Post --> Note

Closes #1411

src/server/activitypub/note.ts

@@ -0,0 +1,43 @@
+import * as express from 'express';
+import context from '../../remote/activitypub/renderer/context';
+import render from '../../remote/activitypub/renderer/note';
+import parseAcct from '../../acct/parse';
+import Note from '../../models/note';
+import User from '../../models/user';
+
+const app = express.Router();
+
+app.get('/@:user/:note', async (req, res, next) => {
+	const accepted = req.accepts(['html', 'application/activity+json', 'application/ld+json']);
+	if (!(['application/activity+json', 'application/ld+json'] as any[]).includes(accepted)) {
+		return next();
+	}
+
+	const { username, host } = parseAcct(req.params.user);
+	if (host !== null) {
+		return res.sendStatus(422);
+	}
+
+	const user = await User.findOne({
+		usernameLower: username.toLowerCase(),
+		host: null
+	});
+	if (user === null) {
+		return res.sendStatus(404);
+	}
+
+	const note = await Note.findOne({
+		_id: req.params.note,
+		userId: user._id
+	});
+	if (note === null) {
+		return res.sendStatus(404);
+	}
+
+	const rendered = await render(user, note);
+	rendered['@context'] = context;
+
+	res.json(rendered);
+});
+
+export default app;