tasks/app/src/main/java/com/todoroo/astrid/voice/VoiceOutputAssistant.java

package com.todoroo.astrid.voice;

import android.content.Context;
import android.media.AudioManager;
import android.speech.tts.TextToSpeech;
import android.speech.tts.TextToSpeech.OnInitListener;
import dagger.hilt.android.qualifiers.ApplicationContext;
import java.util.HashMap;
import java.util.Locale;
import java.util.UUID;
import javax.inject.Inject;
import timber.log.Timber;

/** @author Arne Jans */
public class VoiceOutputAssistant implements OnInitListener {

  private final Context context;

  private TextToSpeech mTts;
  private boolean isTTSInitialized;
  private String lastTextToSpeak;

  @Inject
  public VoiceOutputAssistant(@ApplicationContext Context context) {
    this.context = context;
  }

  public boolean isTTSInitialized() {
    return isTTSInitialized;
  }

  public void initTTS() {
    if (mTts == null) {
      mTts = new TextToSpeech(context, this);
      Timber.d("Initialized %s", mTts);
    }
  }

  public void speak(String textToSpeak) {
    if (mTts != null && isTTSInitialized) {
      final String id = UUID.randomUUID().toString();
      Timber.d("%s: %s (%s)", mTts, textToSpeak, id);
      mTts.setOnUtteranceCompletedListener(
          utteranceId -> {
            Timber.d("%s: onUtteranceCompleted", utteranceId);
            if (utteranceId.equals(id)) {
              shutdown();
            }
          });
      HashMap<String, String> params = new HashMap<>();
      params.put(
          TextToSpeech.Engine.KEY_PARAM_STREAM, String.valueOf(AudioManager.STREAM_NOTIFICATION));
      params.put(TextToSpeech.Engine.KEY_PARAM_UTTERANCE_ID, id);
      mTts.speak(textToSpeak, TextToSpeech.QUEUE_ADD, params);
    } else {
      lastTextToSpeak = textToSpeak;
      initTTS();
    }
  }

  @Override
  public void onInit(int status) {
    // status can be either TextToSpeech.SUCCESS or TextToSpeech.ERROR.
    if (status == TextToSpeech.SUCCESS && mTts != null) {
      // Set preferred language to US english.
      // Note that a language may not be available, and the result will indicate this.
      int result = mTts.setLanguage(Locale.getDefault());
      // Try this someday for some interesting results.
      // int result mTts.setLanguage(Locale.FRANCE);
      if (result == TextToSpeech.LANG_MISSING_DATA) {
        Timber.e("Language data missing");
      } else if (result == TextToSpeech.LANG_NOT_SUPPORTED) {
        Timber.e("Language not supported");
      } else {
        // Check the documentation for other possible result codes.
        // For example, the language may be available for the locale,
        // but not for the specified country and variant.

        mTts.speak("", 0, null);

        // The TTS engine has been successfully initialized.
        isTTSInitialized = true;
        // if this request came from speak, then speak it and reset the memento
        if (lastTextToSpeak != null) {
          speak(lastTextToSpeak);
          lastTextToSpeak = null;
        }
      }
    } else {
      Timber.e("Could not initialize TextToSpeech.");
    }
  }

  public void shutdown() {
    if (mTts != null && isTTSInitialized) {
      try {
        mTts.shutdown();
        Timber.d("Shutdown %s", mTts);
        mTts = null;
        isTTSInitialized = false;
      } catch (VerifyError e) {
        Timber.e(e);
      }
    }
  }
}