fix: Handling markdown before replacing or appending signature [CW-2532] (#7944)

Co-authored-by: Sivin Varghese <64252451+iamsivin@users.noreply.github.com>

app/javascript/dashboard/helper/editorHelper.js

@@ -1,3 +1,9 @@
+import {
+  messageSchema,
+  MessageMarkdownTransformer,
+  MessageMarkdownSerializer,
+} from '@chatwoot/prosemirror-schema';
+
 /**
  * The delimiter used to separate the signature from the rest of the body.
  * @type {string}
@@ -5,25 +11,12 @@
 export const SIGNATURE_DELIMITER = '--';
 
 /**
- * Remove trailing spaces from each line in a markdown text
- * @param {string} markdownText
- * @returns
- */
-function removeTrailingSpaces(markdownText) {
-  return markdownText
-    .split('\n')
-    .map(line => line.replace(/\s+$/, ''))
-    .join('\n');
-}
-
-/**
- * Trim the signature and remove all " \r" from the signature
- * 1. Trim any extra lines or spaces at the start or end of the string
- * 2. Converts all \r or \r\n to \f
+ * Parse and Serialize the markdown text to remove any extra spaces or new lines
  */
 export function cleanSignature(signature) {
-  const cleaned = signature.trim().replace(/\r\n?/g, '\n');
-  return removeTrailingSpaces(cleaned);
+  // convert from markdown to common mark format
+  const nodes = new MessageMarkdownTransformer(messageSchema).parse(signature);
+  return MessageMarkdownSerializer.serialize(nodes);
 }
 
 /**