Add middleware-custom package with basic message handling API

- Created package.json for middleware-custom with express dependency
- Implemented server.js to handle health check and message CRUD operations
- Added middleware for request logging and API key validation

Author: enjoy15

.gitignore

@@ -0,0 +1,29 @@
+# Node
+node_modules/
+
+# Env files
+.env
+.env.*
+
+# Logs
+logs/
+*.log
+npm-debug.log*
+
+# Runtime data
+pids/
+*.pid
+*.seed
+*.pid.lock
+
+# Coverage
+coverage/
+.nyc_output/
+
+# Build output
+dist/
+build/
+
+# OS/editor
+.DS_Store
+.vscode/

README.md

@@ -1,3 +1,12 @@
 # Coursework
 
 Exercises to practice and solidify your understanding of the Decomposition module of the Software Development Course.
+
+## Middleware exercises
+
+This repo includes two Express examples for the Sprint 3 middleware prep:
+
+- Custom middlewares: [middleware-custom/](middleware-custom)
+- Off-the-shelf middleware: [middleware-off-the-shelf/](middleware-off-the-shelf)
+
+Each folder has its own README with run instructions.

middleware-custom/README.md

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+# Custom middleware example
+
+This Express app uses two custom middlewares:
+- `requestLogger` logs each request with status and duration.
+- `requireApiKey` protects `POST /messages` using an API key header.
+
+## Run locally
+
+```bash
+npm install
+npm start
+```
+
+Set a custom API key (optional):
+
+```bash
+API_KEY=my-secret npm start
+```
+
+## Try it
+
+```bash
+curl http://localhost:3000/health
+curl http://localhost:3000/messages
+curl -X POST http://localhost:3000/messages \
+  -H "Content-Type: application/json" \
+  -H "x-api-key: cyf" \
+  -d '{"user":"Azin","message":"Hello"}'
+```

middleware-custom/middlewares/requestLogger.js

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+module.exports = function requestLogger(req, res, next) {
+  const startedAt = Date.now();
+
+  res.on("finish", () => {
+    const durationMs = Date.now() - startedAt;
+    console.log(`${req.method} ${req.originalUrl} ${res.statusCode} ${durationMs}ms`);
+  });
+
+  next();
+};

middleware-custom/middlewares/requireApiKey.js

@@ -0,0 +1,10 @@
+module.exports = function requireApiKey(req, res, next) {
+  const expectedKey = process.env.API_KEY || "cyf";
+  const providedKey = req.header("x-api-key");
+
+  if (providedKey !== expectedKey) {
+    return res.status(401).json({ error: "Invalid API key" });
+  }
+
+  next();
+};