/**
 * React hooks for WebSocket — typed event subscription,
 * room management, typing indicators, and connection status.
 */
import { useEffect, useRef, useCallback, useState } from 'react';
import { WsClient } from './client';
import type { ConnectionStatus, WsClientConfig } from './client';
import { useWsStore } from './store';
import type { WsOutEventName, WsOutEvent } from './types/outbound';
import type { RoomId } from './types/core';

/** Global singleton WsClient instance. */
let globalClient: WsClient | null = null;
/** Monotonically increasing ID — incremented each time initWsClient creates a new client.
 *  Used as a React dependency so hooks re-register listeners after client re-init. */
let clientId = 0;

/** Get the global WsClient instance, or null if not initialized. */
export function getWsClient(): WsClient | null {
  return globalClient;
}

/** Get the current client identity counter — changes when client is re-initialized. */
export function getWsClientId(): number {
  return clientId;
}

/** Initialize the global WsClient with config. */
export function initWsClient(config: WsClientConfig): WsClient {
  if (globalClient) globalClient.destroy();
  globalClient = new WsClient(config);
  clientId++;

  // Bridge status changes to Zustand store
  globalClient.onStatusChange((status) => {
    useWsStore.getState().setStatus(status);
    if (status === 'reconnecting') {
      useWsStore.getState().setReconnecting(true);
    } else {
      useWsStore.getState().setReconnecting(false);
    }
    if (status === 'connected') {
      useWsStore.getState().setLastError(null);
    }
  });

  // Bridge error events to store
  globalClient.on('error', (event) => {
    useWsStore.getState().setLastError(event.message);
  });

  return globalClient;
}

// ── Initialization hook ─────────────────────────────────

export interface UseWsInitOptions {
  url: string;
  backendUrl?: string;
  mode?: 'socketio' | 'raw-ws';
  autoReconnect?: boolean;
  token?: string;
  connectOnMount?: boolean;
}

/** Initialize and optionally auto-connect the WsClient on mount. */
export function useWsInit(options: UseWsInitOptions): WsClient {
  const [client] = useState(() => initWsClient(options));

  useEffect(() => {
    if (options.connectOnMount !== false) {
      client.connect();
    }
    return () => {
      client.disconnect();
    };
  // eslint-disable-next-line react-hooks/exhaustive-deps
  }, []);

  return client;
}

// ── Connection status hook ──────────────────────────────

/** Reactive connection status — updates via Zustand. */
export function useWsStatus(): ConnectionStatus {
  return useWsStore((s) => s.status);
}

/** Whether the client is connected. */
export function useWsConnected(): boolean {
  return useWsStore((s) => s.status === 'connected');
}

/** Last error from the server. */
export function useWsError(): string | null {
  return useWsStore((s) => s.lastError);
}

// ── Typed event subscription hook ───────────────────────

/** Subscribe to a typed outbound event. Auto-cleanup on unmount. Re-registers on client re-init. */
export function useWsEvent<N extends WsOutEventName>(
  eventName: N,
  callback: (data: Extract<WsOutEvent, { type: N }>) => void,
): void {
  const cbRef = useRef(callback);
  useEffect(() => {
    cbRef.current = callback;
  });

  useEffect(() => {
    const client = getWsClient();
    if (!client) return;
    const handler = (data: Extract<WsOutEvent, { type: N }>) => cbRef.current(data);
    client.on(eventName, handler);
    return () => { client.off(eventName, handler); };
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [eventName, clientId]);
}

// ── Room subscription hook ──────────────────────────────

/** Subscribe to a room on mount, keep subscription alive on unmount/room-change. */
export function useRoomSubscription(roomId: RoomId | null): void {
  useEffect(() => {
    if (!roomId) return;
    const client = getWsClient();
    if (!client) return;
    client.joinRoom(roomId);
    useWsStore.getState().addSubscribedRoom(roomId);
    return () => {
      // Cleanup: unsubscribe and sync Zustand store on unmount
      client.leaveRoom(roomId);
      useWsStore.getState().removeSubscribedRoom(roomId);
    };
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [roomId, clientId]);
}

/** Get the set of currently subscribed rooms (reactive). */
export function useSubscribedRooms(): Set<RoomId> {
  return useWsStore((s) => s.subscribedRooms);
}

// ── Typing indicator hook ───────────────────────────────

export interface TypingUser {
  user_id: string;
  username: string;
  avatar_url: string | null;
}

/** Track typing users in a room. Clears on unmount. */
export function useTypingIndicator(roomId: RoomId | null): TypingUser[] {
  const [typingUsers, setTypingUsers] = useState<Map<string, TypingUser>>(new Map());

  useWsEvent('typing_start', (event) => {
    if (event.room_id === roomId && roomId) {
      const data = event.data;
      setTypingUsers((prev) => {
        const next = new Map(prev);
        next.set(data.user, { user_id: data.user, username: data.username, avatar_url: data.avatar_url ?? null });
        return next;
      });
    }
  });

  useWsEvent('typing_stop', (event) => {
    if (event.room_id === roomId && roomId) {
      setTypingUsers((prev) => {
        const next = new Map(prev);
        next.delete(event.data.user);
        return next;
      });
    }
  });

  return [...typingUsers.values()];
}

// ── Notification count hook ─────────────────────────────

/** Track unread notification count via notify_created events. */
export function useNotificationCount(): number {
  const [count, setCount] = useState(0);

  useWsEvent('notify_created', () => {
    setCount((c) => c + 1);
  });

  useWsEvent('notify_read', () => {
    setCount((c) => Math.max(0, c - 1));
  });

  return count;
}

// ── Convenience message sender hook ─────────────────────

/** Returns stable send functions bound to a room. */
export function useRoomSender(roomId: RoomId | null) {
  const client = getWsClient();

  const sendMessage = useCallback(
    (content: string, opts?: { content_type?: string; thread?: string; in_reply_to?: string }) => {
      if (!roomId || !client) return;
      client.sendMessage(roomId, content, opts);
    },
    [roomId, client],
  );

  const sendTypingStart = useCallback(() => {
    if (!roomId || !client) return;
    client.sendTypingStart(roomId);
  }, [roomId, client]);

  const sendTypingStop = useCallback(() => {
    if (!roomId || !client) return;
    client.sendTypingStop(roomId);
  }, [roomId, client]);

  const sendReadReceipt = useCallback(
    (lastReadSeq: number) => {
      if (!roomId || !client) return;
      client.sendReadReceipt(roomId, lastReadSeq);
    },
    [roomId, client],
  );

  const addReaction = useCallback(
    (messageId: string, emoji: string) => {
      if (!roomId || !client) return;
      client.addReaction(roomId, messageId, emoji);
    },
    [roomId, client],
  );

  const removeReaction = useCallback(
    (messageId: string, emoji: string) => {
      if (!roomId || !client) return;
      client.removeReaction(roomId, messageId, emoji);
    },
    [roomId, client],
  );

  return { sendMessage, sendTypingStart, sendTypingStop, sendReadReceipt, addReaction, removeReaction };
}