fixup! refactor(sync): cache steps in sync service

src/services/Outbox.ts

@@ -0,0 +1,68 @@
+/**
+ * SPDX-FileCopyrightText: 2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+import { encodeArrayBuffer } from '../helpers/base64.js'
+import { logger } from '../helpers/logger.js'
+
+type Sendable = {
+	steps: string[], awareness: string
+}
+
+export default class Outbox {
+	#awarenessUpdate = ''
+	#syncUpdate = ''
+	#syncQuery = ''
+
+	storeStep(step: Uint8Array) {
+		const encoded = encodeArrayBuffer(step)
+		if (encoded < 'AAA') {
+			logger.warn('Unexpected step type:', { step, encoded })
+			return
+		}
+		if (encoded < 'AAE') {
+			this.#syncQuery = encoded
+			return
+		}
+		if (encoded < 'AQ') {
+			this.#syncUpdate = encoded
+			return
+		}
+		if (encoded < 'Ag') {
+			this.#awarenessUpdate = encoded
+			return
+		}
+		logger.warn('Unexpected step type:', { step, encoded })
+	}
+
+	getDataToSend(): Sendable {
+		return  {
+			steps: [this.#syncUpdate, this.#syncQuery].filter(s => s),
+			awareness: this.#awarenessUpdate,
+		}
+	}
+
+	get hasUpdate(): boolean {
+		return !!this.#syncUpdate
+	}
+
+	/*
+	 * Clear data that has just been
+	 *
+	 * Only clear data that has not changed in the meantime.
+	 * @param {Sendable} - data that was to the server
+	 */
+	clearSentData({ steps, awareness }: Sendable) {
+		if (steps.includes(this.#syncUpdate)) {
+			this.#syncUpdate = ''
+		}
+		if (steps.includes(this.#syncQuery)) {
+			this.#syncQuery = ''
+		}
+		if (this.#awarenessUpdate === awareness) {
+			this.#awarenessUpdate = ''
+		}
+	}
+
+}