    "foobar\n"
  "0004"            ""
----
*/

// I'm really using this more as a namespace.
// There's not a lot of "state" in a pkt-line

class GitPktLine {
  static flush() {
    return Buffer.from('0000', 'utf8')
  }

  static delim() {
    return Buffer.from('0001', 'utf8')
  }

  static encode(line) {
    if (typeof line === 'string') {
      line = Buffer.from(line);
    }
    const length = line.length + 4;
    const hexlength = padHex(4, length);
    return Buffer.concat([Buffer.from(hexlength, 'utf8'), line])
  }

  static streamReader(stream) {
    const reader = new StreamReader(stream);
    return async function read() {
      try {
        let length = await reader.read(4);
        if (length == null) return true
        length = parseInt(length.toString('utf8'), 16);
        if (length === 0) return null
        if (length === 1) return null // delim packets
        const buffer = await reader.read(length - 4);
        if (buffer == null) return true
        return buffer
      } catch (err) {
        stream.error = err;
        return true
      }
    }
  }
}

// @ts-check

/**
 * @param {function} read
 */
async function parseCapabilitiesV2(read) {
  /** @type {Object<string, string | true>} */
  const capabilities2 = {};

  let line;
  while (true) {
    line = await read();
    if (line === true) break
    if (line === null) continue
    line = line.toString('utf8').replace(/\n$/, '');
    const i = line.indexOf('=');
    if (i > -1) {
      const key = line.slice(0, i);
      const value = line.slice(i + 1);
      capabilities2[key] = value;
    } else {
      capabilities2[line] = true;
    }
  }
  return { protocolVersion: 2, capabilities2 }
}

async function parseRefsAdResponse(stream, { service }) {
  const capabilities = new Set();
  const refs = new Map();
  const symrefs = new Map();

  // There is probably a better way to do this, but for now
  // let's just throw the result parser inline here.
  const read = GitPktLine.streamReader(stream);
  let lineOne = await read();
  // skip past any flushes
  while (lineOne === null) lineOne = await read();

  if (lineOne === true) throw new EmptyServerResponseError()

  // Handle protocol v2 responses (Bitbucket Server doesn't include a `# service=` line)
  if (lineOne.includes('version 2')) {
    return parseCapabilitiesV2(read)
  }

  // Clients MUST ignore an LF at the end of the line.
  if (lineOne.toString('utf8').replace(/\n$/, '') !== `# service=${service}`) {
    throw new ParseError(`# service=${service}\\n`, lineOne.toString('utf8'))
  }
  let lineTwo = await read();
  // skip past any flushes
  while (lineTwo === null) lineTwo = await read();
  // In the edge case of a brand new repo, zero refs (and zero capabilities)
  // are returned.
  if (lineTwo === true) return { capabilities, refs, symrefs }
  lineTwo = lineTwo.toString('utf8');

  // Handle protocol v2 responses
  if (lineTwo.includes('version 2')) {
    return parseCapabilitiesV2(read)
  }

  const [firstRef, capabilitiesLine] = splitAndAssert(lineTwo, '\x00', '\\x00');
  capabilitiesLine.split(' ').map(x => capabilities.add(x));
  // see no-refs in https://git-scm.com/docs/pack-protocol#_reference_discovery (since git 2.41.0)
  if (firstRef !== '0000000000000000000000000000000000000000 capabilities^{}') {
    const [ref, name] = splitAndAssert(firstRef, ' ', ' ');
    refs.set(name, ref);
    while (true) {
      const line = await read();
      if (line === true) break
      if (line !== null) {
        const [ref, name] = splitAndAssert(line.toString('utf8'), ' ', ' ');
        refs.set(name, ref);
      }
    }
  }
  // Symrefs are thrown into the "capabilities" unfortunately.
  for (const cap of capabilities) {
    if (cap.startsWith('symref=')) {
      const m = cap.match(/symref=([^:]+):(.*)/);
      if (m.length === 3) {
        symrefs.set(m[1], m[2]);
      }
    }
  }
  return { protocolVersion: 1, capabilities, refs, symrefs }
}

function splitAndAssert(line, sep, expected) {
  const split = line.trim().split(sep);
  if (split.length !== 2) {
    throw new ParseError(
      `Two strings separated by '${expected}'`,
      line.toString('utf8')
    )
  }
  return split
}

// Try to accommodate known CORS proxy implementations:
// - https://jcubic.pl/proxy.php?  <-- uses query string
// - https://cors.isomorphic-git.org  <-- uses path
const corsProxify = (corsProxy, url) =>
  corsProxy.endsWith('?')
    ? `${corsProxy}${url}`
    : `${corsProxy}/${url.replace(/^https?:\/\//, '')}`;

const updateHeaders = (headers, auth) => {
  // Update the basic auth header
  if (auth.username || auth.password) {
    headers.Authorization = calculateBasicAuthHeader(auth);
  }
  // but any manually provided headers take precedence
  if (auth.headers) {
    Object.assign(headers, auth.headers);
  }
};

/**
 * @param {GitHttpResponse} res
 *
 * @returns {{ preview: string, response: string, data: Buffer }}
 */
const stringifyBody = async res => {
  try {
    // Some services provide a meaningful error message in the body of 403s like "token lacks the scopes necessary to perform this action"
    const data = Buffer.from(await collect(res.body));
    const response = data.toString('utf8');
    const preview =
      response.length < 256 ? response : response.slice(0, 256) + '...';
    return { preview, response, data }
  } catch (e) {
    return {}
  }
};

class GitRemoteHTTP {
  /**
   * Returns the capabilities of the GitRemoteHTTP class.
   *
   * @returns {Promise<string[]>} - An array of supported capabilities.
   */
  static async capabilities() {
    return ['discover', 'connect']
  }

  /**
   * Discovers references from a remote Git repository.
   *
   * @param {Object} args
   * @param {HttpClient} args.http - The HTTP client to use for requests.
   * @param {ProgressCallback} [args.onProgress] - Callback for progress updates.
   * @param {AuthCallback} [args.onAuth] - Callback for providing authentication credentials.
   * @param {AuthFailureCallback} [args.onAuthFailure] - Callback for handling authentication failures.
   * @param {AuthSuccessCallback} [args.onAuthSuccess] - Callback for handling successful authentication.
   * @param {string} [args.corsProxy] - Optional CORS proxy URL.
   * @param {string} args.service - The Git service (e.g., "git-upload-pack").
   * @param {string} args.url - The URL of the remote repository.
   * @param {Object<string, string>} args.headers - HTTP headers to include in the request.
   * @param {1 | 2} args.protocolVersion - The Git protocol version to use.
   * @returns {Promise<Object>} - The parsed response from the remote repository.
   * @throws {HttpError} - If the HTTP request fails.
   * @throws {SmartHttpError} - If the response cannot be parsed.
   * @throws {UserCanceledError} - If the user cancels the operation.
   */
  static async discover({
    http,
    onProgress,
    onAuth,
    onAuthSuccess,
    onAuthFailure,
    corsProxy,
    service,
    url: _origUrl,
    headers,
    protocolVersion,
  }) {
    let { url, auth } = extractAuthFromUrl(_origUrl);
    const proxifiedURL = corsProxy ? corsProxify(corsProxy, url) : url;
    if (auth.username || auth.password) {
      headers.Authorization = calculateBasicAuthHeader(auth);
    }
    if (protocolVersion === 2) {
      headers['Git-Protocol'] = 'version=2';
    }

    let res;
    let tryAgain;
    let providedAuthBefore = false;
    do {
      res = await http.request({
        onProgress,
        method: 'GET',
        url: `${proxifiedURL}/info/refs?service=${service}`,
        headers,
      });

      // the default loop behavior
      tryAgain = false;

      // 401 is the "correct" response for access denied. 203 is Non-Authoritative Information and comes from Azure DevOps, which
      // apparently doesn't realize this is a git request and is returning the HTML for the "Azure DevOps Services | Sign In" page.
      if (res.statusCode === 401 || res.statusCode === 203) {
        // On subsequent 401s, call `onAuthFailure` instead of `onAuth`.
        // This is so that naive `onAuth` callbacks that return a fixed value don't create an infinite loop of retrying.
        const getAuth = providedAuthBefore ? onAuthFailure : onAuth;
        if (getAuth) {
          // Acquire credentials and try again
          // TODO: read `useHttpPath` value from git config and pass along?
          auth = await getAuth(url, {
            ...auth,
            headers: { ...headers },
          });
          if (auth && auth.cancel) {
            throw new UserCanceledError()
          } else if (auth) {
            updateHeaders(headers, auth);
            providedAuthBefore = true;
            tryAgain = true;
          }
        }
      } else if (
        res.statusCode === 200 &&
        providedAuthBefore &&
        onAuthSuccess
      ) {
        await onAuthSuccess(url, auth);
      }
    } while (tryAgain)

    if (res.statusCode !== 200) {
      const { response } = await stringifyBody(res);
      throw new HttpError(res.statusCode, res.statusMessage, response)
    }
    // Git "smart" HTTP servers should respond with the correct Content-Type header.
    if (
      res.headers['content-type'] === `application/x-${service}-advertisement`
    ) {
      const remoteHTTP = await parseRefsAdResponse(res.body, { service });
      remoteHTTP.auth = auth;
      return remoteHTTP
    } else {
      // If they don't send the correct content-type header, that's a good indicator it is either a "dumb" HTTP
      // server, or the user specified an incorrect remote URL and the response is actually an HTML page.
      // In this case, we save the response as plain text so we can generate a better error message if needed.
      const { preview, response, data } = await stringifyBody(res);
      // For backwards compatibility, try to parse it anyway.
      // TODO: maybe just throw instead of trying?
      try {
        const remoteHTTP = await parseRefsAdResponse([data], { service });
        remoteHTTP.auth = auth;
        return remoteHTTP
      } catch (e) {
        throw new SmartHttpError(preview, response)
      }
    }
  }

  /**
   * Connects to a remote Git repository and sends a request.
   *
   * @param {Object} args
   * @param {HttpClient} args.http - The HTTP client to use for requests.
   * @param {ProgressCallback} [args.onProgress] - Callback for progress updates.
   * @param {string} [args.corsProxy] - Optional CORS proxy URL.
   * @param {string} args.service - The Git service (e.g., "git-upload-pack").
   * @param {string} args.url - The URL of the remote repository.
   * @param {Object<string, string>} [args.headers] - HTTP headers to include in the request.
   * @param {any} args.body - The request body to send.
   * @param {any} args.auth - Authentication credentials.
   * @returns {Promise<GitHttpResponse>} - The HTTP response from the remote repository.
   * @throws {HttpError} - If the HTTP request fails.
   */
  static async connect({
    http,
    onProgress,
    corsProxy,
    service,
    url,
    auth,
    body,
    headers,
  }) {
    // We already have the "correct" auth value at this point, but
    // we need to strip out the username/password from the URL yet again.
    const urlAuth = extractAuthFromUrl(url);
    if (urlAuth) url = urlAuth.url;

    if (corsProxy) url = corsProxify(corsProxy, url);

    headers['content-type'] = `application/x-${service}-request`;
    headers.accept = `application/x-${service}-result`;
    updateHeaders(headers, auth);

    const res = await http.request({
      onProgress,
      method: 'POST',
      url: `${url}/${service}`,
      body,
      headers,
    });
    if (res.statusCode !== 200) {
      const { response } = stringifyBody(res);
      throw new HttpError(res.statusCode, res.statusMessage, response)
    }
    return res
  }
}

class UnknownTransportError extends BaseError {
  /**
   * @param {string} url
   * @param {string} transport
   * @param {string} [suggestion]
   */
  constructor(url, transport, suggestion) {
    super(
      `Git remote "${url}" uses an unrecognized transport protocol: "${transport}"`
    );
    this.code = this.name = UnknownTransportError.code;
    this.data = { url, transport, suggestion };
  }
}
/** @type {'UnknownTransportError'} */
UnknownTransportError.code = 'UnknownTransportError';

class UrlParseError extends BaseError {
  /**
   * @param {string} url
   */
  constructor(url) {
    super(`Cannot parse remote URL: "${url}"`);
    this.code = this.name = UrlParseError.code;
    this.data = { url };
  }
}
/** @type {'UrlParseError'} */
UrlParseError.code = 'UrlParseError';

function translateSSHtoHTTP(url) {
  // handle "shorter scp-like syntax"
  url = url.replace(/^git@([^:]+):/, 'https://$1/');
  // handle proper SSH URLs
  url = url.replace(/^ssh:\/\//, 'https://');
  return url
}

/**
 * A class for managing Git remotes and determining the appropriate remote helper for a given URL.
 */
class GitRemoteManager {
  /**
   * Determines the appropriate remote helper for the given URL.
   *
   * @param {Object} args
   * @param {string} args.url - The URL of the remote repository.
   * @returns {Object} - The remote helper class for the specified transport.
   * @throws {UrlParseError} - If the URL cannot be parsed.
   * @throws {UnknownTransportError} - If the transport is not supported.
   */
  static getRemoteHelperFor({ url }) {
    // TODO: clean up the remoteHelper API and move into PluginCore
    const remoteHelpers = new Map();
    remoteHelpers.set('http', GitRemoteHTTP);
    remoteHelpers.set('https', GitRemoteHTTP);

    const parts = parseRemoteUrl({ url });
    if (!parts) {
      throw new UrlParseError(url)
    }
    if (remoteHelpers.has(parts.transport)) {
      return remoteHelpers.get(parts.transport)
    }
    throw new UnknownTransportError(
      url,
      parts.transport,
      parts.transport === 'ssh' ? translateSSHtoHTTP(url) : undefined
    )
  }
}

/**
 * Parses a remote URL and extracts its transport and address.
 *
 * @param {Object} args
 * @param {string} args.url - The URL of the remote repository.
 * @returns {Object|undefined} - An object containing the transport and address, or undefined if parsing fails.
 */
function parseRemoteUrl({ url }) {
  // the stupid "shorter scp-like syntax"
  if (url.startsWith('git@')) {
    return {
      transport: 'ssh',
      address: url,
    }
  }
  const matches = url.match(/(\w+)(:\/\/|::)(.*)/);
  if (matches === null) return
  /*
   * When git encounters a URL of the form <transport>://<address>, where <transport> is
   * a protocol that it cannot handle natively, it automatically invokes git remote-<transport>
   * with the full URL as the second argument.
   *
   * @see https://git-scm.com/docs/git-remote-helpers
   */
  if (matches[2] === '://') {
    return {
      transport: matches[1],
      address: matches[0],
    }
  }
  /*
   * A URL of the form <transport>::<address> explicitly instructs git to invoke
   * git remote-<transport> with <address> as the second argument.
   *
   * @see https://git-scm.com/docs/git-remote-helpers
   */
  if (matches[2] === '::') {
    return {
      transport: matches[1],
      address: matches[3],
    }
  }
}

let lock$2 = null;

class GitShallowManager {
  /**
   * Reads the `shallow` file in the Git repository and returns a set of object IDs (OIDs).
   *
   * @param {Object} args
   * @param {FSClient} args.fs - A file system implementation.
   * @param {string} [args.gitdir] - [required] The [git directory](dir-vs-gitdir.md) path
   * @returns {Promise<Set<string>>} - A set of shallow object IDs.
   */
  static async read({ fs, gitdir }) {
    if (lock$2 === null) lock$2 = new AsyncLock();
    const filepath = join(gitdir, 'shallow');
    const oids = new Set();
    await lock$2.acquire(filepath, async function () {
      const text = await fs.read(filepath, { encoding: 'utf8' });
      if (text === null) return oids // no file
      if (text.trim() === '') return oids // empty file
      text
        .trim()
        .split('\n')
        .map(oid => oids.add(oid));
    });
    return oids
  }

  /**
   * Writes a set of object IDs (OIDs) to the `shallow` file in the Git repository.
   * If the set is empty, the `shallow` file is removed.
   *
   * @param {Object} args
   * @param {FSClient} args.fs - A file system implementation.
   * @param {string} [args.gitdir] - [required] The [git directory](dir-vs-gitdir.md) path
   * @param {Set<string>} args.oids - A set of shallow object IDs to write.
   * @returns {Promise<void>}
   */
  static async write({ fs, gitdir, oids }) {
    if (lock$2 === null) lock$2 = new AsyncLock();
    const filepath = join(gitdir, 'shallow');
    if (oids.size > 0) {
      const text = [...oids].join('\n') + '\n';
      await lock$2.acquire(filepath, async function () {
        await fs.write(filepath, text, {
          encoding: 'utf8',
        });
      });
    } else {
      // No shallows
      await lock$2.acquire(filepath, async function () {
        await fs.rm(filepath);
      });
    }
  }
}

class ObjectTypeError extends BaseError {
  /**
   * @param {string} oid
   * @param {'blob'|'commit'|'tag'|'tree'} actual
   * @param {'blob'|'commit'|'tag'|'tree'} expected
   * @param {string} [filepath]
   */
  constructor(oid, actual, expected, filepath) {
    super(
      `Object ${oid} ${
        filepath ? `at ${filepath}` : ''
      }was anticipated to be a ${expected} but it is a ${actual}.`
    );
    this.code = this.name = ObjectTypeError.code;
    this.data = { oid, actual, expected, filepath };
  }
}
/** @type {'ObjectTypeError'} */
ObjectTypeError.code = 'ObjectTypeError';

function formatAuthor({ name, email, timestamp, timezoneOffset }) {
  timezoneOffset = formatTimezoneOffset(timezoneOffset);
  return `${name} <${email}> ${timestamp} ${timezoneOffset}`
}

// The amount of effort that went into crafting these cases to handle
// -0 (just so we don't lose that information when parsing and reconstructing)
// but can also default to +0 was extraordinary.

function formatTimezoneOffset(minutes) {
  const sign = simpleSign(negateExceptForZero(minutes));
  minutes = Math.abs(minutes);
  const hours = Math.floor(minutes / 60);
  minutes -= hours * 60;
  let strHours = String(hours);
  let strMinutes = String(minutes);
  if (strHours.length < 2) strHours = '0' + strHours;
  if (strMinutes.length < 2) strMinutes = '0' + strMinutes;
  return (sign === -1 ? '-' : '+') + strHours + strMinutes
}

function simpleSign(n) {
  return Math.sign(n) || (Object.is(n, -0) ? -1 : 1)
}

function negateExceptForZero(n) {
  return n === 0 ? n : -n
}

function normalizeNewlines(str) {
  // remove all <CR>
  str = str.replace(/\r/g, '');
  // no extra newlines up front
  str = str.replace(/^\n+/, '');
  // and a single newline at the end
  str = str.replace(/\n+$/, '') + '\n';
  return str
}

function parseAuthor(author) {
  const [, name, email, timestamp, offset] = author.match(
    /^(.*) <(.*)> (.*) (.*)$/
  );
  return {
    name,
    email,
    timestamp: Number(timestamp),
    timezoneOffset: parseTimezoneOffset(offset),
  }
}

// The amount of effort that went into crafting these cases to handle
// -0 (just so we don't lose that information when parsing and reconstructing)
// but can also default to +0 was extraordinary.

function parseTimezoneOffset(offset) {
  let [, sign, hours, minutes] = offset.match(/(\+|-)(\d\d)(\d\d)/);
  minutes = (sign === '+' ? 1 : -1) * (Number(hours) * 60 + Number(minutes));
  return negateExceptForZero$1(minutes)
}

function negateExceptForZero$1(n) {
  return n === 0 ? n : -n
}

class GitAnnotatedTag {
  constructor(tag) {
    if (typeof tag === 'string') {
      this._tag = tag;
    } else if (Buffer.isBuffer(tag)) {
      this._tag = tag.toString('utf8');
    } else if (typeof tag === 'object') {
      this._tag = GitAnnotatedTag.render(tag);
    } else {
      throw new InternalError(
        'invalid type passed to GitAnnotatedTag constructor'
      )
    }
  }

  static from(tag) {
    return new GitAnnotatedTag(tag)
  }

  static render(obj) {
    return `object ${obj.object}
type ${obj.type}
tag ${obj.tag}
tagger ${formatAuthor(obj.tagger)}

${obj.message}
${obj.gpgsig ? obj.gpgsig : ''}`
  }

  justHeaders() {
    return this._tag.slice(0, this._tag.indexOf('\n\n'))
  }

  message() {
    const tag = this.withoutSignature();
    return tag.slice(tag.indexOf('\n\n') + 2)
  }

  parse() {
    return Object.assign(this.headers(), {
      message: this.message(),
      gpgsig: this.gpgsig(),
    })
  }

  render() {
    return this._tag
  }

  headers() {
    const headers = this.justHeaders().split('\n');
    const hs = [];
    for (const h of headers) {
      if (h[0] === ' ') {
        // combine with previous header (without space indent)
        hs[hs.length - 1] += '\n' + h.slice(1);
      } else {
        hs.push(h);
      }
    }
    const obj = {};
    for (const h of hs) {
      const key = h.slice(0, h.indexOf(' '));
      const value = h.slice(h.indexOf(' ') + 1);
      if (Array.isArray(obj[key])) {
        obj[key].push(value);
      } else {
        obj[key] = value;
      }
    }
    if (obj.tagger) {
      obj.tagger = parseAuthor(obj.tagger);
    }
    if (obj.committer) {
      obj.committer = parseAuthor(obj.committer);
    }
    return obj
  }

  withoutSignature() {
    const tag = normalizeNewlines(this._tag);
    if (tag.indexOf('\n-----BEGIN PGP SIGNATURE-----') === -1) return tag
    return tag.slice(0, tag.lastIndexOf('\n-----BEGIN PGP SIGNATURE-----'))
  }

  gpgsig() {
    if (this._tag.indexOf('\n-----BEGIN PGP SIGNATURE-----') === -1) return
    const signature = this._tag.slice(
      this._tag.indexOf('-----BEGIN PGP SIGNATURE-----'),
      this._tag.indexOf('-----END PGP SIGNATURE-----') +
        '-----END PGP SIGNATURE-----'.length
    );
    return normalizeNewlines(signature)
  }

  payload() {
    return this.withoutSignature() + '\n'
  }

  toObject() {
    return Buffer.from(this._tag, 'utf8')
  }

  static async sign(tag, sign, secretKey) {
    const payload = tag.payload();
    let { signature } = await sign({ payload, secretKey });
    // renormalize the line endings to the one true line-ending
    signature = normalizeNewlines(signature);
    const signedTag = payload + signature;
    // return a new tag object
    return GitAnnotatedTag.from(signedTag)
  }
}

function indent(str) {
  return (
    str
      .trim()
      .split('\n')
      .map(x => ' ' + x)
      .join('\n') + '\n'
  )
}

function outdent(str) {
  return str
    .split('\n')
    .map(x => x.replace(/^ /, ''))
    .join('\n')
}

class GitCommit {
  constructor(commit) {
    if (typeof commit === 'string') {
      this._commit = commit;
    } else if (Buffer.isBuffer(commit)) {
      this._commit = commit.toString('utf8');
    } else if (typeof commit === 'object') {
      this._commit = GitCommit.render(commit);
    } else {
      throw new InternalError('invalid type passed to GitCommit constructor')
    }
  }

  static fromPayloadSignature({ payload, signature }) {
    const headers = GitCommit.justHeaders(payload);
    const message = GitCommit.justMessage(payload);
    const commit = normalizeNewlines(
      headers + '\ngpgsig' + indent(signature) + '\n' + message
    );
    return new GitCommit(commit)
  }

  static from(commit) {
    return new GitCommit(commit)
  }

  toObject() {
    return Buffer.from(this._commit, 'utf8')
  }

  // Todo: allow setting the headers and message
  headers() {
    return this.parseHeaders()
  }

  // Todo: allow setting the headers and message
  message() {
    return GitCommit.justMessage(this._commit)
  }

  parse() {
    return Object.assign({ message: this.message() }, this.headers())
  }

  static justMessage(commit) {
    return normalizeNewlines(commit.slice(commit.indexOf('\n\n') + 2))
  }

  static justHeaders(commit) {
    return commit.slice(0, commit.indexOf('\n\n'))
  }

  parseHeaders() {
    const headers = GitCommit.justHeaders(this._commit).split('\n');
    const hs = [];
    for (const h of headers) {
      if (h[0] === ' ') {
        // combine with previous header (without space indent)
        hs[hs.length - 1] += '\n' + h.slice(1);
      } else {
        hs.push(h);
      }
    }
    const obj = {
      parent: [],
    };
    for (const h of hs) {
      const key = h.slice(0, h.indexOf(' '));
      const value = h.slice(h.indexOf(' ') + 1);
      if (Array.isArray(obj[key])) {
        obj[key].push(value);
      } else {
        obj[key] = value;
      }
    }
    if (obj.author) {
      obj.author = parseAuthor(obj.author);
    }
    if (obj.committer) {
      obj.committer = parseAuthor(obj.committer);
    }
    return obj
  }

  static renderHeaders(obj) {
    let headers = '';
    if (obj.tree) {
      headers += `tree ${obj.tree}\n`;
    } else {
      headers += `tree 4b825dc642cb6eb9a060e54bf8d69288fbee4904\n`; // the null tree
    }
    if (obj.parent) {
      if (obj.parent.length === undefined) {
        throw new InternalError(`commit 'parent' property should be an array`)
      }
      for (const p of obj.parent) {
        headers += `parent ${p}\n`;
      }
    }
    const author = obj.author;
    headers += `author ${formatAuthor(author)}\n`;
    const committer = obj.committer || obj.author;
    headers += `committer ${formatAuthor(committer)}\n`;
    if (obj.gpgsig) {
      headers += 'gpgsig' + indent(obj.gpgsig);
    }
    return headers
  }

  static render(obj) {
    return GitCommit.renderHeaders(obj) + '\n' + normalizeNewlines(obj.message)
  }

  render() {
    return this._commit
  }

  withoutSignature() {
    const commit = normalizeNewlines(this._commit);
    if (commit.indexOf('\ngpgsig') === -1) return commit
    const headers = commit.slice(0, commit.indexOf('\ngpgsig'));
    const message = commit.slice(
      commit.indexOf('-----END PGP SIGNATURE-----\n') +
        '-----END PGP SIGNATURE-----\n'.length
    );
    return normalizeNewlines(headers + '\n' + message)
  }

  isolateSignature() {
    const signature = this._commit.slice(
      this._commit.indexOf('-----BEGIN PGP SIGNATURE-----'),
      this._commit.indexOf('-----END PGP SIGNATURE-----') +
        '-----END PGP SIGNATURE-----'.length
    );
    return outdent(signature)
  }

  static async sign(commit, sign, secretKey) {
    const payload = commit.withoutSignature();
    const message = GitCommit.justMessage(commit._commit);
    let { signature } = await sign({ payload, secretKey });
    // renormalize the line endings to the one true line-ending
    signature = normalizeNewlines(signature);
    const headers = GitCommit.justHeaders(commit._commit);
    const signedCommit =
      headers + '\n' + 'gpgsig' + indent(signature) + '\n' + message;
    // return a new commit object
    return GitCommit.from(signedCommit)
  }
}

/**
 * Represents a Git object and provides methods to wrap and unwrap Git objects
 * according to the Git object format.
 */
class GitObject {
  /**
   * Wraps a raw object with a Git header.
   *
   * @param {Object} params - The parameters for wrapping.
   * @param {string} params.type - The type of the Git object (e.g., 'blob', 'tree', 'commit').
   * @param {Uint8Array} params.object - The raw object data to wrap.
   * @returns {Uint8Array} The wrapped Git object as a single buffer.
   */
  static wrap({ type, object }) {
    const header = `${type} ${object.length}\x00`;
    const headerLen = header.length;
    const totalLength = headerLen + object.length;

    // Allocate a single buffer for the header and object, rather than create multiple buffers
    const wrappedObject = new Uint8Array(totalLength);
    for (let i = 0; i < headerLen; i++) {
      wrappedObject[i] = header.charCodeAt(i);
    }
    wrappedObject.set(object, headerLen);

    return wrappedObject
  }

  /**
   * Unwraps a Git object buffer into its type and raw object data.
   *
   * @param {Buffer|Uint8Array} buffer - The buffer containing the wrapped Git object.
   * @returns {{ type: string, object: Buffer }} An object containing the type and the raw object data.
   * @throws {InternalError} If the length specified in the header does not match the actual object length.
   */
  static unwrap(buffer) {
    const s = buffer.indexOf(32); // first space
    const i = buffer.indexOf(0); // first null value
    const type = buffer.slice(0, s).toString('utf8'); // get type of object
    const length = buffer.slice(s + 1, i).toString('utf8'); // get type of object
    const actualLength = buffer.length - (i + 1);
    // verify length
    if (parseInt(length) !== actualLength) {
      throw new InternalError(
        `Length mismatch: expected ${length} bytes but got ${actualLength} instead.`
      )
    }
    return {
      type,
      object: Buffer.from(buffer.slice(i + 1)),
    }
  }
}

async function readObjectLoose({ fs, gitdir, oid }) {
  const source = `objects/${oid.slice(0, 2)}/${oid.slice(2)}`;
  const file = await fs.read(`${gitdir}/${source}`);
  if (!file) {
    return null
  }
  return { object: file, format: 'deflated', source }
}

/**
 * @param {Buffer} delta
 * @param {Buffer} source
 * @returns {Buffer}
 */
function applyDelta(delta, source) {
  const reader = new BufferCursor(delta);
  const sourceSize = readVarIntLE(reader);

  if (sourceSize !== source.byteLength) {
    throw new InternalError(
      `applyDelta expected source buffer to be ${sourceSize} bytes but the provided buffer was ${source.length} bytes`
    )
  }
  const targetSize = readVarIntLE(reader);
  let target;

  const firstOp = readOp(reader, source);
  // Speed optimization - return raw buffer if it's just single simple copy
  if (firstOp.byteLength === targetSize) {
    target = firstOp;
  } else {
    // Otherwise, allocate a fresh buffer and slices
    target = Buffer.alloc(targetSize);
    const writer = new BufferCursor(target);
    writer.copy(firstOp);

    while (!reader.eof()) {
      writer.copy(readOp(reader, source));
    }

    const tell = writer.tell();
    if (targetSize !== tell) {
      throw new InternalError(
        `applyDelta expected target buffer to be ${targetSize} bytes but the resulting buffer was ${tell} bytes`
      )
    }
  }
  return target
}

function readVarIntLE(reader) {
  let result = 0;
  let shift = 0;
  let byte = null;
  do {
    byte = reader.readUInt8();
    result |= (byte & 0b01111111) << shift;
    shift += 7;
  } while (byte & 0b10000000)
  return result
}

function readCompactLE(reader, flags, size) {
  let result = 0;
  let shift = 0;
  while (size--) {
    if (flags & 0b00000001) {
      result |= reader.readUInt8() << shift;
    }
    flags >>= 1;
    shift += 8;
  }
  return result
}

function readOp(reader, source) {
  /** @type {number} */
  const byte = reader.readUInt8();
  const COPY = 0b10000000;
  const OFFS = 0b00001111;
  const SIZE = 0b01110000;
  if (byte & COPY) {
    // copy consists of 4 byte offset, 3 byte size (in LE order)
    const offset = readCompactLE(reader, byte & OFFS, 4);
    let size = readCompactLE(reader, (byte & SIZE) >> 4, 3);
    // Yup. They really did this optimization.
    if (size === 0) size = 0x10000;
    return source.slice(offset, offset + size)
  } else {
    // insert
    return reader.slice(byte)
  }
}

// My version of git-list-pack - roughly 15x faster than the original

async function listpack(stream, onData) {
  const reader = new StreamReader(stream);
  let PACK = await reader.read(4);
  PACK = PACK.toString('utf8');
  if (PACK !== 'PACK') {
    throw new InternalError(`Invalid PACK header '${PACK}'`)
  }

  let version = await reader.read(4);
  version = version.readUInt32BE(0);
  if (version !== 2) {
    throw new InternalError(`Invalid packfile version: ${version}`)
  }

  let numObjects = await reader.read(4);
  numObjects = numObjects.readUInt32BE(0);
  // If (for some godforsaken reason) this is an empty packfile, abort now.
  if (numObjects < 1) return

  while (!reader.eof() && numObjects--) {
    const offset = reader.tell();
    const { type, length, ofs, reference } = await parseHeader(reader);
    const inflator = new pako.Inflate();
    while (!inflator.result) {
      const chunk = await reader.chunk();
      if (!chunk) break
      inflator.push(chunk, false);
      if (inflator.err) {
        throw new InternalError(`Pako error: ${inflator.msg}`)
      }
      if (inflator.result) {
        if (inflator.result.length !== length) {
          throw new InternalError(
            `Inflated object size is different from that stated in packfile.`
          )
        }

        // Backtrack parser to where deflated data ends
        await reader.undo();
        await reader.read(chunk.length - inflator.strm.avail_in);
        const end = reader.tell();
        await onData({
          data: inflator.result,
          type,
          num: numObjects,
          offset,
          end,
          reference,
          ofs,
        });
      }
    }
  }
}

async function parseHeader(reader) {
  // Object type is encoded in bits 654
  let byte = await reader.byte();
  const type = (byte >> 4) & 0b111;
  // The length encoding get complicated.
  // Last four bits of length is encoded in bits 3210
  let length = byte & 0b1111;
  // Whether the next byte is part of the variable-length encoded number
  // is encoded in bit 7
  if (byte & 0b10000000) {
    let shift = 4;
    do {
      byte = await reader.byte();
      length |= (byte & 0b01111111) << shift;
      shift += 7;
    } while (byte & 0b10000000)
  }
  // Handle deltified objects
  let ofs;
  let reference;
  if (type === 6) {
    let shift = 0;
    ofs = 0;
    const bytes = [];
    do {
      byte = await reader.byte();
      ofs |= (byte & 0b01111111) << shift;
      shift += 7;
      bytes.push(byte);
    } while (byte & 0b10000000)
    reference = Buffer.from(bytes);
  }
  if (type === 7) {
    const buf = await reader.read(20);
    reference = buf;
  }
  return { type, length, ofs, reference }
}

/* eslint-env node, browser */

let supportsDecompressionStream = false;

async function inflate(buffer) {
  if (supportsDecompressionStream === null) {
    supportsDecompressionStream = testDecompressionStream();
  }
  return supportsDecompressionStream
    ? browserInflate(buffer)
    : pako.inflate(buffer)
}

async function browserInflate(buffer) {
  const ds = new DecompressionStream('deflate');
  const d = new Blob([buffer]).stream().pipeThrough(ds);
  return new Uint8Array(await new Response(d).arrayBuffer())
}

function testDecompressionStream() {
  try {
    const ds = new DecompressionStream('deflate');
    if (ds) return true
  } catch (_) {
    // no bother
  }
  return false
}

function decodeVarInt(reader) {
  const bytes = [];
  let byte = 0;
  let multibyte = 0;
  do {
    byte = reader.readUInt8();
    // We keep bits 6543210
    const lastSeven = byte & 0b01111111;
    bytes.push(lastSeven);
    // Whether the next byte is part of the variable-length encoded number
    // is encoded in bit 7
    multibyte = byte & 0b10000000;
  } while (multibyte)
  // Now that all the bytes are in big-endian order,
  // alternate shifting the bits left by 7 and OR-ing the next byte.
  // And... do a weird increment-by-one thing that I don't quite understand.
  return bytes.reduce((a, b) => ((a + 1) << 7) | b, -1)
}

// I'm pretty much copying this one from the git C source code,
// because it makes no sense.
function otherVarIntDecode(reader, startWith) {
  let result = startWith;
  let shift = 4;
  let byte = null;
  do {
    byte = reader.readUInt8();
    result |= (byte & 0b01111111) << shift;
    shift += 7;
  } while (byte & 0b10000000)
  return result
}

class GitPackIndex {
  constructor(stuff) {
    Object.assign(this, stuff);
    this.offsetCache = {};
  }

  static async fromIdx({ idx, getExternalRefDelta }) {
    const reader = new BufferCursor(idx);
    const magic = reader.slice(4).toString('hex');
    // Check for IDX v2 magic number
    if (magic !== 'ff744f63') {
      return // undefined
    }
    const version = reader.readUInt32BE();
    if (version !== 2) {
      throw new InternalError(
        `Unable to read version ${version} packfile IDX. (Only version 2 supported)`
      )
    }
    if (idx.byteLength > 2048 * 1024 * 1024) {
      throw new InternalError(
        `To keep implementation simple, I haven't implemented the layer 5 feature needed to support packfiles > 2GB in size.`
      )
    }
    // Skip over fanout table
    reader.seek(reader.tell() + 4 * 255);
    // Get hashes
    const size = reader.readUInt32BE();
    const hashes = [];
    for (let i = 0; i < size; i++) {
      const hash = reader.slice(20).toString('hex');
      hashes[i] = hash;
    }
    reader.seek(reader.tell() + 4 * size);
    // Skip over CRCs
    // Get offsets
    const offsets = new Map();
    for (let i = 0; i < size; i++) {
      offsets.set(hashes[i], reader.readUInt32BE());
    }
    const packfileSha = reader.slice(20).toString('hex');
    return new GitPackIndex({
      hashes,
      crcs: {},
      offsets,
      packfileSha,
      getExternalRefDelta,
    })
  }

  static async fromPack({ pack, getExternalRefDelta, onProgress }) {
    const listpackTypes = {
      1: 'commit',
      2: 'tree',
      3: 'blob',
      4: 'tag',
      6: 'ofs-delta',
      7: 'ref-delta',
    };
    const offsetToObject = {};

    // Older packfiles do NOT use the shasum of the pack itself,
    // so it is recommended to just use whatever bytes are in the trailer.
    // Source: https://github.com/git/git/commit/1190a1acf800acdcfd7569f87ac1560e2d077414
    const packfileSha = pack.slice(-20).toString('hex');

    const hashes = [];
    const crcs = {};
    const offsets = new Map();
    let totalObjectCount = null;
    let lastPercent = null;

    await listpack([pack], async ({ data, type, reference, offset, num }) => {
      if (totalObjectCount === null) totalObjectCount = num;
      const percent = Math.floor(
        ((totalObjectCount - num) * 100) / totalObjectCount
      );
      if (percent !== lastPercent) {
        if (onProgress) {
          await onProgress({
            phase: 'Receiving objects',
            loaded: totalObjectCount - num,
            total: totalObjectCount,
          });
        }
      }
      lastPercent = percent;
      // Change type from a number to a meaningful string
      type = listpackTypes[type];

      if (['commit', 'tree', 'blob', 'tag'].includes(type)) {
        offsetToObject[offset] = {
          type,
          offset,
        };
      } else if (type === 'ofs-delta') {
        offsetToObject[offset] = {
          type,
          offset,
        };
      } else if (type === 'ref-delta') {
        offsetToObject[offset] = {
          type,
          offset,
        };
      }
    });

    // We need to know the lengths of the slices to compute the CRCs.
    const offsetArray = Object.keys(offsetToObject).map(Number);
    for (const [i, start] of offsetArray.entries()) {
      const end =
        i + 1 === offsetArray.length ? pack.byteLength - 20 : offsetArray[i + 1];
      const o = offsetToObject[start];
      const crc = crc32.buf(pack.slice(start, end)) >>> 0;
      o.end = end;
      o.crc = crc;
    }

    // We don't have the hashes yet. But we can generate them using the .readSlice function!
    const p = new GitPackIndex({
      pack: Promise.resolve(pack),
      packfileSha,
      crcs,
      hashes,
      offsets,
      getExternalRefDelta,
    });

    // Resolve deltas and compute the oids
    lastPercent = null;
    let count = 0;
    const objectsByDepth = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0];
    for (let offset in offsetToObject) {
      offset = Number(offset);
      const percent = Math.floor((count * 100) / totalObjectCount);
      if (percent !== lastPercent) {
        if (onProgress) {
          await onProgress({
            phase: 'Resolving deltas',
            loaded: count,
            total: totalObjectCount,
          });
        }
      }
      count++;
      lastPercent = percent;

      const o = offsetToObject[offset];
      if (o.oid) continue
      try {
        p.readDepth = 0;
        p.externalReadDepth = 0;
        const { type, object } = await p.readSlice({ start: offset });
        objectsByDepth[p.readDepth] += 1;
        const oid = await shasum(GitObject.wrap({ type, object }));
        o.oid = oid;
        hashes.push(oid);
        offsets.set(oid, offset);
        crcs[oid] = o.crc;
      } catch (err) {
        continue
      }
    }

    hashes.sort();
    return p
  }

  async toBuffer() {
    const buffers = [];
    const write = (str, encoding) => {
      buffers.push(Buffer.from(str, encoding));
    };
    // Write out IDX v2 magic number
    write('ff744f63', 'hex');
    // Write out version number 2
    write('00000002', 'hex');
    // Write fanout table
    const fanoutBuffer = new BufferCursor(Buffer.alloc(256 * 4));
    for (let i = 0; i < 256; i++) {
      let count = 0;
      for (const hash of this.hashes) {
        if (parseInt(hash.slice(0, 2), 16) <= i) count++;
      }
      fanoutBuffer.writeUInt32BE(count);
    }
    buffers.push(fanoutBuffer.buffer);
    // Write out hashes
    for (const hash of this.hashes) {
      write(hash, 'hex');
    }
    // Write out crcs
    const crcsBuffer = new BufferCursor(Buffer.alloc(this.hashes.length * 4));
    for (const hash of this.hashes) {
      crcsBuffer.writeUInt32BE(this.crcs[hash]);
    }
    buffers.push(crcsBuffer.buffer);
    // Write out offsets
    const offsetsBuffer = new BufferCursor(Buffer.alloc(this.hashes.length * 4));
    for (const hash of this.hashes) {
      offsetsBuffer.writeUInt32BE(this.offsets.get(hash));
    }
    buffers.push(offsetsBuffer.buffer);
    // Write out packfile checksum
    write(this.packfileSha, 'hex');
    // Write out shasum
    const totalBuffer = Buffer.concat(buffers);
    const sha = await shasum(totalBuffer);
    const shaBuffer = Buffer.alloc(20);
    shaBuffer.write(sha, 'hex');
    return Buffer.concat([totalBuffer, shaBuffer])
  }

  async load({ pack }) {
    this.pack = pack;
  }

  async unload() {
    this.pack = null;
  }

  async read({ oid }) {
    if (!this.offsets.get(oid)) {
      if (this.getExternalRefDelta) {
        this.externalReadDepth++;
        return this.getExternalRefDelta(oid)
      } else {
        throw new InternalError(`Could not read object ${oid} from packfile`)
      }
    }
    const start = this.offsets.get(oid);
    return this.readSlice({ start })
  }

  async readSlice({ start }) {
    if (this.offsetCache[start]) {
      return Object.assign({}, this.offsetCache[start])
    }
    this.readDepth++;
    const types = {
      0b0010000: 'commit',
      0b0100000: 'tree',
      0b0110000: 'blob',
      0b1000000: 'tag',
      0b1100000: 'ofs_delta',
      0b1110000: 'ref_delta',
    };
    if (!this.pack) {
      throw new InternalError(
        'Tried to read from a GitPackIndex with no packfile loaded into memory'
      )
    }
    const raw = (await this.pack).slice(start);
    const reader = new BufferCursor(raw);
    const byte = reader.readUInt8();
    // Object type is encoded in bits 654
    const btype = byte & 0b1110000;
    let type = types[btype];
    if (type === undefined) {
      throw new InternalError('Unrecognized type: 0b' + btype.toString(2))
    }
    // The length encoding get complicated.
    // Last four bits of length is encoded in bits 3210
    const lastFour = byte & 0b1111;
    let length = lastFour;
    // Whether the next byte is part of the variable-length encoded number
    // is encoded in bit 7
    const multibyte = byte & 0b10000000;
    if (multibyte) {
      length = otherVarIntDecode(reader, lastFour);
    }
    let base = null;
    let object = null;
    // Handle deltified objects
    if (type === 'ofs_delta') {
      const offset = decodeVarInt(reader);
      const baseOffset = start - offset
      ;({ object: base, type } = await this.readSlice({ start: baseOffset }));
    }
    if (type === 'ref_delta') {
      const oid = reader.slice(20).toString('hex')
      ;({ object: base, type } = await this.read({ oid }));
    }
    // Handle undeltified objects
    const buffer = raw.slice(reader.tell());
    object = Buffer.from(await inflate(buffer));
    // Assert that the object length is as expected.
    if (object.byteLength !== length) {
      throw new InternalError(
        `Packfile told us object would have length ${length} but it had length ${object.byteLength}`
      )
    }
    if (base) {
      object = Buffer.from(applyDelta(object, base));
    }
    // Cache the result based on depth.
    if (this.readDepth > 3) {
      // hand tuned for speed / memory usage tradeoff
      this.offsetCache[start] = { type, object };
    }
    return { type, format: 'content', object }
  }
}

const PackfileCache = Symbol('PackfileCache');

async function loadPackIndex({
  fs,
  filename,
  getExternalRefDelta,
  emitter,
  emitterPrefix,
}) {
  const idx = await fs.read(filename);
  return GitPackIndex.fromIdx({ idx, getExternalRefDelta })
}

function readPackIndex({
  fs,
  cache,
  filename,
  getExternalRefDelta,
  emitter,
  emitterPrefix,
}) {
  // Try to get the packfile index from the in-memory cache
  if (!cache[PackfileCache]) cache[PackfileCache] = new Map();
  let p = cache[PackfileCache].get(filename);
  if (!p) {
    p = loadPackIndex({
      fs,
      filename,
      getExternalRefDelta,
      emitter,
      emitterPrefix,
    });
    cache[PackfileCache].set(filename, p);
  }
  return p
}

async function readObjectPacked({
  fs,
  cache,
  gitdir,
  oid,
  format = 'content',
  getExternalRefDelta,
}) {
  // Check to see if it's in a packfile.
  // Iterate through all the .idx files
  let list = await fs.readdir(join(gitdir, 'objects/pack'));
  list = list.filter(x => x.endsWith('.idx'));
  for (const filename of list) {
    const indexFile = `${gitdir}/objects/pack/${filename}`;
    const p = await readPackIndex({
      fs,
      cache,
      filename: indexFile,
      getExternalRefDelta,
    });
    if (p.error) throw new InternalError(p.error)
    // If the packfile DOES have the oid we're looking for...
    if (p.offsets.has(oid)) {
      // Get the resolved git object from the packfile
      if (!p.pack) {
        const packFile = indexFile.replace(/idx$/, 'pack');
        p.pack = fs.read(packFile);
      }
      const result = await p.read({ oid, getExternalRefDelta });
      result.format = 'content';
      result.source = `objects/pack/${filename.replace(/idx$/, 'pack')}`;
      return result
    }
  }
  // Failed to find it
  return null
}

/**
 * @param {object} args
 * @param {import('../models/FileSystem.js').FileSystem} args.fs
 * @param {any} args.cache
 * @param {string} args.gitdir
 * @param {string} args.oid
 * @param {string} [args.format]
 */
async function _readObject({
  fs,
  cache,
  gitdir,
  oid,
  format = 'content',
}) {
  // Curry the current read method so that the packfile un-deltification
  // process can acquire external ref-deltas.
  const getExternalRefDelta = oid => _readObject({ fs, cache, gitdir, oid });

  let result;
  // Empty tree - hard-coded so we can use it as a shorthand.
  // Note: I think the canonical git implementation must do this too because
  // `git cat-file -t 4b825dc642cb6eb9a060e54bf8d69288fbee4904` prints "tree" even in empty repos.
  if (oid === '4b825dc642cb6eb9a060e54bf8d69288fbee4904') {
    result = { format: 'wrapped', object: Buffer.from(`tree 0\x00`) };
  }
  // Look for it in the loose object directory.
  if (!result) {
    result = await readObjectLoose({ fs, gitdir, oid });
  }
  // Check to see if it's in a packfile.
  if (!result) {
    result = await readObjectPacked({
      fs,
      cache,
      gitdir,
      oid,
      getExternalRefDelta,
    });

    if (!result) {
      throw new NotFoundError(oid)
    }

    // Directly return packed result, as specified: packed objects always return the 'content' format.
    return result
  }

  // Loose objects are always deflated, return early
  if (format === 'deflated') {
    return result
  }

  // All loose objects are deflated but the hard-coded empty tree is `wrapped` so we have to check if we need to inflate the object.
  if (result.format === 'deflated') {
    result.object = Buffer.from(await inflate(result.object));
    result.format = 'wrapped';
  }

  if (format === 'wrapped') {
    return result
  }

  const sha = await shasum(result.object);
  if (sha !== oid) {
    throw new InternalError(
      `SHA check failed! Expected ${oid}, computed ${sha}`
    )
  }
  const { object, type } = GitObject.unwrap(result.object);
  result.type = type;
  result.object = object;
  result.format = 'content';

  if (format === 'content') {
    return result
  }

  throw new InternalError(`invalid requested format "${format}"`)
}

async function resolveCommit({ fs, cache, gitdir, oid }) {
  const { type, object } = await _readObject({ fs, cache, gitdir, oid });
  // Resolve annotated tag objects to whatever
  if (type === 'tag') {
    oid = GitAnnotatedTag.from(object).parse().object;
    return resolveCommit({ fs, cache, gitdir, oid })
  }
  if (type !== 'commit') {
    throw new ObjectTypeError(oid, type, 'commit')
  }
  return { commit: GitCommit.from(object), oid }
}

// @ts-check

/**
 * @param {object} args
 * @param {import('../models/FileSystem.js').FileSystem} args.fs
 * @param {any} args.cache
 * @param {string} args.gitdir
 * @param {string} args.oid
 *
 * @returns {Promise<ReadCommitResult>} Resolves successfully with a git commit object
 * @see ReadCommitResult
 * @see CommitObject
 *
 */
async function _readCommit({ fs, cache, gitdir, oid }) {
  const { commit, oid: commitOid } = await resolveCommit({
    fs,
    cache,
    gitdir,
    oid,
  });
  const result = {
    oid: commitOid,
    commit: commit.parse(),
    payload: commit.withoutSignature(),
  };
  // @ts-ignore
  return result
}

async function writeObjectLoose({ fs, gitdir, object, format, oid }) {
  if (format !== 'deflated') {
    throw new InternalError(
      'GitObjectStoreLoose expects objects to write to be in deflated format'
    )
  }
  const source = `objects/${oid.slice(0, 2)}/${oid.slice(2)}`;
  const filepath = `${gitdir}/${source}`;
  // Don't overwrite existing git objects - this helps avoid EPERM errors.
  // Although I don't know how we'd fix corrupted objects then. Perhaps delete them
  // on read?
  if (!(await fs.exists(filepath))) await fs.write(filepath, object);
}

/* eslint-env node, browser */

let supportsCompressionStream = null;

async function deflate(buffer) {
  if (supportsCompressionStream === null) {
    supportsCompressionStream = testCompressionStream();
  }
  return supportsCompressionStream
    ? browserDeflate(buffer)
    : pako.deflate(buffer)
}

async function browserDeflate(buffer) {
  const cs = new CompressionStream('deflate');
  const c = new Blob([buffer]).stream().pipeThrough(cs);
  return new Uint8Array(await new Response(c).arrayBuffer())
}

function testCompressionStream() {
  try {
    const cs = new CompressionStream('deflate');
    cs.writable.close();
    // Test if `Blob.stream` is present. React Native does not have the `stream` method
    const stream = new Blob([]).stream();
    stream.cancel();
    return true
  } catch (_) {
    return false
  }
}

async function _writeObject({
  fs,
  gitdir,
  type,
  object,
  format = 'content',
  oid = undefined,
  dryRun = false,
}) {
  if (format !== 'deflated') {
    if (format !== 'wrapped') {
      object = GitObject.wrap({ type, object });
    }
    oid = await shasum(object);
    object = Buffer.from(await deflate(object));
  }
  if (!dryRun) {
    await writeObjectLoose({ fs, gitdir, object, format: 'deflated', oid });
  }
  return oid
}

// @ts-check

/**
 * @param {object} args
 * @param {import('../models/FileSystem.js').FileSystem} args.fs
 * @param {string} args.gitdir
 * @param {CommitObject} args.commit
 *
 * @returns {Promise<string>}
 * @see CommitObject
 *
 */
async function _writeCommit({ fs, gitdir, commit }) {
  // Convert object to buffer
  const object = GitCommit.from(commit).toObject();
  const oid = await _writeObject({
    fs,
    gitdir,
    type: 'commit',
    object,
    format: 'content',
  });
  return oid
}

class InvalidRefNameError extends BaseError {
  /**
   * @param {string} ref
   * @param {string} suggestion
   * @param {boolean} canForce
   */
  constructor(ref, suggestion) {
    super(
      `"${ref}" would be an invalid git reference. (Hint: a valid alternative would be "${suggestion}".)`
    );
    this.code = this.name = InvalidRefNameError.code;
    this.data = { ref, suggestion };
  }
}
/** @type {'InvalidRefNameError'} */
InvalidRefNameError.code = 'InvalidRefNameError';

class MissingNameError extends BaseError {
  /**
   * @param {'author'|'committer'|'tagger'} role
   */
  constructor(role) {
    super(
      `No name was provided for ${role} in the argument or in the .git/config file.`
    );
    this.code = this.name = MissingNameError.code;
    this.data = { role };
  }
}
/** @type {'MissingNameError'} */
MissingNameError.code = 'MissingNameError';

class GitRefStash {
  // constructor removed

  static get timezoneOffsetForRefLogEntry() {
    const offsetMinutes = new Date().getTimezoneOffset();
    const offsetHours = Math.abs(Math.floor(offsetMinutes / 60));
    const offsetMinutesFormatted = Math.abs(offsetMinutes % 60)
      .toString()
      .padStart(2, '0');
    const sign = offsetMinutes > 0 ? '-' : '+';
    return `${sign}${offsetHours
      .toString()
      .padStart(2, '0')}${offsetMinutesFormatted}`
  }

  static createStashReflogEntry(author, stashCommit, message) {
    const nameNoSpace = author.name.replace(/\s/g, '');
    const z40 = '0000000000000000000000000000000000000000'; // hard code for now, works with `git stash list`
    const timestamp = Math.floor(Date.now() / 1000);
    const timezoneOffset = GitRefStash.timezoneOffsetForRefLogEntry;
    return `${z40} ${stashCommit} ${nameNoSpace} ${author.email} ${timestamp} ${timezoneOffset}\t${message}\n`
  }

  static getStashReflogEntry(reflogString, parsed = false) {
    const reflogLines = reflogString.split('\n');
    const entries = reflogLines
      .filter(l => l)
      .reverse()
      .map((line, idx) =>
        parsed ? `stash@{${idx}}: ${line.split('\t')[1]}` : line
      );
    return entries
  }
}

// @ts-check

/**
 * @param {Object} args
 * @param {import('../models/FileSystem.js').FileSystem} args.fs
 * @param {string} args.gitdir
 * @param {string} args.path
 *
 * @returns {Promise<any>} Resolves with the config value
 *
 * @example
 * // Read config value
 * let value = await git.getConfig({
 *   dir: '$input((/))',
 *   path: '$input((user.name))'
 * })
 * console.log(value)
 *
 */
async function _getConfig({ fs, gitdir, path }) {
  const config = await GitConfigManager.get({ fs, gitdir });
  return config.get(path)
}

// Like Object.assign but ignore properties with undefined values
// ref: https://stackoverflow.com/q/39513815
function assignDefined(target, ...sources) {
  for (const source of sources) {
    if (source) {
      for (const key of Object.keys(source)) {
        const val = source[key];
        if (val !== undefined) {
          target[key] = val;
        }
      }
    }
  }
  return target
}

/**
 * Return author object by using properties following this priority:
 * (1) provided author object
 * -> (2) author of provided commit object
 * -> (3) Config and current date/time
 *
 * @param {Object} args
 * @param {FsClient} args.fs - a file system implementation
 * @param {string} [args.gitdir] - The [git directory](dir-vs-gitdir.md) path
 * @param {Object} [args.author] - The author object.
 * @param {CommitObject} [args.commit] - A commit object.
 *
 * @returns {Promise<void | {name: string, email: string, timestamp: number, timezoneOffset: number }>}
 */
async function normalizeAuthorObject({ fs, gitdir, author, commit }) {
  const timestamp = Math.floor(Date.now() / 1000);

  const defaultAuthor = {
    name: await _getConfig({ fs, gitdir, path: 'user.name' }),
    email: (await _getConfig({ fs, gitdir, path: 'user.email' })) || '', // author.email is allowed to be empty string
    timestamp,
    timezoneOffset: new Date(timestamp * 1000).getTimezoneOffset(),
  };

  // Populate author object by using properties with this priority:
  // (1) provided author object
  // -> (2) author of provided commit object
  // -> (3) default author
  const normalizedAuthor = assignDefined(
    {},
    defaultAuthor,
    commit ? commit.author : undefined,
    author
  );

  if (normalizedAuthor.name === undefined) {
    return undefined
  }

  return normalizedAuthor
}

/*::
type Node = {
  type: string,
  fullpath: string,
  basename: string,
  metadata: Object, // mode, oid
  parent?: Node,
  children: Array<Node>
}
*/

function flatFileListToDirectoryStructure(files) {
  const inodes = new Map();
  const mkdir = function (name) {
    if (!inodes.has(name)) {
      const dir = {
        type: 'tree',
        fullpath: name,
        basename: basename(name),
        metadata: {},
        children: [],
      };
      inodes.set(name, dir);
      // This recursively generates any missing parent folders.
      // We do it after we've added the inode to the set so that
      // we don't recurse infinitely trying to create the root '.' dirname.
      dir.parent = mkdir(dirname(name));
      if (dir.parent && dir.parent !== dir) dir.parent.children.push(dir);
    }
    return inodes.get(name)
  };

  const mkfile = function (name, metadata) {
    if (!inodes.has(name)) {
      const file = {
        type: 'blob',
        fullpath: name,
        basename: basename(name),
        metadata,
        // This recursively generates any missing parent folders.
        parent: mkdir(dirname(name)),
        children: [],
      };
      if (file.parent) file.parent.children.push(file);
      inodes.set(name, file);
    }
    return inodes.get(name)
  };

  mkdir('.');
  for (const file of files) {
    mkfile(file.path, file);
  }
  return inodes
}

/**
 *
 * @param {number} mode
 */
function mode2type(mode) {
  // prettier-ignore
  switch (mode) {
    case 0o040000: return 'tree'
    case 0o100644: return 'blob'
    case 0o100755: return 'blob'
    case 0o120000: return 'blob'
    case 0o160000: return 'commit'
  }
  throw new InternalError(`Unexpected GitTree entry mode: ${mode.toString(8)}`)
}

class GitWalkerIndex {
  constructor({ fs, gitdir, cache }) {
    this.treePromise = GitIndexManager.acquire(
      { fs, gitdir, cache },
      async function (index) {
        return flatFileListToDirectoryStructure(index.entries)
      }
    );
    const walker = this;
    this.ConstructEntry = class StageEntry {
      constructor(fullpath) {
        this._fullpath = fullpath;
        this._type = false;
        this._mode = false;
        this._stat = false;
        this._oid = false;
      }

      async type() {
        return walker.type(this)
      }

      async mode() {
        return walker.mode(this)
      }

      async stat() {
        return walker.stat(this)
      }

      async content() {
        return walker.content(this)
      }

      async oid() {
        return walker.oid(this)
      }
    };
  }

  async readdir(entry) {
    const filepath = entry._fullpath;
    const tree = await this.treePromise;
    const inode = tree.get(filepath);
    if (!inode) return null
    if (inode.type === 'blob') return null
    if (inode.type !== 'tree') {
      throw new Error(`ENOTDIR: not a directory, scandir '${filepath}'`)
    }
    const names = inode.children.map(inode => inode.fullpath);
    names.sort(compareStrings);
    return names
  }

  async type(entry) {
    if (entry._type === false) {
      await entry.stat();
    }
    return entry._type
  }

  async mode(entry) {
    if (entry._mode === false) {
      await entry.stat();
    }
    return entry._mode
  }

  async stat(entry) {
    if (entry._stat === false) {
      const tree = await this.treePromise;
      const inode = tree.get(entry._fullpath);
      if (!inode) {
        throw new Error(
          `ENOENT: no such file or directory, lstat '${entry._fullpath}'`
        )
      }
      const stats = inode.type === 'tree' ? {} : normalizeStats(inode.metadata);
      entry._type = inode.type === 'tree' ? 'tree' : mode2type(stats.mode);
      entry._mode = stats.mode;
      if (inode.type === 'tree') {
        entry._stat = undefined;
      } else {
        entry._stat = stats;
      }
    }
    return entry._stat
  }

  async content(_entry) {
    // Cannot get content for an index entry
  }

  async oid(entry) {
    if (entry._oid === false) {
      const tree = await this.treePromise;
      const inode = tree.get(entry._fullpath);
      entry._oid = inode.metadata.oid;
    }
    return entry._oid
  }
}

// This is part of an elaborate system to facilitate code-splitting / tree-shaking.
// commands/walk.js can depend on only this, and the actual Walker classes exported
// can be opaque - only having a single property (this symbol) that is not enumerable,
// and thus the constructor can be passed as an argument to walk while being "unusable"
// outside of it.
const GitWalkSymbol = Symbol('GitWalkSymbol');

// @ts-check

/**
 * @returns {Walker}
 */
function STAGE() {
  const o = Object.create(null);
  Object.defineProperty(o, GitWalkSymbol, {
    value: function ({ fs, gitdir, cache }) {
      return new GitWalkerIndex({ fs, gitdir, cache })
    },
  });
  Object.freeze(o);
  return o
}

function compareTreeEntryPath(a, b) {
  // Git sorts tree entries as if there is a trailing slash on directory names.
  return compareStrings(appendSlashIfDir(a), appendSlashIfDir(b))
}

function appendSlashIfDir(entry) {
  return entry.mode === '040000' ? entry.path + '/' : entry.path
}

/**
 *
 * @typedef {Object} TreeEntry
 * @property {string} mode - the 6 digit hexadecimal mode
 * @property {string} path - the name of the file or directory
 * @property {string} oid - the SHA-1 object id of the blob or tree
 * @property {'commit'|'blob'|'tree'} type - the type of object
 */

function mode2type$1(mode) {
  // prettier-ignore
  switch (mode) {
    case '040000': return 'tree'
    case '100644': return 'blob'
    case '100755': return 'blob'
    case '120000': return 'blob'
    case '160000': return 'commit'
  }
  throw new InternalError(`Unexpected GitTree entry mode: ${mode}`)
}

function parseBuffer(buffer) {
  const _entries = [];
  let cursor = 0;
  while (cursor < buffer.length) {
    const space = buffer.indexOf(32, cursor);
    if (space === -1) {
      throw new InternalError(
        `GitTree: Error parsing buffer at byte location ${cursor}: Could not find the next space character.`
      )
    }
    const nullchar = buffer.indexOf(0, cursor);
    if (nullchar === -1) {
      throw new InternalError(
        `GitTree: Error parsing buffer at byte location ${cursor}: Could not find the next null character.`
      )
    }
    let mode = buffer.slice(cursor, space).toString('utf8');
    if (mode === '40000') mode = '040000'; // makes it line up neater in printed output
    const type = mode2type$1(mode);
    const path = buffer.slice(space + 1, nullchar).toString('utf8');

    // Prevent malicious git repos from writing to "..\foo" on clone etc
    if (path.includes('\\') || path.includes('/')) {
      throw new UnsafeFilepathError(path)
    }

    const oid = buffer.slice(nullchar + 1, nullchar + 21).toString('hex');
    cursor = nullchar + 21;
    _entries.push({ mode, path, oid, type });
  }
  return _entries
}

function limitModeToAllowed(mode) {
  if (typeof mode === 'number') {
    mode = mode.toString(8);
  }
  // tree
  if (mode.match(/^0?4.*/)) return '040000' // Directory
  if (mode.match(/^1006.*/)) return '100644' // Regular non-executable file
  if (mode.match(/^1007.*/)) return '100755' // Regular executable file
  if (mode.match(/^120.*/)) return '120000' // Symbolic link
  if (mode.match(/^160.*/)) return '160000' // Commit (git submodule reference)
  throw new InternalError(`Could not understand file mode: ${mode}`)
}

function nudgeIntoShape(entry) {
  if (!entry.oid && entry.sha) {
    entry.oid = entry.sha; // Github
  }
  entry.mode = limitModeToAllowed(entry.mode); // index
  if (!entry.type) {
    entry.type = mode2type$1(entry.mode); // index
  }
  return entry
}

class GitTree {
  constructor(entries) {
    if (Buffer.isBuffer(entries)) {
      this._entries = parseBuffer(entries);
    } else if (Array.isArray(entries)) {
      this._entries = entries.map(nudgeIntoShape);
    } else {
      throw new InternalError('invalid type passed to GitTree constructor')
    }
    // Tree entries are not sorted alphabetically in the usual sense (see `compareTreeEntryPath`)
    // but it is important later on that these be sorted in the same order as they would be returned from readdir.
    this._entries.sort(comparePath);
  }

  static from(tree) {
    return new GitTree(tree)
  }

  render() {
    return this._entries
      .map(entry => `${entry.mode} ${entry.type} ${entry.oid}    ${entry.path}`)
      .join('\n')
  }

  toObject() {
    // Adjust the sort order to match git's
    const entries = [...this._entries];
    entries.sort(compareTreeEntryPath);
    return Buffer.concat(
      entries.map(entry => {
        const mode = Buffer.from(entry.mode.replace(/^0/, ''));
        const space = Buffer.from(' ');
        const path = Buffer.from(entry.path, 'utf8');
        const nullchar = Buffer.from([0]);
        const oid = Buffer.from(entry.oid, 'hex');
        return Buffer.concat([mode, space, path, nullchar, oid])
      })
    )
  }

  /**
   * @returns {TreeEntry[]}
   */
  entries() {
    return this._entries
  }

  *[Symbol.iterator]() {
    for (const entry of this._entries) {
      yield entry;
    }
  }
}

class AlreadyExistsError extends BaseError {
  /**
   * @param {'note'|'remote'|'tag'|'branch'} noun
   * @param {string} where
   * @param {boolean} canForce
   */
  constructor(noun, where, canForce = true) {
    super(
      `Failed to create ${noun} at ${where} because it already exists.${
        canForce
          ? ` (Hint: use 'force: true' parameter to overwrite existing ${noun}.)`
          : ''
      }`
    );
    this.code = this.name = AlreadyExistsError.code;
    this.data = { noun, where, canForce };
  }
}
/** @type {'AlreadyExistsError'} */
AlreadyExistsError.code = 'AlreadyExistsError';

class AmbiguousError extends BaseError {
  /**
   * @param {'oids'|'refs'} nouns
   * @param {string} short
   * @param {string[]} matches
   */
  constructor(nouns, short, matches) {
    super(
      `Found multiple ${nouns} matching "${short}" (${matches.join(
        ', '
      )}). Use a longer abbreviation length to disambiguate them.`
    );
    this.code = this.name = AmbiguousError.code;
    this.data = { nouns, short, matches };
  }
}
/** @type {'AmbiguousError'} */
AmbiguousError.code = 'AmbiguousError';

class CheckoutConflictError extends BaseError {
  /**
   * @param {string[]} filepaths
   */
  constructor(filepaths) {
    super(
      `Your local changes to the following files would be overwritten by checkout: ${filepaths.join(
        ', '
      )}`
    );
    this.code = this.name = CheckoutConflictError.code;
    this.data = { filepaths };
  }
}
/** @type {'CheckoutConflictError'} */
CheckoutConflictError.code = 'CheckoutConflictError';

class CommitNotFetchedError extends BaseError {
  /**
   * @param {string} ref
   * @param {string} oid
   */
  constructor(ref, oid) {
    super(
      `Failed to checkout "${ref}" because commit ${oid} is not available locally. Do a git fetch to make the branch available locally.`
    );
    this.code = this.name = CommitNotFetchedError.code;
    this.data = { ref, oid };
  }
}
/** @type {'CommitNotFetchedError'} */
CommitNotFetchedError.code = 'CommitNotFetchedError';

class FastForwardError extends BaseError {
  constructor() {
    super(`A simple fast-forward merge was not possible.`);
    this.code = this.name = FastForwardError.code;
    this.data = {};
  }
}
/** @type {'FastForwardError'} */
FastForwardError.code = 'FastForwardError';

class GitPushError extends BaseError {
  /**
   * @param {string} prettyDetails
   * @param {PushResult} result
   */
  constructor(prettyDetails, result) {
    super(`One or more branches were not updated: ${prettyDetails}`);
    this.code = this.name = GitPushError.code;
    this.data = { prettyDetails, result };
  }
}
/** @type {'GitPushError'} */
GitPushError.code = 'GitPushError';

class InvalidFilepathError extends BaseError {
  /**
   * @param {'leading-slash'|'trailing-slash'|'directory'} [reason]
   */
  constructor(reason) {
    let message = 'invalid filepath';
    if (reason === 'leading-slash' || reason === 'trailing-slash') {
      message = `"filepath" parameter should not include leading or trailing directory separators because these can cause problems on some platforms.`;
    } else if (reason === 'directory') {
      message = `"filepath" should not be a directory.`;
    }
    super(message);
    this.code = this.name = InvalidFilepathError.code;
    this.data = { reason };
  }
}
/** @type {'InvalidFilepathError'} */
InvalidFilepathError.code = 'InvalidFilepathError';

class MaxDepthError extends BaseError {
  /**
   * @param {number} depth
   */
  constructor(depth) {
    super(`Maximum search depth of ${depth} exceeded.`);
    this.code = this.name = MaxDepthError.code;
    this.data = { depth };
  }
}
/** @type {'MaxDepthError'} */
MaxDepthError.code = 'MaxDepthError';

class MergeNotSupportedError extends BaseError {
  constructor() {
    super(`Merges with conflicts are not supported yet.`);
    this.code = this.name = MergeNotSupportedError.code;
    this.data = {};
  }
}
/** @type {'MergeNotSupportedError'} */
MergeNotSupportedError.code = 'MergeNotSupportedError';

class MergeConflictError extends BaseError {
  /**
   * @param {Array<string>} filepaths
   * @param {Array<string>} bothModified
   * @param {Array<string>} deleteByUs
   * @param {Array<string>} deleteByTheirs
   */
  constructor(filepaths, bothModified, deleteByUs, deleteByTheirs) {
    super(
      `Automatic merge failed with one or more merge conflicts in the following files: ${filepaths.toString()}. Fix conflicts then commit the result.`
    );
    this.code = this.name = MergeConflictError.code;
    this.data = { filepaths, bothModified, deleteByUs, deleteByTheirs };
  }
}
/** @type {'MergeConflictError'} */
MergeConflictError.code = 'MergeConflictError';

class MissingParameterError extends BaseError {
  /**
   * @param {string} parameter
   */
  constructor(parameter) {
    super(
      `The function requires a "${parameter}" parameter but none was provided.`
    );
    this.code = this.name = MissingParameterError.code;
    this.data = { parameter };
  }
}
/** @type {'MissingParameterError'} */
MissingParameterError.code = 'MissingParameterError';

class MultipleGitError extends BaseError {
  /**
   * @param {Error[]} errors
   * @param {string} message
   */
  constructor(errors) {
    super(
      `There are multiple errors that were thrown by the method. Please refer to the "errors" property to see more`
    );
    this.code = this.name = MultipleGitError.code;
    this.data = { errors };
    this.errors = errors;
  }
}
/** @type {'MultipleGitError'} */
MultipleGitError.code = 'MultipleGitError';

class PushRejectedError extends BaseError {
  /**
   * @param {'not-fast-forward'|'tag-exists'} reason
   */
  constructor(reason) {
    let message = '';
    if (reason === 'not-fast-forward') {
      message = ' because it was not a simple fast-forward';
    } else if (reason === 'tag-exists') {
      message = ' because tag already exists';
    }
    super(`Push rejected${message}. Use "force: true" to override.`);
    this.code = this.name = PushRejectedError.code;
    this.data = { reason };
  }
}
/** @type {'PushRejectedError'} */
PushRejectedError.code = 'PushRejectedError';

class RemoteCapabilityError extends BaseError {
  /**
   * @param {'shallow'|'deepen-since'|'deepen-not'|'deepen-relative'} capability
   * @param {'depth'|'since'|'exclude'|'relative'} parameter
   */
  constructor(capability, parameter) {
    super(
      `Remote does not support the "${capability}" so the "${parameter}" parameter cannot be used.`
    );
    this.code = this.name = RemoteCapabilityError.code;
    this.data = { capability, parameter };
  }
}
/** @type {'RemoteCapabilityError'} */
RemoteCapabilityError.code = 'RemoteCapabilityError';

class IndexResetError extends BaseError {
  /**
   * @param {Array<string>} filepaths
   */
  constructor(filepath) {
    super(
      `Could not merge index: Entry for '${filepath}' is not up to date. Either reset the index entry to HEAD, or stage your unstaged changes.`
    );
    this.code = this.name = IndexResetError.code;
    this.data = { filepath };
  }
}
/** @type {'IndexResetError'} */
IndexResetError.code = 'IndexResetError';

class NoCommitError extends BaseError {
  /**
   * @param {string} ref
   */
  constructor(ref) {
    super(
      `"${ref}" does not point to any commit. You're maybe working on a repository with no commits yet. `
    );
    this.code = this.name = NoCommitError.code;
    this.data = { ref };
  }
}
/** @type {'NoCommitError'} */
NoCommitError.code = 'NoCommitError';

async function resolveTree({ fs, cache, gitdir, oid }) {
  // Empty tree - bypass `readObject`
  if (oid === '4b825dc642cb6eb9a060e54bf8d69288fbee4904') {
    return { tree: GitTree.from([]), oid }
  }
  const { type, object } = await _readObject({ fs, cache, gitdir, oid });
  // Resolve annotated tag objects to whatever
  if (type === 'tag') {
    oid = GitAnnotatedTag.from(object).parse().object;
    return resolveTree({ fs, cache, gitdir, oid })
  }
  // Resolve commits to trees
  if (type === 'commit') {
    oid = GitCommit.from(object).parse().tree;
    return resolveTree({ fs, cache, gitdir, oid })
  }
  if (type !== 'tree') {
    throw new ObjectTypeError(oid, type, 'tree')
  }
  return { tree: GitTree.from(object), oid }
}

class GitWalkerRepo {
  constructor({ fs, gitdir, ref, cache }) {
    this.fs = fs;
    this.cache = cache;
    this.gitdir = gitdir;
    this.mapPromise = (async () => {
      const map = new Map();
      let oid;
      try {
        oid = await GitRefManager.resolve({ fs, gitdir, ref });
      } catch (e) {
        if (e instanceof NotFoundError) {
          // Handle fresh branches with no commits
          oid = '4b825dc642cb6eb9a060e54bf8d69288fbee4904';
        }
      }
      const tree = await resolveTree({ fs, cache: this.cache, gitdir, oid });
      tree.type = 'tree';
      tree.mode = '40000';
      map.set('.', tree);
      return map
    })();
    const walker = this;
    this.ConstructEntry = class TreeEntry {
      constructor(fullpath) {
        this._fullpath = fullpath;
        this._type = false;
        this._mode = false;
        this._stat = false;
        this._content = false;
        this._oid = false;
      }

      async type() {
        return walker.type(this)
      }

      async mode() {
        return walker.mode(this)
      }

      async stat() {
        return walker.stat(this)
      }

      async content() {
        return walker.content(this)
      }

      async oid() {
        return walker.oid(this)
      }
    };
  }

  async readdir(entry) {
    const filepath = entry._fullpath;
    const { fs, cache, gitdir } = this;
    const map = await this.mapPromise;
    const obj = map.get(filepath);
    if (!obj) throw new Error(`No obj for ${filepath}`)
    const oid = obj.oid;
    if (!oid) throw new Error(`No oid for obj ${JSON.stringify(obj)}`)
    if (obj.type !== 'tree') {
      // TODO: support submodules (type === 'commit')
      return null
    }
    const { type, object } = await _readObject({ fs, cache, gitdir, oid });
    if (type !== obj.type) {
      throw new ObjectTypeError(oid, type, obj.type)
    }
    const tree = GitTree.from(object);
    // cache all entries
    for (const entry of tree) {
      map.set(join(filepath, entry.path), entry);
    }
    return tree.entries().map(entry => join(filepath, entry.path))
  }

  async type(entry) {
    if (entry._type === false) {
      const map = await this.mapPromise;
      const { type } = map.get(entry._fullpath);
      entry._type = type;
    }
    return entry._type
  }

  async mode(entry) {
    if (entry._mode === false) {
      const map = await this.mapPromise;
      const { mode } = map.get(entry._fullpath);
      entry._mode = normalizeMode(parseInt(mode, 8));
    }
    return entry._mode
  }

  async stat(_entry) {}

  async content(entry) {
    if (entry._content === false) {
      const map = await this.mapPromise;
      const { fs, cache, gitdir } = this;
      const obj = map.get(entry._fullpath);
      const oid = obj.oid;
      const { type, object } = await _readObject({ fs, cache, gitdir, oid });
      if (type !== 'blob') {
        entry._content = undefined;
      } else {
        entry._content = new Uint8Array(object);
      }
    }
    return entry._content
  }

  async oid(entry) {
    if (entry._oid === false) {
      const map = await this.mapPromise;
      const obj = map.get(entry._fullpath);
      entry._oid = obj.oid;
    }
    return entry._oid
  }
}

// @ts-check

/**
 * @param {object} args
 * @param {string} [args.ref='HEAD']
 * @returns {Walker}
 */
function TREE({ ref = 'HEAD' } = {}) {
  const o = Object.create(null);
  Object.defineProperty(o, GitWalkSymbol, {
    value: function ({ fs, gitdir, cache }) {
      return new GitWalkerRepo({ fs, gitdir, ref, cache })
    },
  });
  Object.freeze(o);
  return o
}

class GitWalkerFs {
  constructor({ fs, dir, gitdir, cache }) {
    this.fs = fs;
    this.cache = cache;
    this.dir = dir;
    this.gitdir = gitdir;

    this.config = null;
    const walker = this;
    this.ConstructEntry = class WorkdirEntry {
      constructor(fullpath) {
        this._fullpath = fullpath;
        this._type = false;
        this._mode = false;
        this._stat = false;
        this._content = false;
        this._oid = false;
      }

      async type() {
        return walker.type(this)
      }

      async mode() {
        return walker.mode(this)
      }

      async stat() {
        return walker.stat(this)
      }

      async content() {
        return walker.content(this)
      }

      async oid() {
        return walker.oid(this)
      }
    };
  }

  async readdir(entry) {
    const filepath = entry._fullpath;
    const { fs, dir } = this;
    const names = await fs.readdir(join(dir, filepath));
    if (names === null) return null
    return names.map(name => join(filepath, name))
  }

  async type(entry) {
    if (entry._type === false) {
      await entry.stat();
    }
    return entry._type
  }

  async mode(entry) {
    if (entry._mode === false) {
      await entry.stat();
    }
    return entry._mode
  }

  async stat(entry) {
    if (entry._stat === false) {
      const { fs, dir } = this;
      let stat = await fs.lstat(`${dir}/${entry._fullpath}`);
      if (!stat) {
        throw new Error(
          `ENOENT: no such file or directory, lstat '${entry._fullpath}'`
        )
      }
      let type = stat.isDirectory() ? 'tree' : 'blob';
      if (type === 'blob' && !stat.isFile() && !stat.isSymbolicLink()) {
        type = 'special';
      }
      entry._type = type;
      stat = normalizeStats(stat);
      entry._mode = stat.mode;
      // workaround for a BrowserFS edge case
      if (stat.size === -1 && entry._actualSize) {
        stat.size = entry._actualSize;
      }
      entry._stat = stat;
    }
    return entry._stat
  }

  async content(entry) {
    if (entry._content === false) {
      const { fs, dir, gitdir } = this;
      if ((await entry.type()) === 'tree') {
        entry._content = undefined;
      } else {
        const config = await this._getGitConfig(fs, gitdir);
        const autocrlf = await config.get('core.autocrlf');
        const content = await fs.read(`${dir}/${entry._fullpath}`, { autocrlf });
        // workaround for a BrowserFS edge case
        entry._actualSize = content.length;
        if (entry._stat && entry._stat.size === -1) {
          entry._stat.size = entry._actualSize;
        }
        entry._content = new Uint8Array(content);
      }
    }
    return entry._content
  }

  async oid(entry) {
    if (entry._oid === false) {
      const self = this;
      const { fs, gitdir, cache } = this;
      let oid;
      // See if we can use the SHA1 hash in the index.
      await GitIndexManager.acquire(
        { fs, gitdir, cache },
        async function (index) {
          const stage = index.entriesMap.get(entry._fullpath);
          const stats = await entry.stat();
          const config = await self._getGitConfig(fs, gitdir);
          const filemode = await config.get('core.filemode');
          const trustino =
            typeof process !== 'undefined'
              ? !(process.platform === 'win32')
              : true;
          if (!stage || compareStats(stats, stage, filemode, trustino)) {
            const content = await entry.content();
            if (content === undefined) {
              oid = undefined;
            } else {
              oid = await shasum(
                GitObject.wrap({ type: 'blob', object: content })
              );
              // Update the stats in the index so we will get a "cache hit" next time
              // 1) if we can (because the oid and mode are the same)
              // 2) and only if we need to (because other stats differ)
              if (
                stage &&
                oid === stage.oid &&
                (!filemode || stats.mode === stage.mode) &&
                compareStats(stats, stage, filemode, trustino)
              ) {
                index.insert({
                  filepath: entry._fullpath,
                  stats,
                  oid,
                });
              }
            }
          } else {
            // Use the index SHA1 rather than compute it
            oid = stage.oid;
          }
        }
      );
      entry._oid = oid;
    }
    return entry._oid
  }

  async _getGitConfig(fs, gitdir) {
    if (this.config) {
      return this.config
    }
    this.config = await GitConfigManager.get({ fs, gitdir });
    return this.config
  }
}

// @ts-check

/**
 * @returns {Walker}
 */
function WORKDIR() {
  const o = Object.create(null);
  Object.defineProperty(o, GitWalkSymbol, {
    value: function ({ fs, dir, gitdir, cache }) {
      return new GitWalkerFs({ fs, dir, gitdir, cache })
    },
  });
  Object.freeze(o);
  return o
}

// https://dev.to/namirsab/comment/2050
function arrayRange(start, end) {
  const length = end - start;
  return Array.from({ length }, (_, i) => start + i)
}

// TODO: Should I just polyfill Array.flat?
const flat =
  typeof Array.prototype.flat === 'undefined'
    ? entries => entries.reduce((acc, x) => acc.concat(x), [])
    : entries => entries.flat();

// This is convenient for computing unions/joins of sorted lists.
class RunningMinimum {
  constructor() {
    // Using a getter for 'value' would just bloat the code.
    // You know better than to set it directly right?
    this.value = null;
  }

  consider(value) {
    if (value === null || value === undefined) return
    if (this.value === null) {
      this.value = value;
    } else if (value < this.value) {
      this.value = value;
    }
  }

  reset() {
    this.value = null;
  }
}

// Take an array of length N of
//   iterators of length Q_n
//     of strings
// and return an iterator of length max(Q_n) for all n
//   of arrays of length N
//     of string|null who all have the same string value
function* unionOfIterators(sets) {
  /* NOTE: We can assume all arrays are sorted.
   * Indexes are sorted because they are defined that way:
   *
   * > Index entries are sorted in ascending order on the name field,
   * > interpreted as a string of unsigned bytes (i.e. memcmp() order, no
   * > localization, no special casing of directory separator '/'). Entries
   * > with the same name are sorted by their stage field.
   *
   * Trees should be sorted because they are created directly from indexes.
   * They definitely should be sorted, or else they wouldn't have a unique SHA1.
   * So that would be very naughty on the part of the tree-creator.
   *
   * Lastly, the working dir entries are sorted because I choose to sort them
   * in my FileSystem.readdir() implementation.
   */

  // Init
  const min = new RunningMinimum();
  let minimum;
  const heads = [];
  const numsets = sets.length;
  for (let i = 0; i < numsets; i++) {
    // Abuse the fact that iterators continue to return 'undefined' for value
    // once they are done
    heads[i] = sets[i].next().value;
    if (heads[i] !== undefined) {
      min.consider(heads[i]);
    }
  }
  if (min.value === null) return
  // Iterate
  while (true) {
    const result = [];
    minimum = min.value;
    min.reset();
    for (let i = 0; i < numsets; i++) {
      if (heads[i] !== undefined && heads[i] === minimum) {
        result[i] = heads[i];
        heads[i] = sets[i].next().value;
      } else {
        // A little hacky, but eh
        result[i] = null;
      }
      if (heads[i] !== undefined) {
        min.consider(heads[i]);
      }
    }
    yield result;
    if (min.value === null) return
  }
}

// @ts-check

/**
 * @param {object} args
 * @param {import('../models/FileSystem.js').FileSystem} args.fs
 * @param {object} args.cache
 * @param {string} [args.dir]
 * @param {string} [args.gitdir=join(dir,'.git')]
 * @param {Walker[]} args.trees
 * @param {WalkerMap} [args.map]
 * @param {WalkerReduce} [args.reduce]
 * @param {WalkerIterate} [args.iterate]
 *
 * @returns {Promise<any>} The finished tree-walking result
 *
 * @see {WalkerMap}
 *
 */
async function _walk({
  fs,
  cache,
  dir,
  gitdir,
  trees,
  // @ts-ignore
  map = async (_, entry) => entry,
  // The default reducer is a flatmap that filters out undefineds.
  reduce = async (parent, children) => {
    const flatten = flat(children);
    if (parent !== undefined) flatten.unshift(parent);
    return flatten
  },
  // The default iterate function walks all children concurrently
  iterate = (walk, children) => Promise.all([...children].map(walk)),
}) {
  const walkers = trees.map(proxy =>
    proxy[GitWalkSymbol]({ fs, dir, gitdir, cache })
  );

  const root = new Array(walkers.length).fill('.');
  const range = arrayRange(0, walkers.length);
  const unionWalkerFromReaddir = async entries => {
    range.forEach(i => {
      const entry = entries[i];
      entries[i] = entry && new walkers[i].ConstructEntry(entry);
    });
    const subdirs = await Promise.all(
      range.map(i => {
        const entry = entries[i];
        return entry ? walkers[i].readdir(entry) : []
      })
    );
    // Now process child directories
    const iterators = subdirs.map(array => {
      return (array === null ? [] : array)[Symbol.iterator]()
    });

    return {
      entries,
      children: unionOfIterators(iterators),
    }
  };

  const walk = async root => {
    const { entries, children } = await unionWalkerFromReaddir(root);
    const fullpath = entries.find(entry => entry && entry._fullpath)._fullpath;
    const parent = await map(fullpath, entries);
    if (parent !== null) {
      let walkedChildren = await iterate(walk, children);
      walkedChildren = walkedChildren.filter(x => x !== undefined);
      return reduce(parent, walkedChildren)
    }
  };
  return walk(root)
}

// @ts-check

/**
 * @param {object} args
 * @param {import('../models/FileSystem.js').FileSystem} args.fs
 * @param {string} args.gitdir
 * @param {TreeObject} args.tree
 *
 * @returns {Promise<string>}
 */
async function _writeTree({ fs, gitdir, tree }) {
  // Convert object to buffer
  const object = GitTree.from(tree).toObject();
  const oid = await _writeObject({
    fs,
    gitdir,
    type: 'tree',
    object,
    format: 'content',
  });
  return oid
}

function posixifyPathBuffer(buffer) {
  let idx;
  while (~(idx = buffer.indexOf(92))) buffer[idx] = 47;
  return buffer
}

const _TreeMap = {
  stage: STAGE,
  workdir: WORKDIR,
};

let lock$3;
async function acquireLock$1(ref, callback) {
  if (lock$3 === undefined) lock$3 = new AsyncLock();
  return lock$3.acquire(ref, callback)
}

// make sure filepath, blob type and blob object (from loose objects) plus oid are in sync and valid
async function checkAndWriteBlob(fs, gitdir, dir, filepath, oid = null) {
  const currentFilepath = join(dir, filepath);
  const stats = await fs.lstat(currentFilepath);
  if (!stats) throw new NotFoundError(currentFilepath)
  if (stats.isDirectory())
    throw new InternalError(
      `${currentFilepath}: file expected, but found directory`
    )

  // Look for it in the loose object directory.
  const objContent = oid
    ? await readObjectLoose({ fs, gitdir, oid })
    : undefined;
  let retOid = objContent ? oid : undefined;
  if (!objContent) {
    await acquireLock$1({ fs, gitdir, currentFilepath }, async () => {
      const object = stats.isSymbolicLink()
        ? await fs.readlink(currentFilepath).then(posixifyPathBuffer)
        : await fs.read(currentFilepath);

      if (object === null) throw new NotFoundError(currentFilepath)

      retOid = await _writeObject({ fs, gitdir, type: 'blob', object });
    });
  }

  return retOid
}

async function processTreeEntries({ fs, dir, gitdir, entries }) {
  // make sure each tree entry has valid oid
  async function processTreeEntry(entry) {
    if (entry.type === 'tree') {
      if (!entry.oid) {
        // Process children entries if the current entry is a tree
        const children = await Promise.all(entry.children.map(processTreeEntry));
        // Write the tree with the processed children
        entry.oid = await _writeTree({
          fs,
          gitdir,
          tree: children,
        });
        entry.mode = 0o40000; // directory
      }
    } else if (entry.type === 'blob') {
      entry.oid = await checkAndWriteBlob(
        fs,
        gitdir,
        dir,
        entry.path,
        entry.oid
      );
      entry.mode = 0o100644; // file
    }

    // remove path from entry.path
    entry.path = entry.path.split('/').pop();
    return entry
  }

  return Promise.all(entries.map(processTreeEntry))
}

async function writeTreeChanges({
  fs,
  dir,
  gitdir,
  treePair, // [TREE({ ref: 'HEAD' }), 'STAGE'] would be the equivalent of `git write-tree`
}) {
  const isStage = treePair[1] === 'stage';
  const trees = treePair.map(t => (typeof t === 'string' ? _TreeMap[t]() : t));

  const changedEntries = [];
  // transform WalkerEntry objects into the desired format
  const map = async (filepath, [head, stage]) => {
    if (
      filepath === '.' ||
      (await GitIgnoreManager.isIgnored({ fs, dir, gitdir, filepath }))
    ) {
      return
    }

    if (stage) {
      if (
        !head ||
        ((await head.oid()) !== (await stage.oid()) &&
          (await stage.oid()) !== undefined)
      ) {
        changedEntries.push([head, stage]);
      }
      return {
        mode: await stage.mode(),
        path: filepath,
        oid: await stage.oid(),
        type: await stage.type(),
      }
    }
  };

  // combine mapped entries with their parent results
  const reduce = async (parent, children) => {
    children = children.filter(Boolean); // Remove undefined entries
    if (!parent) {
      return children.length > 0 ? children : undefined
    } else {
      parent.children = children;
      return parent
    }
  };

  // if parent is skipped, skip the children
  const iterate = async (walk, children) => {
    const filtered = [];
    for (const child of children) {
      const [head, stage] = child;
      if (isStage) {
        if (stage) {
          // for deleted file in work dir, it also needs to be added on stage
          if (await fs.exists(`${dir}/${stage.toString()}`)) {
            filtered.push(child);
          } else {
            changedEntries.push([null, stage]); // record the change (deletion) while stop the iteration
          }
        }
      } else if (head) {
        // for deleted file in workdir, "stage" (workdir in our case) will be undefined
        if (!stage) {
          changedEntries.push([head, null]); // record the change (deletion) while stop the iteration
        } else {
          filtered.push(child); // workdir, tracked only
        }
      }
    }
    return filtered.length ? Promise.all(filtered.map(walk)) : []
  };

  const entries = await _walk({
    fs,
    cache: {},
    dir,
    gitdir,
    trees,
    map,
    reduce,
    iterate,
  });

  if (changedEntries.length === 0 || entries.length === 0) {
    return null // no changes found to stash
  }

  const processedEntries = await processTreeEntries({
    fs,
    dir,
    gitdir,
    entries,
  });

  const treeEntries = processedEntries.filter(Boolean).map(entry => ({
    mode: entry.mode,
    path: entry.path,
    oid: entry.oid,
    type: entry.type,
  }));

  return _writeTree({ fs, gitdir, tree: treeEntries })
}

async function applyTreeChanges({
  fs,
  dir,
  gitdir,
  stashCommit,
  parentCommit,
  wasStaged,
}) {
  const dirRemoved = [];
  const stageUpdated = [];

  // analyze the changes
  const ops = await _walk({
    fs,
    cache: {},
    dir,
    gitdir,
    trees: [TREE({ ref: parentCommit }), TREE({ ref: stashCommit })],
    map: async (filepath, [parent, stash]) => {
      if (
        filepath === '.' ||
        (await GitIgnoreManager.isIgnored({ fs, dir, gitdir, filepath }))
      ) {
        return
      }
      const type = stash ? await stash.type() : await parent.type();
      if (type !== 'tree' && type !== 'blob') {
        return
      }

      // deleted tree or blob
      if (!stash && parent) {
        const method = type === 'tree' ? 'rmdir' : 'rm';
        if (type === 'tree') dirRemoved.push(filepath);
        if (type === 'blob' && wasStaged)
          stageUpdated.push({ filepath, oid: await parent.oid() }); // stats is undefined, will stage the deletion with index.insert
        return { method, filepath }
      }

      const oid = await stash.oid();
      if (!parent || (await parent.oid()) !== oid) {
        // only apply changes if changed from the parent commit or doesn't exist in the parent commit
        if (type === 'tree') {
          return { method: 'mkdir', filepath }
        } else {
          if (wasStaged)
            stageUpdated.push({
              filepath,
              oid,
              stats: await fs.lstat(join(dir, filepath)),
            });
          return {
            method: 'write',
            filepath,
            oid,
          }
        }
      }
    },
  });

  // apply the changes to work dir
  await acquireLock$1({ fs, gitdir, dirRemoved, ops }, async () => {
    for (const op of ops) {
      const currentFilepath = join(dir, op.filepath);
      switch (op.method) {
        case 'rmdir':
          await fs.rmdir(currentFilepath);
          break
        case 'mkdir':
          await fs.mkdir(currentFilepath);
          break
        case 'rm':
          await fs.rm(currentFilepath);
          break
        case 'write':
          // only writes if file is not in the removedDirs
          if (
            !dirRemoved.some(removedDir =>
              currentFilepath.startsWith(removedDir)
            )
          ) {
            const { object } = await _readObject({
              fs,
              cache: {},
              gitdir,
              oid: op.oid,
            });
            // just like checkout, since mode only applicable to create, not update, delete first
            if (await fs.exists(currentFilepath)) {
              await fs.rm(currentFilepath);
            }
            await fs.write(currentFilepath, object); // only handles regular files for now
          }
          break
      }
    }
  });

  // update the stage
  await GitIndexManager.acquire({ fs, gitdir, cache: {} }, async index => {
    stageUpdated.forEach(({ filepath, stats, oid }) => {
      index.insert({ filepath, stats, oid });
    });
  });
}

class GitStashManager {
  /**
   * Creates an instance of GitStashManager.
   *
   * @param {Object} args
   * @param {FSClient} args.fs - A file system implementation.
   * @param {string} args.dir - The working directory.
   * @param {string}[args.gitdir=join(dir, '.git')] - [required] The [git directory](dir-vs-gitdir.md) path
   */
  constructor({ fs, dir, gitdir = join(dir, '.git') }) {
    Object.assign(this, {
      fs,
      dir,
      gitdir,
      _author: null,
    });
  }

  /**
   * Gets the reference name for the stash.
   *
   * @returns {string} - The stash reference name.
   */
  static get refStash() {
    return 'refs/stash'
  }

  /**
   * Gets the reference name for the stash reflogs.
   *
   * @returns {string} - The stash reflogs reference name.
   */
  static get refLogsStash() {
    return 'logs/refs/stash'
  }

  /**
   * Gets the file path for the stash reference.
   *
   * @returns {string} - The file path for the stash reference.
   */
  get refStashPath() {
    return join(this.gitdir, GitStashManager.refStash)
  }

  /**
   * Gets the file path for the stash reflogs.
   *
   * @returns {string} - The file path for the stash reflogs.
   */
  get refLogsStashPath() {
    return join(this.gitdir, GitStashManager.refLogsStash)
  }

  /**
   * Retrieves the author information for the stash.
   *
   * @returns {Promise<Object>} - The author object.
   * @throws {MissingNameError} - If the author name is missing.
   */
  async getAuthor() {
    if (!this._author) {
      this._author = await normalizeAuthorObject({
        fs: this.fs,
        gitdir: this.gitdir,
        author: {},
      });
      if (!this._author) throw new MissingNameError('author')
    }
    return this._author
  }

  /**
   * Gets the SHA of a stash entry by its index.
   *
   * @param {number} refIdx - The index of the stash entry.
   * @param {string[]} [stashEntries] - Optional preloaded stash entries.
   * @returns {Promise<string|null>} - The SHA of the stash entry or `null` if not found.
   */
  async getStashSHA(refIdx, stashEntries) {
    if (!(await this.fs.exists(this.refStashPath))) {
      return null
    }

    const entries =
      stashEntries || (await this.readStashReflogs({ parsed: false }));
    return entries[refIdx].split(' ')[1]
  }

  /**
   * Writes a stash commit to the repository.
   *
   * @param {Object} args
   * @param {string} args.message - The commit message.
   * @param {string} args.tree - The tree object ID.
   * @param {string[]} args.parent - The parent commit object IDs.
   * @returns {Promise<string>} - The object ID of the written commit.
   */
  async writeStashCommit({ message, tree, parent }) {
    return _writeCommit({
      fs: this.fs,
      gitdir: this.gitdir,
      commit: {
        message,
        tree,
        parent,
        author: await this.getAuthor(),
        committer: await this.getAuthor(),
      },
    })
  }

  /**
   * Reads a stash commit by its index.
   *
   * @param {number} refIdx - The index of the stash entry.
   * @returns {Promise<Object>} - The stash commit object.
   * @throws {InvalidRefNameError} - If the index is invalid.
   */
  async readStashCommit(refIdx) {
    const stashEntries = await this.readStashReflogs({ parsed: false });
    if (refIdx !== 0) {
      // non-default case, throw exceptions if not valid
      if (refIdx < 0 || refIdx > stashEntries.length - 1) {
        throw new InvalidRefNameError(
          `stash@${refIdx}`,
          'number that is in range of [0, num of stash pushed]'
        )
      }
    }

    const stashSHA = await this.getStashSHA(refIdx, stashEntries);
    if (!stashSHA) {
      return {} // no stash found
    }

    // get the stash commit object
    return _readCommit({
      fs: this.fs,
      cache: {},
      gitdir: this.gitdir,
      oid: stashSHA,
    })
  }

  /**
   * Writes a stash reference to the repository.
   *
   * @param {string} stashCommit - The object ID of the stash commit.
   * @returns {Promise<void>}
   */
  async writeStashRef(stashCommit) {
    return GitRefManager.writeRef({
      fs: this.fs,
      gitdir: this.gitdir,
      ref: GitStashManager.refStash,
      value: stashCommit,
    })
  }

  /**
   * Writes a reflog entry for a stash commit.
   *
   * @param {Object} args
   * @param {string} args.stashCommit - The object ID of the stash commit.
   * @param {string} args.message - The reflog message.
   * @returns {Promise<void>}
   */
  async writeStashReflogEntry({ stashCommit, message }) {
    const author = await this.getAuthor();
    const entry = GitRefStash.createStashReflogEntry(
      author,
      stashCommit,
      message
    );
    const filepath = this.refLogsStashPath;

    await acquireLock$1({ filepath, entry }, async () => {
      const appendTo = (await this.fs.exists(filepath))
        ? await this.fs.read(filepath, 'utf8')
        : '';
      await this.fs.write(filepath, appendTo + entry, 'utf8');
    });
  }

  /**
   * Reads the stash reflogs.
   *
   * @param {Object} args
   * @param {boolean} [args.parsed=false] - Whether to parse the reflog entries.
   * @returns {Promise<string[]|Object[]>} - The reflog entries as strings or parsed objects.
   */
  async readStashReflogs({ parsed = false }) {
    if (!(await this.fs.exists(this.refLogsStashPath))) {
      return []
    }

    const reflogString = await this.fs.read(this.refLogsStashPath, 'utf8');

    return GitRefStash.getStashReflogEntry(reflogString, parsed)
  }
}

export { GitConfigManager, GitIgnoreManager, GitIndexManager, GitRefManager, GitRemoteHTTP, GitRemoteManager, GitShallowManager, GitStashManager };