import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
import { assetAssignmentApi } from '@/services/assetAssignmentApi';
import { AssetAssignment, AssetAssignmentCreateRequest, AssetAssignmentUpdateRequest } from '@/types/asset-management';
import { toast } from '@/lib/custom-toast';
import { assetQueryKeys } from './useAssets';

// Query keys for asset assignment-related queries
export const assignmentQueryKeys = {
  all: ['assignments'] as const,
  lists: () => [...assignmentQueryKeys.all, 'list'] as const,
  list: (filters?: any) => [...assignmentQueryKeys.lists(), { filters }] as const,
  details: () => [...assignmentQueryKeys.all, 'detail'] as const,
  detail: (id: number) => [...assignmentQueryKeys.details(), id] as const,
  byAsset: (assetId: number) => [...assignmentQueryKeys.all, 'byAsset', assetId] as const,
  byEmployee: (employeeId: number) => [...assignmentQueryKeys.all, 'byEmployee', employeeId] as const,
  history: (assetId: number) => [...assignmentQueryKeys.all, 'history', assetId] as const,
  active: () => [...assignmentQueryKeys.all, 'active'] as const,
};

/**
 * Hook for fetching all asset assignments
 */
export const useAssignments = () => {
  return useQuery({
    queryKey: assignmentQueryKeys.lists(),
    queryFn: () => assetAssignmentApi.getAll(),
    staleTime: 5 * 60 * 1000, // 5 minutes
    gcTime: 10 * 60 * 1000, // 10 minutes
  });
};

/**
 * Hook for fetching a single asset assignment by ID
 */
export const useAssignment = (id: number) => {
  return useQuery({
    queryKey: assignmentQueryKeys.detail(id),
    queryFn: () => assetAssignmentApi.getById(id),
    staleTime: 5 * 60 * 1000, // 5 minutes
    gcTime: 10 * 60 * 1000, // 10 minutes
    enabled: !!id && id > 0, // Only run query if ID is valid
  });
};

/**
 * Hook for fetching asset assignments by asset ID
 */
export const useAssignmentsByAsset = (assetId: number) => {
  return useQuery({
    queryKey: assignmentQueryKeys.byAsset(assetId),
    queryFn: () => assetAssignmentApi.getByAssetId(assetId),
    staleTime: 5 * 60 * 1000, // 5 minutes
    gcTime: 10 * 60 * 1000, // 10 minutes
    enabled: !!assetId && assetId > 0, // Only run query if asset ID is valid
  });
};

/**
 * Hook for fetching asset assignments by employee ID
 */
export const useAssignmentsByEmployee = (employeeId: number) => {
  return useQuery({
    queryKey: assignmentQueryKeys.byEmployee(employeeId),
    queryFn: () => assetAssignmentApi.getByEmployeeId(employeeId),
    staleTime: 5 * 60 * 1000, // 5 minutes
    gcTime: 10 * 60 * 1000, // 10 minutes
    enabled: !!employeeId && employeeId > 0, // Only run query if employee ID is valid
  });
};

/**
 * Hook for creating a new asset assignment
 */
export const useCreateAssignment = () => {
  const queryClient = useQueryClient();

  return useMutation({
    mutationFn: (assignment: AssetAssignmentCreateRequest) => {
      // Ensure dates are properly formatted before sending to API
      const formattedAssignment = {
        ...assignment,
        assignedDate: assignment.assignedDate || new Date().toISOString(),
        returnedDate: assignment.returnedDate || null,
      };
      return assetAssignmentApi.create(formattedAssignment);
    },
    onSuccess: (newAssignment) => {
      // Invalidate and refetch assignment lists
      queryClient.invalidateQueries({ queryKey: assignmentQueryKeys.lists() });
      
      // Invalidate assignments for the specific asset
      queryClient.invalidateQueries({ 
        queryKey: assignmentQueryKeys.byAsset(newAssignment.assetID) 
      });
      
      // Invalidate assignments for the specific employee
      queryClient.invalidateQueries({ 
        queryKey: assignmentQueryKeys.byEmployee(newAssignment.employeeID) 
      });
      
      // Optionally add the new assignment to the cache
      queryClient.setQueryData(
        assignmentQueryKeys.detail(newAssignment.assignmentID), 
        newAssignment
      );
      
      // Invalidate the asset details to refresh related data
      queryClient.invalidateQueries({ 
        queryKey: assetQueryKeys.detail(newAssignment.assetID) 
      });
      
      toast.success('Asset assignment created successfully');
    },
    onError: (error) => {
      console.error('Create assignment error:', error);
      toast.error('Failed to create asset assignment');
    },
  });
};

/**
 * Hook for updating an existing asset assignment
 */
export const useUpdateAssignment = () => {
  const queryClient = useQueryClient();

  return useMutation({
    mutationFn: ({ id, assignment }: { id: number; assignment: AssetAssignmentUpdateRequest }) => {
      // Ensure dates are properly formatted before sending to API
      const formattedAssignment = {
        ...assignment,
        assignedDate: assignment.assignedDate || new Date().toISOString(),
        returnedDate: assignment.returnedDate || null,
      };
      return assetAssignmentApi.update(id, formattedAssignment);
    },
    onMutate: async ({ id, assignment }) => {
      // Cancel any outgoing refetches
      await queryClient.cancelQueries({ queryKey: assignmentQueryKeys.detail(id) });

      // Snapshot the previous value
      const previousAssignment = queryClient.getQueryData(assignmentQueryKeys.detail(id));

      // Optimistically update to the new value
      queryClient.setQueryData(assignmentQueryKeys.detail(id), assignment);

      // Return a context object with the snapshotted value
      return { 
        previousAssignment, 
        id, 
        assetId: assignment.assetID, 
        employeeId: assignment.employeeID 
      };
    },
    onError: (error, variables, context) => {
      // If the mutation fails, use the context returned from onMutate to roll back
      if (context?.previousAssignment) {
        queryClient.setQueryData(
          assignmentQueryKeys.detail(context.id), 
          context.previousAssignment
        );
      }
      console.error('Update assignment error:', error);
      toast.error('Failed to update asset assignment');
    },
    onSuccess: (updatedAssignment, { id }) => {
      // Update the assignment in the cache
      queryClient.setQueryData(assignmentQueryKeys.detail(id), updatedAssignment);
      
      // Invalidate assignment lists to ensure consistency
      queryClient.invalidateQueries({ queryKey: assignmentQueryKeys.lists() });
      
      // Invalidate assignments for the specific asset
      queryClient.invalidateQueries({ 
        queryKey: assignmentQueryKeys.byAsset(updatedAssignment.assetID) 
      });
      
      // Invalidate assignments for the specific employee
      queryClient.invalidateQueries({ 
        queryKey: assignmentQueryKeys.byEmployee(updatedAssignment.employeeID) 
      });
      
      // Invalidate the asset details to refresh related data
      queryClient.invalidateQueries({ 
        queryKey: assetQueryKeys.detail(updatedAssignment.assetID) 
      });
      
      toast.success('Asset assignment updated successfully');
    },
  });
};

/**
 * Hook for deleting an asset assignment
 */
export const useDeleteAssignment = () => {
  const queryClient = useQueryClient();

  return useMutation({
    mutationFn: (id: number) => assetAssignmentApi.delete(id),
    onMutate: async (id) => {
      // Cancel any outgoing refetches
      await queryClient.cancelQueries({ queryKey: assignmentQueryKeys.detail(id) });
      await queryClient.cancelQueries({ queryKey: assignmentQueryKeys.lists() });

      // Snapshot the previous values
      const previousAssignment = queryClient.getQueryData(assignmentQueryKeys.detail(id));
      const previousAssignmentsList = queryClient.getQueryData(assignmentQueryKeys.lists());

      // Get the asset and employee IDs from the assignment to invalidate related queries
      const assignment = previousAssignment as AssetAssignment;
      const assetId = assignment?.assetID;
      const employeeId = assignment?.employeeID;

      // Optimistically remove the assignment from the list
      if (previousAssignmentsList) {
        queryClient.setQueryData(
          assignmentQueryKeys.lists(),
          (previousAssignmentsList as AssetAssignment[]).filter(
            assignment => assignment.assignmentID !== id
          )
        );
      }

      // Optimistically remove from asset-specific list if we have the asset ID
      if (assetId) {
        const previousAssetAssignments = queryClient.getQueryData(
          assignmentQueryKeys.byAsset(assetId)
        );
        if (previousAssetAssignments) {
          queryClient.setQueryData(
            assignmentQueryKeys.byAsset(assetId),
            (previousAssetAssignments as AssetAssignment[]).filter(
              assignment => assignment.assignmentID !== id
            )
          );
        }
      }

      // Optimistically remove from employee-specific list if we have the employee ID
      if (employeeId) {
        const previousEmployeeAssignments = queryClient.getQueryData(
          assignmentQueryKeys.byEmployee(employeeId)
        );
        if (previousEmployeeAssignments) {
          queryClient.setQueryData(
            assignmentQueryKeys.byEmployee(employeeId),
            (previousEmployeeAssignments as AssetAssignment[]).filter(
              assignment => assignment.assignmentID !== id
            )
          );
        }
      }

      // Return a context object with the snapshotted values
      return { 
        previousAssignment, 
        previousAssignmentsList, 
        id, 
        assetId, 
        employeeId 
      };
    },
    onError: (error, id, context) => {
      // If the mutation fails, use the context to roll back
      if (context?.previousAssignmentsList) {
        queryClient.setQueryData(assignmentQueryKeys.lists(), context.previousAssignmentsList);
      }
      if (context?.previousAssignment) {
        queryClient.setQueryData(assignmentQueryKeys.detail(id), context.previousAssignment);
      }
      if (context?.assetId) {
        // Invalidate asset-specific assignments to refresh from server
        queryClient.invalidateQueries({ 
          queryKey: assignmentQueryKeys.byAsset(context.assetId) 
        });
      }
      if (context?.employeeId) {
        // Invalidate employee-specific assignments to refresh from server
        queryClient.invalidateQueries({ 
          queryKey: assignmentQueryKeys.byEmployee(context.employeeId) 
        });
      }
      console.error('Delete assignment error:', error);
      toast.error('Failed to delete asset assignment');
    },
    onSuccess: (_, id, context) => {
      // Remove the assignment from the cache
      queryClient.removeQueries({ queryKey: assignmentQueryKeys.detail(id) });
      
      // Invalidate assignment lists to ensure consistency
      queryClient.invalidateQueries({ queryKey: assignmentQueryKeys.lists() });
      
      // Invalidate assignments for the specific asset if we have the asset ID
      if (context?.assetId) {
        queryClient.invalidateQueries({ 
          queryKey: assignmentQueryKeys.byAsset(context.assetId) 
        });
        
        // Invalidate the asset details to refresh related data
        queryClient.invalidateQueries({ 
          queryKey: assetQueryKeys.detail(context.assetId) 
        });
      }
      
      // Invalidate assignments for the specific employee if we have the employee ID
      if (context?.employeeId) {
        queryClient.invalidateQueries({ 
          queryKey: assignmentQueryKeys.byEmployee(context.employeeId) 
        });
      }
      
      toast.success('Asset assignment deleted successfully');
    },
  });
};

/**
 * Hook for fetching assignment history by asset ID
 */
export const useAssignmentHistory = (assetId: number) => {
  return useQuery({
    queryKey: assignmentQueryKeys.history(assetId),
    queryFn: () => assetAssignmentApi.getAssignmentHistory(assetId),
    staleTime: 5 * 60 * 1000, // 5 minutes
    gcTime: 10 * 60 * 1000, // 10 minutes
    enabled: !!assetId && assetId > 0, // Only run query if asset ID is valid
  });
};

/**
 * Hook for fetching all active assignments
 */
export const useActiveAssignments = () => {
  return useQuery({
    queryKey: assignmentQueryKeys.active(),
    queryFn: () => assetAssignmentApi.getActiveAssignments(),
    staleTime: 2 * 60 * 1000, // 2 minutes (shorter for active data)
    gcTime: 5 * 60 * 1000, // 5 minutes
  });
};

/**
 * Hook for bulk returning multiple assignments
 */
export const useBulkReturnAssignments = () => {
  const queryClient = useQueryClient();

  return useMutation({
    mutationFn: (request: {
      assignmentIds: number[];
      returnedDate: string;
      returnReason?: string;
      remarks?: string;
      performedBy?: {
        employeeID: number;
        name: string;
      };
    }) => assetAssignmentApi.bulkReturn(request),
    onSuccess: (result) => {
      // Invalidate all assignment-related queries to refresh data
      queryClient.invalidateQueries({ queryKey: assignmentQueryKeys.all });
      
      // Invalidate active assignments specifically
      queryClient.invalidateQueries({ queryKey: assignmentQueryKeys.active() });
      
      // Invalidate asset queries to refresh asset status
      queryClient.invalidateQueries({ queryKey: assetQueryKeys.all });
      
      // Show success/failure summary
      const { successful, failed } = result.summary;
      if (successful > 0 && failed === 0) {
        toast.success(`Successfully returned ${successful} assignment${successful > 1 ? 's' : ''}`);
      } else if (successful > 0 && failed > 0) {
        toast.warning(`Returned ${successful} assignment${successful > 1 ? 's' : ''}, ${failed} failed`);
      } else {
        toast.error(`Failed to return assignments: ${result.message}`);
      }
    },
    onError: (error) => {
      console.error('Bulk return assignments error:', error);
      toast.error('Failed to return assignments');
    },
  });
};