Temporarily move sync into package

packages/excalidraw/cloudflare/changes.ts

@@ -0,0 +1,64 @@
+import type {
+  ChangesRepository,
+  CLIENT_CHANGE,
+  SERVER_CHANGE,
+} from "../sync/protocol";
+
+// TODO: add senderId, possibly roomId as well
+export class DurableChangesRepository implements ChangesRepository {
+  constructor(private storage: DurableObjectStorage) {
+    // #region DEV ONLY
+    this.storage.sql.exec(`DROP TABLE IF EXISTS changes;`);
+    // #endregion
+
+    this.storage.sql.exec(`CREATE TABLE IF NOT EXISTS changes(
+			id			TEXT PRIMARY KEY,
+			payload		TEXT NOT NULL,
+			version		INTEGER NOT NULL DEFAULT 1,
+			createdAt	TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP
+		);`);
+  }
+
+  public saveAll = (changes: Array<CLIENT_CHANGE>) =>
+    this.storage.transactionSync(() => {
+      const prevVersion = this.getLastVersion();
+      const nextVersion = prevVersion + changes.length;
+
+      // TODO: in theory payload could contain array of changes, if we would need to optimize writes
+      for (const [index, change] of changes.entries()) {
+        const version = prevVersion + index + 1;
+        // unique id ensures that we don't acknowledge the same change twice
+        this.storage.sql.exec(
+          `INSERT INTO changes (id, payload, version) VALUES (?, ?, ?);`,
+          change.id,
+          JSON.stringify(change),
+          version,
+        );
+      }
+
+      // sanity check
+      if (nextVersion !== this.getLastVersion()) {
+        throw new Error(
+          `Expected last acknowledged version to be "${nextVersion}", but it is "${this.getLastVersion()}!"`,
+        );
+      }
+
+      return this.getSinceVersion(prevVersion);
+    });
+
+  public getSinceVersion = (version: number): Array<SERVER_CHANGE> =>
+    this.storage.sql
+      .exec<SERVER_CHANGE>(
+        `SELECT id, payload, version FROM changes WHERE version > (?) ORDER BY version ASC;`,
+        version,
+      )
+      .toArray();
+
+  public getLastVersion = (): number => {
+    const result = this.storage.sql
+      .exec(`SELECT MAX(version) FROM changes;`)
+      .one();
+
+    return result ? Number(result["MAX(version)"]) : 0;
+  };
+}