/**
 * ChessEcon — Real Backend WebSocket Hook
 * Connects to the Python FastAPI /ws endpoint and dispatches
 * all game, coaching, economy, and training events to the dashboard.
 */
import { useEffect, useRef, useCallback } from "react";

export type WSEventType =
  | "game_start"
  | "move"
  | "coaching_request"
  | "coaching_result"
  | "game_end"
  | "training_step"
  | "economy_update"
  | "pong";

export interface WSMessage {
  type: WSEventType;
  data: Record<string, unknown>;
}

interface UseBackendWSOptions {
  url: string;
  onMessage: (msg: WSMessage) => void;
  onOpen?: () => void;
  onClose?: () => void;
  enabled?: boolean;
}

export function useBackendWS({
  url,
  onMessage,
  onOpen,
  onClose,
  enabled = true,
}: UseBackendWSOptions) {
  const wsRef = useRef<WebSocket | null>(null);
  const reconnectTimer = useRef<ReturnType<typeof setTimeout> | null>(null);
  const mountedRef = useRef(true);

  const connect = useCallback(() => {
    if (!enabled || !mountedRef.current) return;
    if (wsRef.current?.readyState === WebSocket.OPEN) return;

    try {
      const ws = new WebSocket(url);
      wsRef.current = ws;

      ws.onopen = () => {
        if (onOpen) onOpen();
        // Start ping interval
        const ping = setInterval(() => {
          if (ws.readyState === WebSocket.OPEN) {
            ws.send(JSON.stringify({ action: "ping" }));
          } else {
            clearInterval(ping);
          }
        }, 30_000);
      };

      ws.onmessage = (event) => {
        try {
          const msg = JSON.parse(event.data) as WSMessage;
          onMessage(msg);
        } catch {
          // ignore malformed messages
        }
      };

      ws.onclose = () => {
        if (onClose) onClose();
        // Auto-reconnect after 3 seconds
        if (mountedRef.current && enabled) {
          reconnectTimer.current = setTimeout(connect, 3_000);
        }
      };

      ws.onerror = () => {
        ws.close();
      };
    } catch {
      // WebSocket not available (e.g., SSR)
    }
  }, [url, onMessage, onOpen, onClose, enabled]);

  const send = useCallback((action: string, payload: Record<string, unknown> = {}) => {
    if (wsRef.current?.readyState === WebSocket.OPEN) {
      wsRef.current.send(JSON.stringify({ action, ...payload }));
    }
  }, []);

  const disconnect = useCallback(() => {
    if (reconnectTimer.current) clearTimeout(reconnectTimer.current);
    wsRef.current?.close();
  }, []);

  useEffect(() => {
    mountedRef.current = true;
    if (enabled) connect();
    return () => {
      mountedRef.current = false;
      disconnect();
    };
  }, [connect, disconnect, enabled]);

  return { send, disconnect, connect };
}