import { CardConfig, GlobalConfig, VendorState, CalculationResult } from '../types';

/**
 * Cross-border payment calculation engine.
 *
 * ─── PATH A: CASH ─────────────────────────────────────────────────────────
 *   IDR input:  Step 1: IDR → USD via bcaBeli (Bali money changer)
 *               Step 2: USD → VND via cashVndUsd (your purchase cost in VN)
 *   USD input:  USD → VND via cashVndUsd
 *
 * ─── PATH B: CARD (Online / POS) ─────────────────────────────────────────
 *   IDR input:  IDR × card.networkRate (final rate incl. fees)
 *   USD input:  USD × card.usdRate (final rate incl. fees)
 */
export const calculateCosts = (
  vendor: VendorState,
  global: GlobalConfig,
  activeCard: CardConfig
): CalculationResult => {
  const price = parseFloat(vendor.price.replace(/[^\d.]/g, '')) || 0;
  if (!price) {
    return {
      usdNeeded: 0, cashVnd: 0, onlineVnd: 0, posVnd: 0, isCashPossible: false,
      formulas: { cash: '', online: '', pos: '' }
    };
  }

  // ── Inputs ───────────────────────────────────────────────────────────────
  const IDR_PER_USD    = global.bcaBeli || 16000;         // Bali rate (CASH ONLY)
  const CASH_USD_VND   = global.cashVndUsd || 26000;      // Cash baseline
  
  // High-precision rates might come as strings from the UI
  const CARD_IDR_VND   = typeof activeCard.networkRate === 'string' 
    ? (parseFloat(activeCard.networkRate) || 0) 
    : (activeCard.networkRate || 1.58);
    
  const CARD_USD_VND   = typeof activeCard.usdRate === 'string'
    ? (parseFloat(activeCard.usdRate) || 0)
    : (activeCard.usdRate || 26000);

  const POS_MULT       = vendor.surcharge ? 1.03 : 1;

  // ── PATH A: CASH ─────────────────────────────────────────────────────────
  let usdNeeded: number;
  let cashVnd: number;

  if (vendor.currency === 'IDR') {
    usdNeeded = price / IDR_PER_USD;
    cashVnd   = usdNeeded * CASH_USD_VND;
  } else {
    usdNeeded = price;
    cashVnd   = price * CASH_USD_VND;
  }

  // ── PATH B: CARD ─────────────────────────────────────────────────────────
  let onlineVnd: number;
  let posVnd: number;

  if (vendor.currency === 'IDR') {
    onlineVnd = price * CARD_IDR_VND;
    posVnd    = price * POS_MULT * CARD_IDR_VND;
  } else {
    onlineVnd = price * CARD_USD_VND;
    posVnd    = price * POS_MULT * CARD_USD_VND;
  }

  // ── Tooltip strings ───────────────────────────────────────────────────────
  let cashFormula: string;
  let onlineFormula: string;
  let posFormula: string;

  if (vendor.currency === 'IDR') {
    cashFormula =
      `B1: ${formatNumber(price)} IDR ÷ ${formatNumber(IDR_PER_USD)} (Tỉ giá Bali)\n` +
      `= $${formatNumber(usdNeeded, 4)}\n` +
      `B2: $${formatNumber(usdNeeded, 4)} × ${formatVND(CASH_USD_VND)} (Giá vốn)\n` +
      `= ${formatVND(cashVnd)}`;

    onlineFormula =
      `${formatNumber(price)} IDR × ${formatNumber(CARD_IDR_VND, 7)} (Tỉ giá thẻ)\n` +
      `= ${formatVND(onlineVnd)}`;

    posFormula =
      `${formatNumber(price)} IDR` +
      `${vendor.surcharge ? ' × 1.03 (Phụ phí POS)' : ''} × ${formatNumber(CARD_IDR_VND, 7)}\n` +
      `= ${formatVND(posVnd)}`;
  } else {
    cashFormula =
      `$${formatNumber(price, 2)} × ${formatVND(CASH_USD_VND)} (Giá vốn USD)\n` +
      `= ${formatVND(cashVnd)}`;

    onlineFormula =
      `$${formatNumber(price, 2)} × ${formatVND(CARD_USD_VND)} (Tỉ giá thẻ)\n` +
      `= ${formatVND(onlineVnd)}`;

    posFormula =
      `$${formatNumber(price, 2)}` +
      `${vendor.surcharge ? ' × 1.03 (Phụ phí POS)' : ''} × ${formatVND(CARD_USD_VND)}\n` +
      `= ${formatVND(posVnd)}`;
  }

  return {
    usdNeeded,
    cashVnd,
    onlineVnd,
    posVnd,
    isCashPossible: usdNeeded <= global.usdAvailable,
    formulas: {
      cash: cashFormula,
      online: onlineFormula,
      pos: posFormula,
    }
  };
};

export const formatVND = (val: number) => {
  const formatted = new Intl.NumberFormat('en-US', {
    style: 'decimal',
    maximumFractionDigits: 0
  }).format(Math.round(val));
  return `${formatted}đ`;
};

export const formatNumber = (val: number | string, decimals = 0) => {
  const num = typeof val === 'string' 
    ? parseFloat(val.replace(/,/g, '')) 
    : val;
  
  if (isNaN(num)) return '';
  
  return new Intl.NumberFormat('en-US', {
    minimumFractionDigits: decimals,
    maximumFractionDigits: decimals,
  }).format(num);
};