feat(nbstore): add cloud implementation (#8810)

packages/backend/server/src/core/doc/storage/doc.ts

@@ -1,8 +1,10 @@
 import {
   applyUpdate,
+  diffUpdate,
   Doc,
   encodeStateAsUpdate,
   encodeStateVector,
+  encodeStateVectorFromUpdate,
   mergeUpdates,
   UndoManager,
 } from 'yjs';
@@ -19,6 +21,12 @@ export interface DocRecord {
   editor?: string;
 }
 
+export interface DocDiff {
+  missing: Uint8Array;
+  state: Uint8Array;
+  timestamp: number;
+}
+
 export interface DocUpdate {
   bin: Uint8Array;
   timestamp: number;
@@ -96,6 +104,27 @@ export abstract class DocStorageAdapter extends Connection {
     return snapshot;
   }
 
+  async getDocDiff(
+    spaceId: string,
+    docId: string,
+    stateVector?: Uint8Array
+  ): Promise<DocDiff | null> {
+    const doc = await this.getDoc(spaceId, docId);
+
+    if (!doc) {
+      return null;
+    }
+
+    const missing = stateVector ? diffUpdate(doc.bin, stateVector) : doc.bin;
+    const state = encodeStateVectorFromUpdate(doc.bin);
+
+    return {
+      missing,
+      state,
+      timestamp: doc.timestamp,
+    };
+  }
+
   abstract pushDocUpdates(
     spaceId: string,
     docId: string,

packages/backend/server/src/core/doc/storage/index.ts

@@ -1,4 +1,6 @@
-// TODO(@forehalo): share with frontend
+// This is a totally copy of definitions in [@affine/space-store]
+// because currently importing cross workspace package from [@affine/server] is not yet supported
+// should be kept updated with the original definitions in [@affine/space-store]
 import type { BlobStorageAdapter } from './blob';
 import { Connection } from './connection';
 import type { DocStorageAdapter } from './doc';