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+/*
+ * Copyright (C) 2019-2020 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 <https://www.gnu.org/licenses/>.
+ */
+
+class TextToSpeechAudio {
+ constructor(text, voice) {
+ this.text = text;
+ this.voice = voice;
+ this._utterance = null;
+ this._volume = 1;
+ }
+
+ get currentTime() {
+ return 0;
+ }
+ set currentTime(value) {
+ // NOP
+ }
+
+ get volume() {
+ return this._volume;
+ }
+ set volume(value) {
+ this._volume = value;
+ if (this._utterance !== null) {
+ this._utterance.volume = value;
+ }
+ }
+
+ play() {
+ try {
+ if (this._utterance === null) {
+ this._utterance = new SpeechSynthesisUtterance(this.text || '');
+ this._utterance.lang = 'ja-JP';
+ this._utterance.volume = this._volume;
+ this._utterance.voice = this.voice;
+ }
+
+ speechSynthesis.cancel();
+ speechSynthesis.speak(this._utterance);
+ } catch (e) {
+ // NOP
+ }
+ }
+
+ pause() {
+ try {
+ speechSynthesis.cancel();
+ } catch (e) {
+ // NOP
+ }
+ }
+}
+
+class AudioSystem {
+ constructor({getAudioUri}) {
+ this._cache = new Map();
+ this._cacheSizeMaximum = 32;
+ this._getAudioUri = getAudioUri;
+
+ if (typeof speechSynthesis !== 'undefined') {
+ // speechSynthesis.getVoices() will not be populated unless some API call is made.
+ speechSynthesis.addEventListener('voiceschanged', this._onVoicesChanged.bind(this));
+ }
+ }
+
+ async getDefinitionAudio(definition, sources, details) {
+ const key = `${definition.expression}:${definition.reading}`;
+ const cacheValue = this._cache.get(definition);
+ if (typeof cacheValue !== 'undefined') {
+ const {audio, uri, source} = cacheValue;
+ return {audio, uri, source};
+ }
+
+ for (const source of sources) {
+ const uri = await this._getAudioUri(definition, source, details);
+ if (uri === null) { continue; }
+
+ try {
+ const audio = await this._createAudio(uri, details);
+ this._cacheCheck();
+ this._cache.set(key, {audio, uri, source});
+ return {audio, uri, source};
+ } catch (e) {
+ // NOP
+ }
+ }
+
+ throw new Error('Could not create audio');
+ }
+
+ createTextToSpeechAudio({text, voiceUri}) {
+ const voice = this._getTextToSpeechVoiceFromVoiceUri(voiceUri);
+ if (voice === null) {
+ throw new Error('Invalid text-to-speech voice');
+ }
+ return new TextToSpeechAudio(text, voice);
+ }
+
+ _onVoicesChanged() {
+ // NOP
+ }
+
+ async _createAudio(uri, details) {
+ const ttsParameters = this._getTextToSpeechParameters(uri);
+ if (ttsParameters !== null) {
+ if (typeof details === 'object' && details !== null) {
+ if (details.tts === false) {
+ throw new Error('Text-to-speech not permitted');
+ }
+ }
+ return this.createTextToSpeechAudio(ttsParameters);
+ }
+
+ return await this._createAudioFromUrl(uri);
+ }
+
+ _createAudioFromUrl(url) {
+ return new Promise((resolve, reject) => {
+ const audio = new Audio(url);
+ audio.addEventListener('loadeddata', () => {
+ const duration = audio.duration;
+ if (duration === 5.694694 || duration === 5.720718) {
+ // Hardcoded values for invalid audio
+ reject(new Error('Could not retrieve audio'));
+ } else {
+ resolve(audio);
+ }
+ });
+ audio.addEventListener('error', () => reject(audio.error));
+ });
+ }
+
+ _getTextToSpeechVoiceFromVoiceUri(voiceUri) {
+ try {
+ for (const voice of speechSynthesis.getVoices()) {
+ if (voice.voiceURI === voiceUri) {
+ return voice;
+ }
+ }
+ } catch (e) {
+ // NOP
+ }
+ return null;
+ }
+
+ _getTextToSpeechParameters(uri) {
+ const m = /^tts:[^#?]*\?([^#]*)/.exec(uri);
+ if (m === null) { return null; }
+
+ const searchParameters = new URLSearchParams(m[1]);
+ const text = searchParameters.get('text');
+ const voiceUri = searchParameters.get('voice');
+ return (text !== null && voiceUri !== null ? {text, voiceUri} : null);
+ }
+
+ _cacheCheck() {
+ const removeCount = this._cache.size - this._cacheSizeMaximum;
+ if (removeCount <= 0) { return; }
+
+ const removeKeys = [];
+ for (const key of this._cache.keys()) {
+ removeKeys.push(key);
+ if (removeKeys.length >= removeCount) { break; }
+ }
+
+ for (const key of removeKeys) {
+ this._cache.delete(key);
+ }
+ }
+}