Refactor main.js: playback and subtitles controllers

renderer/lib/torrent-player.js

@@ -2,7 +2,8 @@ module.exports = {
   isPlayable,
   isVideo,
   isAudio,
-  isPlayableTorrent
+  isPlayableTorrent,
+  pickFileToPlay
 }
 
 var path = require('path')
@@ -43,3 +44,25 @@ function isAudio (file) {
 function isPlayableTorrent (torrentSummary) {
   return torrentSummary.files && torrentSummary.files.some(isPlayable)
 }
+
+// Picks the default file to play from a list of torrent or torrentSummary files
+// Returns an index or undefined, if no files are playable
+function pickFileToPlay (files) {
+  // first, try to find the biggest video file
+  var videoFiles = files.filter(isVideo)
+  if (videoFiles.length > 0) {
+    var largestVideoFile = videoFiles.reduce(function (a, b) {
+      return a.length > b.length ? a : b
+    })
+    return files.indexOf(largestVideoFile)
+  }
+
+  // if there are no videos, play the first audio file
+  var audioFiles = files.filter(isAudio)
+  if (audioFiles.length > 0) {
+    return files.indexOf(audioFiles[0])
+  }
+
+  // no video or audio means nothing is playable
+  return undefined
+}