fix: Create idempotent y.js doc for initial content

Signed-off-by: Julius Härtl <[email protected]>

package.json

@@ -108,6 +108,7 @@
     "vue-click-outside": "^1.1.0",
     "vue-material-design-icons": "^5.3.0",
     "vuex": "^3.6.2",
+    "y-prosemirror": "^1.0.20",
     "y-protocols": "^1.0.6",
     "y-websocket": "^1.5.4",
     "yjs": "^13.6.14"

src/EditorFactory.js

@@ -49,7 +49,7 @@ const loadSyntaxHighlight = async (language) => {
 	}
 }
 
-const createEditor = ({ language, onCreate, onUpdate = () => {}, extensions, enableRichEditing, session, relativePath }) => {
+const createEditor = ({ language, onCreate = () => {}, onUpdate = () => {}, extensions, enableRichEditing, session, relativePath }) => {
 	let defaultExtensions
 	if (enableRichEditing) {
 		defaultExtensions = [

src/components/Editor.vue

@@ -494,6 +494,8 @@ export default {
 					logger.debug('onLoaded: Pushing local changes to server')
 					this.$queue.push(updateMessage)
 				}
+			} else {
+				this.setInitialYjsState(documentSource, { isRich: this.isRichEditor })
 			}
 
 			this.hasConnectionIssue = false
@@ -538,12 +540,6 @@ export default {
 							enableRichEditing: this.isRichEditor,
 						})
 						this.hasEditor = true
-						if (!documentState && documentSource) {
-							this.setContent(documentSource, {
-								isRich: this.isRichEditor,
-								addToHistory: false,
-							})
-						}
 						this.listenEditorEvents()
 					} else {
 						// $editor already existed. So this is a reconnect.

src/mixins/setContent.js

@@ -22,6 +22,11 @@
 
 import escapeHtml from 'escape-html'
 import markdownit from './../markdownit/index.js'
+import { Doc, encodeStateAsUpdate, XmlFragment, applyUpdate } from 'yjs'
+import { generateJSON } from '@tiptap/core'
+import { prosemirrorToYXmlFragment } from 'y-prosemirror'
+import { Node } from '@tiptap/pm/model'
+import { createEditor } from '../EditorFactory.js'
 
 export default {
 	methods: {
@@ -38,5 +43,38 @@ export default {
 				.run()
 		},
 
+		setInitialYjsState(content, { isRich }) {
+			const html = isRich
+				? markdownit.render(content) + '<p/>'
+				: `<pre>${escapeHtml(content)}</pre>`
+
+			const editor = createEditor({
+				enableRichEditing: isRich,
+			})
+			const json = generateJSON(html, editor.extensionManager.extensions)
+
+			const doc = Node.fromJSON(editor.schema, json)
+			const getBaseDoc = (doc) => {
+				const ydoc = new Doc()
+				// In order to make the initial document state idempotent, we need to reset the clientID
+				// While this is not recommended, we cannot avoid it here as we lack another mechanism
+				// generate the initial state on the server side
+				// The only other option to avoid this could be to generate the initial state once and push
+				// it to the server immediately, however this would require read only sessions to be able
+				// to still push a state
+				ydoc.clientID = 0
+				const type = /** @type {XmlFragment} */ (ydoc.get('default', XmlFragment))
+				if (!type.doc) {
+					prosemirrorToYXmlFragment(doc, ydoc)
+					return ydoc
+				}
+
+				prosemirrorToYXmlFragment(doc, type)
+				return ydoc
+			}
+
+			const baseUpdate = encodeStateAsUpdate(getBaseDoc(doc))
+			applyUpdate(this.$ydoc, baseUpdate)
+		},
 	},
 }