feat: Document presence indicator (#1114)

* Update websockets to allow joining document-based rooms

* dynamic websocket joining

* emit user.join/leave events when entering and exiting document rooms

* presence storage

* feat: frontend presence store

* lint

* UI updates

* First pass editing state

* refactoring

* Timeout per user/doc
lint

* Document data loading refactor to keep Socket mounted

* restore: Mark as viewed functionality
Add display of 'you' to collaborators

* fix: Socket/document remount when document slug changes due to title change

* Revert unneccessary package update

* Move editing ping interval to a shared constant

* fix: Flash of sidebar when loading page directly on editing mode

* separate document and revision loading

* add comments for socket events

* fix: Socket events getting bound multiple times on reconnect

* fix: Clear client side presence state on disconnect

* fix: Don't ignore server side error
Improved documentation

* More comments / why comments

* rename Socket -> SocketPresence

* fix: Handle redis is down
remove unneccessary join

* fix: PR feedback

app/scenes/Document/components/MarkAsViewed.js

@@ -0,0 +1,34 @@
+// @flow
+import * as React from 'react';
+import Document from 'models/Document';
+
+const MARK_AS_VIEWED_AFTER = 3 * 1000;
+
+type Props = {|
+  document: Document,
+  children?: React.Node,
+|};
+
+class MarkAsViewed extends React.Component<Props> {
+  viewTimeout: TimeoutID;
+
+  componentDidMount() {
+    const { document } = this.props;
+
+    this.viewTimeout = setTimeout(() => {
+      if (document.publishedAt) {
+        document.view();
+      }
+    }, MARK_AS_VIEWED_AFTER);
+  }
+
+  componentWillUnmount() {
+    clearTimeout(this.viewTimeout);
+  }
+
+  render() {
+    return this.props.children || null;
+  }
+}
+
+export default MarkAsViewed;