Middleware Router - OOD Coding Interview

Question

## Problem

Implement a `MiddlewareRouter` that processes HTTP-style requests through a chain of middleware functions before reaching the final handler.

```python
from typing import Callable

Request = dict   # e.g. {"method": "GET", "path": "/api/user", "headers": {}, "body": None}
Response = dict  # e.g. {"status": 200, "body": "..."}
Handler = Callable[[Request], Response]
Middleware = Callable[[Request, Handler], Response]

class MiddlewareRouter:
    def use(self, middleware: Middleware) -> None: ...
    def route(self, method: str, path: str, handler: Handler) -> None: ...
    def handle(self, request: Request) -> Response: ...
```

Middleware has the signature `(request, next_handler) -> response` and may short-circuit by returning without calling `next_handler`.

**Example middleware:** auth check, request logger, rate limiter.

**Example:**
```
router = MiddlewareRouter()
router.use(auth_middleware)   # returns 401 if no token
router.use(log_middleware)    # logs path + latency
router.route("GET", "/ping", lambda req: {"status":200,"body":"pong"})
router.handle({"method":"GET","path":"/ping","headers":{"token":"abc"}})
# -> auth passes, logger runs, handler returns 200
```

## Follow-ups
- How do you ensure middleware runs in the order `use()` was called?
- How would you support path parameters like `/user/:id`?
- Extend to support async middleware in Python using `asyncio`.

Middleware Router - OOD Coding Interview

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