import { computed, onUnmounted, ref, shallowRef } from 'vue';
import type { ConversationSessionDto } from '@mento/shared';
import { api } from '@/lib/api';

export type ChatMessage = {
  id: string;
  roomId: string;
  senderId: string;
  content: string;
  type: 'text' | 'image' | 'voice';
  createdAt: string;
  reply: string | null;
  optimistic?: boolean;
};

const PAGE_SIZE = 50;

let socket: WebSocket | null = null;
let sessionCache: ConversationSessionDto | null = null;
const status = ref<'idle' | 'connecting' | 'open' | 'closed'>('idle');
const messages = shallowRef<ChatMessage[]>([]);
const activeRoomId = ref('');
let pingTimer: ReturnType<typeof setInterval> | null = null;

function messageTs(item: ChatMessage): number {
  const t = new Date(item.createdAt).getTime();
  return Number.isNaN(t) ? 0 : t;
}

/** قدیمی → جدید (آخرین پیام پایین لیست) */
function sortAsc(items: ChatMessage[]): ChatMessage[] {
  return [...items].sort((a, b) => {
    const d = messageTs(a) - messageTs(b);
    if (d !== 0) return d;
    return a.id.localeCompare(b.id);
  });
}

function normalizeIncoming(
  raw: Record<string, unknown>,
  roomFallback: string,
): ChatMessage | null {
  const base =
    raw.message && typeof raw.message === 'object'
      ? (raw.message as Record<string, unknown>)
      : raw;
  const content = String(base.content ?? base.text ?? base.body ?? '').trim();
  if (!content && !base.attachments) return null;
  const id = String(base.id ?? base.message_id ?? '').trim();
  return {
    id: id || `tmp-${Date.now()}-${Math.random().toString(36).slice(2, 8)}`,
    roomId: String(base.room_id ?? raw.room_id ?? roomFallback),
    senderId: String(
      base.sender_id ?? base.user_id ?? base.from_user_id ?? raw.sender_id ?? '',
    ),
    content,
    type: (String(base.type_content ?? base.type ?? 'text') as ChatMessage['type']) || 'text',
    createdAt: String(
      base.created_at ?? base.createdAt ?? raw.created_at ?? new Date().toISOString(),
    ),
    reply: base.reply ? String(base.reply) : null,
  };
}

/** ادغام: همان id جایگزین می‌شود؛ optimistic مشابه با echo سوکت یکی می‌شود */
function mergeMessages(incoming: ChatMessage, list: ChatMessage[]): ChatMessage[] {
  const byId = list.findIndex((m) => m.id === incoming.id);
  if (byId >= 0) {
    const next = [...list];
    next[byId] = { ...list[byId], ...incoming, optimistic: false };
    return sortAsc(next);
  }

  // echo سوکت بعد از optimistic با همان متن/فرستنده/اتاق
  const optimisticIdx = list.findIndex(
    (m) =>
      m.optimistic &&
      m.roomId === incoming.roomId &&
      m.senderId === incoming.senderId &&
      m.content === incoming.content,
  );
  if (optimisticIdx >= 0) {
    const next = [...list];
    next[optimisticIdx] = {
      ...list[optimisticIdx],
      ...incoming,
      optimistic: false,
    };
    return sortAsc(next);
  }

  return sortAsc([...list, incoming]);
}

async function ensureSession(): Promise<ConversationSessionDto> {
  if (sessionCache) return sessionCache;
  const { data } = await api.get<ConversationSessionDto>('/conversations/session');
  sessionCache = data;
  return data;
}

function clearPing() {
  if (pingTimer) {
    clearInterval(pingTimer);
    pingTimer = null;
  }
}

function disconnectSocket() {
  clearPing();
  if (socket) {
    socket.close();
    socket = null;
  }
  status.value = 'closed';
}

function onSocketMessage(event: MessageEvent) {
  const raw = String(event.data ?? '').trim();
  if (!raw || raw === 'pong' || raw === 'ping') return;
  try {
    const parsed = JSON.parse(raw) as Record<string, unknown>;
    const type = String(parsed.type ?? '').toLowerCase();
    if (type === 'seen' || type === 'typing' || type === 'read' || type === 'pong') return;
    const msg = normalizeIncoming(parsed, activeRoomId.value);
    if (!msg || !activeRoomId.value || msg.roomId !== activeRoomId.value) return;
    messages.value = mergeMessages(msg, messages.value);
  } catch {
    // ignore
  }
}

async function connectSocket() {
  const session = await ensureSession();
  if (socket?.readyState === WebSocket.OPEN) return;

  disconnectSocket();
  status.value = 'connecting';
  socket = new WebSocket(session.wsUrl);

  socket.addEventListener('open', () => {
    status.value = 'open';
    pingTimer = setInterval(() => {
      if (socket?.readyState === WebSocket.OPEN) socket.send('ping');
    }, 15000);
  });

  socket.addEventListener('close', () => {
    status.value = 'closed';
    clearPing();
  });

  socket.addEventListener('message', onSocketMessage);

  await new Promise<void>((resolve, reject) => {
    if (!socket) return reject(new Error('socket missing'));
    const t = setTimeout(() => reject(new Error('ws timeout')), 12000);
    socket.addEventListener(
      'open',
      () => {
        clearTimeout(t);
        resolve();
      },
      { once: true },
    );
    socket.addEventListener(
      'error',
      () => {
        clearTimeout(t);
        reject(new Error('ws error'));
      },
      { once: true },
    );
  });
}

export function useOrgChat() {
  const loadingMessages = ref(false);

  async function loadMessages(roomId: string) {
    activeRoomId.value = roomId;
    loadingMessages.value = true;
    try {
      const session = await ensureSession();
      await connectSocket();
      const params = new URLSearchParams({
        api_key: new URL(session.wsUrl).searchParams.get('api_key') ?? '',
        room_id: roomId,
        user_id: session.chatUserId,
        limit: String(PAGE_SIZE),
        offset: '0',
      });
      const url = `${session.messagesBaseUrl}/api/messages?${params.toString()}`;
      const res = await fetch(url, { headers: { Accept: 'application/json' }, cache: 'no-store' });
      if (!res.ok) throw new Error('messages failed');
      const body = await res.json();
      const list = Array.isArray(body) ? body : body?.data ?? [];
      const normalized = list
        .map((item: Record<string, unknown>) => normalizeIncoming(item, roomId))
        .filter(Boolean) as ChatMessage[];
      messages.value = sortAsc(normalized);
    } finally {
      loadingMessages.value = false;
    }
  }

  async function sendText(roomId: string, text: string, reply: string | null = null) {
    const trimmed = text.trim();
    if (!trimmed) return;
    await connectSocket();
    if (!socket || socket.readyState !== WebSocket.OPEN) throw new Error('ws not open');
    const session = await ensureSession();
    const id = crypto.randomUUID();
    const payload: Record<string, string> = {
      id,
      type: 'text',
      room_id: roomId,
      content: trimmed,
    };
    if (reply) payload.reply = reply;
    const optimistic: ChatMessage = {
      id,
      roomId,
      senderId: session.chatUserId,
      content: trimmed,
      type: 'text',
      createdAt: new Date().toISOString(),
      reply,
      optimistic: true,
    };
    messages.value = mergeMessages(optimistic, messages.value);
    socket.send(JSON.stringify(payload));
    sendRead(roomId);
  }

  function sendRead(roomId: string) {
    if (!socket || socket.readyState !== WebSocket.OPEN) return;
    socket.send(JSON.stringify({ type: 'read', room_id: roomId }));
  }

  function resetSession() {
    sessionCache = null;
    disconnectSocket();
    messages.value = [];
    activeRoomId.value = '';
  }

  onUnmounted(() => {
    disconnectSocket();
  });

  return {
    status: computed(() => status.value),
    messages: computed(() => messages.value),
    loadingMessages,
    loadMessages,
    sendText,
    sendRead,
    resetSession,
    ensureSession,
  };
}