Added comments

src/server.js

@@ -38,6 +38,8 @@ fastify.get('/yt/:id', async (req, res) => {
 //Normal shorturls
 fastify.get('/:shortcode', async (req, res) => {
     const shortcode = req.params.shortcode;
+
+    //This should never happen but better safe than 500
     if (!shortcode) {
         return 404;
     }
@@ -51,7 +53,7 @@ fastify.get('/:shortcode', async (req, res) => {
     res.redirect(302, target[0].target)
 })
 
-//Create new urls
+//Create new url schema
 const newUrlSchema = {
     body: {
         type: 'object',
@@ -62,14 +64,22 @@ const newUrlSchema = {
     }
 };
 
+//Create new url route
 fastify.post('/new', { newUrlSchema }, async (req, res) => {
     const target = req.body?.target;
     let shortcode = req.body?.shortcode;
+
+    //Check if the user provided a target
     if (!target) {
         res.statusCode = 400;
         return "Missing target";
     }
 
+    /**
+     * If no custom shortcode is provided: Check if a code for the target already exists.
+     * If it exists: No new get's generated => The existing code get's used.
+     * If it doesn't exist: Generate a new code and proceed to creating a new db entry.
+     */
     if (!shortcode) {
         const exists = await knex.select('shortcode')
             .from('urls')
@@ -85,6 +95,11 @@ fastify.post('/new', { newUrlSchema }, async (req, res) => {
         }
         shortcode = uniqid();
     }
+    /**
+     * If a custom shortcode is provided: Check for collisions.
+     * Collision detected: Warn user
+     * No collision: Proceed to db entry creation
+     */
     else {
         const exists = await knex.select('shortcode')
             .from('urls')
@@ -95,6 +110,8 @@ fastify.post('/new', { newUrlSchema }, async (req, res) => {
             return "Shortcode already exists, please choose another code";
         }
     }
+
+    //Create a new db entry
     await knex('urls').insert({target, shortcode});
 
     return {