add solution

src/createServer.js

@@ -1,8 +1,60 @@
 'use strict';
 
+const http = require('http');
+const fs = require('fs');
+
 function createServer() {
   /* Write your code here */
   // Return instance of http.Server class
+  return http.createServer(async (req, res) => {
+    if (req.method === 'POST' && req.url === '/add-expense') {
+      try {
+        let body = '';
+
+        req.on('data', (chunk) => {
+          body += chunk.toString();
+        });
+
+        req.on('end', () => {
+          const expense = JSON.parse(body);
+
+          const { date, title, amount } = expense;
+
+          if (!date || !title || !amount) {
+            res.writeHead(400);
+
+            return res.end('Missing required fields');
+          }
+
+          fs.writeFileSync('db/expense.json', JSON.stringify(expense));
+
+          const file = fs.readFileSync('db/expense.json');
+
+          res.statusCode = 200;
+          res.setHeader('Content-Type', 'application/json');
+          res.end(file);
+        });
+      } catch (err) {
+        res.writeHead(500);
+        res.end('Error parsing form');
+      }
+    } else if (req.method === 'GET' && req.url === '/') {
+      res.statusCode = 200;
+      res.setHeader('Content-type', 'text/html');
+
+      res.end(`<h1>Input data</h1>
+        <form method="POST" action="/add-expense">
+        <input name="date" type="date" required>
+        <input name="title" type="text" required>
+        <input name="amount" type="number" required>
+
+        <button type="submit">Submit</button>
+      </form>`);
+    } else {
+      res.statusCode = 404;
+      res.end('Page not found');
+    }
+  });
 }
 
 module.exports = {