/**
 * usePayrollSettings — React hook for fetching org payroll settings
 * and returning the correct TaxJurisdiction plugin instance.
 *
 * Usage:
 *   const { jurisdiction, settings, loading, error } = usePayrollSettings();
 *   if (jurisdiction) {
 *     console.log(jurisdiction.name, jurisdiction.currency);
 *   }
 */

import { useState, useEffect, useCallback } from "react";
import { getTaxJurisdiction } from "@/lib/payroll";
import { fetchPayrollSettings } from "@/lib/supabase/payroll-settings-actions";
import type { PayrollSettings } from "@/lib/payroll-settings-types";
import type { TaxJurisdiction } from "@/lib/payroll/types";

interface UsePayrollSettingsReturn {
  settings: PayrollSettings | null;
  jurisdiction: TaxJurisdiction | null;
  loading: boolean;
  error: string | null;
  refetch: () => void;
}

export function usePayrollSettings(): UsePayrollSettingsReturn {
  const [settings, setSettings] = useState<PayrollSettings | null>(null);
  const [jurisdiction, setJurisdiction] = useState<TaxJurisdiction | null>(null);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState<string | null>(null);

  const fetchSettings = useCallback(() => {
    setLoading(true);
    setError(null);

    fetchPayrollSettings()
      .then((s) => {
        setSettings(s);

        if (s) {
          // Build the appropriate TaxJurisdiction plugin
          const opts: Record<string, unknown> = {};

          if (s.country_code === "US" && s.state_code) {
            opts.stateTaxRate = s.state_tax_rate ?? 0;
            opts.stateName = s.state_name ?? s.state_code;
          }

          if (s.country_code === "SG") {
            opts.isCPRorSC = s.is_singapore_citizen_or_pr ?? true;
          }

          if (!s.is_natively_supported) {
            opts.flatIncomeTaxRate = s.flat_income_tax_rate ?? 0.2;
            opts.employerPensionRate = s.employer_pension_rate ?? 0;
            opts.employerTaxRate = s.employer_tax_rate ?? 0;
            opts.displayName = s.country_name;
            opts.currency = s.currency;
            opts.countryCode = s.country_code;
            opts.taxFreeAllowance = s.tax_free_allowance ?? 0;
          }

          const j = getTaxJurisdiction(s.country_code, opts);
          setJurisdiction(j);
        } else {
          setJurisdiction(null);
        }
      })
      .catch((e: Error) => {
        setError(e.message || "Failed to load payroll settings");
        setSettings(null);
        setJurisdiction(null);
      })
      .finally(() => setLoading(false));
  }, []);

  useEffect(() => {
    fetchSettings();
  }, [fetchSettings]);

  return { settings, jurisdiction, loading, error, refetch: fetchSettings };
}