Use real persistence to IndexedDB

src/sync.ts

@@ -1,15 +1,56 @@
+import _ from 'lodash';
 import * as Y from 'yjs';
+import { openDB } from 'idb';
 
-const fakeStore = new Map<string, Uint8Array[]>();
+const DB_NAME = 'synced-docs';
+const LOCAL_UPDATE_STORE = 'local-updates';
 
-export function syncDoc(id: string, doc: Y.Doc) {
-  const updates = fakeStore.get(id) ?? [];
-  fakeStore.set(id, updates);
-  for (const update of updates) {
-    Y.applyUpdate(doc, update);
+const db = await openDB(DB_NAME, 2, {
+  upgrade(db, oldVersion, newVersion) {
+    console.log(`Running upgrade from ${oldVersion} to ${newVersion}`);
+    db.createObjectStore(LOCAL_UPDATE_STORE);
+  },
+});
+
+export class LocalDocument {
+  readonly id: string;
+  readonly doc: Y.Doc;
+  private updates: Uint8Array[];
+
+  constructor(id: string) {
+    this.id = id;
+    this.doc = new Y.Doc();
+    this.updates = [];
+
+    const flush = _.debounce(() => this.flush(), 1000);
+    this.doc.on('update', (update: Uint8Array) => {
+      this.updates.push(update);
+      flush();
+    });
   }
 
-  doc.on('update', (update: Uint8Array) => {
-    updates.push(update);
-  });
+  public static async load(id: string): Promise<LocalDocument> {
+    const updates: Uint8Array[] = await db.getAll(
+      LOCAL_UPDATE_STORE,
+      IDBKeyRange.bound([id, -Infinity], [id, Infinity])
+    );
+    const result = new LocalDocument(id);
+    Y.applyUpdate(result.doc, Y.mergeUpdates(updates));
+    return result;
+  }
+
+  public async flush(): Promise<void> {
+    const batch = this.updates;
+    this.updates = [];
+    if (batch.length > 0) {
+      const update = Y.mergeUpdates(batch);
+      const key = [this.id, new Date().valueOf()];
+      await db.add(LOCAL_UPDATE_STORE, update, key);
+    }
+  }
+
+  public async finish(): Promise<void> {
+    await this.flush();
+    this.doc.destroy();
+  }
 }