Implement audio fallbacks

2 files changed, 76 insertions, 23 deletions

diff --git a/ext/mixed/js/audio.js b/ext/mixed/js/audio.js
new file mode 100644
index 00000000..b905140c
--- /dev/null
+++ b/ext/mixed/js/audio.js
@@ -0,0 +1,60 @@
+/*
+ * Copyright (C) 2019  Alex Yatskov <alex@foosoft.net>
+ * Author: Alex Yatskov <alex@foosoft.net>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+
+function audioGetFromUrl(url) {
+    return new Promise((resolve, reject) => {
+        const audio = new Audio(url);
+        audio.addEventListener('loadeddata', () => {
+            if (audio.duration === 5.694694 || audio.duration === 5.720718) {
+                // Hardcoded values for invalid audio
+                reject(new Error('Could not retrieve audio'));
+            } else {
+                resolve(audio);
+            }
+        });
+        audio.addEventListener('error', () => reject(audio.error));
+    });
+}
+
+async function audioGetFromSources(expression, sources, optionsContext, createAudioObject, cache=null) {
+    const key = `${expression.expression}:${expression.reading}`;
+    if (cache !== null && cache.hasOwnProperty(expression)) {
+        return cache[key];
+    }
+
+    for (let i = 0, ii = sources.length; i < ii; ++i) {
+        const source = sources[i];
+        const url = await apiAudioGetUrl(expression, source, optionsContext);
+        if (url === null) {
+            continue;
+        }
+
+        try {
+            const audio = createAudioObject ? await audioGetFromUrl(url) : null;
+            const result = {audio, url, source};
+            if (cache !== null) {
+                cache[key] = result;
+            }
+            return result;
+        } catch (e) {
+            // NOP
+        }
+    }
+    return {audio: null, source: null};
+}
diff --git a/ext/mixed/js/display.js b/ext/mixed/js/display.js
index c1224084..8d4e1e68 100644
--- a/ext/mixed/js/display.js
+++ b/ext/mixed/js/display.js
@@ -26,6 +26,8 @@ class Display {
         this.context = null;
         this.sequence = 0;
         this.index = 0;
+        this.audioPlaying = null;
+        this.audioFallback = null;
         this.audioCache = {};
         this.optionsContext = {};
         this.eventListeners = [];
@@ -404,33 +406,24 @@ class Display {
             this.setSpinnerVisible(true);
 
             const expression = expressionIndex === -1 ? definition : definition.expressions[expressionIndex];
-            let url = await apiAudioGetUrl(expression, this.options.audio.sources[0], this.optionsContext);
-            if (!url) {
-                url = '/mixed/mp3/button.mp3';
-            }
 
-            for (const key in this.audioCache) {
-                this.audioCache[key].pause();
+            if (this.audioPlaying !== null) {
+                this.audioPlaying.pause();
+                this.audioPlaying = null;
             }
 
-            const volume = this.options.audio.volume / 100.0;
-            let audio = this.audioCache[url];
-            if (audio) {
-                audio.currentTime = 0;
-                audio.volume = volume;
-                audio.play();
-            } else {
-                audio = new Audio(url);
-                audio.onloadeddata = () => {
-                    if (audio.duration === 5.694694 || audio.duration === 5.720718) {
-                        audio = new Audio('/mixed/mp3/button.mp3');
-                    }
-
-                    this.audioCache[url] = audio;
-                    audio.volume = volume;
-                    audio.play();
-                };
+            let {audio} = await audioGetFromSources(expression, this.options.audio.sources, this.optionsContext, true, this.audioCache);
+            if (audio === null) {
+                if (this.audioFallback === null) {
+                    this.audioFallback = new Audio('/mixed/mp3/button.mp3');
+                }
+                audio = this.audioFallback;
             }
+
+            this.audioPlaying = audio;
+            audio.currentTime = 0;
+            audio.volume = this.options.audio.volume / 100.0;
+            audio.play();
         } catch (e) {
             this.onError(e);
         } finally {