import { DefaultEventsMap, Server } from "socket.io";
import { createAdapter } from "@socket.io/redis-adapter";
import { createClient } from "redis";

let io: Server<DefaultEventsMap, DefaultEventsMap, DefaultEventsMap, any>;
let pubClient: ReturnType<typeof createClient>;
let subClient: ReturnType<typeof createClient>;

export const initWebsocket = (server: any) => {
    io = new Server(server, {
        cors: { origin: "*" },
        transports: ["websocket"],
    });
    io.on("connection", (socket) => {
        console.log(`New client connected: ${socket.id}`);

        socket.on("join", (login: string) => {
            if (login && typeof login === "string") {
                socket.join(`user:${login}`);
            }
        });

        socket.on("message", (message) => {
            io.emit("message", message);
        });

        socket.on("disconnect", () => {
            console.log(`Client disconnected: ${socket.id}`);
        });
    });
    return io;
};

/** Připojí Redis adapter pro cross-pod broadcasting. Volat až po inicializaci Redis klienta. */
export const initRedisAdapter = async () => {
    const HOST = process.env.REDIS_HOST ?? 'localhost';
    const PORT = process.env.REDIS_PORT ?? 6379;
    const url = `redis://${HOST}:${PORT}`;
    pubClient = createClient({ url }) as ReturnType<typeof createClient>;
    subClient = pubClient.duplicate();
    await Promise.all([pubClient.connect(), subClient.connect()]);
    io.adapter(createAdapter(pubClient as any, subClient as any));
    console.log('Socket.io: Redis adapter connected');
};

/** Zavře pub/sub Redis klienty adaptéru při graceful shutdown. */
export const shutdownWebsocketClients = async () => {
    await Promise.allSettled([pubClient?.quit(), subClient?.quit()]);
};

export const getWebsocket = () => io;

/** Pošle event konkrétnímu přihlášenému uživateli (pokud je připojen). */
export const emitToUser = (login: string, event: string, data: unknown) => {
    if (!io) return;
    io.to(`user:${login}`).emit(event, data);
};