refactor: reimplement realtime-communication

This commit refactors a lot of things that are not easy to separate.
It replaces the binary protocol of y-protocols with json.
It introduces event based message processing.
It implements our own code mirror plugins for synchronisation of content and remote cursors

Signed-off-by: Tilman Vatteroth <git@tilmanvatteroth.de>

backend/src/realtime/realtime-note/test-utils/mock-connection.ts

@@ -3,21 +3,61 @@
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
+import {
+  MockedBackendMessageTransporter,
+  YDocSyncServerAdapter,
+} from '@hedgedoc/commons';
 import { Mock } from 'ts-mockery';
 
 import { User } from '../../../users/user.entity';
-import { WebsocketConnection } from '../websocket-connection';
+import { RealtimeConnection } from '../realtime-connection';
+import { RealtimeNote } from '../realtime-note';
+import { RealtimeUserStatusAdapter } from '../realtime-user-status-adapter';
 
-/**
- * Provides a partial mock for {@link WebsocketConnection}.
- *
- * @param synced Defines the return value for the `isSynced` function.
- */
-export function mockConnection(synced: boolean): WebsocketConnection {
-  return Mock.of<WebsocketConnection>({
-    isSynced: jest.fn(() => synced),
-    send: jest.fn(),
-    getUser: jest.fn(() => Mock.of<User>({ username: 'mockedUser' })),
-    getUsername: jest.fn(() => 'mocked user'),
-  });
+export class MockConnectionBuilder {
+  private username = 'mock';
+  private includeRealtimeUserState = false;
+
+  constructor(private readonly realtimeNote: RealtimeNote) {}
+
+  public withUsername(username: string): this {
+    this.username = username;
+    return this;
+  }
+
+  public withRealtimeUserState(): this {
+    this.includeRealtimeUserState = true;
+    return this;
+  }
+
+  public build(): RealtimeConnection {
+    const transporter = new MockedBackendMessageTransporter('');
+    let realtimeUserStateAdapter: RealtimeUserStatusAdapter =
+      Mock.of<RealtimeUserStatusAdapter>();
+
+    const connection = Mock.of<RealtimeConnection>({
+      getUser: jest.fn(() => Mock.of<User>({ username: this.username })),
+      getDisplayName: jest.fn(() => this.username),
+      getSyncAdapter: jest.fn(() => Mock.of<YDocSyncServerAdapter>({})),
+      getTransporter: jest.fn(() => transporter),
+      getRealtimeUserStateAdapter: () => realtimeUserStateAdapter,
+      getRealtimeNote: () => this.realtimeNote,
+    });
+
+    transporter.on('disconnected', () =>
+      this.realtimeNote.removeClient(connection),
+    );
+
+    if (this.includeRealtimeUserState) {
+      realtimeUserStateAdapter = new RealtimeUserStatusAdapter(
+        this.username,
+        this.username,
+        connection,
+      );
+    }
+
+    this.realtimeNote.addClient(connection);
+
+    return connection;
+  }
 }