Post --> Note

Closes #1411

src/services/note/watch.ts

@@ -0,0 +1,26 @@
+import * as mongodb from 'mongodb';
+import Watching from '../../models/note-watching';
+
+export default async (me: mongodb.ObjectID, note: object) => {
+	// 自分の投稿はwatchできない
+	if (me.equals((note as any).userId)) {
+		return;
+	}
+
+	// if watching now
+	const exist = await Watching.findOne({
+		noteId: (note as any)._id,
+		userId: me,
+		deletedAt: { $exists: false }
+	});
+
+	if (exist !== null) {
+		return;
+	}
+
+	await Watching.insert({
+		createdAt: new Date(),
+		noteId: (note as any)._id,
+		userId: me
+	});
+};