/**
 * Vela Payroll Engine — Jurisdiction Factory & Barrel Exports
 *
 * Factory function: getTaxJurisdiction(countryCode, options?)
 * Returns the appropriate TaxJurisdiction plugin for the given country.
 */

import { TaxJurisdiction, PayFrequency, PayrollInput, PayslipCalculation } from "./types";
import { PayrollEngine } from "./engine";

// Jurisdiction implementations
import { AustraliaTax } from "./jurisdictions/australia";
import { USTax, USTaxOptions } from "./jurisdictions/usa";
import { UKTax } from "./jurisdictions/uk";
import { CanadaTax } from "./jurisdictions/canada";
import { NewZealandTax } from "./jurisdictions/new-zealand";
import { SingaporeTax, SingaporeTaxOptions } from "./jurisdictions/singapore";
import { FlatRateTax, FlatRateTaxOptions } from "./jurisdictions/flat-rate";

// ── Registry of supported jurisdictions ──────────────────────

const jurisdictionRegistry: Record<string, (options?: any) => TaxJurisdiction> = {
  // Australia — ATO PAYG
  AU: () => new AustraliaTax(),
  AUS: () => new AustraliaTax(),

  // United States — IRS federal + state override
  US: (opts?: USTaxOptions) => new USTax(opts),
  USA: (opts?: USTaxOptions) => new USTax(opts),

  // United Kingdom — HMRC PAYE
  GB: () => new UKTax(),
  GBR: () => new UKTax(),
  UK: () => new UKTax(),

  // Canada — CRA federal
  CA: () => new CanadaTax(),
  CAN: () => new CanadaTax(),

  // New Zealand — IRD PAYE
  NZ: () => new NewZealandTax(),
  NZL: () => new NewZealandTax(),

  // Singapore — IRAS (no withholding) + CPF
  SG: (opts?: SingaporeTaxOptions) => new SingaporeTax(opts),
  SGP: (opts?: SingaporeTaxOptions) => new SingaporeTax(opts),

  // EU countries — Flat Rate Tax (customise via options)
  DE: (opts?: FlatRateTaxOptions) => new FlatRateTax({
    flatIncomeTaxRate: 0.25,
    employerPensionRate: 0.0965,
    employerTaxRate: 0.0,
    displayName: "Germany",
    currency: "EUR",
    countryCode: "DE",
    taxFreeAllowance: 11_604,
    ...opts,
  }),
  DEU: (opts?: FlatRateTaxOptions) => jurisdictionRegistry["DE"](opts),

  FR: (opts?: FlatRateTaxOptions) => new FlatRateTax({
    flatIncomeTaxRate: 0.20,
    employerPensionRate: 0.0855,
    employerTaxRate: 0.0,
    displayName: "France",
    currency: "EUR",
    countryCode: "FR",
    taxFreeAllowance: 11_294,
    ...opts,
  }),
  FRA: (opts?: FlatRateTaxOptions) => jurisdictionRegistry["FR"](opts),

  ES: (opts?: FlatRateTaxOptions) => new FlatRateTax({
    flatIncomeTaxRate: 0.24,
    employerPensionRate: 0.236,
    employerTaxRate: 0.0,
    displayName: "Spain",
    currency: "EUR",
    countryCode: "ES",
    taxFreeAllowance: 5_550,
    ...opts,
  }),
  ESP: (opts?: FlatRateTaxOptions) => jurisdictionRegistry["ES"](opts),

  IT: (opts?: FlatRateTaxOptions) => new FlatRateTax({
    flatIncomeTaxRate: 0.23,
    employerPensionRate: 0.2381,
    employerTaxRate: 0.0,
    displayName: "Italy",
    currency: "EUR",
    countryCode: "IT",
    taxFreeAllowance: 8_500,
    ...opts,
  }),
  ITA: (opts?: FlatRateTaxOptions) => jurisdictionRegistry["IT"](opts),

  IE: (opts?: FlatRateTaxOptions) => new FlatRateTax({
    flatIncomeTaxRate: 0.20,
    employerPensionRate: 0.0,
    employerTaxRate: 0.1105,
    displayName: "Ireland",
    currency: "EUR",
    countryCode: "IE",
    taxFreeAllowance: 20_000,
    ...opts,
  }),
  IRL: (opts?: FlatRateTaxOptions) => jurisdictionRegistry["IE"](opts),

  NL: (opts?: FlatRateTaxOptions) => new FlatRateTax({
    flatIncomeTaxRate: 0.3697,
    employerPensionRate: 0.0,
    employerTaxRate: 0.179,
    displayName: "Netherlands",
    currency: "EUR",
    countryCode: "NL",
    taxFreeAllowance: 3_693,
    ...opts,
  }),
  NLD: (opts?: FlatRateTaxOptions) => jurisdictionRegistry["NL"](opts),

  BE: (opts?: FlatRateTaxOptions) => new FlatRateTax({
    flatIncomeTaxRate: 0.25,
    employerPensionRate: 0.0886,
    employerTaxRate: 0.0,
    displayName: "Belgium",
    currency: "EUR",
    countryCode: "BE",
    taxFreeAllowance: 10_160,
    ...opts,
  }),
  BEL: (opts?: FlatRateTaxOptions) => jurisdictionRegistry["BE"](opts),

  AT: (opts?: FlatRateTaxOptions) => new FlatRateTax({
    flatIncomeTaxRate: 0.25,
    employerPensionRate: 0.1025,
    employerTaxRate: 0.0,
    displayName: "Austria",
    currency: "EUR",
    countryCode: "AT",
    taxFreeAllowance: 12_810,
    ...opts,
  }),
  AUT: (opts?: FlatRateTaxOptions) => jurisdictionRegistry["AT"](opts),

  PT: (opts?: FlatRateTaxOptions) => new FlatRateTax({
    flatIncomeTaxRate: 0.23,
    employerPensionRate: 0.1875,
    employerTaxRate: 0.0,
    displayName: "Portugal",
    currency: "EUR",
    countryCode: "PT",
    taxFreeAllowance: 4_704,
    ...opts,
  }),
  PRT: (opts?: FlatRateTaxOptions) => jurisdictionRegistry["PT"](opts),

  FI: (opts?: FlatRateTaxOptions) => new FlatRateTax({
    flatIncomeTaxRate: 0.24,
    employerPensionRate: 0.121,
    employerTaxRate: 0.0,
    displayName: "Finland",
    currency: "EUR",
    countryCode: "FI",
    taxFreeAllowance: 9_310,
    ...opts,
  }),
  FIN: (opts?: FlatRateTaxOptions) => jurisdictionRegistry["FI"](opts),

  SE: (opts?: FlatRateTaxOptions) => new FlatRateTax({
    flatIncomeTaxRate: 0.32,
    employerPensionRate: 0.1021,
    employerTaxRate: 0.0,
    displayName: "Sweden",
    currency: "SEK",
    countryCode: "SE",
    taxFreeAllowance: 0,
    ...opts,
  }),
  SWE: (opts?: FlatRateTaxOptions) => jurisdictionRegistry["SE"](opts),

  DK: (opts?: FlatRateTaxOptions) => new FlatRateTax({
    flatIncomeTaxRate: 0.37,
    employerPensionRate: 0.0,
    employerTaxRate: 0.0,
    displayName: "Denmark",
    currency: "DKK",
    countryCode: "DK",
    taxFreeAllowance: 46_700,
    ...opts,
  }),
  DNK: (opts?: FlatRateTaxOptions) => jurisdictionRegistry["DK"](opts),

  NO: (opts?: FlatRateTaxOptions) => new FlatRateTax({
    flatIncomeTaxRate: 0.22,
    employerPensionRate: 0.0,
    employerTaxRate: 0.141,
    displayName: "Norway",
    currency: "NOK",
    countryCode: "NO",
    taxFreeAllowance: 94_850,
    ...opts,
  }),
  NOR: (opts?: FlatRateTaxOptions) => jurisdictionRegistry["NO"](opts),

  PL: (opts?: FlatRateTaxOptions) => new FlatRateTax({
    flatIncomeTaxRate: 0.12,
    employerPensionRate: 0.0976,
    employerTaxRate: 0.0953,
    displayName: "Poland",
    currency: "PLN",
    countryCode: "PL",
    taxFreeAllowance: 30_000,
    ...opts,
  }),
  POL: (opts?: FlatRateTaxOptions) => jurisdictionRegistry["PL"](opts),

  // Generic fallback for any unsupported country
  DEFAULT: (opts?: FlatRateTaxOptions) => new FlatRateTax({
    flatIncomeTaxRate: opts?.flatIncomeTaxRate ?? 0.20,
    employerPensionRate: opts?.employerPensionRate ?? 0,
    employerTaxRate: opts?.employerTaxRate ?? 0,
    displayName: opts?.displayName ?? "Custom Jurisdiction",
    currency: opts?.currency ?? "USD",
    countryCode: opts?.countryCode ?? "XX",
    taxFreeAllowance: opts?.taxFreeAllowance ?? 0,
    ...opts,
  }),
};

// ── Factory Function ─────────────────────────────────────────

/**
 * Get the appropriate TaxJurisdiction plugin for a country code.
 *
 * @param countryCode — ISO 3166-1 alpha-2 or alpha-3 country code
 * @param options — Jurisdiction-specific options (e.g. stateTaxRate for US)
 * @returns TaxJurisdiction instance
 *
 * @example
 *   const au = getTaxJurisdiction("AU");
 *   const us = getTaxJurisdiction("US", { stateTaxRate: 0.06, stateName: "NY" });
 *   const de = getTaxJurisdiction("DE", { flatIncomeTaxRate: 0.30 });
 *   const custom = getTaxJurisdiction("XX", { flatIncomeTaxRate: 0.15, displayName: "Custom" });
 */
export function getTaxJurisdiction(
  countryCode: string,
  options?: Record<string, unknown>
): TaxJurisdiction {
  const key = countryCode.trim().toUpperCase();
  const factory = jurisdictionRegistry[key] ?? jurisdictionRegistry["DEFAULT"];
  return factory(options);
}

/**
 * List all supported jurisdiction codes.
 */
export function getSupportedJurisdictions(): string[] {
  return Object.keys(jurisdictionRegistry).filter((k) => k !== "DEFAULT");
}

/**
 * Check if a jurisdiction code is supported natively (not via FlatRateTax).
 */
export function isNativelySupported(countryCode: string): boolean {
  const key = countryCode.trim().toUpperCase();
  return ["AU", "AUS", "US", "USA", "GB", "GBR", "UK", "CA", "CAN", "NZ", "NZL", "SG", "SGP"].includes(key);
}

// ── Core Engine ──────────────────────────────────────────────

/**
 * Calculate a complete payslip for the given input.
 *
 * @example
 *   const result = calculatePayslip({
 *     grossAnnual: 95000,
 *     payFrequency: "monthly",
 *     jurisdiction: getTaxJurisdiction("AU"),
 *   });
 *   console.log(result.netPay); // monthly net pay
 */
export function calculatePayslip(input: PayrollInput): PayslipCalculation {
  const engine = new PayrollEngine();
  return engine.calculate(input);
}

// ── Barrel Exports ───────────────────────────────────────────

export { PayrollEngine } from "./engine";

// Re-export all types
export type {
  TaxBracket,
  DeductionLineItem,
  EmployerContribution,
  PayslipCalculation,
  TaxJurisdiction,
  PayFrequency,
  PayrollInput,
} from "./types";

export {
  hourlyToAnnual,
  toPeriod,
  progressiveTaxCalc,
  round2,
} from "./types";

// Re-export all jurisdiction classes
export { AustraliaTax } from "./jurisdictions/australia";
export { USTax } from "./jurisdictions/usa";
export type { USTaxOptions } from "./jurisdictions/usa";
export { UKTax } from "./jurisdictions/uk";
export { CanadaTax } from "./jurisdictions/canada";
export { NewZealandTax } from "./jurisdictions/new-zealand";
export { SingaporeTax } from "./jurisdictions/singapore";
export type { SingaporeTaxOptions } from "./jurisdictions/singapore";
export { FlatRateTax } from "./jurisdictions/flat-rate";
export type { FlatRateTaxOptions } from "./jurisdictions/flat-rate";