import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
import { epicsApi } from '@/lib/api/pm';
import type { Epic, CreateEpicDto, UpdateEpicDto, WorkItemStatus } from '@/types/project';
import { toast } from 'sonner';

// ==================== Query Hooks ====================
export function useEpics(projectId?: string) {
  return useQuery<Epic[]>({
    queryKey: ['epics', projectId],
    queryFn: async () => {
      console.log('[useEpics] Fetching epics...', { projectId });
      try {
        const result = await epicsApi.list(projectId);
        console.log('[useEpics] Fetch successful:', result);
        return result;
      } catch (error) {
        console.error('[useEpics] Fetch failed:', error);
        throw error;
      }
    },
    staleTime: 5 * 60 * 1000, // 5 minutes
    retry: 1,
  });
}

export function useEpic(id: string) {
  return useQuery<Epic>({
    queryKey: ['epics', id],
    queryFn: () => epicsApi.get(id),
    enabled: !!id,
  });
}

// ==================== Mutation Hooks ====================
export function useCreateEpic() {
  const queryClient = useQueryClient();

  return useMutation({
    mutationFn: (data: CreateEpicDto) => epicsApi.create(data),
    onSuccess: (newEpic) => {
      // Invalidate all epic queries (including filtered by projectId)
      queryClient.invalidateQueries({ queryKey: ['epics'] });

      // Also invalidate project details if exists
      queryClient.invalidateQueries({ queryKey: ['projects', newEpic.projectId] });

      toast.success('Epic created successfully!');
    },
    onError: (error: any) => {
      console.error('[useCreateEpic] Error:', error);
      toast.error(error.response?.data?.detail || 'Failed to create epic');
    },
  });
}

export function useUpdateEpic() {
  const queryClient = useQueryClient();

  return useMutation({
    mutationFn: ({ id, data }: { id: string; data: UpdateEpicDto }) =>
      epicsApi.update(id, data),
    onMutate: async ({ id, data }) => {
      // Cancel outgoing refetches
      await queryClient.cancelQueries({ queryKey: ['epics', id] });

      // Snapshot previous value
      const previousEpic = queryClient.getQueryData<Epic>(['epics', id]);

      // Optimistically update
      queryClient.setQueryData<Epic>(['epics', id], (old) => ({
        ...old!,
        ...data,
      }));

      return { previousEpic };
    },
    onError: (error: any, variables, context) => {
      console.error('[useUpdateEpic] Error:', error);

      // Rollback
      if (context?.previousEpic) {
        queryClient.setQueryData(['epics', variables.id], context.previousEpic);
      }

      toast.error(error.response?.data?.detail || 'Failed to update epic');
    },
    onSuccess: (updatedEpic) => {
      toast.success('Epic updated successfully!');
    },
    onSettled: (_, __, variables) => {
      queryClient.invalidateQueries({ queryKey: ['epics', variables.id] });
      queryClient.invalidateQueries({ queryKey: ['epics'] });
    },
  });
}

export function useDeleteEpic() {
  const queryClient = useQueryClient();

  return useMutation({
    mutationFn: (id: string) => epicsApi.delete(id),
    onSuccess: (_, id) => {
      queryClient.invalidateQueries({ queryKey: ['epics'] });
      queryClient.removeQueries({ queryKey: ['epics', id] });
      toast.success('Epic deleted successfully!');
    },
    onError: (error: any) => {
      console.error('[useDeleteEpic] Error:', error);
      toast.error(error.response?.data?.detail || 'Failed to delete epic');
    },
  });
}

export function useChangeEpicStatus() {
  const queryClient = useQueryClient();

  return useMutation({
    mutationFn: ({ id, status }: { id: string; status: WorkItemStatus }) =>
      epicsApi.changeStatus(id, status),
    onMutate: async ({ id, status }) => {
      await queryClient.cancelQueries({ queryKey: ['epics', id] });

      const previousEpic = queryClient.getQueryData<Epic>(['epics', id]);

      queryClient.setQueryData<Epic>(['epics', id], (old) => ({
        ...old!,
        status,
      }));

      return { previousEpic };
    },
    onError: (error: any, variables, context) => {
      console.error('[useChangeEpicStatus] Error:', error);

      if (context?.previousEpic) {
        queryClient.setQueryData(['epics', variables.id], context.previousEpic);
      }

      toast.error(error.response?.data?.detail || 'Failed to change epic status');
    },
    onSuccess: () => {
      toast.success('Epic status changed successfully!');
    },
    onSettled: (_, __, variables) => {
      queryClient.invalidateQueries({ queryKey: ['epics', variables.id] });
      queryClient.invalidateQueries({ queryKey: ['epics'] });
    },
  });
}

export function useAssignEpic() {
  const queryClient = useQueryClient();

  return useMutation({
    mutationFn: ({ id, assigneeId }: { id: string; assigneeId: string }) =>
      epicsApi.assign(id, assigneeId),
    onSuccess: (_, variables) => {
      queryClient.invalidateQueries({ queryKey: ['epics', variables.id] });
      queryClient.invalidateQueries({ queryKey: ['epics'] });
      toast.success('Epic assigned successfully!');
    },
    onError: (error: any) => {
      console.error('[useAssignEpic] Error:', error);
      toast.error(error.response?.data?.detail || 'Failed to assign epic');
    },
  });
}