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

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

import { parseAssistantSplitListKey } from '@/features/conversation/message-split';

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

function isLaterSegmentOfSameAssistantBubble(
  current: PlaybackItem | null | undefined,
  incoming: PlaybackItem,
): boolean {
  if (incoming.kind !== 'tts_auto' || current?.kind !== 'tts_auto') {
    return false;
  }
  const a = parseAssistantSplitListKey(current.messageRef?.listKey);
  const b = parseAssistantSplitListKey(incoming.messageRef?.listKey);
  if (!a || !b) return false;
  return (
    a.messageId === b.messageId && b.segmentIndex > a.segmentIndex
  );
}

interface UsePlayerResult {
  status: PlayerStatus;
  queueLength: number;
  /** Current playback source URI (file, https, or data URL). */
  currentSource: string | null;
  /** 当前正在播放的队列项（含 kind / messageRef），队列为空或未开始为 null */
  currentPlaybackItem: PlaybackItem | null;
  enqueue: (item: PlaybackItem) => void;
  /** Replace queue and play this item (e.g. user voice bubble vs other sources). */
  enqueueExclusive: (item: PlaybackItem) => Promise<void>;
  /** Pause native playback without draining queue（与 stop 清空队列不同）。 */
  pausePlayback: () => void;
  /** Continue after pausePlayback（需 status === 'paused'） */
  resumePlayback: () => 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 [currentPlaybackItem, setCurrentPlaybackItem] =
    useState<PlaybackItem | null>(null);
  const isPlayingRef = useRef(false);
  const wasBlockedByRecorderRef = useRef(false);
  const isPlayNextInProgressRef = useRef(false);
  /** 供 `enqueue` 判断「同一条助手消息的下一段 TTS」；不依赖 React state 闭包陈旧。 */
  const currentPlaybackItemRef = useRef<PlaybackItem | null>(null);
  /** 与 `status` 同步；`pausePlayback` 等在同一事件循环内立即更新，避免 WS 紧跟着 `enqueue(tts_auto)` 时读到陈旧 `playing`。 */
  const statusRef = useRef<PlayerStatus>('idle');
  /** 同步反映「当前是否正在播放某条 URI」；enqueue 不能依赖 state，否则 await stop() 后仍为陈旧闭包。 */
  const playbackActiveUriRef = useRef<string | null>(null);
  /** 当前 source 是否已进入过 playing=true，避免换源瞬间 playerStatus 仍带上一首的 duration 而误判「已播完」。 */
  const trackHasPlayedRef = useRef(false);

  /** 远程 HTTPS 需先下载再解码，否则再读（仅 URL、无 base64）可能无声；本地/data URL 保持 false */
  const playerOptions = useMemo(() => {
    const remote =
      typeof currentSource === 'string' &&
      (currentSource.startsWith('https://') ||
        currentSource.startsWith('http://'));
    return {
      downloadFirst: remote,
      // Expo's native player deactivates AVAudioSession on pause by default.
      // We manage session ownership centrally via audioFocus, so keep it active
      // until audioFocus.release() explicitly tears it down.
      keepAudioSessionActive: true,
    };
  }, [currentSource]);

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

  useEffect(() => {
    statusRef.current = status;
  }, [status]);

  useEffect(() => {
    currentPlaybackItemRef.current = currentPlaybackItem;
  }, [currentPlaybackItem]);

  /**
   * 必须在 `isLoaded` 之后再 `play()`。
   * expo-audio 在 `downloadFirst: true` 时先用 null 建 player，再在内部 effect 里异步
   * `resolveSourceWithDownload` 后 `replace()`（见 node_modules/expo-audio/build/ExpoAudio.js）。
   * 若仅在 `currentSource` 变化时立刻 `play()`，会在 replace 完成前播放 → 远程 URL（再读）无声。
   */
  useEffect(() => {
    if (!currentSource || !player) return;
    if (!playerStatus.isLoaded) return;
    /** 先于 isLoaded「抢暂停」时需保留暂停，避免本条自动 play 覆盖 pause */
    if (status === 'paused') return;
    player.play();
    isPlayingRef.current = true;
  }, [currentSource, player, playerStatus.isLoaded, status]);

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

      const acquired = await audioFocus.acquireForPlayback();
      if (!acquired) {
        /**
         * 录音占用时 acquire 失败且队列尚未 shift；若用户进入会话前焦点已在
         * `recorder`，可能不会再次触发 `onOwnerChange('recorder')`，旧的
         * `wasBlockedByRecorderRef` 不会被置位，录音结束后也不会重试 playNext。
         */
        wasBlockedByRecorderRef.current = true;
        statusRef.current = 'idle';
        setStatus('idle');
        return;
      }

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

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

  useEffect(() => {
    if (playerStatus.playing) {
      trackHasPlayedRef.current = true;
    }
  }, [playerStatus.playing]);

  // Detect playback completion → advance queue（必须曾 playing，避免换源瞬间沿用上一条的 duration/currentTime）
  useEffect(() => {
    if (status === 'paused') return;
    if (!currentSource || !isPlayingRef.current) return;

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

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

  const pausePlayback = useCallback(() => {
    setStatus((s) => {
      if (s !== 'playing') return s;
      if (player) {
        player.pause();
      }
      isPlayingRef.current = false;
      statusRef.current = 'paused';
      return 'paused';
    });
  }, [player]);

  const resumePlayback = useCallback(async () => {
    if (status !== 'paused') return;
    const acquired = await audioFocus.acquireForPlayback();
    if (!acquired) {
      statusRef.current = 'idle';
      setStatus('idle');
      return;
    }
    if (!player) return;
    if (!playerStatus.isLoaded) return;
    player.play();
    statusRef.current = 'playing';
    setStatus('playing');
    isPlayingRef.current = true;
  }, [status, player, playerStatus.isLoaded]);

  // 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 &&
          playbackActiveUriRef.current === null
        ) {
          void playNext();
        }
      }
    });

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

  const enqueue = useCallback(
    async (item: PlaybackItem) => {
      /**
       * 用户在助手自动朗读中途点暂停时，`playbackActiveUriRef` 仍指向当前条，
       * 后续 `tts_auto` 默认堆在队列里且不会 `playNext`。
       * 无分段 listKey 时：新片段到达表示「另一条 / 最新一条」应只播它 → 清暂停态与队列。
       * 有 `{uuid}_seg_{n}` 且 n 递增：同一落库助手消息的多段 TTS → 只入队，不抢轨。
       */
      const skipPausedClearForSplitContinue =
        item.kind === 'tts_auto' &&
        statusRef.current === 'paused' &&
        isLaterSegmentOfSameAssistantBubble(
          currentPlaybackItemRef.current,
          item,
        );

      if (
        item.kind === 'tts_auto' &&
        statusRef.current === 'paused' &&
        !skipPausedClearForSplitContinue
      ) {
        queueRef.current = [];
        setQueueLength(0);
        isPlayingRef.current = false;
        if (player) {
          player.pause();
        }
        playbackActiveUriRef.current = null;
        setCurrentPlaybackItem(null);
        setCurrentSource(null);
        statusRef.current = 'idle';
        setStatus('idle');
        await audioFocus.releaseIfOwnedBy('player');
      }

      queueRef.current.push(item);
      setQueueLength(queueRef.current.length);

      const shouldKick =
        queueRef.current.length === 1 && playbackActiveUriRef.current === null;

      if (shouldKick) {
        await playNext();
      }
    },
    [playNext, player],
  );

  const enqueueExclusive = useCallback(
    async (item: PlaybackItem) => {
      queueRef.current = [item];
      setQueueLength(1);
      isPlayingRef.current = false;
      if (player) {
        player.pause();
      }
      playbackActiveUriRef.current = null;
      setCurrentPlaybackItem(null);
      setCurrentSource(null);
      statusRef.current = 'idle';
      setStatus('idle');
      await audioFocus.releaseIfOwnedBy('player');
      await playNext();
    },
    [player, playNext],
  );

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

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

    playbackActiveUriRef.current = null;
    setCurrentPlaybackItem(null);
    setCurrentSource(null);
    statusRef.current = 'idle';
    setStatus('idle');
    await audioFocus.releaseIfOwnedBy('player');
  }, [player]);

  return {
    status,
    queueLength,
    currentSource,
    currentPlaybackItem,
    enqueue,
    enqueueExclusive,
    pausePlayback,
    resumePlayback,
    stop,
  };
}