old_contents: module.exports = FileStream
  
  var debug = require('debug')('webtorrent:file-stream')
  var inherits = require('inherits')
  var stream = require('readable-stream')
  
  inherits(FileStream, stream.Readable)
  
  /**
   * Readable stream of a torrent file
   *
   * @param {File} file
   * @param {Object} opts
   * @param {number} opts.start stream slice of file, starting from this byte (inclusive)
   * @param {number} opts.end stream slice of file, ending with this byte (inclusive)
   */
  function FileStream (file, opts) {
    stream.Readable.call(this, opts)
  
    this.destroyed = false
    this._torrent = file._torrent
  
    var start = (opts && opts.start) || 0
    var end = (opts && opts.end && opts.end < file.length)
      ? opts.end
      : file.length - 1
  
    var pieceLength = file._torrent.pieceLength
  
    this._startPiece = (start + file.offset) / pieceLength | 0
    this._endPiece = (end + file.offset) / pieceLength | 0
  
    this._piece = this._startPiece
    this._offset = (start + file.offset) - (this._startPiece * pieceLength)
  
    this._missing = end - start + 1
    this._reading = false
    this._notifying = false
    this._criticalLength = Math.min((1024 * 1024 / pieceLength) | 0, 2)
  }
  
  FileStream.prototype._read = function () {
    if (this._reading) return
    this._reading = true
    this._notify()
  }
  
  FileStream.prototype._notify = function () {
    var self = this
  
    if (!self._reading || self._missing === 0) return
    if (!self._torrent.bitfield.get(self._piece)) {
      return self._torrent.critical(self._piece, self._piece + self._criticalLength)
    }
  
    if (self._notifying) return
    self._notifying = true
  
    var p = self._piece
    self._torrent.store.get(p, function (err, buffer) {
      self._notifying = false
      if (self.destroyed) return
      if (err) return self._destroy(err)
      debug('read %s (length %s) (err %s)', p, buffer.length, err && err.message)
  
      if (self._offset) {
        buffer = buffer.slice(self._offset)
        self._offset = 0
      }
  
      if (self._missing < buffer.length) {
        buffer = buffer.slice(0, self._missing)
      }
      self._missing -= buffer.length
  
      debug('pushing buffer of length %s', buffer.length)
      self._reading = false
      self.push(buffer)
  
      if (self._missing === 0) self.push(null)
    })
    self._piece += 1
  }
  
  FileStream.prototype.destroy = function (onclose) {
    this._destroy(null, onclose)
  }
  
  FileStream.prototype._destroy = function (err, onclose) {
    if (this.destroyed) return
    this.destroyed = true
  
    if (!this._torrent.destroyed) {
      this._torrent.deselect(this._startPiece, this._endPiece, true)
    }
  
    if (err) this.emit('error', err)
    this.emit('close')
    if (onclose) onclose()
  }
  
new_contents: module.exports = FileStream
  
  var debug = require('debug')('webtorrent:file-stream')
  var inherits = require('inherits')
  var stream = require('readable-stream')
  
  inherits(FileStream, stream.Readable)
  
  /**
   * Readable stream of a torrent file
   *
   * @param {File} file
   * @param {Object} opts
   * @param {number} opts.start stream slice of file, starting from this byte (inclusive)
   * @param {number} opts.end stream slice of file, ending with this byte (inclusive)
   */
  function FileStream (file, opts) {
    stream.Readable.call(this, opts)
  
    this.destroyed = false
    this._torrent = file._torrent
  
    var start = (opts && opts.start) || 0
    var end = (opts && opts.end && opts.end < file.length)
      ? opts.end
      : file.length - 1
  
    var pieceLength = file._torrent.pieceLength
  
    this._startPiece = (start + file.offset) / pieceLength | 0
    this._endPiece = (end + file.offset) / pieceLength | 0
  
    this._piece = this._startPiece
    this._offset = (start + file.offset) - (this._startPiece * pieceLength)
  
    this._missing = end - start + 1
    this._reading = false
    this._notifying = false
    this._criticalLength = Math.min((1024 * 1024 / pieceLength) | 0, 2)
  }
  
  FileStream.prototype._read = function () {
    if (this._reading) return
    this._reading = true
    this._notify()
  }
  
  FileStream.prototype._notify = function () {
    var self = this
  
    if (!self._reading || self._missing === 0) return
    if (!self._torrent.bitfield.get(self._piece)) {
      return self._torrent.critical(self._piece, self._piece + self._criticalLength)
    }
  
    if (self._notifying) return
    self._notifying = true
  
    if (self._torrent.destroyed) return self._destroy(new Error('Torrent removed'))
  
    var p = self._piece
    self._torrent.store.get(p, function (err, buffer) {
      self._notifying = false
      if (self.destroyed) return
      if (err) return self._destroy(err)
      debug('read %s (length %s) (err %s)', p, buffer.length, err && err.message)
  
      if (self._offset) {
        buffer = buffer.slice(self._offset)
        self._offset = 0
      }
  
      if (self._missing < buffer.length) {
        buffer = buffer.slice(0, self._missing)
      }
      self._missing -= buffer.length
  
      debug('pushing buffer of length %s', buffer.length)
      self._reading = false
      self.push(buffer)
  
      if (self._missing === 0) self.push(null)
    })
    self._piece += 1
  }
  
  FileStream.prototype.destroy = function (onclose) {
    this._destroy(null, onclose)
  }
  
  FileStream.prototype._destroy = function (err, onclose) {
    if (this.destroyed) return
    this.destroyed = true
  
    if (!this._torrent.destroyed) {
      this._torrent.deselect(this._startPiece, this._endPiece, true)
    }
  
    if (err) this.emit('error', err)
    this.emit('close')
    if (onclose) onclose()
  }
  
subject: Raise error when streaming from a removed torrent