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src/lib/iranNationalCode.ts

@@ -0,0 +1,15 @@
+/** Standard Iranian national-code (کد ملی) checksum validator. */
+export function isValidIranNationalCode(code: string): boolean {
+  const value = String(code || "");
+  if (!/^\d{10}$/.test(value)) return false;
+  if (/^(\d)\1{9}$/.test(value)) return false;
+
+  const digits = value.split("").map(Number);
+  const sum = digits
+    .slice(0, 9)
+    .reduce((acc, digit, index) => acc + digit * (10 - index), 0);
+  const remainder = sum % 11;
+  const checkDigit = remainder < 2 ? remainder : 11 - remainder;
+
+  return checkDigit === digits[9];
+}