fix(banking): use custom renderer for translated strings and parser for rules (backport #56643) (#56647)

fix(banking): use custom renderer for translated strings and parser for rules (#56643)

fix(banking): use custom renderer for translated strings and parser for formula evaluation

(cherry picked from commit 8447f551e7)

Co-authored-by: Nikhil Kothari <nik.kothari22@live.com>

banking/src/lib/amountFormula.ts

@@ -0,0 +1,26 @@
+import { Parser } from 'safe-expr-eval'
+
+const parser = new Parser()
+
+const PLAIN_NUMBER_PATTERN = /^-?\d+(\.\d+)?$/
+
+export function evaluateAmountFormula(expression: string, transactionAmount: number): number {
+    const trimmed = expression.trim()
+    if (!trimmed) {
+        return 0
+    }
+
+    if (PLAIN_NUMBER_PATTERN.test(trimmed)) {
+        return Number(trimmed)
+    }
+
+    try {
+        const result = parser.parse(trimmed).evaluate({ transaction_amount: transactionAmount })
+        if (typeof result !== 'number' || !Number.isFinite(result)) {
+            return 0
+        }
+        return result
+    } catch {
+        return 0
+    }
+}