import { useState, useEffect, useCallback, useMemo } from "react";
import { useDebounce } from "../useDebounce";
import usePayrollService from "./usePayrollService";
import {
  type SalarySlip,
  type SalarySlipFilters,
} from "../../services/payrollService";

interface UseSalarySlipsState {
  salarySlips: SalarySlip[];
  total: number;
  currentPage: number;
  totalPages: number;
  itemsPerPage: number;
  searchTerm: string;
  monthFilter: number | undefined;
  yearFilter: number | undefined;
  loading: boolean;
  error: string | null;
}

interface UseSalarySlipsActions {
  setSearchTerm: (term: string) => void;
  setMonthFilter: (month: number | undefined) => void;
  setYearFilter: (year: number | undefined) => void;
  setCurrentPage: (page: number) => void;
  setItemsPerPage: (items: number) => void;
  clearFilters: () => void;
  refreshData: () => Promise<void>;
  getSalarySlipById: (id: string) => Promise<any>;
}

const INITIAL_STATE: UseSalarySlipsState = {
  salarySlips: [],
  total: 0,
  currentPage: 1,
  totalPages: 0,
  itemsPerPage: 100,
  searchTerm: "",
  monthFilter: undefined,
  yearFilter: undefined,
  loading: false,
  error: null,
};

function useSalarySlips() {
  const [state, setState] = useState<UseSalarySlipsState>(INITIAL_STATE);
  const service = usePayrollService();

  // Debounce search term with 500ms delay
  const debouncedSearchTerm = useDebounce(state.searchTerm, 500);

  // Memoize filters to prevent unnecessary API calls
  const filters = useMemo<SalarySlipFilters>(() => {
    const result: SalarySlipFilters = {
      search: debouncedSearchTerm,
      page: state.currentPage,
      limit: state.itemsPerPage,
    };

    if (state.monthFilter !== undefined) {
      result.month = state.monthFilter;
    }

    if (state.yearFilter !== undefined) {
      result.year = state.yearFilter;
    }

    return result;
  }, [
    debouncedSearchTerm,
    state.monthFilter,
    state.yearFilter,
    state.currentPage,
    state.itemsPerPage,
  ]);

  // Auto-fetch when filters change
  useEffect(() => {
    const fetchSalarySlips = async () => {
      setState((prev) => ({ ...prev, loading: true, error: null }));

      const result = await service.getEmployeeSalarySlips(filters);

      if (result.success && result.data) {
        const total = result.data.data?.total ?? 0;
        const limit = filters.limit ?? 10;

        setState((prev) => ({
          ...prev,
          salarySlips: result.data!.data?.data ?? [],
          total,
          totalPages: Math.ceil(total / limit),
          loading: false,
          error: null,
        }));
      } else {
        setState((prev) => ({
          ...prev,
          salarySlips: [],
          total: 0,
          totalPages: 0,
          loading: false,
          error: result.message,
        }));
      }
    };

    fetchSalarySlips();
  }, [filters]);

  // Action handlers
  const setSearchTerm = useCallback((term: string) => {
    setState((prev) => ({ ...prev, searchTerm: term, currentPage: 1 }));
  }, []);

  const setMonthFilter = useCallback((month: number | undefined) => {
    setState((prev) => ({ ...prev, monthFilter: month, currentPage: 1 }));
  }, []);

  const setYearFilter = useCallback((year: number | undefined) => {
    setState((prev) => ({ ...prev, yearFilter: year, currentPage: 1 }));
  }, []);

  const setCurrentPage = useCallback((page: number) => {
    setState((prev) => ({ ...prev, currentPage: page }));
  }, []);

  const setItemsPerPage = useCallback((items: number) => {
    setState((prev) => ({ ...prev, itemsPerPage: items, currentPage: 1 }));
  }, []);

  // Clear only filter dropdowns (month, year); do not clear search
  const clearFilters = useCallback(() => {
    setState((prev) => ({
      ...prev,
      monthFilter: undefined,
      yearFilter: undefined,
      currentPage: 1,
    }));
  }, []);

  // Refresh data
  const refreshData = useCallback(async () => {
    setState((prev) => ({ ...prev, loading: true, error: null }));

    const result = await service.getEmployeeSalarySlips(filters);

    if (result.success && result.data) {
      const total = result.data.data?.total ?? 0;
      const limit = filters.limit ?? 10;

      setState((prev) => ({
        ...prev,
        salarySlips: result.data!.data?.data ?? [],
        total,
        totalPages: Math.ceil(total / limit),
        loading: false,
        error: null,
      }));
    } else {
      setState((prev) => ({
        ...prev,
        salarySlips: [],
        total: 0,
        totalPages: 0,
        loading: false,
        error: result.message,
      }));
    }
  }, [filters]);

  // Get salary slip by ID
  const getSalarySlipById = useCallback(
    async (id: string) => {
      const result = await service.getSalarySlipById(id);
      return result.success && result.data ? result.data.data : null;
    },
    []
  );

  const actions: UseSalarySlipsActions = {
    setSearchTerm,
    setMonthFilter,
    setYearFilter,
    setCurrentPage,
    setItemsPerPage,
    clearFilters,
    refreshData,
    getSalarySlipById,
  };

  return {
    ...state,
    loading: state.loading || service.loading,
    ...actions,
  };
}

export default useSalarySlips;