fix(repository): Move backend code into subdirectory

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

backend/src/realtime/realtime-note/websocket-connection.ts

@@ -0,0 +1,100 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+import { WebsocketTransporter } from '@hedgedoc/realtime';
+import { Logger } from '@nestjs/common';
+import WebSocket from 'ws';
+import { Awareness, removeAwarenessStates } from 'y-protocols/awareness';
+
+import { User } from '../../users/user.entity';
+import { RealtimeNote } from './realtime-note';
+import { ClientIdUpdate } from './websocket-awareness';
+
+/**
+ * Manages the websocket connection to a specific client.
+ */
+export class WebsocketConnection {
+  protected readonly logger = new Logger(WebsocketConnection.name);
+  private controlledAwarenessIds: Set<number> = new Set();
+  private transporter: WebsocketTransporter;
+
+  /**
+   * Instantiates the websocket connection wrapper for a websocket connection.
+   *
+   * @param websocket The client's raw websocket.
+   * @param user The user of the client
+   * @param realtimeNote The {@link RealtimeNote} that the client connected to.
+   * @throws Error if the socket is not open
+   */
+  constructor(
+    websocket: WebSocket,
+    private user: User,
+    realtimeNote: RealtimeNote,
+  ) {
+    const awareness = realtimeNote.getAwareness();
+    this.transporter = new WebsocketTransporter(
+      realtimeNote.getYDoc(),
+      awareness,
+    );
+    this.transporter.on('disconnected', () => {
+      realtimeNote.removeClient(this);
+    });
+    this.transporter.setupWebsocket(websocket);
+    this.bindAwarenessMessageEvents(awareness);
+  }
+
+  /**
+   * Binds all additional events that are needed for awareness processing.
+   */
+  private bindAwarenessMessageEvents(awareness: Awareness): void {
+    const callback = this.updateControlledAwarenessIds.bind(this);
+    awareness.on('update', callback);
+    this.transporter.on('disconnected', () => {
+      awareness.off('update', callback);
+      removeAwarenessStates(awareness, [...this.controlledAwarenessIds], this);
+    });
+  }
+
+  private updateControlledAwarenessIds(
+    { added, removed }: ClientIdUpdate,
+    origin: WebsocketConnection,
+  ): void {
+    if (origin === this) {
+      added.forEach((id) => this.controlledAwarenessIds.add(id));
+      removed.forEach((id) => this.controlledAwarenessIds.delete(id));
+    }
+  }
+
+  /**
+   * Defines if the current connection has received at least one full synchronisation.
+   */
+  public isSynced(): boolean {
+    return this.transporter.isSynced();
+  }
+
+  /**
+   * Sends the given content to the client.
+   *
+   * @param content The content to send
+   */
+  public send(content: Uint8Array): void {
+    this.transporter.send(content);
+  }
+
+  /**
+   * Stops the connection
+   */
+  public disconnect(): void {
+    this.transporter.disconnect();
+  }
+
+  public getControlledAwarenessIds(): ReadonlySet<number> {
+    return this.controlledAwarenessIds;
+  }
+
+  public getUser(): User {
+    return this.user;
+  }
+}