fix(sync): bump version after loading document state

* Emit the documents last saved version in the push response
  if document state is send as well.
* Otherwise send the version as 0 so it cannot increase the sync service version.
* Use the versions returned by create and push requests alongside the document state
  to construct a consistent step with the last saved version that matches the document state.

This will result in the sync service version getting bumped
to the documents last saved version
once the coresponding document state has been processed.

Signed-off-by: Max <max@nextcloud.com>

Author: max-nextcloud

lib/Service/DocumentService.php

@@ -265,7 +265,7 @@ public function addStep(Document $document, Session $session, array $steps, int
 
 		return [
 			'steps' => $stepsToReturn,
-			'version' => $newVersion,
+			'version' => isset($documentState) ? $document->getLastSavedVersion() : 0,
 			'documentState' => $documentState
 		];
 	}

src/helpers/yjs.ts

@@ -43,11 +43,12 @@ export function applyDocumentState(
  * and encode it and wrap it in a step data structure.
  *
  * @param documentState - base64 encoded doc state
+ * @param version - last saved version for the document state
  * @return base64 encoded yjs sync protocol update message and version
  */
-export function documentStateToStep(documentState: string): Step {
+export function documentStateToStep(documentState: string, version: number): Step {
 	const message = documentStateToUpdateMessage(documentState)
-	return { data: [encodeArrayBuffer(message)], sessionId: 0, version: -1 }
+	return { data: [encodeArrayBuffer(message)], sessionId: 0, version }
 }
 
 /**

src/services/SyncService.ts

@@ -173,13 +173,12 @@ class SyncService {
 			console.error('Opened the connection but now it is undefined')
 			return
 		}
-		this.version = data.document.lastSavedVersion
 		this.backend = new PollingBackend(this, this.connection.value, data)
 		// Make sure to only emit this once the backend is in place.
 		this.bus.emit('opened', data)
 		// Emit sync after opened, so websocket onmessage comes after onopen.
 		if (data.documentState) {
-			this._emitDocumentStateStep(data.documentState)
+			this._emitDocumentStateStep(data.documentState, data.document.lastSavedVersion)
 		}
 	}
 
@@ -202,8 +201,8 @@ class SyncService {
 		}
 	}
 
-	_emitDocumentStateStep(documentState: string) {
-		const documentStateStep = documentStateToStep(documentState)
+	_emitDocumentStateStep(documentState: string, version: number) {
+		const documentStateStep = documentStateToStep(documentState, version)
 		this.bus.emit('sync', {
 			steps: [documentStateStep],
 		})
@@ -249,12 +248,13 @@ class SyncService {
 		})
 			.then((response) => {
 				this.#outbox.clearSentData(sendable)
-				const { steps, documentState } = response.data as {
+				const { steps, documentState, version } = response.data as {
 					steps: Step[]
 					documentState: string
+					version: number
 				}
 				if (documentState) {
-					this._emitDocumentStateStep(documentState)
+					this._emitDocumentStateStep(documentState, version)
 				}
 				this.pushError = 0
 				this.#sending = false