File size: 5,041 Bytes
95f4e64
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
import EventEmitter from 'events'
import { Readable } from 'streamx'
import { chunkStoreRead } from 'chunk-store-iterator'
import mime from 'mime/lite.js'
import FileIterator from './file-iterator.js'

export default class File extends EventEmitter {
  constructor (torrent, file) {
    super()

    this._torrent = torrent
    this._destroyed = false
    this._fileStreams = new Set()
    this._iterators = new Set()

    this.name = file.name
    this.path = file.path
    this.length = file.length
    this.size = file.length
    this.type = mime.getType(this.name) || 'application/octet-stream'
    this.offset = file.offset

    this.done = false

    const start = file.offset
    const end = start + file.length - 1

    this._startPiece = start / this._torrent.pieceLength | 0
    this._endPiece = end / this._torrent.pieceLength | 0

    if (this.length === 0) {
      this.done = true
      this.emit('done')
    }

    this._client = torrent.client
  }

  get downloaded () {
    if (this._destroyed || !this._torrent.bitfield) return 0

    const { pieces, bitfield, pieceLength, lastPieceLength } = this._torrent
    const { _startPiece: start, _endPiece: end } = this

    const getPieceLength = (pieceIndex) => (
      pieceIndex === pieces.length - 1 ? lastPieceLength : pieceLength
    )

    const getPieceDownloaded = (pieceIndex) => {
      const len = pieceIndex === pieces.length - 1 ? lastPieceLength : pieceLength
      if (bitfield.get(pieceIndex)) {
        // verified data
        return len
      } else {
        // "in progress" data
        return len - pieces[pieceIndex].missing
      }
    }

    let downloaded = 0
    for (let index = start; index <= end; index += 1) {
      const pieceDownloaded = getPieceDownloaded(index)
      downloaded += pieceDownloaded

      if (index === start) {
        // First piece may have an offset, e.g. irrelevant bytes from the end of
        // the previous file
        const irrelevantFirstPieceBytes = this.offset % pieceLength
        downloaded -= Math.min(irrelevantFirstPieceBytes, pieceDownloaded)
      }

      if (index === end) {
        // Last piece may have an offset, e.g. irrelevant bytes from the start
        // of the next file
        const irrelevantLastPieceBytes = getPieceLength(end) - (this.offset + this.length) % pieceLength
        downloaded -= Math.min(irrelevantLastPieceBytes, pieceDownloaded)
      }
    }

    return downloaded
  }

  get progress () {
    return this.length ? this.downloaded / this.length : 0
  }

  select (priority) {
    if (this.length === 0) return
    this._torrent.select(this._startPiece, this._endPiece, priority)
  }

  deselect () {
    if (this.length === 0) return
    this._torrent.deselect(this._startPiece, this._endPiece)
  }

  [Symbol.asyncIterator] (opts = {}) {
    if (this.length === 0) return (async function * empty () {})()

    const { start = 0 } = opts ?? {}
    const end = (opts?.end && opts.end < this.length)
      ? opts.end
      : this.length - 1

    if (this.done) {
      return chunkStoreRead(this._torrent.store, { offset: start + this.offset, length: end - start + 1 })
    }

    const iterator = new FileIterator(this, { start, end })
    this._iterators.add(iterator)
    iterator.once('return', () => {
      this._iterators.delete(iterator)
    })

    return iterator
  }

  createReadStream (opts) {
    const iterator = this[Symbol.asyncIterator](opts)
    const fileStream = Readable.from(iterator)

    this._fileStreams.add(fileStream)
    fileStream.once('close', () => {
      this._fileStreams.delete(fileStream)
    })

    return fileStream
  }

  async arrayBuffer (opts) {
    const data = new Uint8Array(this.length)
    let offset = 0
    for await (const chunk of this[Symbol.asyncIterator](opts)) {
      data.set(chunk, offset)
      offset += chunk.length
    }
    return data.buffer
  }

  async blob (opts) {
    return new Blob([await this.arrayBuffer(opts)], { type: this.type })
  }

  stream (opts) {
    let iterator
    return new ReadableStream({
      start: () => {
        iterator = this[Symbol.asyncIterator](opts)
      },
      async pull (controller) {
        const { value, done } = await iterator.next()
        if (done) {
          controller.close()
        } else {
          controller.enqueue(value)
        }
      },
      cancel () {
        iterator.return()
      }
    })
  }

  get streamURL () {
    if (!this._client._server) throw new Error('No server created')
    return `${this._client._server.pathname}/${this._torrent.infoHash}/${this.path}`
  }

  streamTo (elem) {
    elem.src = this.streamURL
    return elem
  }

  includes (piece) {
    return this._startPiece <= piece && this._endPiece >= piece
  }

  _destroy () {
    this._destroyed = true
    this._torrent = null

    for (const fileStream of this._fileStreams) {
      fileStream.destroy()
    }
    this._fileStreams.clear()
    for (const iterator of this._iterators) {
      iterator.destroy()
    }
    this._iterators.clear()
  }
}