import { useMutation, useQuery, useQueryClient } from '@tanstack/react-query';
import { File, Paths } from 'expo-file-system';
import { useCallback, useEffect, useRef, useState } from 'react';
import { AppState, type AppStateStatus } from 'react-native';

import type { WsConnectionState } from '@/core/ws/types';

import { conversationApi } from './api';
import {
  acquireBackgroundConversationWs,
  disposeAllBackgroundConversationWs,
  disposeBackgroundConversationWs,
  releaseConversationWsUi,
} from './conversation-ws-background-pool';
import { conversationMessagesRepository } from './conversation-messages-repository';
import { conversationKeys } from './query-keys';
import { takePreparedRealtimeSession } from './prepared-session-registry';
import {
  type ErrorCallback,
  type StreamingTextCallback,
  type TtsSegmentPayload,
  type RealtimeSession,
} from './realtime-session';
import {
  type ConversationListItem,
  type MessageItem,
  type StreamingAgentMessage,
} from './types';
import { voiceSegmentStore } from '@/features/voice/voice-segment-store';

/** Expo `File` 需要规范 `file://` URI；部分录音 API 会返回裸绝对路径。 */
function ensureFileUri(uri: string): string {
  const u = uri.trim();
  if (u.startsWith('file://')) return u;
  if (u.startsWith('/')) return `file://${u}`;
  return u;
}

function guessAudioExtension(uri: string): string {
  const pathOnly = uri.split('?')[0] ?? uri;
  const m = /\.[^/.]+$/u.exec(pathOnly);
  return m ? m[0] : '.m4a';
}

/**
 * 使用主包 `File`/`Paths`（见 Expo 文档：新 File 与旧 readAsStringAsync 互操作示例）。
 * 先 copy 到 cache 下唯一文件名再 `base64()`，避免直接读源路径时偶发读到陈旧/错误内容。
 */
async function readRecordingPayload(uri: string): Promise<string> {
  const resolved = ensureFileUri(uri);
  const source = new File(resolved);
  if (!source.exists) {
    throw new Error('recording file missing');
  }
  const stagedName = `voice-upload-${Date.now()}-${Math.random().toString(36).slice(2, 10)}${guessAudioExtension(resolved)}`;
  const staged = new File(Paths.cache, stagedName);
  try {
    source.copy(staged);
  } catch {
    return await source.base64();
  }
  try {
    return await staged.base64();
  } finally {
    try {
      staged.delete();
    } catch {
      // ignore
    }
  }
}

// ─── Query hooks ───

// TODO: 连接不上后端时 isLoading 可能一直为 true，需加超时或展示错误态
export function useConversations() {
  return useQuery({
    queryKey: conversationKeys.lists(),
    queryFn: () => conversationApi.list(),
  });
}

export function useConversationDetail(conversationId: string) {
  return useQuery({
    queryKey: conversationKeys.detail(conversationId),
    queryFn: () => conversationApi.detail(conversationId),
    enabled: !!conversationId,
  });
}

export function useMessages(conversationId: string) {
  return useQuery({
    queryKey: conversationKeys.messages(conversationId),
    queryFn: () => conversationMessagesRepository.loadMessages(conversationId),
    enabled: !!conversationId,
  });
}

// ─── Mutation hooks ───

export function useCreateConversation() {
  const queryClient = useQueryClient();

  return useMutation({
    mutationFn: () => conversationApi.create(),
    onSuccess: (newConversation) => {
      queryClient.setQueryData<ConversationListItem[]>(
        conversationKeys.lists(),
        (old) => {
          const startedMs = Date.parse(newConversation.started_at);
          const now = Date.now();
          const item: ConversationListItem = {
            id: newConversation.id,
            title: '岁月知己',
            avatarUrl: null,
            latestMessagePreview: '',
            latestMessageTime: now,
            startedAt: Number.isFinite(startedMs) ? startedMs : now,
            unreadCount: 0,
            isDefaultAssistant: true,
            hasUserMessage: false,
          };
          return [item, ...(old ?? [])];
        },
      );
    },
  });
}

export function useDeleteConversation() {
  const queryClient = useQueryClient();

  return useMutation({
    mutationFn: (conversationId: string) =>
      conversationApi.delete(conversationId),
    onSuccess: async (_, conversationId) => {
      disposeBackgroundConversationWs(conversationId);
      await voiceSegmentStore.clearConversation(conversationId);
      queryClient.setQueryData<ConversationListItem[]>(
        conversationKeys.lists(),
        (old) => old?.filter((item) => item.id !== conversationId),
      );
      queryClient.removeQueries({
        queryKey: conversationKeys.detail(conversationId),
      });
      queryClient.removeQueries({
        queryKey: conversationKeys.messages(conversationId),
      });
    },
  });
}

export function useEndConversation() {
  const queryClient = useQueryClient();

  return useMutation({
    mutationFn: (conversationId: string) => conversationApi.end(conversationId),
    onSuccess: (_, conversationId) => {
      queryClient.invalidateQueries({
        queryKey: conversationKeys.detail(conversationId),
      });
      queryClient.invalidateQueries({
        queryKey: conversationKeys.lists(),
      });
    },
  });
}

// ─── Realtime session hook ───

interface UseRealtimeSessionOptions {
  conversationId: string;
  enabled?: boolean;
  onTtsSegment?: (payload: TtsSegmentPayload) => void;
  /** 用户发出下一条文本/语音成功后调用，用于恢复接受 TTS 片段（打断后丢弃迟到片段） */
  onTtsPlaybackResume?: () => void;
  /** 本条发送是否请求了「本轮助手朗读」，用于仅在该轮自动播放 WS TTS */
  onUserSendTtsPreference?: (requestedTts: boolean) => void;
}

const MIN_RECORDING_DURATION_SEC = 1;

function generateUUID(): string {
  return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, (c) => {
    const r = (Math.random() * 16) | 0;
    const v = c === 'x' ? r : (r & 0x3) | 0x8;
    return v.toString(16);
  });
}

interface RealtimeSessionState {
  connectionState: WsConnectionState;
  streamingMessage: StreamingAgentMessage | null;
  /** 已发出用户消息，尚未收到助手首段流式文本（用于「正在回复」气泡） */
  awaitingAssistantReply: boolean;
  error: string | null;
  sendText: (text: string, options?: { ttsThisTurn?: boolean }) => void;
  sendVoiceMessage: (
    uri: string,
    durationMs: number,
    options?: { ttsThisTurn?: boolean },
  ) => Promise<boolean>;
  sendEndConversation: () => void;
  sendTtsCancel: () => void;
  requestAssistantSegmentTts: (body: {
    assistantMessageId: string;
    segmentIndex: number;
    segmentText?: string;
  }) => boolean;
}

export function useRealtimeSession({
  conversationId,
  enabled = true,
  onTtsSegment,
  onTtsPlaybackResume,
  onUserSendTtsPreference,
}: UseRealtimeSessionOptions): RealtimeSessionState {
  const queryClient = useQueryClient();
  const sessionRef = useRef<RealtimeSession | null>(null);
  const uiRef = useRef({
    handleStreamingText: (() => {}) as StreamingTextCallback,
    handleError: (() => {}) as ErrorCallback,
    onTtsSegment: undefined as
      | ((payload: TtsSegmentPayload) => void)
      | undefined,
  });

  const [connectionState, setConnectionState] =
    useState<WsConnectionState>('disconnected');
  const [streamingMessage, setStreamingMessage] =
    useState<StreamingAgentMessage | null>(null);
  const [awaitingAssistantReply, setAwaitingAssistantReply] = useState(false);
  const [error, setError] = useState<string | null>(null);

  const [foregroundResumeGeneration, setForegroundResumeGeneration] =
    useState(0);
  const needsResumeAfterBackgroundRef = useRef(false);

  const handleStreamingText: StreamingTextCallback = useCallback(
    (text, isComplete) => {
      if (text.trim().length > 0) {
        setAwaitingAssistantReply(false);
      }
      if (isComplete) {
        setStreamingMessage(null);
        setAwaitingAssistantReply(false);
        return;
      }
      setStreamingMessage({ text, isComplete });
    },
    [],
  );

  const handleError: ErrorCallback = useCallback((message) => {
    setAwaitingAssistantReply(false);
    setError(message);
  }, []);

  uiRef.current.handleStreamingText = handleStreamingText;
  uiRef.current.handleError = handleError;
  uiRef.current.onTtsSegment = onTtsSegment;

  useEffect(() => {
    if (!enabled || !conversationId) return;

    const sub = AppState.addEventListener('change', (next: AppStateStatus) => {
      if (next === 'background') {
        needsResumeAfterBackgroundRef.current = true;
        disposeAllBackgroundConversationWs();
        sessionRef.current = null;
        setConnectionState('disconnected');
        setStreamingMessage(null);
        setAwaitingAssistantReply(false);
      } else if (next === 'active' && needsResumeAfterBackgroundRef.current) {
        needsResumeAfterBackgroundRef.current = false;
        setForegroundResumeGeneration((g) => g + 1);
      }
    });

    return () => sub.remove();
  }, [enabled, conversationId]);

  useEffect(() => {
    if (!enabled || !conversationId) return;

    const prepared = takePreparedRealtimeSession(conversationId);
    const session = acquireBackgroundConversationWs(
      conversationId,
      queryClient,
      prepared,
    );

    session.attachUiCallbacks({
      onStreamingText: (text, isComplete) => {
        uiRef.current.handleStreamingText(text, isComplete);
      },
      onTtsSegment: (payload) => uiRef.current.onTtsSegment?.(payload),
      onError: (message, code) => uiRef.current.handleError(message, code),
      onStateChange: setConnectionState,
    });

    sessionRef.current = session;
    setConnectionState(session.getConnectionState());

    return () => {
      releaseConversationWsUi(session);
      sessionRef.current = null;
      setConnectionState('disconnected');
      setStreamingMessage(null);
      setAwaitingAssistantReply(false);
    };
  }, [conversationId, enabled, queryClient, foregroundResumeGeneration]);

  const sendText = useCallback(
    (text: string, options?: { ttsThisTurn?: boolean }) => {
      if (!sessionRef.current) return;

      const sent = sessionRef.current.sendText(text, options);
      if (!sent) {
        setError('消息发送失败，连接未就绪');
        return;
      }

      onUserSendTtsPreference?.(options?.ttsThisTurn === true);

      setAwaitingAssistantReply(true);
      onTtsPlaybackResume?.();

      const localId = `pending_${Date.now()}`;

      queryClient.setQueryData<MessageItem[]>(
        conversationKeys.messages(conversationId),
        (old) => {
          const msg: MessageItem = {
            id: localId,
            conversationId,
            content: text,
            senderType: 'user',
            timestamp: Date.now(),
            messageType: 'text',
          };
          return [...(old ?? []), msg];
        },
      );

      queryClient.setQueryData<ConversationListItem[]>(
        conversationKeys.lists(),
        (old) => {
          if (!old) return old;
          return old.map((item) =>
            item.id === conversationId
              ? { ...item, hasUserMessage: true }
              : item,
          );
        },
      );
    },
    [conversationId, queryClient, onTtsPlaybackResume, onUserSendTtsPreference],
  );

  const sendVoiceMessage = useCallback(
    async (
      uri: string,
      durationMs: number,
      options?: { ttsThisTurn?: boolean },
    ): Promise<boolean> => {
      const session = sessionRef.current;
      if (!session) return false;

      const durationSec = Math.round(durationMs / 1000);
      if (durationSec < MIN_RECORDING_DURATION_SEC) return false;

      try {
        const base64 = await readRecordingPayload(uri);
        if (!base64) return false;

        const voiceSessionId = generateUUID();
        const sent = session.sendAudioSegment(base64, 0, {
          voiceSessionId,
          clientSegmentId: `${voiceSessionId}-0`,
          isLast: true,
          duration: durationSec,
          ttsThisTurn: options?.ttsThisTurn,
        });
        if (!sent) {
          setError('语音发送失败，连接未就绪');
          return false;
        }

        onUserSendTtsPreference?.(options?.ttsThisTurn === true);

        setAwaitingAssistantReply(true);
        const localId = `pending_voice_${Date.now()}`;
        await voiceSegmentStore.recordSentSegment({
          voiceSessionId,
          conversationId,
          fileUri: uri,
          durationMs,
        });
        queryClient.setQueryData<MessageItem[]>(
          conversationKeys.messages(conversationId),
          (old) => {
            const msg: MessageItem = {
              id: localId,
              conversationId,
              content: '',
              senderType: 'user',
              timestamp: Date.now(),
              messageType: 'voice',
              voiceSessionId,
              durationSeconds: durationSec,
              audioUri: uri,
            };
            return [...(old ?? []), msg];
          },
        );

        queryClient.setQueryData<ConversationListItem[]>(
          conversationKeys.lists(),
          (old) => {
            if (!old) return old;
            return old.map((item) =>
              item.id === conversationId
                ? { ...item, hasUserMessage: true }
                : item,
            );
          },
        );
        onTtsPlaybackResume?.();
        return true;
      } catch {
        setError('语音文件读取失败');
        return false;
      }
    },
    [conversationId, queryClient, onTtsPlaybackResume, onUserSendTtsPreference],
  );

  const sendEndConversation = useCallback(() => {
    sessionRef.current?.sendEndConversation();
  }, []);

  const sendTtsCancel = useCallback(() => {
    sessionRef.current?.sendTtsCancel();
  }, []);

  const requestAssistantSegmentTts = useCallback(
    (body: {
      assistantMessageId: string;
      segmentIndex: number;
      segmentText?: string;
    }) => sessionRef.current?.requestAssistantSegmentTts(body) ?? false,
    [],
  );

  return {
    connectionState,
    streamingMessage,
    awaitingAssistantReply,
    error,
    sendText,
    sendVoiceMessage,
    sendEndConversation,
    sendTtsCancel,
    requestAssistantSegmentTts,
  };
}