"use client";

import { useEffect, useRef, useCallback, useState } from "react";

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

interface UseSSEOptions {
  url: string;
  onEvent?: (event: SSEEvent) => void;
  enabled?: boolean;
}

export function useSSE({ url, onEvent, enabled = true }: UseSSEOptions) {
  const [isConnected, setIsConnected] = useState(false);
  const [lastEvent, setLastEvent] = useState<SSEEvent | null>(null);
  const eventSourceRef = useRef<EventSource | null>(null);
  const onEventRef = useRef(onEvent);

  // Keep callback ref updated
  onEventRef.current = onEvent;

  const connect = useCallback(() => {
    if (eventSourceRef.current) {
      eventSourceRef.current.close();
    }

    const es = new EventSource(url);
    eventSourceRef.current = es;

    es.onopen = () => setIsConnected(true);
    es.onerror = () => {
      setIsConnected(false);
      // Auto-reconnect is built into EventSource
    };

    // Listen for all event types
    const eventTypes = ["heartbeat", "task", "stats", "online", "offline", "connected", "registered"];
    eventTypes.forEach((type) => {
      es.addEventListener(type, (e: MessageEvent) => {
        try {
          const data = JSON.parse(e.data);
          const event: SSEEvent = { type, data };
          setLastEvent(event);
          onEventRef.current?.(event);
        } catch {
          // skip malformed events
        }
      });
    });

    return es;
  }, [url]);

  useEffect(() => {
    if (!enabled) return;

    const es = connect();
    return () => {
      es.close();
      setIsConnected(false);
    };
  }, [connect, enabled]);

  return { isConnected, lastEvent };
}