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

cypress/component/helpers/yjs.cy.js

@@ -21,14 +21,14 @@ describe('Yjs base64 wrapped with our helpers', function() {
 		sourceMap.set('keyA', 'valueA')
 
 		const stateA = getDocumentState(source)
-		const step0A = documentStateToStep(stateA)
+		const step0A = documentStateToStep(stateA, 123)
 		applyStep(target, step0A)
 		expect(targetMap.get('keyA')).to.be.eq('valueA')
 
 		// Add keyB to source, don't apply to target yet
 		sourceMap.set('keyB', 'valueB')
 		const stateB = getDocumentState(source)
-		const step0B = documentStateToStep(stateB)
+		const step0B = documentStateToStep(stateB, 124)
 
 		// Add keyC to source, apply to target
 		sourceMap.set('keyC', 'valueC')

cypress/e2e/api/SessionApi.spec.js

@@ -93,7 +93,7 @@ describe('The session Api', function() {
 					const version = 0
 					cy.pushSteps({ connection, steps, version })
 						.its('version')
-						.should('be.at.least', 1)
+						.should('eql', 0)
 					cy.syncSteps(connection)
 						.its('steps[0].data')
 						.should('eql', steps)
@@ -151,7 +151,7 @@ describe('The session Api', function() {
 		it('saves', function() {
 			cy.pushSteps({ connection, steps: [messages.update], version })
 				.its('version')
-				.should('be.at.least', 1)
+				.should('be', 0)
 			cy.save(connection, { version: 1, autosaveContent: '# Heading 1', manualSave: true })
 			cy.downloadFile(filePath)
 				.its('data')

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

@@ -201,7 +201,10 @@ class SyncService {
 		this.bus.emit('loaded', connectionState)
 		// Emit sync after opened, so websocket onmessage comes after onopen.
 		if (connectionState.documentState) {
-			this._emitDocumentStateStep(connectionState.documentState)
+			this._emitDocumentStateStep(
+				connectionState.documentState,
+				connectionState.document.lastSavedVersion,
+			)
 		}
 		return connectionState
 	}
@@ -222,8 +225,8 @@ 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],
 		})
@@ -277,9 +280,13 @@ class SyncService {
 		return this.connection?.push({ ...sendable, version: this.version })
 			.then((response) => {
 				this.#outbox.clearSentData(sendable)
-				const { steps, documentState } = response.data
+				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