From 13902daedddce2b186518b8468ba22f1a689d54f Mon Sep 17 00:00:00 2001
From: DC <dcposch@dcpos.ch>
Date: Mon, 21 Mar 2016 17:49:19 -0700
Subject: [PATCH] Use largest image in torrent as the poster

...as a fallback, if no the torrent doesn't contain any video files
---
 renderer/index.js              |  5 +++--
 renderer/lib/torrent-poster.js | 34 ++++++++++++++++++++++++++--------
 2 files changed, 29 insertions(+), 10 deletions(-)

diff --git a/renderer/index.js b/renderer/index.js
index 01054815..810ace96 100644
--- a/renderer/index.js
+++ b/renderer/index.js
@@ -510,6 +510,7 @@ function updateTorrentProgress () {
   var changed = false
   state.client.torrents.forEach(function (torrent) {
     var torrentSummary = getTorrentSummary(torrent.infoHash)
+    if (!torrentSummary) return
     torrent.files.forEach(function (file, index) {
       var numPieces = file._endPiece - file._startPiece + 1
       var numPiecesPresent = 0
@@ -530,12 +531,12 @@ function updateTorrentProgress () {
 }
 
 function generateTorrentPoster (torrent, torrentSummary) {
-  torrentPoster(torrent, function (err, buf) {
+  torrentPoster(torrent, function (err, buf, extension) {
     if (err) return onWarning(err)
     // save it for next time
     mkdirp(config.CONFIG_POSTER_PATH, function (err) {
       if (err) return onWarning(err)
-      var posterFilePath = path.join(config.CONFIG_POSTER_PATH, torrent.infoHash + '.jpg')
+      var posterFilePath = path.join(config.CONFIG_POSTER_PATH, torrent.infoHash + extension)
       fs.writeFile(posterFilePath, buf, function (err) {
         if (err) return onWarning(err)
         // show the poster
diff --git a/renderer/lib/torrent-poster.js b/renderer/lib/torrent-poster.js
index 9e0f7463..087c6d0f 100644
--- a/renderer/lib/torrent-poster.js
+++ b/renderer/lib/torrent-poster.js
@@ -4,19 +4,32 @@ var captureVideoFrame = require('./capture-video-frame')
 var path = require('path')
 
 function torrentPoster (torrent, cb) {
-  // filter out file formats that the <video> tag definitely can't play
+  // First, try to use the largest video file
+  // Filter out file formats that the <video> tag definitely can't play
+  var videoFile = getLargestFileByExtension(torrent, ['.mp4', '.m4v', '.webm', '.mov', '.mkv'])
+  if (videoFile) return torrentPosterFromVideo(videoFile, torrent, cb)
+
+  // Second, try to use the largest image file
+  var imgFile = getLargestFileByExtension(torrent, ['.gif', '.jpg', '.png'])
+  if (imgFile) return torrentPosterFromImage(imgFile, torrent, cb)
+
+  // TODO: generate a waveform from the largest sound file
+  // Finally, admit defeat
+  return cb(new Error('Cannot generate a poster from any files in the torrent'))
+}
+
+function getLargestFileByExtension (torrent, extensions) {
   var files = torrent.files.filter(function (file) {
     var extname = path.extname(file.name)
-    return ['.mp4', '.m4v', '.webm', '.mov', '.mkv'].indexOf(extname) !== -1
+    return extensions.indexOf(extname) !== -1
   })
-
-  if (files.length === 0) return cb(new Error('cannot make screenshot for any files in torrent'))
-
-  // use largest file
-  var file = files.reduce(function (a, b) {
+  if (files.length === 0) return undefined
+  return files.reduce(function (a, b) {
     return a.length > b.length ? a : b
   })
+}
 
+function torrentPosterFromVideo (file, torrent, cb) {
   var index = torrent.files.indexOf(file)
 
   var server = torrent.createServer(0)
@@ -51,7 +64,12 @@ function torrentPoster (torrent, cb) {
 
       server.destroy()
 
-      cb(null, buf)
+      cb(null, buf, '.jpg')
     }
   }
 }
+
+function torrentPosterFromImage (file, torrent, cb) {
+  var extname = path.extname(file.name)
+  file.getBuffer((err, buf) => cb(err, buf, extname))
+}