Add Sprint 3 task: custom middleware version

Author: ebrahimbeiati

middleware-custom/.gitignore

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+node_modules

middleware-custom/app.js

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+import express from "express";
+import usernameMiddleware from "./middleware/usernameMiddleware.js";
+import jsonArrayMiddleware from "./middleware/jsonArrayMiddleware.js";
+
+const app = express();
+
+// POST route using both the JSON body parser and the username middleware
+app.post("/", usernameMiddleware, jsonArrayMiddleware, (req, res) => {
+  const username = req.username;
+  const subjects = req.jsonArray;
+
+  const authMessage = username
+    ? `You are authenticated as ${username}!`
+    : "You are not authenticated.";
+
+  const count = subjects.length;
+  const list = subjects.join(", ");
+
+  let subjectMessage;
+  if (count === 0) {
+    subjectMessage = "You have no subjects.";
+  } else if (count === 1) {
+    subjectMessage = `You have 1 subject: ${list}.`;
+  } else {
+    subjectMessage = `You have ${count} subjects: ${list}.`;
+  }
+  res.send(`${authMessage} ${subjectMessage}`);
+});
+
+app.listen(3000, () => {
+  console.log("Server is running on port 3000");
+});

middleware-custom/middleware/jsonArrayMiddleware.js

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+export default function jsonArrayMiddleware(req, res, next) {
+  let data = "";
+
+  req.on("data", (chunk) => {
+    data += chunk.toString();
+  });
+
+  req.on("end", () => {
+    try {
+      const parsedData = JSON.parse(data);
+
+      if (!Array.isArray(parsedData)) {
+        return res.status(400).send("Expected an array in the request body");
+      }
+      const allStrings = parsedData.every((item) => typeof item === "string");
+
+      if (!allStrings) {
+        return res.status(400).send("All items in the array must be strings");
+      }
+
+      req.jsonArray = parsedData;
+      next();
+    } catch (err) {
+      console.error("Error parsing JSON:", err);
+      res.status(400).send("Invalid JSON format");
+    }
+  });
+}

middleware-custom/middleware/usernameMiddleware.js

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+export default function usernameMiddleware(req, res, next) {
+  const username = req.headers["x-username"];
+
+  req.username = username ?? null;
+
+  next();
+}