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const EventEmitter = require('events')
const { PassThrough } = require('streamx')
const { BlobWriteStream } = require('fast-blob-stream')
const streamToBuffer = require('stream-with-known-length-to-buffer')
const queueMicrotask = require('queue-microtask')
const mime = require('mime')
const FileStream = require('./file-stream.js')
class File extends EventEmitter {
constructor (torrent, file) {
super()
this._torrent = torrent
this._destroyed = false
this._fileStreams = new Set()
this.name = file.name
this.path = file.path
this.length = file.length
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._server = torrent.client._server
}
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, false)
}
createReadStream (opts) {
if (this.length === 0) {
const empty = new PassThrough()
queueMicrotask(() => {
empty.end()
})
return empty
}
const fileStream = new FileStream(this, opts)
this._fileStreams.add(fileStream)
fileStream.once('close', () => {
this._fileStreams.delete(fileStream)
})
return fileStream
}
getBuffer (cb) {
streamToBuffer(this.createReadStream(), this.length, cb)
}
getBlob (cb) {
if (typeof window === 'undefined') throw new Error('browser-only method')
const writeStream = new BlobWriteStream(blob => {
cb(null, blob)
}, { mimeType: mime.getType(this.name) || 'application/octet-stream' })
this.createReadStream().pipe(writeStream)
}
getBlobURL (cb) {
this.getBlob((_err, blob) => {
cb(null, URL.createObjectURL(blob))
})
}
getStreamURL () {
if (!this._server) throw new Error('No server created')
const url = `${this._server.pathname}/${this._torrent.infoHash}/${encodeURI(this.path)}`
return url
}
streamTo (elem) {
elem.src = this.getStreamURL()
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()
}
}
module.exports = File
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