From 8a1e5a3555aa2afe5014f80bcfdb4d533eac0e4a Mon Sep 17 00:00:00 2001
From: Eric Mc Sween <5454374+emcsween@users.noreply.github.com>
Date: Fri, 30 May 2025 07:34:24 -0400
Subject: [PATCH] Merge pull request #25952 from
 overleaf/em-split-editor-facade

Split EditorFacade functionality for history OT (2nd attempt)

GitOrigin-RevId: 2bc6d6c54a9f336fd4a69f0eb548dd06b9f06f5f
---
 .../features/ide-react/editor/share-js-doc.ts |  2 +-
 .../source-editor/extensions/realtime.ts      | 73 ++++++++++++++-----
 2 files changed, 57 insertions(+), 18 deletions(-)

diff --git a/services/web/frontend/js/features/ide-react/editor/share-js-doc.ts b/services/web/frontend/js/features/ide-react/editor/share-js-doc.ts
index 96e866afec..a773684dcb 100644
--- a/services/web/frontend/js/features/ide-react/editor/share-js-doc.ts
+++ b/services/web/frontend/js/features/ide-react/editor/share-js-doc.ts
@@ -365,7 +365,7 @@ export class ShareJsDoc extends EventEmitter {
 
   attachToCM6(cm6: EditorFacade) {
     this.attachToEditor(cm6, () => {
-      cm6.attachShareJs(this._doc, getMeta('ol-maxDocLength'))
+      cm6.attachShareJs(this._doc, getMeta('ol-maxDocLength'), this.type)
     })
   }
 
diff --git a/services/web/frontend/js/features/source-editor/extensions/realtime.ts b/services/web/frontend/js/features/source-editor/extensions/realtime.ts
index 36d9956a76..9118e4f151 100644
--- a/services/web/frontend/js/features/source-editor/extensions/realtime.ts
+++ b/services/web/frontend/js/features/source-editor/extensions/realtime.ts
@@ -5,6 +5,7 @@ import RangesTracker from '@overleaf/ranges-tracker'
 import { ShareDoc } from '../../../../../types/share-doc'
 import { debugConsole } from '@/utils/debugging'
 import { DocumentContainer } from '@/features/ide-react/editor/document-container'
+import { OTType } from '@/features/ide-react/editor/share-js-doc'
 
 /*
  * Integrate CodeMirror 6 with the real-time system, via ShareJS.
@@ -76,15 +77,22 @@ export const realtime = (
   return Prec.highest([realtimePlugin, ensureRealtimePlugin])
 }
 
+type OTAdapter = {
+  handleUpdateFromCM(
+    transactions: readonly Transaction[],
+    ranges?: RangesTracker
+  ): void
+  attachShareJs(): void
+}
+
 export class EditorFacade extends EventEmitter {
-  public shareDoc: ShareDoc | null
+  private otAdapter: OTAdapter | null
   public events: EventEmitter
-  private maxDocLength?: number
 
   constructor(public view: EditorView) {
     super()
     this.view = view
-    this.shareDoc = null
+    this.otAdapter = null
     this.events = new EventEmitter()
   }
 
@@ -118,23 +126,56 @@ export class EditorFacade extends EventEmitter {
     this.cmChange({ from: position, to: position + text.length }, origin)
   }
 
+  attachShareJs(shareDoc: ShareDoc, maxDocLength?: number, type?: OTType) {
+    this.otAdapter =
+      type === 'history-ot'
+        ? new HistoryOTAdapter(this, shareDoc, maxDocLength)
+        : new ShareLatexOTAdapter(this, shareDoc, maxDocLength)
+    this.otAdapter.attachShareJs()
+  }
+
+  detachShareJs() {
+    this.otAdapter = null
+  }
+
+  handleUpdateFromCM(
+    transactions: readonly Transaction[],
+    ranges?: RangesTracker
+  ) {
+    if (this.otAdapter == null) {
+      throw new Error('Trying to process updates with no otAdapter')
+    }
+
+    this.otAdapter.handleUpdateFromCM(transactions, ranges)
+  }
+}
+
+class ShareLatexOTAdapter {
+  constructor(
+    public editor: EditorFacade,
+    private shareDoc: ShareDoc,
+    private maxDocLength?: number
+  ) {
+    this.editor = editor
+    this.shareDoc = shareDoc
+    this.maxDocLength = maxDocLength
+  }
+
   // Connect to ShareJS, passing changes to the CodeMirror view
   // as new transactions.
   // This is a broad immitation of helper functions supplied in
   // the sharejs library. (See vendor/libs/sharejs, in particular
   // the 'attach_ace' helper)
-  attachShareJs(shareDoc: ShareDoc, maxDocLength?: number) {
-    this.shareDoc = shareDoc
-    this.maxDocLength = maxDocLength
-
+  attachShareJs() {
+    const shareDoc = this.shareDoc
     const check = () => {
       // run in a timeout so it checks the editor content once this update has been applied
       window.setTimeout(() => {
-        const editorText = this.getValue()
+        const editorText = this.editor.getValue()
         const otText = shareDoc.getText()
 
         if (editorText !== otText) {
-          shareDoc.emit('error', 'Text does not match in CodeMirror 6')
+          this.shareDoc.emit('error', 'Text does not match in CodeMirror 6')
           debugConsole.error('Text does not match!')
           debugConsole.error('editor: ' + editorText)
           debugConsole.error('ot:     ' + otText)
@@ -143,12 +184,12 @@ export class EditorFacade extends EventEmitter {
     }
 
     const onInsert = (pos: number, text: string) => {
-      this.cmInsert(pos, text, 'remote')
+      this.editor.cmInsert(pos, text, 'remote')
       check()
     }
 
     const onDelete = (pos: number, text: string) => {
-      this.cmDelete(pos, text, 'remote')
+      this.editor.cmDelete(pos, text, 'remote')
       check()
     }
 
@@ -161,7 +202,7 @@ export class EditorFacade extends EventEmitter {
       shareDoc.removeListener('insert', onInsert)
       shareDoc.removeListener('delete', onDelete)
       delete shareDoc.detach_cm6
-      this.shareDoc = null
+      this.editor.detachShareJs()
     }
   }
 
@@ -175,10 +216,6 @@ export class EditorFacade extends EventEmitter {
     const trackedDeletesLength =
       ranges != null ? ranges.getTrackedDeletesLength() : 0
 
-    if (!shareDoc) {
-      throw new Error('Trying to process updates with no shareDoc')
-    }
-
     for (const transaction of transactions) {
       if (transaction.docChanged) {
         const origin = chooseOrigin(transaction)
@@ -234,7 +271,7 @@ export class EditorFacade extends EventEmitter {
               removed,
             }
 
-            this.emit('change', this, changeDescription)
+            this.editor.emit('change', this.editor, changeDescription)
           }
         )
       }
@@ -242,6 +279,8 @@ export class EditorFacade extends EventEmitter {
   }
 }
 
+class HistoryOTAdapter extends ShareLatexOTAdapter {}
+
 export const trackChangesAnnotation = Annotation.define()
 
 const chooseOrigin = (transaction: Transaction) => {