Use formula for the optimistic expense report

src/libs/ReportUtils.ts

@@ -1,3 +1,4 @@
+import {format} from 'date-fns';
 import ExpensiMark from 'expensify-common/lib/ExpensiMark';
 import Str from 'expensify-common/lib/str';
 import {isEmpty} from 'lodash';
@@ -1996,6 +1997,13 @@ function getFormulaTypeReportField(reportFields: PolicyReportFields) {
     return Object.values(reportFields).find((field) => field.type === 'formula');
 }
 
+/**
+ * Given a set of report fields, return the field that refers to title
+ */
+function getTitleReportField(reportFields: PolicyReportFields) {
+    return Object.values(reportFields).find((field) => isReportFieldOfTypeTitle(field));
+}
+
 /**
  * Get the report fields attached to the policy given policyID
  */
@@ -2904,6 +2912,26 @@ function buildOptimisticIOUReport(payeeAccountID: number, payerAccountID: number
     };
 }
 
+/**
+ * Populates the report field formula with the values from the report and policy.
+ * Currently, is supports only optimistic expense reports.
+ * Each formula field is either replaced with a value, or removed.
+ * If after all replacements the formula is empty, the original formula is returned.
+ */
+function populateOptimisticReportFormula(formula: string, report: OptimisticExpenseReport, policy: Policy | EmptyObject): string {
+    const result = formula
+        .replaceAll('{report:id}', report.reportID)
+        // We don't translate because the server response is always in English
+        .replaceAll('{report:type}', 'Expense Report')
+        .replaceAll('{report:startdate}', report.lastVisibleActionCreated ? format(new Date(report.lastVisibleActionCreated), CONST.DATE.FNS_FORMAT_STRING) : '')
+        .replaceAll('{report:total}', report.total?.toString() ?? '')
+        .replaceAll('{report:currency}', report.currency ?? '')
+        .replaceAll('{report:policyname}', policy.name ?? '')
+        .replaceAll(/\{report:(.+)}/g, '');
+
+    return result.trim().length ? result : formula;
+}
+
 /**
  * Builds an optimistic Expense report with a randomly generated reportID
  *
@@ -2913,7 +2941,6 @@ function buildOptimisticIOUReport(payeeAccountID: number, payerAccountID: number
  * @param total - Amount in cents
  * @param currency
  */
-
 function buildOptimisticExpenseReport(chatReportID: string, policyID: string, payeeAccountID: number, total: number, currency: string): OptimisticExpenseReport {
     // The amount for Expense reports are stored as negative value in the database
     const storedTotal = total * -1;
@@ -2934,7 +2961,6 @@ function buildOptimisticExpenseReport(chatReportID: string, policyID: string, pa
         type: CONST.REPORT.TYPE.EXPENSE,
         ownerAccountID: payeeAccountID,
         currency,
-
         // We don't translate reportName because the server response is always in English
         reportName: `${policyName} owes ${formattedTotal}`,
         stateNum,
@@ -2950,6 +2976,11 @@ function buildOptimisticExpenseReport(chatReportID: string, policyID: string, pa
         expenseReport.managerID = policy.submitsTo;
     }
 
+    const titleReportField = getTitleReportField(getReportFieldsByPolicyID(policyID) ?? {});
+    if (!!titleReportField && reportFieldsEnabled(expenseReport)) {
+        expenseReport.reportName = populateOptimisticReportFormula(titleReportField.defaultValue, expenseReport, policy);
+    }
+
     return expenseReport;
 }