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'use strict'
const fs = require('fs')
const fse = require('fs-extra')
const fetch = require('node-fetch')
const promisifyProcess = require('./promisify-process')
const tempy = require('tempy')
const path = require('path')
const sanitize = require('sanitize-filename')
const { spawn } = require('child_process')
const { promisify } = require('util')
const writeFile = promisify(fs.writeFile)
const copyFile = fse.copy
function makeHTTPDownloader() {
return function(arg) {
const dir = tempy.directory()
const out = dir + '/' + sanitize(decodeURIComponent(path.basename(arg)))
return fetch(arg)
.then(response => response.buffer())
.then(buffer => writeFile(out, buffer))
.then(() => out)
}
}
function makeYouTubeDownloader() {
return function(arg) {
const tempDir = tempy.directory()
const opts = [
'--quiet',
'--extract-audio',
'--audio-format', 'mp3',
'--output', tempDir + '/dl.%(ext)s',
arg
]
return promisifyProcess(spawn('youtube-dl', opts))
.then(() => tempDir + '/dl.mp3')
}
}
function makeLocalDownloader() {
// Usually we'd just return the given argument in a local
// downloader, which is efficient, since there's no need to
// copy a file from one place on the hard drive to another.
// But reading from a separate drive (e.g. a USB stick or a
// CD) can take a lot longer than reading directly from the
// computer's own drive, so this downloader copies the file
// to a temporary file on the computer's drive.
// Ideally, we'd be able to check whether a file is on the
// computer's main drive mount or not before going through
// the steps to copy, but I'm not sure if there's a way to
// do that (and it's even less likely there'd be a cross-
// platform way).
return function(arg) {
// It's possible the downloader argument start with the "file://" protocol
// string; in that case we'll want to snip it off and URL-decode the
// string.
const fileProto = 'file://'
if (arg.startsWith(fileProto)) {
arg = decodeURIComponent(arg.slice(fileProto.length))
}
const dir = tempy.directory()
// TODO: Is it necessary to sanitize here?
// Haha, the answer to "should I sanitize" is probably always YES..
const base = path.basename(arg, path.extname(arg))
const file = dir + '/' + sanitize(base) + '.mp3'
return copyFile(arg, file)
.then(() => file)
}
}
function makeLocalEchoDownloader() {
return function(arg) {
// Since we're grabbing the file from the local file system, there's no
// need to download or copy it!
return arg
}
}
function makePowerfulDownloader(downloader, maxAttempts = 5) {
// This should totally be named better..
return async function recursive(arg, attempts = 0) {
try {
return await downloader(arg)
} catch(err) {
if (attempts < maxAttempts) {
console.warn('Failed - attempting again:', arg)
return await recursive(arg, attempts + 1)
} else {
throw err
}
}
}
}
module.exports = {
makeHTTPDownloader,
makeYouTubeDownloader,
makeLocalDownloader,
makePowerfulDownloader,
getDownloaderFor(arg) {
if (arg.startsWith('http://') || arg.startsWith('https://')) {
if (arg.includes('youtube.com')) {
return makeYouTubeDownloader()
} else {
return makeHTTPDownloader()
}
} else {
return makeLocalDownloader()
}
}
}
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