asar = process.binding 'atom_common_asar'
child_process = require 'child_process'
path = require 'path'
util = require 'util'

### Cache asar archive objects. ###
cachedArchives = {}
getOrCreateArchive = (p) ->
  archive = cachedArchives[p]
  return archive if archive?
  archive = asar.createArchive p
  return false unless archive
  cachedArchives[p] = archive

### Clean cache on quit. ###
process.on 'exit', ->
  archive.destroy() for own p, archive of cachedArchives

### Separate asar package's path from full path. ###
splitPath = (p) ->
  ### shortcut to disable asar. ###
  return [false] if process.noAsar

  return [false] if typeof p isnt 'string'
  return [true, p, ''] if p.substr(-5) is '.asar'
  p = path.normalize p
  index = p.lastIndexOf ".asar#{path.sep}"
  return [false] if index is -1
  [true, p.substr(0, index + 5), p.substr(index + 6)]

### Convert asar archive's Stats object to fs's Stats object. ###
nextInode = 0
uid = if process.getuid? then process.getuid() else 0
gid = if process.getgid? then process.getgid() else 0
fakeTime = new Date()
asarStatsToFsStats = (stats) ->
  {
    dev: 1,
    ino: ++nextInode,
    mode: 33188,
    nlink: 1,
    uid: uid,
    gid: gid,
    rdev: 0,
    atime: stats.atime || fakeTime,
    birthtime: stats.birthtime || fakeTime,
    mtime: stats.mtime || fakeTime,
    ctime: stats.ctime || fakeTime,
    size: stats.size,
    isFile: -> stats.isFile
    isDirectory: -> stats.isDirectory
    isSymbolicLink: -> stats.isLink
    isBlockDevice: -> false
    isCharacterDevice: -> false
    isFIFO: -> false
    isSocket: -> false
  }

### Create a ENOENT error. ###
notFoundError = (asarPath, filePath, callback) ->
  error = new Error("ENOENT, #{filePath} not found in #{asarPath}")
  error.code = "ENOENT"
  error.errno = -2
  unless typeof callback is 'function'
    throw error
  process.nextTick -> callback error

### Create a ENOTDIR error. ###
notDirError = (callback) ->
  error = new Error('ENOTDIR, not a directory')
  error.code = 'ENOTDIR'
  error.errno = -20
  unless typeof callback is 'function'
    throw error
  process.nextTick -> callback error

### Create invalid archive error. ###
invalidArchiveError = (asarPath, callback) ->
  error = new Error("Invalid package #{asarPath}")
  unless typeof callback is 'function'
    throw error
  process.nextTick -> callback error

### Override APIs that rely on passing file path instead of content to C++. ###
overrideAPISync = (module, name, arg = 0) ->
  old = module[name]
  module[name] = ->
    p = arguments[arg]
    [isAsar, asarPath, filePath] = splitPath p
    return old.apply this, arguments unless isAsar

    archive = getOrCreateArchive asarPath
    invalidArchiveError asarPath unless archive

    newPath = archive.copyFileOut filePath
    notFoundError asarPath, filePath unless newPath

    arguments[arg] = newPath
    old.apply this, arguments

overrideAPI = (module, name, arg = 0) ->
  old = module[name]
  module[name] = ->
    p = arguments[arg]
    [isAsar, asarPath, filePath] = splitPath p
    return old.apply this, arguments unless isAsar

    callback = arguments[arguments.length - 1]
    return overrideAPISync module, name, arg unless typeof callback is 'function'

    archive = getOrCreateArchive asarPath
    return invalidArchiveError asarPath, callback unless archive

    newPath = archive.copyFileOut filePath
    return notFoundError asarPath, filePath, callback unless newPath

    arguments[arg] = newPath
    old.apply this, arguments

### Override fs APIs. ###
exports.wrapFsWithAsar = (fs) ->
  lstatSync = fs.lstatSync
  fs.lstatSync = (p) ->
    [isAsar, asarPath, filePath] = splitPath p
    return lstatSync p unless isAsar

    archive = getOrCreateArchive asarPath
    invalidArchiveError asarPath unless archive

    stats = archive.stat filePath
    notFoundError asarPath, filePath unless stats

    asarStatsToFsStats stats

  lstat = fs.lstat
  fs.lstat = (p, callback) ->
    [isAsar, asarPath, filePath] = splitPath p
    return lstat p, callback unless isAsar

    archive = getOrCreateArchive asarPath
    return invalidArchiveError asarPath, callback unless archive

    stats = getOrCreateArchive(asarPath).stat filePath
    return notFoundError asarPath, filePath, callback unless stats

    process.nextTick -> callback null, asarStatsToFsStats stats

  statSync = fs.statSync
  fs.statSync = (p) ->
    [isAsar, asarPath, filePath] = splitPath p
    return statSync p unless isAsar

    ### Do not distinguish links for now. ###
    fs.lstatSync p

  stat = fs.stat
  fs.stat = (p, callback) ->
    [isAsar, asarPath, filePath] = splitPath p
    return stat p, callback unless isAsar

    ### Do not distinguish links for now. ###
    process.nextTick -> fs.lstat p, callback

  statSyncNoException = fs.statSyncNoException
  fs.statSyncNoException = (p) ->
    [isAsar, asarPath, filePath] = splitPath p
    return statSyncNoException p unless isAsar

    archive = getOrCreateArchive asarPath
    return false unless archive
    stats = archive.stat filePath
    return false unless stats
    asarStatsToFsStats stats

  realpathSync = fs.realpathSync
  fs.realpathSync = (p) ->
    [isAsar, asarPath, filePath] = splitPath p
    return realpathSync.apply this, arguments unless isAsar

    archive = getOrCreateArchive asarPath
    invalidArchiveError asarPath unless archive

    real = archive.realpath filePath
    notFoundError asarPath, filePath if real is false

    path.join realpathSync(asarPath), real

  realpath = fs.realpath
  fs.realpath = (p, cache, callback) ->
    [isAsar, asarPath, filePath] = splitPath p
    return realpath.apply this, arguments unless isAsar

    if typeof cache is 'function'
      callback = cache
      cache = undefined

    archive = getOrCreateArchive asarPath
    return invalidArchiveError asarPath, callback unless archive

    real = archive.realpath filePath
    if real is false
      return notFoundError asarPath, filePath, callback

    realpath asarPath, (err, p) ->
      return callback err if err
      callback null, path.join(p, real)

  exists = fs.exists
  fs.exists = (p, callback) ->
    [isAsar, asarPath, filePath] = splitPath p
    return exists p, callback unless isAsar

    archive = getOrCreateArchive asarPath
    return invalidArchiveError asarPath, callback unless archive

    process.nextTick -> callback archive.stat(filePath) isnt false

  existsSync = fs.existsSync
  fs.existsSync = (p) ->
    [isAsar, asarPath, filePath] = splitPath p
    return existsSync p unless isAsar

    archive = getOrCreateArchive asarPath
    return false unless archive

    archive.stat(filePath) isnt false

  open = fs.open
  readFile = fs.readFile
  fs.readFile = (p, options, callback) ->
    [isAsar, asarPath, filePath] = splitPath p
    return readFile.apply this, arguments unless isAsar

    if typeof options is 'function'
      callback = options
      options = undefined

    archive = getOrCreateArchive asarPath
    return invalidArchiveError asarPath, callback unless archive

    info = archive.getFileInfo filePath
    return notFoundError asarPath, filePath, callback unless info

    if info.size is 0
      return process.nextTick -> callback null, new Buffer(0)

    if info.unpacked
      realPath = archive.copyFileOut filePath
      return fs.readFile realPath, options, callback

    if not options
      options = encoding: null
    else if util.isString options
      options = encoding: options
    else if not util.isObject options
      throw new TypeError('Bad arguments')

    encoding = options.encoding

    buffer = new Buffer(info.size)
    fd = archive.getFd()
    return notFoundError asarPath, filePath, callback unless fd >= 0

    fs.read fd, buffer, 0, info.size, info.offset, (error) ->
      callback error, if encoding then buffer.toString encoding else buffer

  openSync = fs.openSync
  readFileSync = fs.readFileSync
  fs.readFileSync = (p, opts) ->
    ### this allows v8 to optimize this function ###
    options = opts

    [isAsar, asarPath, filePath] = splitPath p
    return readFileSync.apply this, arguments unless isAsar

    archive = getOrCreateArchive asarPath
    invalidArchiveError asarPath unless archive

    info = archive.getFileInfo filePath
    notFoundError asarPath, filePath unless info

    if info.size is 0
      return if options then '' else new Buffer(0)

    if info.unpacked
      realPath = archive.copyFileOut filePath
      return fs.readFileSync realPath, options

    if not options
      options = encoding: null
    else if util.isString options
      options = encoding: options
    else if not util.isObject options
      throw new TypeError('Bad arguments')

    encoding = options.encoding

    buffer = new Buffer(info.size)
    fd = archive.getFd()
    notFoundError asarPath, filePath unless fd >= 0

    fs.readSync fd, buffer, 0, info.size, info.offset
    if encoding then buffer.toString encoding else buffer

  readdir = fs.readdir
  fs.readdir = (p, callback) ->
    [isAsar, asarPath, filePath] = splitPath p
    return readdir.apply this, arguments unless isAsar

    archive = getOrCreateArchive asarPath
    return invalidArchiveError asarPath, callback unless archive

    files = archive.readdir filePath
    return notFoundError asarPath, filePath, callback unless files

    process.nextTick -> callback null, files

  readdirSync = fs.readdirSync
  fs.readdirSync = (p) ->
    [isAsar, asarPath, filePath] = splitPath p
    return readdirSync.apply this, arguments unless isAsar

    archive = getOrCreateArchive asarPath
    invalidArchiveError asarPath unless archive

    files = archive.readdir filePath
    notFoundError asarPath, filePath unless files

    files

  internalModuleReadFile = process.binding('fs').internalModuleReadFile
  process.binding('fs').internalModuleReadFile = (p) ->
    [isAsar, asarPath, filePath] = splitPath p
    return internalModuleReadFile p unless isAsar

    archive = getOrCreateArchive asarPath
    return undefined unless archive

    info = archive.getFileInfo filePath
    return undefined unless info
    return '' if info.size is 0

    if info.unpacked
      realPath = archive.copyFileOut filePath
      return fs.readFileSync realPath, encoding: 'utf8'

    buffer = new Buffer(info.size)
    fd = archive.getFd()
    return undefined unless fd >= 0

    fs.readSync fd, buffer, 0, info.size, info.offset
    buffer.toString 'utf8'

  internalModuleStat = process.binding('fs').internalModuleStat
  process.binding('fs').internalModuleStat = (p) ->
    [isAsar, asarPath, filePath] = splitPath p
    return internalModuleStat p unless isAsar

    archive = getOrCreateArchive asarPath
    ### -ENOENT ###
    return -34 unless archive

    stats = archive.stat filePath
    ### -ENOENT ###
    return -34 unless stats

    if stats.isDirectory then return 1 else return 0

  ###
    Calling mkdir for directory inside asar archive should throw ENOTDIR
    error, but on Windows it throws ENOENT.
    This is to work around the recursive looping bug of mkdirp since it is
    widely used.
  ###
  if process.platform is 'win32'
    mkdir = fs.mkdir
    fs.mkdir = (p, mode, callback) ->
      callback = mode if typeof mode is 'function'
      [isAsar, asarPath, filePath] = splitPath p
      return notDirError callback if isAsar and filePath.length
      mkdir p, mode, callback

    mkdirSync = fs.mkdirSync
    fs.mkdirSync = (p, mode) ->
      [isAsar, asarPath, filePath] = splitPath p
      notDirError() if isAsar and filePath.length
      mkdirSync p, mode

  overrideAPI fs, 'open'
  overrideAPI child_process, 'execFile'
  overrideAPISync process, 'dlopen', 1
  overrideAPISync require('module')._extensions, '.node', 1
  overrideAPISync fs, 'openSync'
  overrideAPISync child_process, 'execFileSync'