feat: Observe notification read and fix #6406 (#6407)

* Resolve https://github.com/syuilo/misskey/pull/6406#issuecomment-633203670

* Improve typing

* Observe notification read

* capture readAllNotifications

* fix

* fix

* Refactor

* Update src/client/components/notification.vue

Co-authored-by: syuilo <Syuilotan@yahoo.co.jp>

* Update src/client/components/notification.vue

Co-authored-by: syuilo <Syuilotan@yahoo.co.jp>

* missing ;

Co-authored-by: syuilo <Syuilotan@yahoo.co.jp>

src/client/components/notification.vue

@@ -90,9 +90,36 @@ export default Vue.extend({
 			getNoteSummary: (text: string) => noteSummary(text, this.$root.i18n.messages[this.$root.i18n.locale]),
 			followRequestDone: false,
 			groupInviteDone: false,
+			connection: null,
+			readObserver: null,
 			faIdCardAlt, faPlus, faQuoteLeft, faQuoteRight, faRetweet, faReply, faAt, faClock, faCheck, faPollH
 		};
 	},
+
+	mounted() {
+		if (!this.notification.isRead) {
+			this.readObserver = new IntersectionObserver((entries, observer) => {
+				if (!entries.some(entry => entry.isIntersecting)) return;
+				this.$root.stream.send('readNotification', {
+					id: this.notification.id
+				});
+				entries.map(({ target }) => observer.unobserve(target));
+			});
+
+			this.readObserver.observe(this.$el);
+
+			this.connection = this.$root.stream.useSharedConnection('main');
+			this.connection.on('readAllNotifications', () => this.readObserver.unobserve(this.$el));
+		}
+	},
+
+	beforeDestroy() {
+		if (!this.notification.isRead) {
+			this.readObserver.unobserve(this.$el);
+			this.connection.dispose();
+		}
+	},
+
 	methods: {
 		acceptFollowRequest() {
 			this.followRequestDone = true;

src/client/components/notifications.vue

@@ -71,10 +71,13 @@ export default Vue.extend({
 
 	methods: {
 		onNotification(notification) {
-			// TODO: ユーザーが画面を見てないと思われるとき(ブラウザやタブがアクティブじゃないなど)は送信しない
-			this.$root.stream.send('readNotification', {
-				id: notification.id
-			});
+			if (document.visibilityState === 'visible') {
+				this.$root.stream.send('readNotification', {
+					id: notification.id
+				});
+
+				notification.isRead = true;
+			}
 
 			this.prepend(notification);
 		},

src/client/components/post-form.vue

@@ -67,6 +67,7 @@ import extractMentions from '../../misc/extract-mentions';
 import getAcct from '../../misc/acct/render';
 import { formatTimeString } from '../../misc/format-time-string';
 import { selectDriveFile } from '../scripts/select-drive-file';
+import { noteVisibilities } from '../../types';
 
 export default Vue.extend({
 	components: {
@@ -407,7 +408,7 @@ export default Vue.extend({
 		},
 
 		applyVisibility(v: string) {
-			this.visibility = ['public', 'home', 'followers', 'specified'].includes(v) ? v : 'public'; // v11互換性のため
+			this.visibility = (noteVisibilities as unknown as string[]).includes(v) ? v : 'public'; // v11互換性のため
 		},
 
 		addVisibleUser() {