add task solution

src/createServer.js

@@ -1,3 +1,104 @@
-// Write code here
-// Also, you can create additional files in the src folder
-// and import (require) them here
+/* eslint-disable max-len */
+const http = require('http');
+const { convertToCase } = require('./convertToCase');
+
+const ERROR_MESSAGES = {
+  NO_TEXT:
+    'Text to convert is required. Correct request is: "/<TEXT_TO_CONVERT>?toCase=<CASE_NAME>".',
+  NO_CASE:
+    '"toCase" query param is required. Correct request is: "/<TEXT_TO_CONVERT>?toCase=<CASE_NAME>".',
+  WRONG_CASE:
+    'This case is not supported. Available cases: SNAKE, KEBAB, CAMEL, PASCAL, UPPER.',
+};
+
+const SUPPORTED_CASES = ['SNAKE', 'KEBAB', 'CAMEL', 'PASCAL', 'UPPER'];
+
+function createServer() {
+  const server = http.createServer((req, res) => {
+    const url = new URL(req.url, `http://${req.headers.host}`);
+    const textToConvert = url.pathname.replace('/', '');
+    const caseType = url.searchParams.get('toCase');
+
+    res.setHeader('Content-Type', 'application/json');
+
+    const validationErrors = validateRequest(textToConvert, caseType);
+
+    if (validationErrors.length) {
+      return handleError(res, validationErrors);
+    }
+
+    try {
+      const { originalCase, convertedText } = convertToCase(
+        textToConvert,
+        caseType,
+      );
+
+      handleSuccess(res, textToConvert, originalCase, caseType, convertedText);
+    } catch (error) {
+      handleInternalError(res);
+    }
+  });
+
+  return server;
+}
+
+function validateRequest(textToConvert, caseType) {
+  const errors = [];
+
+  if (!textToConvert) {
+    errors.push({ message: ERROR_MESSAGES.NO_TEXT });
+  }
+
+  if (!caseType) {
+    errors.push({ message: ERROR_MESSAGES.NO_CASE });
+  }
+
+  if (caseType && !SUPPORTED_CASES.includes(caseType.toUpperCase())) {
+    errors.push({ message: ERROR_MESSAGES.WRONG_CASE });
+  }
+
+  return errors;
+}
+
+function handleError(res, errors) {
+  res.statusCode = 400;
+  res.statusMessage = 'Bad request';
+  res.end(JSON.stringify({ errors }));
+}
+
+function handleSuccess(
+  res,
+  originalText,
+  originalCase,
+  targetCase,
+  convertedText,
+) {
+  res.statusCode = 200;
+  res.statusMessage = 'OK';
+
+  const result = {
+    originalCase,
+    targetCase,
+    originalText,
+    convertedText,
+  };
+
+  res.end(JSON.stringify(result));
+}
+
+function handleInternalError(res) {
+  res.statusCode = 500;
+  res.statusMessage = 'Internal Server Error';
+
+  res.end(
+    JSON.stringify({
+      errors: [
+        {
+          message: 'An unexpected error occurred. Please try again later.',
+        },
+      ],
+    }),
+  );
+}
+
+module.exports = { createServer };