Suppress comment notifications when viewing document (#4987)

* Updating views from collaboration server

* refactor

* Suppress comment notifications based on views

* test

server/collaboration/ViewsExtension.ts

@@ -0,0 +1,73 @@
+import {
+  Extension,
+  onAwarenessUpdatePayload,
+  onDisconnectPayload,
+} from "@hocuspocus/server";
+import { Second } from "@shared/utils/time";
+import Logger from "@server/logging/Logger";
+import { trace } from "@server/logging/tracing";
+import { View } from "@server/models";
+
+@trace()
+export class ViewsExtension implements Extension {
+  /**
+   * Map of socketId -> intervals
+   */
+  intervalsBySocket: Map<string, NodeJS.Timer> = new Map();
+
+  /**
+   * onAwarenessUpdate hook
+   * @param data The awareness payload
+   */
+  async onAwarenessUpdate({
+    documentName,
+    // @ts-expect-error Hocuspocus types are wrong
+    connection,
+    context,
+    socketId,
+  }: onAwarenessUpdatePayload) {
+    if (this.intervalsBySocket.get(socketId)) {
+      return;
+    }
+
+    const [, documentId] = documentName.split(".");
+
+    const updateView = async () => {
+      Logger.debug(
+        "multiplayer",
+        `Updating last viewed at for "${documentName}"`
+      );
+      try {
+        await View.touch(documentId, context.user.id, !connection.readOnly);
+      } catch (err) {
+        Logger.error(
+          `Failed to update last viewed at for "${documentName}"`,
+          err,
+          {
+            documentId,
+            userId: context.user.id,
+          }
+        );
+      }
+    };
+
+    // Set up an interval to update the last viewed at timestamp continuously
+    // while the user is connected. This should only be done once per socket.
+    const interval = setInterval(updateView, 30 * Second);
+    updateView();
+
+    this.intervalsBySocket.set(socketId, interval);
+  }
+
+  /**
+   * onDisconnect hook
+   * @param data The disconnect payload
+   */
+  async onDisconnect({ socketId }: onDisconnectPayload) {
+    const interval = this.intervalsBySocket.get(socketId);
+    if (interval) {
+      clearInterval(interval);
+      this.intervalsBySocket.delete(socketId);
+    }
+  }
+}