add replacemailvaribles function to change varibale from custom mail

apps/OpenSignServer/Utils.js

@@ -17,3 +17,24 @@ export const color = [
   '#66ccff',
   '#ffffcc',
 ];
+
+export function replaceMailVaribles(subject, body, variables) {
+  let replacedSubject = subject;
+  let replacedBody = body;
+
+  for (const variable in variables) {
+    const regex = new RegExp(`{{${variable}}}`, 'g');
+    if (subject) {
+      replacedSubject = replacedSubject.replace(regex, variables[variable]);
+    }
+    if (body) {
+      replacedBody = replacedBody.replace(regex, variables[variable]);
+    }
+  }
+
+  const result = {
+    subject: replacedSubject,
+    body: replacedBody,
+  };
+  return result;
+}