chore: Replace plain editor with advanced editor (#13071)

# Pull Request Template

## Description

This PR reverts the plain text editor back to the **advanced editor**,
which was previously removed in
[https://github.com/chatwoot/chatwoot/pull/13058](https://github.com/chatwoot/chatwoot/pull/13058).
All channels now use the **ProseMirror editor**, with formatting applied
based on each channel’s configuration.

This PR also fixes issues where **new lines were not properly preserved
during Markdown serialization**, for both:

* `Enter or CMD/Ctrl+enter` (new paragraph)
* `Shift+Enter` (`hard_break`)

Additionally, it resolves related **[Sentry
issue](https://chatwoot-p3.sentry.io/issues/?environment=production&project=4507182691975168&query=is%3Aunresolved%20markdown&referrer=issue-list&statsPeriod=7d)**.

With these changes:

* Line breaks and spacing are now preserved correctly when saving canned
responses.
* When editing a canned response, the content retains the exact spacing
and formatting as saved in editor.
* Canned responses are now correctly converted to plain text where
required and displayed consistently in the canned response list.

### https://github.com/chatwoot/prosemirror-schema/pull/38

---

## Type of change

- [x] New feature (non-breaking change which adds functionality)

## How Has This Been Tested?



## Checklist:

- [x] My code follows the style guidelines of this project
- [x] I have performed a self-review of my code
- [x] I have commented on my code, particularly in hard-to-understand
areas
- [ ] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [x] I have added tests that prove my fix is effective or that my
feature works
- [x] New and existing unit tests pass locally with my changes
- [ ] Any dependent changes have been merged and published in downstream
modules

---------

Co-authored-by: Muhsin Keloth <muhsinkeramam@gmail.com>

app/javascript/dashboard/helper/editorHelper.js

@@ -34,6 +34,7 @@ export function extractTextFromMarkdown(markdown) {
 
 /**
  * Strip unsupported markdown formatting based on channel capabilities.
+ * Uses MARKDOWN_PATTERNS from editor constants.
  *
  * @param {string} markdown - markdown text to process
  * @param {string} channelType - The channel type to check supported formatting
@@ -43,35 +44,16 @@ export function stripUnsupportedSignatureMarkdown(markdown, channelType) {
   if (!markdown) return '';
 
   const { marks = [], nodes = [] } = FORMATTING[channelType] || {};
-  const has = (arr, key) => arr.includes(key);
+  const supported = [...marks, ...nodes];
 
-  // Define stripping rules: [condition, pattern, replacement]
-  const rules = [
-    [!has(nodes, 'image'), /!\[.*?\]\(.*?\)/g, ''],
-    [!has(marks, 'link'), /\[([^\]]+)\]\([^)]+\)/g, '$1'],
-    [!has(nodes, 'codeBlock'), /```[\s\S]*?```/g, ''],
-    [!has(marks, 'code'), /`([^`]+)`/g, '$1'],
-    [!has(marks, 'strong'), /\*\*([^*]+)\*\*/g, '$1'],
-    [!has(marks, 'strong'), /__([^_]+)__/g, '$1'],
-    [!has(marks, 'em'), /\*([^*]+)\*/g, '$1'],
-    // Match _text_ only at word boundaries (whitespace/string start/end)
-    // Preserves underscores in URLs (e.g., https://example.com/path_name) and variable names
-    [
-      !has(marks, 'em'),
-      /(?<=^|[\s])_([^_\s][^_]*[^_\s]|[^_\s])_(?=$|[\s])/g,
-      '$1',
-    ],
-    [!has(marks, 'strike'), /~~([^~]+)~~/g, '$1'],
-    [!has(nodes, 'blockquote'), /^>\s?/gm, ''],
-    [!has(nodes, 'bulletList'), /^[-*+]\s+/gm, ''],
-    [!has(nodes, 'orderedList'), /^\d+\.\s+/gm, ''],
-  ];
-
-  const result = rules.reduce(
-    (text, [shouldStrip, pattern, replacement]) =>
-      shouldStrip ? text.replace(pattern, replacement) : text,
-    markdown
-  );
+  // Apply patterns from MARKDOWN_PATTERNS for unsupported types
+  const result = MARKDOWN_PATTERNS.reduce((text, { type, patterns }) => {
+    if (supported.includes(type)) return text;
+    return patterns.reduce(
+      (t, { pattern, replacement }) => t.replace(pattern, replacement),
+      text
+    );
+  }, markdown);
 
   return result
     .split('\n')
@@ -186,27 +168,22 @@ export function appendSignature(body, signature, channelType) {
 
 /**
  * Removes the signature from the body, along with the signature delimiter.
- * Tries to find both the original signature and the stripped version.
+ * Tries multiple signature variants: original, channel-stripped, and fully stripped.
  *
  * @param {string} body - The body to remove the signature from.
  * @param {string} signature - The signature to remove.
  * @param {string} channelType - Optional. The effective channel type for channel-specific stripping.
- *                               For Twilio channels, pass the result of getEffectiveChannelType().
  * @returns {string} - The body with the signature removed.
  */
 export function removeSignature(body, signature, channelType) {
-  // Build list of signatures to try: original, channel-stripped, and fully stripped
-  const cleanedSignature = cleanSignature(signature);
+  // Build unique list of signature variants to try
   const channelStripped = channelType
     ? cleanSignature(stripUnsupportedSignatureMarkdown(signature, channelType))
     : null;
-  const fullyStripped = cleanSignature(extractTextFromMarkdown(signature));
-
-  // Try signatures in order: original → channel-specific → fully stripped
   const signaturesToTry = [
-    cleanedSignature,
+    cleanSignature(signature),
     channelStripped,
-    fullyStripped,
+    cleanSignature(extractTextFromMarkdown(signature)),
   ].filter((sig, i, arr) => sig && arr.indexOf(sig) === i); // Remove nulls and duplicates
 
   // Find the first matching signature
@@ -225,17 +202,12 @@ export function removeSignature(body, signature, channelType) {
     newBody = newBody.substring(0, signatureIndex).trimEnd();
   }
 
-  // let's find the delimiter and remove it
-  const delimiterIndex = newBody.lastIndexOf(SIGNATURE_DELIMITER);
-  if (
-    delimiterIndex !== -1 &&
-    delimiterIndex === newBody.length - SIGNATURE_DELIMITER.length // this will ensure the delimiter is at the end
-  ) {
+  // Remove delimiter if it's at the end
+  if (newBody.endsWith(SIGNATURE_DELIMITER)) {
     // if the delimiter is at the end, remove it
-    newBody = newBody.substring(0, delimiterIndex);
+    newBody = newBody.slice(0, -SIGNATURE_DELIMITER.length);
   }
 
-  // return the value
   return newBody;
 }