Implement audio fallbacks

1 files changed, 60 insertions, 0 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};
+}