life-echo/app-expo/src/features/voice/hooks/use-player.ts

import { useAudioPlayer, useAudioPlayerStatus } from 'expo-audio';
import { useCallback, useEffect, useRef, useState } from 'react';

import { audioFocus } from '@/core/audio/audio-focus';

import type { PlaybackItem, PlayerStatus } from '../types';

interface UsePlayerResult {
  status: PlayerStatus;
  queueLength: number;
  enqueueTtsAudio: (audioBase64: string) => void;
  enqueue: (item: PlaybackItem) => void;
  stop: () => void;
}

/**
 * Self-contained audio playback hook with queue management.
 *
 * - Uses useAudioPlayer + useAudioPlayerStatus for native playback
 * - Detects playback completion to auto-advance the queue
 * - Coordinates with audioFocus for recording/playback mutual exclusion
 * - Subscribes to audioFocus owner changes to resume after recording ends
 */
export function usePlayer(): UsePlayerResult {
  const queueRef = useRef<PlaybackItem[]>([]);
  const [status, setStatus] = useState<PlayerStatus>('idle');
  const [queueLength, setQueueLength] = useState(0);
  const [currentSource, setCurrentSource] = useState<string | null>(null);
  const isPlayingRef = useRef(false);
  const wasBlockedByRecorderRef = useRef(false);
  const isPlayNextInProgressRef = useRef(false);

  const player = useAudioPlayer(currentSource);
  const playerStatus = useAudioPlayerStatus(player);

  // Start playback when a new source is set
  useEffect(() => {
    if (currentSource && player) {
      player.play();
      isPlayingRef.current = true;
    }
  }, [currentSource, player]);

  const playNext = useCallback(async () => {
    if (isPlayNextInProgressRef.current) return;
    isPlayNextInProgressRef.current = true;
    try {
      if (queueRef.current.length === 0) {
        setCurrentSource(null);
        setStatus('idle');
        setQueueLength(0);
        await audioFocus.release();
        return;
      }

      const acquired = await audioFocus.acquireForPlayback();
      if (!acquired) {
        setStatus('idle');
        return;
      }

      if (queueRef.current.length === 0) return;

      const next = queueRef.current.shift()!;
      setQueueLength(queueRef.current.length);
      setStatus('playing');
      setCurrentSource(next.uri);
    } finally {
      isPlayNextInProgressRef.current = false;
    }
  }, []);

  // Detect playback completion → advance queue
  useEffect(() => {
    if (!currentSource || !isPlayingRef.current) return;

    const { playing, currentTime, duration } = playerStatus;
    const finished = !playing && duration > 0 && currentTime >= duration - 0.05;

    if (finished) {
      isPlayingRef.current = false;
      playNext();
    }
  }, [playerStatus, currentSource, playNext]);

  // Subscribe to audioFocus owner changes for recorder → idle recovery
  useEffect(() => {
    const unsub = audioFocus.onOwnerChange((owner) => {
      if (owner === 'recorder') {
        wasBlockedByRecorderRef.current =
          queueRef.current.length > 0 || currentSource !== null;
      }

      if (owner === null && wasBlockedByRecorderRef.current) {
        wasBlockedByRecorderRef.current = false;
        if (queueRef.current.length > 0 && status === 'idle') {
          playNext();
        }
      }
    });

    return unsub;
  }, [status, currentSource, playNext]);

  const enqueue = useCallback(
    async (item: PlaybackItem) => {
      queueRef.current.push(item);
      setQueueLength(queueRef.current.length);

      if (status === 'idle' && !currentSource) {
        await playNext();
      }
    },
    [status, currentSource, playNext],
  );

  const enqueueTtsAudio = useCallback(
    (audioBase64: string) => {
      const uri = `data:audio/mp3;base64,${audioBase64}`;
      enqueue({ uri, label: 'TTS' });
    },
    [enqueue],
  );

  const stop = useCallback(async () => {
    queueRef.current = [];
    setQueueLength(0);
    isPlayingRef.current = false;

    if (player) {
      player.pause();
    }

    setCurrentSource(null);
    setStatus('idle');
    await audioFocus.release();
  }, [player]);

  return { status, queueLength, enqueueTtsAudio, enqueue, stop };
}