task

src/createServer.js

@@ -1,8 +1,111 @@
 'use strict';
 
+const fs = require('fs');
+const path = require('path');
+const http = require('http');
+
+const TEXT_PLAIN = 'text/plain';
+
+function sendText(res, statusCode, body) {
+  res.writeHead(statusCode, { 'Content-Type': TEXT_PLAIN });
+  res.end(body);
+}
+
+function sendInvalidFilePath(res) {
+  sendText(res, 400, 'Invalid file path');
+}
+
+function sendFileNotFound(res) {
+  sendText(res, 404, 'File not found');
+}
+
+function readTextFile(res, filePath) {
+  fs.readFile(filePath, (error, data) => {
+    if (error) {
+      sendFileNotFound(res);
+
+      return;
+    }
+
+    sendText(res, 200, data);
+  });
+}
+
+function decodePathname(requestPath) {
+  try {
+    return decodeURIComponent(requestPath);
+  } catch (error) {
+    return null;
+  }
+}
+
 function createServer() {
-  /* Write your code here */
-  // Return instance of http.Server class
+  const publicFolderPath = path.resolve(__dirname, '../public');
+
+  const server = http.createServer((req, res) => {
+    const rawUrl = req.url || '';
+    // Remove query parameters
+    const requestPath = rawUrl.split('?')[0];
+    // handle URL-encoded characters
+    const decodedPathname = decodePathname(requestPath);
+
+    if (!decodedPathname) {
+      sendInvalidFilePath(res);
+
+      return;
+    }
+
+    if (rawUrl.includes('..') || decodedPathname.includes('..')) {
+      sendInvalidFilePath(res);
+
+      return;
+    }
+
+    if (decodedPathname === '/file' || decodedPathname === '/file/') {
+      readTextFile(res, path.resolve(publicFolderPath, 'index.html'));
+
+      return;
+    }
+
+    if (!decodedPathname.startsWith('/file/')) {
+      if (path.extname(decodedPathname)) {
+        sendInvalidFilePath(res);
+
+        return;
+      }
+
+      sendText(res, 200, 'Invalid path. To load files, use: /file/filename');
+
+      return;
+    }
+
+    const requestedFile = decodedPathname.replace(/^\/file\//, '');
+    const pathSegments = requestedFile.split('/');
+
+    if (pathSegments.includes('..')) {
+      sendInvalidFilePath(res);
+
+      return;
+    }
+
+    if (pathSegments.some((segment) => segment.length === 0)) {
+      sendFileNotFound(res);
+
+      return;
+    }
+
+    const filePath = path.resolve(publicFolderPath, requestedFile);
+
+    if (!filePath.startsWith(`${publicFolderPath}${path.sep}`)) {
+      sendInvalidFilePath(res);
+
+      return;
+    }
+
+    readTextFile(res, filePath);
+  });
+
+  return server;
 }
 
 module.exports = {