class DashboardWebSocket {
  constructor({ onGamesUpdate, onShutdown } = {}) {
    this._socket = null;
    this._reconnectTimer = null;
    this._shuttingDown = false;
    this._pendingRequests = new Map();
    this._requestSeq = 0;
    this._onGamesUpdate = onGamesUpdate || (() => {});
    this._onShutdown = onShutdown || (() => {});
  }

  get isShuttingDown() { return this._shuttingDown; }

  connect() {
    if (this._shuttingDown) return;
    if (this._socket && (
      this._socket.readyState === WebSocket.OPEN ||
      this._socket.readyState === WebSocket.CONNECTING
    )) return;

    const wsUrl = this._buildUrl();
    try {
      this._socket = new WebSocket(wsUrl);
    } catch {
      this._scheduleReconnect();
      return;
    }

    this._socket.addEventListener("message", (event) => {
      let payload = null;
      try { payload = JSON.parse(event.data); } catch { return; }
      if (!payload || !payload.type) return;

      if (payload.type === "dashboard_ws_shutdown") {
        this._shuttingDown = true;
        if (this._reconnectTimer) {
          clearTimeout(this._reconnectTimer);
          this._reconnectTimer = null;
        }
        this._rejectAll("Server shutting down");
        if (this._socket) this._socket.close();
        this._onShutdown();
        return;
      }

      if (payload.type === "dashboard_game_replay") {
        const requestId = String(payload.request_id || "");
        if (!requestId) return;
        const pending = this._pendingRequests.get(requestId);
        if (!pending) return;
        this._pendingRequests.delete(requestId);
        window.clearTimeout(pending.timeoutId);
        if (payload.error) {
          pending.reject(new Error(String(payload.error)));
          return;
        }
        pending.resolve(payload.replay || null);
        return;
      }

      if (payload.type === "dashboard_games_update") {
        this._onGamesUpdate(payload);
      }
    });

    this._socket.addEventListener("close", () => {
      this._socket = null;
      this._rejectAll("Dashboard websocket disconnected");
      if (!this._shuttingDown) this._scheduleReconnect();
    });

    this._socket.addEventListener("error", () => {
      if (this._socket) this._socket.close();
    });
  }

  waitForOpen(timeoutMs = 4000) {
    if (this._shuttingDown) return Promise.resolve(false);
    if (!this._socket || this._socket.readyState === WebSocket.CLOSED) this.connect();
    if (this._socket && this._socket.readyState === WebSocket.OPEN) return Promise.resolve(true);

    return new Promise((resolve) => {
      if (!this._socket) { resolve(false); return; }
      const socketRef = this._socket;
      let settled = false;
      const cleanup = () => {
        socketRef.removeEventListener("open", onOpen);
        socketRef.removeEventListener("close", onClose);
        socketRef.removeEventListener("error", onError);
        window.clearTimeout(timeoutId);
      };
      const finish = (value) => {
        if (settled) return;
        settled = true;
        cleanup();
        resolve(value);
      };
      const onOpen = () => finish(true);
      const onClose = () => finish(false);
      const onError = () => finish(false);
      const timeoutId = window.setTimeout(() => finish(false), timeoutMs);
      socketRef.addEventListener("open", onOpen);
      socketRef.addEventListener("close", onClose);
      socketRef.addEventListener("error", onError);
    });
  }

  async requestReplay(gameId) {
    const isOpen = await this.waitForOpen();
    if (!isOpen || !this._socket || this._socket.readyState !== WebSocket.OPEN) {
      throw new Error("Dashboard websocket unavailable");
    }

    const requestId = `replay-${Date.now()}-${this._requestSeq++}`;
    return await new Promise((resolve, reject) => {
      const timeoutId = window.setTimeout(() => {
        this._pendingRequests.delete(requestId);
        reject(new Error(`Replay websocket timeout for ${gameId}`));
      }, 4000);

      this._pendingRequests.set(requestId, { resolve, reject, timeoutId });
      try {
        this._socket.send(JSON.stringify({
          type: "dashboard_game_replay_request",
          request_id: requestId,
          game_id: gameId,
        }));
      } catch (error) {
        window.clearTimeout(timeoutId);
        this._pendingRequests.delete(requestId);
        reject(error);
      }
    });
  }

  shutdown() {
    this._shuttingDown = true;
    if (this._reconnectTimer) {
      clearTimeout(this._reconnectTimer);
      this._reconnectTimer = null;
    }
    this._rejectAll("Dashboard unloading");
    if (this._socket) {
      this._socket.close();
      this._socket = null;
    }
  }

  _buildUrl() {
    const protocol = window.location.protocol === "https:" ? "wss" : "ws";
    return `${protocol}://${window.location.host}/dashboard/ws/games`;
  }

  _scheduleReconnect() {
    if (this._shuttingDown) return;
    if (this._reconnectTimer) return;
    this._reconnectTimer = window.setTimeout(() => {
      this._reconnectTimer = null;
      this.connect();
    }, 1500);
  }

  _rejectAll(message) {
    for (const pending of this._pendingRequests.values()) {
      window.clearTimeout(pending.timeoutId);
      pending.reject(new Error(message));
    }
    this._pendingRequests.clear();
  }
}