チャンネルで入力中ユーザーを表示するように、Chat UIでタイムラインでは投稿フォームを上に表示するように

src/server/api/stream/channels/channel.ts

@@ -1,14 +1,17 @@
 import autobind from 'autobind-decorator';
 import Channel from '../channel';
-import { Notes } from '../../../../models';
+import { Notes, Users } from '../../../../models';
 import { isMutedUserRelated } from '../../../../misc/is-muted-user-related';
 import { PackedNote } from '../../../../models/repositories/note';
+import { User } from '../../../../models/entities/user';
 
 export default class extends Channel {
 	public readonly chName = 'channel';
 	public static shouldShare = false;
 	public static requireCredential = false;
 	private channelId: string;
+	private typers: Record<User['id'], Date> = {};
+	private emitTypersIntervalId: ReturnType<typeof setInterval>;
 
 	@autobind
 	public async init(params: any) {
@@ -16,6 +19,8 @@ export default class extends Channel {
 
 		// Subscribe stream
 		this.subscriber.on('notesStream', this.onNote);
+		this.subscriber.on(`channelStream:${this.channelId}`, this.onEvent);
+		this.emitTypersIntervalId = setInterval(this.emitTypers, 5000);
 	}
 
 	@autobind
@@ -41,9 +46,41 @@ export default class extends Channel {
 		this.send('note', note);
 	}
 
+	@autobind
+	private onEvent(data: any) {
+		if (data.type === 'typing') {
+			const id = data.body;
+			const begin = this.typers[id] == null;
+			this.typers[id] = new Date();
+			if (begin) {
+				this.emitTypers();
+			}
+		}
+	}
+
+	@autobind
+	private async emitTypers() {
+		const now = new Date();
+
+		// Remove not typing users
+		for (const [userId, date] of Object.entries(this.typers)) {
+			if (now.getTime() - date.getTime() > 5000) delete this.typers[userId];
+		}
+
+		const users = await Users.packMany(Object.keys(this.typers), null, { detail: false });
+
+		this.send({
+			type: 'typers',
+			body: users,
+		});
+	}
+
 	@autobind
 	public dispose() {
 		// Unsubscribe events
 		this.subscriber.off('notesStream', this.onNote);
+		this.subscriber.off(`channelStream:${this.channelId}`, this.onEvent);
+
+		clearInterval(this.emitTypersIntervalId);
 	}
 }