feat: update RBI reserve return form 1 & 9 UI and FD accounting mapping

src/app/deposits/fixed-deposits/fixed-deposit-account-stepper/fixed-deposit-account-interest-rate-chart-step/fixed-deposit-account-interest-rate-chart-step.component.ts

@@ -334,17 +334,18 @@ export class FixedDepositAccountInterestRateChartStepComponent implements OnChan
     const frequencyId = this.resolveFrequencyId(this.tenurePeriodUnit);
 
     if (this.principalAmount && this.principalAmount > 0) {
-      // Convert tenure to months for backend API. A Days tenure under 30 days rounds down to 0
-      // months, which the backend rejects -- send it as tenureInDays instead in that case.
+      // Years and Months convert exactly; a Days tenure is sent as days and never converted.
       let tenureInMonths: number | undefined;
       let tenureInDays: number | undefined;
       if (this.tenurePeriodUnit === 'Years') {
         tenureInMonths = this.tenureValue * 12;
       } else if (this.tenurePeriodUnit === 'Months') {
         tenureInMonths = this.tenureValue;
-      } else if (enteredDays >= 30) {
-        tenureInMonths = Math.floor(enteredDays / 30);
       } else {
+        // Sent as days, whatever the count. Converting to whole months silently dropped the
+        // remainder — a 200-day deposit quoted as six months lost 20 days of interest, and the
+        // screen still said "200 Days" above the figure. The backend takes days directly and
+        // works the calendar out itself.
         tenureInDays = enteredDays;
       }
 
@@ -423,10 +424,17 @@ export class FixedDepositAccountInterestRateChartStepComponent implements OnChan
             } else {
               const n = 12 / compMonths;
               const effectiveMonths = tenureInMonths ?? enteredDays / 30;
-              const totalCompoundings = Math.floor(effectiveMonths / compMonths);
               const rPerCompounding = rate / (n * 100);
-              result.maturityAmount =
-                Math.round(this.principalAmount * Math.pow(1 + rPerCompounding, totalCompoundings) * 100) / 100;
+              // Whole compounding periods, then simple interest on the days left over. Flooring the
+              // periods and stopping there dropped the remainder entirely: a 200-day deposit
+              // compounding monthly quoted only six months of interest and lost the other twenty
+              // days, which is the depositor's money.
+              const wholePeriods = Math.floor(effectiveMonths / compMonths);
+              const compounded = this.principalAmount * Math.pow(1 + rPerCompounding, wholePeriods);
+              const leftoverDays = enteredDays - wholePeriods * compMonths * 30;
+              const leftoverInterest =
+                leftoverDays > 0 ? (compounded * rate * leftoverDays) / (100 * daysInYearVal) : 0;
+              result.maturityAmount = Math.round((compounded + leftoverInterest) * 100) / 100;
             }
             result.interestEarned = Math.round((result.maturityAmount - this.principalAmount) * 100) / 100;
             this.matchResult = { ...result };