refactor: organize backend by business responsibility

src/modules/banking/bank-cards/domain/rub-money.ts

@@ -0,0 +1,27 @@
+import { decimalFromString, formatDecimal } from '../../../../common/decimal';
+import type { Money } from '../../../../common/money.types';
+
+export function parseRubMoney(money: Money, positive = false): bigint {
+  if (
+    money?.currency !== 'RUB' ||
+    typeof money.value !== 'string' ||
+    money.value !== money.value.trim()
+  )
+    throw new TypeError('Expected RUB money with a decimal string');
+  const amount = decimalFromString(money.value);
+  if (amount.scale > 2)
+    throw new RangeError('RUB money supports at most two decimal places');
+  const kopecks = amount.value * 10n ** BigInt(2 - amount.scale);
+  if (kopecks < -(2n ** 63n) || kopecks > 2n ** 63n - 1n)
+    throw new RangeError('RUB money is outside the signed 64-bit range');
+  if (positive && kopecks <= 0n)
+    throw new RangeError('Operation amount must be positive');
+  return kopecks;
+}
+
+export function rubMoney(kopecks: bigint): Money {
+  return {
+    currency: 'RUB',
+    value: formatDecimal({ value: kopecks, scale: 2 }),
+  };
+}