1 files changed, 69 insertions, 0 deletions
diff --git a/src/loop-play.js b/src/loop-play.js
new file mode 100644
index 0000000..e59fbc2
--- /dev/null
+++ b/src/loop-play.js
@@ -0,0 +1,69 @@
+'use strict'
+
+const fs = require('fs')
+
+const { spawn } = require('child_process')
+const { promisify } = require('util')
+const fetch = require('node-fetch')
+const sanitize = require('sanitize-filename')
+const promisifyProcess = require('./promisify-process')
+
+const writeFile = promisify(fs.writeFile)
+const unlink = promisify(fs.unlink)
+
+module.exports = async function loopPlay(fn) {
+  // Looping play function. Takes one argument, the "pick" function,
+  // which returns a track to play. Preemptively downloads the next
+  // track while the current one is playing for seamless continuation
+  // from one song to the next. Stops when the result of the pick
+  // function is null (or similar).
+
+  async function downloadNext() {
+    const picked = fn()
+
+    if (picked == null) {
+      return false
+    }
+
+    const [ title, href ] = picked
+    console.log(`Downloading ${title}..\n${href}`)
+
+    const wavFile = `.${sanitize(title)}.wav`
+
+    const res = await fetch(href)
+    const buffer = await res.buffer()
+    await writeFile('./.temp-track', buffer)
+
+    try {
+      await convert('./.temp-track', wavFile)
+    } catch(err) {
+      console.warn('Failed to convert ' + title)
+      console.warn('Selecting a new track\n')
+
+      return await downloadNext()
+    }
+
+    await unlink('./.temp-track')
+
+    return wavFile
+  }
+
+  let wavFile = await downloadNext()
+
+  while (wavFile) {
+    const nextPromise = downloadNext()
+    await playFile(wavFile)
+    await unlink(wavFile)
+    wavFile = await nextPromise
+  }
+}
+
+function convert(fromFile, toFile) {
+  const avconv = spawn('avconv', ['-y', '-i', fromFile, toFile])
+  return promisifyProcess(avconv, false)
+}
+
+function playFile(file) {
+  const play = spawn('play', [file])
+  return promisifyProcess(play)
+}