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#!/usr/bin/env node
'use strict'
const MAX_DOWNLOAD_ATTEMPTS = 5
const fetch = require('node-fetch')
const $ = require('cheerio')
function crawl(absURL, attempts = 0) {
// Recursively crawls a given URL, following every link to a deeper path and
// recording all links in a tree (in the same format playlists use). Makes
// multiple attempts to download failed paths.
return fetch(absURL)
.then(
res => res.text().then(text => {
const links = getHTMLLinks(text)
const verbose = process.argv.includes('--verbose')
return Promise.all(links.map(link => {
const [ title, href ] = link
if (href.endsWith('/')) {
// It's a directory!
if (verbose) console.log("[Dir] " + absURL + href)
return crawl(absURL + href)
.then(res => [title, res])
} else {
// It's a file!
if (verbose) console.log("[File] " + absURL + href)
return Promise.resolve([title, absURL + href])
}
}))
}),
err => {
console.warn("Failed to download: " + absURL)
if (attempts < MAX_DOWNLOAD_ATTEMPTS) {
console.warn(
"Trying again. Attempt " + (attempts + 1) +
"/" + MAX_DOWNLOAD_ATTEMPTS + "..."
)
return crawl(absURL, attempts + 1)
} else {
console.error(
"We've hit the download attempt limit (" +
MAX_DOWNLOAD_ATTEMPTS + "). Giving up on this path."
)
throw 'FAILED_DOWNLOAD'
}
}
)
.catch(error => {
if (error === 'FAILED_DOWNLOAD') {
// Debug logging for this is already handled above.
return []
} else {
throw error
}
})
}
function getHTMLLinks(text) {
// Never parse HTML with a regex!
return $(text).find('a').get().map(a => {
const $a = $(a)
return [$a.text(), $a.attr('href')]
})
}
if (process.argv.length === 2) {
console.log("Usage: http-music-crawl-recursive http://.../example/path/")
console.log("..or, npm run crawl-recursive -- http://...")
} else {
let url = process.argv[2]
if (!(url.endsWith('/'))) {
url = url + '/'
}
crawl(url)
.then(res => console.log(JSON.stringify(res, null, 2)))
.catch(err => console.error(err))
}
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