# middleware/decorators.py
"""
FastAPI decorators for cross-cutting concerns.

This module provides classes and functions for:
- Rate limiting decorators for endpoint protection
- Request throttling and abuse prevention
- Consistent error handling for rate limit violations
"""

import asyncio
from functools import wraps

from starlette.requests import Request

from app.exceptions.base import RateLimitException
from middleware.cloudflare import get_real_client_ip
from middleware.rate_limiter import RateLimiter

# Initialize rate limiter instance
rate_limiter = RateLimiter()


def _find_request(*args, **kwargs) -> Request | None:
    """Extract a Request object from function args/kwargs."""
    # Check kwargs first (FastAPI usually passes request= as keyword)
    for val in kwargs.values():
        if isinstance(val, Request):
            return val
    # Check positional args (e.g. self, request, ...)
    for val in args:
        if isinstance(val, Request):
            return val
    return None


def rate_limit(max_requests: int = 100, window_seconds: int = 3600):
    """Rate limiting decorator for FastAPI endpoints.

    Works with both sync and async endpoint functions.
    Extracts the real client IP from the Request object for per-client limiting.
    """

    def decorator(func):
        if asyncio.iscoroutinefunction(func):

            @wraps(func)
            async def async_wrapper(*args, **kwargs):
                request = _find_request(*args, **kwargs)
                client_id = (
                    get_real_client_ip(request) if request else "anonymous"
                )

                if not rate_limiter.allow_request(
                    client_id, max_requests, window_seconds
                ):
                    raise RateLimitException(
                        message="Rate limit exceeded",
                        retry_after=window_seconds,
                    )

                return await func(*args, **kwargs)

            return async_wrapper

        @wraps(func)
        def sync_wrapper(*args, **kwargs):
            request = _find_request(*args, **kwargs)
            client_id = (
                get_real_client_ip(request) if request else "anonymous"
            )

            if not rate_limiter.allow_request(
                client_id, max_requests, window_seconds
            ):
                raise RateLimitException(
                    message="Rate limit exceeded",
                    retry_after=window_seconds,
                )

            return func(*args, **kwargs)

        return sync_wrapper

    return decorator