backend001/basic-http-server.js at main · parth-476/backend001 · GitHub

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// ============================================
// LECTURE 13-16: HTTP Module & Creating Endpoints
// ============================================
// This demonstrates creating a server using native HTTP module
// Before frameworks like Express, this is how we created servers

const http = require("http");  // Built-in Node.js module
const fs = require("fs");      // File System module
const path = require("path");  // Path module
const url = require("url");    // URL parsing module

const PORT = process.env.HTTP_PORT || 4000;

// ============================================
// LECTURE 21-24: Request Handler Function
// ============================================
const server = http.createServer((req, res) => {
  // Parse URL with query parameters
  const parsedUrl = url.parse(req.url, true);
  const pathname = parsedUrl.pathname;
  const query = parsedUrl.query;

  // ============================================
  // Route 1: Home Page (GET method)
  // ============================================
  if (req.method === "GET" && pathname === "/") {
    res.writeHead(200, { "Content-Type": "text/html; charset=utf-8" });
    res.end(`
      <html>
        <head>
          <title>Native HTTP Server</title>
          <style>
            body { font-family: Arial; max-width: 800px; margin: 50px auto; padding: 20px; }
            h1 { color: #333; }
            .endpoint { background: #f4f4f4; padding: 10px; margin: 10px 0; border-radius: 5px; }
            code { background: #333; color: #fff; padding: 2px 6px; border-radius: 3px; }
          </style>
        </head>
        <body>
          <h1>🚀 Native HTTP Module Server</h1>
          <p>This server demonstrates HTTP module without any framework</p>
          <h2>Available Endpoints:</h2>
          <div class="endpoint">
            <strong>GET /api/info</strong> - Server information
          </div>
          <div class="endpoint">
            <strong>GET /api/data?name=value</strong> - Query parameters demo
          </div>
          <div class="endpoint">
            <strong>POST /api/submit</strong> - POST request handling
          </div>
          <div class="endpoint">
            <strong>GET /file/sample.txt</strong> - File streaming demo
          </div>
        </body>
      </html>
    `);
    return;
  }

  // ============================================
  // Route 2: API Info (GET with JSON response)
  // Response Methods: res.writeHead(), res.end()
  // ============================================
  if (req.method === "GET" && pathname === "/api/info") {
    const payload = {
      topic: "Node.js HTTP module endpoint demo",
      evaluation: "Backend first evaluation",
      module: "Native HTTP (no framework)",
      time: new Date().toISOString(),
      port: PORT
    };

    res.writeHead(200, { "Content-Type": "application/json" });
    res.end(JSON.stringify(payload, null, 2));
    return;
  }

  // ============================================
  // Route 3: Query Parameters Demo
  // LECTURE 21-24: Route parameters handling
  // ============================================
  if (req.method === "GET" && pathname === "/api/data") {
    const response = {
      message: "Query parameters received",
      queryParams: query,
      example: "Try: /api/data?name=John&age=25"
    };

    res.writeHead(200, { "Content-Type": "application/json" });
    res.end(JSON.stringify(response, null, 2));
    return;
  }

  // ============================================
  // Route 4: POST Request Handling
  // LECTURE 13-16: Handling request body
  // ============================================
  if (req.method === "POST" && pathname === "/api/submit") {
    let body = "";

    // Collect data chunks
    req.on("data", (chunk) => {
      body += chunk.toString();
    });

    // Process complete data
    req.on("end", () => {
      try {
        const data = JSON.parse(body);
        const response = {
          success: true,
          message: "Data received successfully",
          receivedData: data,
          timestamp: new Date().toISOString()
        };

        res.writeHead(200, { "Content-Type": "application/json" });
        res.end(JSON.stringify(response, null, 2));
      } catch (error) {
        // Exception handling
        res.writeHead(400, { "Content-Type": "application/json" });
        res.end(JSON.stringify({ error: "Invalid JSON format" }));
      }
    });
    return;
  }

  // ============================================
  // Route 5: File Streaming Demo
  // LECTURE 21-24: Handling static pages with file stream
  // ============================================
  if (req.method === "GET" && pathname.startsWith("/file/")) {
    const fileName = pathname.split("/file/")[1];
    const filePath = path.join(__dirname, "data", fileName);

    // Check if file exists
    fs.access(filePath, fs.constants.F_OK, (err) => {
      if (err) {
        res.writeHead(404, { "Content-Type": "application/json" });
        res.end(JSON.stringify({ error: "File not found" }));
        return;
      }

      // Stream file to response
      const readStream = fs.createReadStream(filePath);

      res.writeHead(200, { "Content-Type": "text/plain" });

      // Pipe file stream to response
      readStream.pipe(res);

      // Handle stream errors
      readStream.on("error", (streamErr) => {
        res.writeHead(500, { "Content-Type": "application/json" });
        res.end(JSON.stringify({ error: "Error reading file" }));
      });
    });
    return;
  }

  // ============================================
  // 404 - Route Not Found (Exception Handling)
  // LECTURE 21-24: Handling exceptions
  // ============================================
  res.writeHead(404, { "Content-Type": "application/json" });
  res.end(JSON.stringify({
    error: "Route not found in native HTTP server",
    requestedPath: pathname,
    method: req.method
  }));
});

// ============================================
// Start Server and Listen on Port
// ============================================
server.listen(PORT, () => {
  console.log(`\n${"=".repeat(50)}`);
  console.log(`🚀 Native HTTP Server Running`);
  console.log(`${"=".repeat(50)}`);
  console.log(`📍 URL: http://localhost:${PORT}`);
  console.log(`📚 This demonstrates Lectures 13-16 & 21-24`);
  console.log(`${"=".repeat(50)}\n`);
});