import { useState, useEffect, useCallback, useMemo } from "react";
import { useDebounce } from "../useDebounce";
import usePayrollService from "./usePayrollService";
import {
  type PayrollCycle,
  type PayrollCycleFilters,
  type ProcessPayrollData,
} from "../../services/payrollService";

interface UsePayrollState {
  cycles: PayrollCycle[];
  total: number;
  currentPage: number;
  totalPages: number;
  itemsPerPage: number;
  searchTerm: string;
  statusFilter: "all" | "draft" | "finalized" | "paid";
  sortField: string | null;
  loading: boolean;
  error: string | null;
}

interface UsePayrollActions {
  setSearchTerm: (term: string) => void;
  setStatusFilter: (filter: "all" | "draft" | "finalized" | "paid") => void;
  setSortField: (field: string | null) => void;
  setCurrentPage: (page: number) => void;
  setItemsPerPage: (items: number) => void;
  clearFilters: () => void;
  refreshData: () => Promise<void>;
  processPayroll: (data: ProcessPayrollData) => Promise<boolean>;
  getCycleById: (id: string) => Promise<PayrollCycle | null>;
}

const INITIAL_STATE: UsePayrollState = {
  cycles: [],
  total: 0,
  currentPage: 1,
  totalPages: 0,
  itemsPerPage: 100,
  searchTerm: "",
  statusFilter: "all",
  sortField: null,
  loading: false,
  error: null,
};

function usePayroll() {
  const [state, setState] = useState<UsePayrollState>(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<PayrollCycleFilters>(() => {
    let status: number | undefined = undefined;

    if (state.statusFilter === "draft") status = 0;
    if (state.statusFilter === "finalized") status = 1;
    if (state.statusFilter === "paid") status = 2;

    return {
      search: debouncedSearchTerm,
      status, // pass 0 for draft, 1 for finalized, 2 for paid, undefined for all
      page: state.currentPage,
      limit: state.itemsPerPage,
    };
  }, [
    debouncedSearchTerm,
    state.statusFilter,
    state.currentPage,
    state.itemsPerPage,
  ]);

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

      const result = await service.getPayrollCycles(filters);

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

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

    fetchCycles();
  }, [filters]);

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

  const setStatusFilter = useCallback((filter: "all" | "draft" | "finalized" | "paid") => {
    setState((prev) => ({ ...prev, statusFilter: filter, currentPage: 1 }));
  }, []);

  const setSortField = useCallback((field: string | null) => {
    setState((prev) => ({ ...prev, sortField: field }));
  }, []);

  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; do not clear search
  const clearFilters = useCallback(() => {
    setState((prev) => ({
      ...prev,
      statusFilter: "all",
      sortField: null,
      currentPage: 1,
    }));
  }, []);

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

    const result = await service.getPayrollCycles(filters);

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

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

  // Process payroll
  const processPayroll = useCallback(
    async (data: ProcessPayrollData): Promise<boolean> => {
      const result = await service.processPayroll(data);
      if (result.success) {
        await refreshData();
      }
      return result.success;
    },
    [service, refreshData]
  );

  // Get cycle by ID
  const getCycleById = useCallback(
    async (id: string): Promise<PayrollCycle | null> => {
      const result = await service.getPayrollCycleById(id);
      return result.success && result.data ? result.data.data : null;
    },
    [service]
  );

  const actions: UsePayrollActions = {
    setSearchTerm,
    setStatusFilter,
    setSortField,
    setCurrentPage,
    setItemsPerPage,
    clearFilters,
    refreshData,
    processPayroll,
    getCycleById,
  };

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

export default usePayroll;