import crypto from 'crypto';

const config = {
  merchantId: process.env.PAYUNI_MERCHANT_ID!,
  hashKey: process.env.PAYUNI_HASH_KEY!,
  hashIV: process.env.PAYUNI_HASH_IV!,
  isTest: process.env.PAYUNI_TEST_MODE === 'true',
};

// AES-256-CBC 加密
function encrypt(data: string): string {
  const key = Buffer.from(config.hashKey.padEnd(32, '\0').slice(0, 32), 'utf8');
  const iv = Buffer.from(config.hashIV.padEnd(16, '\0').slice(0, 16), 'utf8');
  
  const cipher = crypto.createCipheriv('aes-256-cbc', key, iv);
  let encrypted = cipher.update(data, 'utf8', 'hex');
  encrypted += cipher.final('hex');
  return encrypted;
}

// SHA256 雜湊
function generateHashInfo(encryptInfo: string): string {
  return crypto
    .createHash('sha256')
    .update(encryptInfo)
    .digest('hex')
    .toUpperCase();
}

// 建立訂單
function createOrder(params: {
  orderId: string;
  amount: number;
  productName: string;
  returnUrl: string;
  notifyUrl: string;
}) {
  const tradeInfo = {
    MerID: config.merchantId,
    MerTradeNo: params.orderId,
    TradeAmt: params.amount,
    ProdDesc: params.productName,
    ReturnURL: params.returnUrl,
    NotifyURL: params.notifyUrl,
  };
  
  const queryString = new URLSearchParams(tradeInfo as any).toString();
  const encryptInfo = encrypt(queryString);
  const hashInfo = generateHashInfo(encryptInfo);
  
  return {
    MerID: config.merchantId,
    EncryptInfo: encryptInfo,
    HashInfo: hashInfo,
  };
}

<form method="post" action="https://sandbox-api.payuni.com.tw/api/upp">
    <input type="hidden" name="MerID" value="{商店代號}">
    <input type="hidden" name="EncryptInfo" value="{加密資料}">
    <input type="hidden" name="HashInfo" value="{SHA256雜湊}">
    <button type="submit">前往付款</button>
</form>

function verifyCheckCode(params: Record<string, string>): boolean {
  const { CheckCode, ...otherParams } = params;
  
  const sortedKeys = Object.keys(otherParams).sort();
  const paramStr = sortedKeys.map(k => `${k}=${otherParams[k]}`).join('&');
  const signStr = `HashKey=${config.hashKey}&${paramStr}&HashIV=${config.hashIV}`;
  
  const calculated = crypto
    .createHash('sha256')
    .update(signStr)
    .digest('hex')
    .toUpperCase();
    
  return calculated === CheckCode;
}