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const EventEmitter = require('events')
const { PassThrough } = require('stream')
const path = require('path')
const render = require('render-media')
const streamToBlob = require('stream-to-blob')
const streamToBlobURL = require('stream-to-blob-url')
const streamToBuffer = require('stream-with-known-length-to-buffer')
const queueMicrotask = require('queue-microtask')
const rangeParser = require('range-parser')
const mime = require('mime')
const eos = require('end-of-stream')
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._serviceWorker = torrent.client.serviceWorker
}
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')
streamToBlob(this.createReadStream(), this._getMimeType())
.then(
blob => cb(null, blob),
err => cb(err)
)
}
getBlobURL (cb) {
if (typeof window === 'undefined') throw new Error('browser-only method')
streamToBlobURL(this.createReadStream(), this._getMimeType())
.then(
blobUrl => cb(null, blobUrl),
err => cb(err)
)
}
appendTo (elem, opts, cb) {
if (typeof window === 'undefined') throw new Error('browser-only method')
render.append(this, elem, opts, cb)
}
renderTo (elem, opts, cb) {
if (typeof window === 'undefined') throw new Error('browser-only method')
render.render(this, elem, opts, cb)
}
_serve (req) {
const res = {
status: 200,
headers: {
// Support range-requests
'Accept-Ranges': 'bytes',
'Content-Type': mime.getType(this.name),
'Cache-Control': 'no-cache, no-store, must-revalidate, max-age=0',
Expires: '0'
},
body: req.method === 'HEAD' ? '' : 'STREAM'
}
// force the browser to download the file if if it's opened in a new tab
if (req.destination === 'document') {
res.headers['Content-Type'] = 'application/octet-stream'
res.headers['Content-Disposition'] = 'attachment'
res.body = 'DOWNLOAD'
}
// `rangeParser` returns an array of ranges, or an error code (number) if
// there was an error parsing the range.
let range = rangeParser(this.length, req.headers.range || '')
if (range.constructor === Array) {
res.status = 206 // indicates that range-request was understood
// no support for multi-range request, just use the first range
range = range[0]
res.headers['Content-Range'] = `bytes ${range.start}-${range.end}/${this.length}`
res.headers['Content-Length'] = `${range.end - range.start + 1}`
} else {
res.headers['Content-Length'] = this.length
}
const stream = req.method === 'GET' && this.createReadStream(range)
let pipe = null
if (stream) {
this.emit('stream', { stream, req, file: this }, piped => {
pipe = piped
// piped stream might not close the original filestream on close/error, this is agressive but necessary
eos(piped, () => {
if (piped) piped.destroy()
stream.destroy()
})
})
}
return [res, pipe || stream, pipe && stream]
}
getStreamURL (cb = () => {}) {
if (typeof window === 'undefined') throw new Error('browser-only method')
if (!this._serviceWorker) throw new Error('No worker registered')
if (this._serviceWorker.state !== 'activated') throw new Error('Worker isn\'t activated')
const workerPath = this._serviceWorker.scriptURL.substr(0, this._serviceWorker.scriptURL.lastIndexOf('/') + 1).slice(window.location.origin.length)
const url = `${workerPath}webtorrent/${this._torrent.infoHash}/${encodeURI(this.path)}`
cb(null, url)
}
streamTo (elem, cb = () => {}) {
if (typeof window === 'undefined') throw new Error('browser-only method')
if (!this._serviceWorker) throw new Error('No worker registered')
if (this._serviceWorker.state !== 'activated') throw new Error('Worker isn\'t activated')
const workerPath = this._serviceWorker.scriptURL.substr(0, this._serviceWorker.scriptURL.lastIndexOf('/') + 1).slice(window.location.origin.length)
elem.src = `${workerPath}webtorrent/${this._torrent.infoHash}/${encodeURI(this.path)}`
cb(null, elem)
}
_getMimeType () {
return render.mime[path.extname(this.name).toLowerCase()]
}
_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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