import { useRef, useEffect, useCallback } from 'react';
import { useMutation } from '@tanstack/react-query';
import api from '@/lib/api';
import type { EventLockInfo } from '@/types';

export function useEventLock(eventId: number | null) {
  const lockHeldRef = useRef(false);
  const activeEventIdRef = useRef<number | null>(null);

  const acquireMutation = useMutation({
    mutationFn: async (id: number) => {
      const { data } = await api.post<EventLockInfo>(
        `/shared-calendars/events/${id}/lock`
      );
      return data;
    },
    onSuccess: (_data, lockedId) => {
      lockHeldRef.current = true;
      activeEventIdRef.current = lockedId;
    },
  });

  const releaseMutation = useMutation({
    mutationFn: async (id: number) => {
      await api.delete(`/shared-calendars/events/${id}/lock`);
    },
    onSuccess: () => {
      lockHeldRef.current = false;
      activeEventIdRef.current = null;
    },
  });

  const acquire = useCallback(async () => {
    if (!eventId) return null;
    const data = await acquireMutation.mutateAsync(eventId);
    return data;
  }, [eventId]);

  const release = useCallback(async () => {
    const id = activeEventIdRef.current;
    if (!id || !lockHeldRef.current) return;
    try {
      await releaseMutation.mutateAsync(id);
    } catch {
      // Fire-and-forget on release errors
    }
  }, []);

  // Auto-release on unmount or eventId change
  useEffect(() => {
    return () => {
      const id = activeEventIdRef.current;
      if (id && lockHeldRef.current) {
        // Fire-and-forget cleanup
        api.delete(`/shared-calendars/events/${id}/lock`).catch(() => {});
        lockHeldRef.current = false;
        activeEventIdRef.current = null;
      }
    };
  }, [eventId]);

  return {
    acquire,
    release,
    isAcquiring: acquireMutation.isPending,
    acquireError: acquireMutation.error,
  };
}