talkie-speaker.js

/*
This file is part of Talkie -- text-to-speech browser extension button.
<https://joelpurra.com/projects/talkie/>

Copyright (c) 2016, 2017 Joel Purra <https://joelpurra.com/>

Talkie 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.

Talkie 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 Talkie.  If not, see <https://www.gnu.org/licenses/>.
*/

import {
    logDebug,
    logInfo,
    logError,
} from "../shared/log";

import {
    promiseTry,
    promiseSeries,
    promiseTimeout,
} from "../shared/promise";

import {
    flatten,
} from "../shared/basic";

import {
    knownEvents,
} from "../shared/events";

import {
    resolveVoice,
    rateRange,
    pitchRange,
} from "../shared/voices";

import TextHelper from "./text-helper";

export default class TalkieSpeaker {
    // https://dvcs.w3.org/hg/speech-api/raw-file/tip/speechapi.html#tts-section
    // https://dvcs.w3.org/hg/speech-api/raw-file/tip/speechapi.html#examples-synthesis
    // https://developer.mozilla.org/en-US/docs/Web/API/Web_Speech_API/Using_the_Web_Speech_API#Speech_synthesis
    constructor(broadcaster, shouldContinueSpeakingProvider, contentLogger) {
        this.broadcaster = broadcaster;
        this.shouldContinueSpeakingProvider = shouldContinueSpeakingProvider;
        this.contentLogger = contentLogger;

        this.resetSynthesizer();

        this.MAX_UTTERANCE_TEXT_LENGTH = 100;
    }

    getSynthesizerFromBrowser() {
        return promiseTry(
            () => {
                logDebug("Start", "getSynthesizerFromBrowser", "Pre-requisites check");

                if (!("speechSynthesis" in window) || typeof window.speechSynthesis.getVoices !== "function" || typeof window.speechSynthesis.speak !== "function") {
                    throw new Error("The browser does not support speechSynthesis.");
                }

                if (!("SpeechSynthesisUtterance" in window)) {
                    throw new Error("The browser does not support SpeechSynthesisUtterance.");
                }

                logDebug("Done", "getSynthesizerFromBrowser", "Pre-requisites check");
            })
            .then(() => {
                logDebug("Start", "getSynthesizerFromBrowser");

                // NOTE: the speech synthesizer can only be used in Chrome after the voices have been loaded.
                const synthesizer = window.speechSynthesis;

                // https://github.com/mdn/web-speech-api/blob/gh-pages/speak-easy-synthesis/script.js#L33-L36
                // NOTE: The synthesizer will work right away in Firefox.
                const voices = synthesizer.getVoices();

                if (Array.isArray(voices) && voices.length > 0) {
                    logDebug("Done", "getSynthesizerFromBrowser (direct)");

                    return synthesizer;
                }

                const asyncSynthesizerInitialization = new Promise(
                    (resolve, reject) => {
                        try {
                            logDebug("Start", "getSynthesizerFromBrowser (event-based)");

                            const handleVoicesChanged = () => {
                                delete synthesizer.onerror;
                                delete synthesizer.onvoiceschanged;

                                logDebug("Variable", "synthesizer", synthesizer);

                                logDebug("Done", "getSynthesizerFromBrowser (event-based)");

                                return resolve(synthesizer);
                            };

                            const handleError = (event) => {
                                delete synthesizer.onerror;
                                delete synthesizer.onvoiceschanged;

                                logError("getSynthesizerFromBrowser", event);

                                return reject(null);
                            };

                            // NOTE: Chrome needs to wait for the onvoiceschanged event before using the synthesizer.
                            synthesizer.onvoiceschanged = handleVoicesChanged;
                            synthesizer.onerror = handleError;
                        } catch (error) {
                            return reject(error);
                        }
                    }
                );

                return promiseTimeout(asyncSynthesizerInitialization, 1000)
                    .catch((error) => {
                        delete synthesizer.onerror;
                        delete synthesizer.onvoiceschanged;

                        if (error && error.name === "PromiseTimeout") {
                            logDebug("Done", "getSynthesizerFromBrowser (timeout)", "asyncSynthesizerInitialization", error);

                            // NOTE: assume the synthesizer has somehow been initialized without triggering the onvoiceschanged event.
                            return synthesizer;
                        }

                        logError("getSynthesizerFromBrowser", "asyncSynthesizerInitialization", error);

                        throw error;
                    });
            }
        )
            .then((synthesizer) => {
                // NOTE: only for logging purposes.
                const voices = synthesizer.getVoices();

                logDebug("Variable", "getSynthesizerFromBrowser", "voices[]", voices.length, voices);

                return synthesizer;
            });
    }

    resetSynthesizer() {
        return promiseTry(
            () => {
                delete this.cachedSynthesizer;
                this.cachedSynthesizer = null;

                return undefined;
            }
        );
    }

    getSynthesizer() {
        return promiseTry(
            () => {
                if (this.cachedSynthesizer !== null) {
                    return this.cachedSynthesizer;
                }

                return this.getSynthesizerFromBrowser()
                    .then((synthesizer) => {
                        this.cachedSynthesizer = synthesizer;

                        return this.cachedSynthesizer;
                    });
            }
        );
    }

    getAllVoices() {
        return promiseTry(
            () => this.getSynthesizer()
                .then((synthesizer) => {
                    return synthesizer.getVoices();
                })
        );
    }

    stopSpeaking() {
        return promiseTry(
            () => {
                logDebug("Start", "stopSpeaking");

                return this.getSynthesizer()
                    .then((synthesizer) => {
                        const eventData = {};

                        return Promise.resolve()
                            .then(() => this.broadcaster.broadcastEvent(knownEvents.stopSpeaking, eventData))
                            .then(() => {
                                synthesizer.cancel();

                                // Reset the system to resume playback, just to be nice to the world.
                                synthesizer.resume();

                                logDebug("Done", "stopSpeaking");

                                return undefined;
                            });
                    });
            }
        );
    }

    speakPartOfText(utterance) {
        return this.getSynthesizer()
            .then((synthesizer) => new Promise(
                (resolve, reject) => {
                    try {
                        logDebug("Start", "speakPartOfText", `Speak text part (length ${utterance.text.length}): "${utterance.text}"`);

                        const handleEnd = (event) => {
                            delete utterance.onend;
                            delete utterance.onerror;

                            logDebug("End", "speakPartOfText", `Speak text part (length ${utterance.text.length}) spoken in ${event.elapsedTime} milliseconds.`);

                            return resolve();
                        };

                        const handleError = (event) => {
                            delete utterance.onend;
                            delete utterance.onerror;

                            logError("speakPartOfText", `Speak text part (length ${utterance.text.length})`, event);

                            return reject();
                        };

                        utterance.onend = handleEnd;
                        utterance.onerror = handleError;

                        // The actual act of speaking the text.
                        synthesizer.speak(utterance);

                        // NOTE: pause/resume suggested (for longer texts) in Chrome bug reports, trying it for shorter texts as well.
                        // https://bugs.chromium.org/p/chromium/issues/detail?id=335907
                        // https://bugs.chromium.org/p/chromium/issues/detail?id=369472
                        synthesizer.pause();
                        synthesizer.resume();

                        logDebug("Variable", "synthesizer", synthesizer);

                        logDebug("Done", "speakPartOfText", `Speak text part (length ${utterance.text.length})`);
                    } catch (error) {
                        return reject(error);
                    }
                }
            )
        );
    }

    getActualVoice(mappedVoice) {
        return promiseTry(
            () => {
                logDebug("Start", "getActualVoice", mappedVoice);

                return resolveVoice(mappedVoice)
                    .then((actualVoice) => {
                        logDebug("Done", "getActualVoice", mappedVoice, actualVoice);

                        return actualVoice;
                    })
                    .catch((error) => {
                        logError("getActualVoice", mappedVoice, error);

                        throw error;
                    });
            }
        );
    }

    splitAndSpeak(text, voice) {
        return promiseTry(
            () => {
                logDebug("Start", "splitAndSpeak", `Speak text (length ${text.length}): "${text}"`);

                const speakingEventData = {
                    text: text,
                    voice: voice.name,
                    language: voice.lang,
                };

                return Promise.resolve()
                    .then(() => this.broadcaster.broadcastEvent(knownEvents.beforeSpeaking, speakingEventData))
                    .then(() => {
                        // HACK: keep a reference to the utterance attached to the window. Not sure why this helps, but might prevent garbage collection or something.
                        delete window.talkieUtterance;

                        return undefined;
                    })
                    .then(() => this.getActualVoice(voice))
                    .then((actualVoice) => {
                        const paragraphs = TextHelper.splitTextToParagraphs(text);
                        const cleanTextParts = paragraphs.map((paragraph) => TextHelper.splitTextToSentencesOfMaxLength(paragraph, this.MAX_UTTERANCE_TEXT_LENGTH));
                        const textParts = flatten(cleanTextParts);

                        const shouldContinueSpeaking = this.shouldContinueSpeakingProvider.getShouldContinueSpeakingProvider();

                        const textPartsPromises = textParts.map((textPart) => () => {
                            const speakingPartEventData = {
                                textPart: textPart,
                                voice: voice.name,
                                language: voice.lang,
                            };

                            return shouldContinueSpeaking()
                                .then((continueSpeaking) => {
                                    if (continueSpeaking) {
                                        return Promise.resolve()
                                            .then(() => this.broadcaster.broadcastEvent(knownEvents.beforeSpeakingPart, speakingPartEventData))
                                            .then(() => {
                                                const utterance = new window.SpeechSynthesisUtterance(textPart);

                                                utterance.voice = actualVoice;
                                                utterance.rate = voice.rate || rateRange.default;
                                                utterance.pitch = voice.pitch || pitchRange.default;

                                                logDebug("Variable", "utterance", utterance);

                                                // HACK: keep a reference to the utterance attached to the window. Not sure why this helps, but might prevent garbage collection or something.
                                                window.talkieUtterance = utterance;

                                                return utterance;
                                            })
                                            .then((utterance) => this.speakPartOfText(utterance))
                                            .then(() => this.broadcaster.broadcastEvent(knownEvents.afterSpeakingPart, speakingPartEventData));
                                    }

                                    return undefined;
                                });
                        });

                        return promiseSeries(textPartsPromises);
                    })
                    .then(() => {
                        // HACK: keep a reference to the utterance attached to the window. Not sure why this helps, but might prevent garbage collection or something.
                        delete window.talkieUtterance;

                        return undefined;
                    })
                    .then(() => this.broadcaster.broadcastEvent(knownEvents.afterSpeaking, speakingEventData));
            }
        );
    }

    speakTextInVoice(text, voice) {
        return promiseTry(
            () => Promise.resolve()
                .then(() => {
                    this.contentLogger.logToPage(`Speaking text (length ${text.length}, ${voice.name}, ${voice.lang}): ${text}`)
                        .catch((error) => {
                            // NOTE: swallowing any logToPage() errors.
                            // NOTE: reduced logging for known tab/page access problems.
                            if (error && typeof error.message === "string" && error.message.startsWith("Cannot access")) {
                                logDebug("getSelectionsWithValidTextAndDetectedLanguageAndEffectiveLanguage", "Error", error);
                            } else {
                                logInfo("getSelectionsWithValidTextAndDetectedLanguageAndEffectiveLanguage", "Error", error);
                            }

                            return undefined;
                        });

                    return this.splitAndSpeak(text, voice);
                })
                .then(() => {
                    logDebug("Done", "speakTextInVoice", `Speak text (length ${text.length}, ${voice.name}, ${voice.lang})`);

                    return undefined;
                })
        );
    }

    speakTextInLanguage(text, language) {
        return promiseTry(
            () => {
                const voice = {
                    name: null,
                    lang: language,
                };

                return Promise.resolve()
                    .then(() => {
                        return this.speakTextInVoice(text, voice);
                    })
                    .then(() => logDebug("Done", "speakTextInLanguage", `Speak text (length ${text.length}, ${language})`));
            }
        );
    }
}