Sheffield | 25-SDC-Nov | Hassan Osman | Sprint 3 | Middleware

.gitignore

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+node_modules/

custom-middlewares/index.js

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+// Middleware 1 looks for a header with name "X-Username"
+function usernameMiddleware(request, response, next) {
+  const usernameHeader = request.header("X-Username");
+  request.username = usernameHeader ? usernameHeader : null;
+  next();
+}
+
+// Middleware 2 parse the POST body as JSON array
+function postBodyAsJsonMiddleware(request, response, next) {
+  let data = '';
+
+  request.on('data', chunk => {
+    data += chunk;
+  });
+
+  request.on('end', () => {
+    try {
+      const parsedData = JSON.parse(data);
+
+      if (!Array.isArray(parsedData) || !parsedData.every(item => typeof item === 'string')) {
+        return response.status(400).send('Invalid request: must be a JSON array of strings')
+      }
+
+      request.body = parsedData;
+      next();
+    } catch (err) {
+      response.status(400).send("Invalid JSON");
+    }
+  });
+}
+
+
+
+const express = require("express");
+
+const app = express();
+const PORT = 3000;
+
+app.use(usernameMiddleware);
+
+
+
+app.post("/", postBodyAsJsonMiddleware, (request, response) => {
+  let responseToClient1;
+  if (request.username) {
+    responseToClient1 = `You are authenticated as ${request.username}.`;
+  } else {
+    responseToClient1 = "You are not authenticated.";
+  }
+
+  const subjects = request.body || [];
+  let responseToClient2;
+
+  if (subjects.length === 0) {
+    responseToClient2 = "You have requested information about 0 subjects.";
+  } else {
+    responseToClient2 = `You have requested information about ${subjects.length} subject${subjects.length > 1 ? 's' : ''}: ${subjects.join(', ')}.`;
+  }
+
+  response.send(`${responseToClient1}\n${responseToClient2}`);
+});
+
+app.listen(PORT, () => {
+  console.log(`Server running on http://localhost:${PORT}`);
+});
+