const testEmails = [
  `Dear Customer, Rs.20.00 has been debited from account 5488 to VPA paytm.s1eeznf@pty SHS CANTEEN 1 on 18-08-25. Your UPI transaction reference number is 109983023268. If you did not authorize this `
];

function parseBankMessage(email) {
  const result = {
    amount: null,
    vendor: null,
    rawVendor: null,
    type: null,
    date: null,
    referenceNumber: null,
  };

  // Amount
  const amtMatch = email.match(/(?:Rs\.?|INR)\s*([\d,]+\.?\d*)/i);
  if (amtMatch) result.amount = parseFloat(amtMatch[1].replace(/,/g, ""));

  // Debit / Credit
  if (/debited/i.test(email)) result.type = "debit";
  else if (/credited/i.test(email)) result.type = "credit";

  // Date
  const dateMatch = email.match(/on\s+(\d{2}[-/]\d{2}[-/]\d{2,4})/i);
  if (dateMatch) result.date = dateMatch[1];

  // Reference Number (flexible regex)
  const refMatch = email.match(/(?:reference number is|UPI reference number is|Ref No:?)\s*([A-Za-z0-9]+)/i);
  if (refMatch) result.referenceNumber = refMatch[1].trim();

  // Vendor extraction - remove emails, pick last uppercase phrase
  let vendorCandidate = email.replace(/[a-z0-9._%+-]+@[a-z0-9.-]+/gi, '').trim();

  const vendorWords = vendorCandidate.match(/(?:\b[A-Z]{2,}\b(?:\s)?)+/g);
  if (vendorWords && vendorWords.length > 0) {
    result.rawVendor = vendorWords[vendorWords.length - 1].trim(); // store raw
  } else {
    // Improved vendor fallback
    const toMatch = email.match(/to\s+(?:VPA\s+)?(?:[^\s@]+\@[^\s]+\s+)?([A-Za-z0-9\s&.-]+)/i);
    if (toMatch) {
      let v = toMatch[1].trim();
      v = v.replace(/[a-z0-9._%+-]+@[a-z0-9.-]+/gi, '').trim(); // remove emails
      v = v.replace(/\s{2,}/g, ' ');
      result.rawVendor = v;
    }
  }

  // ---------- Cleaning Pipeline ----------
  if (result.rawVendor) {
    let v = result.rawVendor;

    // Remove noise keywords
    v = v.replace(/\b(?:UPI|VPA|REF|Txn|Order|Payment|NEFT|IMPS)\b/gi, '');

    // Replace underscores/dashes with space
    v = v.replace(/[_\-]+/g, ' ');

    // Collapse multiple spaces
    v = v.replace(/\s{2,}/g, ' ').trim();

    // Normalize casing (title case)
    v = v.toLowerCase().replace(/\b\w/g, c => c.toUpperCase());

    result.vendor = v;
  }

  return result;
}

console.log("=== Bank Email Regex Test ===");
testEmails.forEach((email, idx) => {
  console.log(`\n-- Email ${idx + 1} --`);
  console.log(email);
  const parsed = parseBankMessage(email);
  console.log("Parsed Result:", parsed);
});