/**
 * Socket.IO 客户端封装（动态加载 socket.io-client）。
 */
export type SocketIoStatus = "connecting" | "open" | "closed" | "error";

export type SocketIoSession = {
  emit(event: string, args: unknown[]): void;
  close(): void;
};

export type SocketIoOptions = {
  url: string;
  /** 附加选项 JSON：{ path?, transports?, auth?, ... } */
  optionsJson?: string;
  /** 监听事件列表；空数组 = onAny 全收 */
  listenEvents: string[];
  onEvent(event: string, args: unknown[]): void;
  onStatus?(s: SocketIoStatus, detail?: string): void;
  onError?(msg: string): void;
};

type IoSocket = {
  emit(ev: string, ...args: unknown[]): void;
  on(ev: string, cb: (...args: unknown[]) => void): void;
  onAny(cb: (ev: string, ...args: unknown[]) => void): void;
  disconnect(): void;
};

export function connectSocketIo(opts: SocketIoOptions): SocketIoSession {
  let socket: IoSocket | null = null;
  let disposed = false;

  void (async () => {
    try {
      opts.onStatus?.("connecting");
      const { io } = await import("socket.io-client");
      const extra: Record<string, unknown> = {};
      if (opts.optionsJson?.trim()) {
        try {
          Object.assign(extra, JSON.parse(opts.optionsJson));
        } catch {
          opts.onError?.("连接选项不是合法 JSON，已忽略");
        }
      }
      const s: IoSocket = io(opts.url, {
        transports: ["websocket", "polling"],
        reconnection: false,
        ...extra,
      }) as unknown as IoSocket;
      socket = s;

      s.on("connect", () => opts.onStatus?.("open"));
      s.on("disconnect", (...args: unknown[]) =>
        opts.onStatus?.("closed", String(args[0] ?? "")),
      );
      s.on("connect_error", (...args: unknown[]) => {
        const err = args[0];
        const msg = err instanceof Error ? err.message : String(err);
        opts.onError?.(msg);
        opts.onStatus?.("error", msg);
      });

      const events = opts.listenEvents.map((e) => e.trim()).filter(Boolean);
      if (events.length === 0 || events.includes("*")) {
        s.onAny((ev, ...args) => opts.onEvent(ev, args));
      } else {
        for (const ev of events) {
          s.on(ev, (...args: unknown[]) => opts.onEvent(ev, args));
        }
      }
      if (disposed) s.disconnect();
    } catch (e) {
      opts.onError?.(`socket.io-client 加载/连接失败：${e instanceof Error ? e.message : String(e)}`);
      opts.onStatus?.("error");
    }
  })();

  return {
    emit(event, args) {
      if (!socket) {
        opts.onError?.("Socket.IO 尚未连接");
        return;
      }
      socket.emit(event, ...args);
    },
    close() {
      disposed = true;
      socket?.disconnect();
      opts.onStatus?.("closed");
    },
  };
}