feat: add link creation and lookup

finally has the bare minimum functionality to say that it works!

src/app.ts

@@ -1,27 +1,33 @@
-import * as dotenv from 'dotenv';
-dotenv.config({ quiet: true });
-
 import express from 'express';
 import { version } from '../package.json';
 import { AppDataSource } from './data-source'
+import { Link } from './entities/Link';
 import inferUser from './middleware/inferUser';
 import miscRouter from './routes/miscRoutes';
 import userRouter from './routes/userRoutes';
 import linkRouter from './routes/linkRoutes';
 import { getCorsConfig } from './tools/cors';
+import { LinkService } from './services/linkService';
+import * as env from './tools/env';
+import * as z from 'zod';
 
 AppDataSource.initialize().then(async () => {
 
 	await AppDataSource.runMigrations();
 
 	const app: express.Express = express();
+	const linkService = new LinkService();
+	const rs = env.getRewriteStrings();
+
+	const removedExpired = await linkService.removeAllExpired();
+	if (removedExpired !== 0) console.log(`[${Date.now() / 1_000}] (DB) Removed ${removedExpired} expired links.`);
 
 	app.use(express.json());
 	app.use(getCorsConfig());
 	app.use(inferUser);
 	app.use(miscRouter, userRouter, linkRouter);
 
-	if (process.env['DEBUG'] === 'true') {
+	if (env.getBool('debug', true)) {
 		const swaggerJsdocOpts = {
 			failOnErrors: true,
 			definition: {
@@ -67,16 +73,65 @@ AppDataSource.initialize().then(async () => {
 
 	// Handle 404s
 	// https://stackoverflow.com/a/9802006
-	app.use(function(req: express.Request, res: express.Response) {
-		res.status(404);
+	app.use(async function(req: express.Request, res: express.Response) {
 
-		if (req.accepts('json')) {
-			res.json({ status: 'error', error: 'Not found' });
-			return;
+		// Check if host header seems right
+		try {
+			z.string()
+			 .includes(rs.fqdn)
+			 .parse(req.headers.host);
+		} catch {
+			return res.status(400)
+			   .json({
+					status: 'error',
+					error: 'Invalid host. Is your browser sending the host header?',
+					code: 'no_host'
+				});
+		}
+		
+		// Retrieve url, subdomain from request.
+		let uri: string = req.url.slice(1); // discards / from /abc, /abc -> abc
+		let subdomain: string | null = req.headers.host!.replace(rs.fqdn, '') || null;
+
+		// Try to lookup the url in DB
+		const reversedLink: Link | null = await linkService.lookupUriWithExpiryValidation(uri, subdomain);
+
+		// Found something? 
+		if (reversedLink !== null) {
+			// Count this as a visit
+			reversedLink.visits += 1;
+			linkService.save(reversedLink);
+
+			// Redirect the user.
+			return res.redirect(302, reversedLink.fullUrl);
 		}
 
-		res.type('txt').send('Not found');
+		// Nothing found? Return the standard 404.
+		res.status(404);
+		if (req.accepts('json')) {
+			return res.json({
+				status: 'error',
+				error: 'Not found',
+				code: 'uri_not_found'
+			});
+		}
+
+		return res.type('txt')
+				  .send('Not found');
 	});
-	app.listen(6567, () => console.log('(HTTP Server) Listening on port 6567.'));
+
+	const errorHandler: express.ErrorRequestHandler = (err, req, res, next) => {
+		console.error(`[${Date.now() / 1_000}] (ErrorHandler) Server error! Error stack:`);
+		console.error(err?.stack);
+		return res.status(500)
+		   .json({
+		   		status: 'error',
+		   		error: 'Server error! Something broke',
+		   		code: 'generic_server_error'
+		   });
+	};
+	app.use(errorHandler);
+
+	app.listen(6567, () => console.log(`[${Date.now() / 1_000}] (HTTP Server) Listening on port 6567.`));
 
 }).catch(error => console.log(error))