YouTube support. Closes #46

src/youtube.js

@@ -0,0 +1,143 @@
+const { GLib, GObject, Gst, Soup } = imports.gi;
+const ByteArray = imports.byteArray;
+const Debug = imports.src.debug;
+
+const { debug } = Debug;
+
+var YouTubeClient = GObject.registerClass(
+class ClapperYouTubeClient extends Soup.Session
+{
+    _init()
+    {
+        super._init({
+            timeout: 5,
+        });
+    }
+
+    getVideoInfoPromise(videoId)
+    {
+        return new Promise(async (resolve, reject) => {
+            const url = `https://www.youtube.com/get_video_info?video_id=${videoId}&el=embedded`;
+            let tries = 2;
+
+            while(tries--) {
+                debug(`obtaining YouTube video info: ${videoId}`);
+
+                const info = await this._getInfoPromise(url).catch(debug);
+                if(!info) {
+                    debug(`failed, remaining tries: ${tries}`);
+                    continue;
+                }
+
+                /* Check if video is playable */
+                if(
+                    !info.playabilityStatus
+                    || !info.playabilityStatus.status === 'OK'
+                )
+                    return reject(new Error('video is not playable'));
+
+                /* Check if data contains streaming URIs */
+                if(!info.streamingData)
+                    return reject(new Error('video response data is missing URIs'));
+
+                return resolve(info);
+            }
+
+            reject(new Error('could not obtain YouTube video info'));
+        });
+    }
+
+    getBestCombinedUri(info)
+    {
+        if(
+            !info.streamingData.formats
+            || !info.streamingData.formats.length
+        )
+            return null;
+
+        const combinedStream = info.streamingData.formats[
+            info.streamingData.formats.length - 1
+        ];
+
+        if(!combinedStream || !combinedStream.url)
+            return null;
+
+        return combinedStream.url;
+    }
+
+    _getInfoPromise(url)
+    {
+        return new Promise((resolve, reject) => {
+            const message = Soup.Message.new('GET', url);
+            let data = '';
+
+            const chunkSignal = message.connect('got-chunk', (msg, chunk) => {
+                debug(`got chunk of data, length: ${chunk.length}`);
+
+                const chunkData = chunk.get_data();
+                data += (chunkData instanceof Uint8Array)
+                    ? ByteArray.toString(chunkData)
+                    : chunkData;
+            });
+
+            this.queue_message(message, (session, msg) => {
+                msg.disconnect(chunkSignal);
+
+                debug('got message response');
+
+                if(msg.status_code !== 200)
+                    return reject(new Error(`response code: ${msg.status_code}`));
+
+                debug('parsing video info JSON');
+
+                const gstUri = Gst.Uri.from_string('?' + data);
+
+                if(!gstUri)
+                    return reject(new Error('could not convert query to URI'));
+
+                const playerResponse = gstUri.get_query_value('player_response');
+
+                if(!playerResponse)
+                    return reject(new Error('no player response in query'));
+
+                let info = null;
+
+                try { info = JSON.parse(playerResponse); }
+                catch(err) { debug(err.message) }
+
+                if(!info)
+                    return reject(new Error('could not parse video info JSON'));
+
+                debug('successfully parsed video info JSON');
+
+                resolve(info);
+            });
+        });
+    }
+});
+
+function checkYouTubeUri(uri)
+{
+    const gstUri = Gst.Uri.from_string(uri);
+    gstUri.normalize();
+
+    const host = gstUri.get_host();
+
+    let success = true;
+    let videoId = null;
+
+    switch(host) {
+        case 'www.youtube.com':
+        case 'youtube.com':
+            videoId = gstUri.get_query_value('v');
+            break;
+        case 'youtu.be':
+            videoId = gstUri.get_path_segments()[1];
+            break;
+        default:
+            success = false;
+            break;
+    }
+
+    return [success, videoId];
+}