"""Fractafrag — Redis-backed rate limiting middleware."""

import time
from fastapi import Request, HTTPException, status
from app.redis import get_redis


async def check_rate_limit(
    key: str,
    max_requests: int,
    window_seconds: int = 60,
):
    """
    Check and enforce rate limit.

    Args:
        key: Unique identifier (e.g., "ip:1.2.3.4" or "user:uuid")
        max_requests: Maximum requests allowed in the window
        window_seconds: Time window in seconds

    Raises:
        HTTPException 429 if rate limit exceeded
    """
    redis = await get_redis()
    redis_key = f"ratelimit:{key}"

    pipe = redis.pipeline()
    now = time.time()
    window_start = now - window_seconds

    # Remove old entries outside the window
    pipe.zremrangebyscore(redis_key, 0, window_start)
    # Count current entries
    pipe.zcard(redis_key)
    # Add current request
    pipe.zadd(redis_key, {str(now): now})
    # Set TTL on the key
    pipe.expire(redis_key, window_seconds)

    results = await pipe.execute()
    current_count = results[1]

    if current_count >= max_requests:
        raise HTTPException(
            status_code=status.HTTP_429_TOO_MANY_REQUESTS,
            detail=f"Rate limit exceeded. Max {max_requests} requests per {window_seconds}s.",
            headers={"Retry-After": str(window_seconds)},
        )


async def rate_limit_ip(request: Request, max_requests: int = 100):
    """Rate limit by IP address. Default: 100 req/min."""
    ip = request.client.host if request.client else "unknown"
    await check_rate_limit(f"ip:{ip}", max_requests)


async def rate_limit_user(user_id: str, max_requests: int = 300):
    """Rate limit by user ID. Default: 300 req/min."""
    await check_rate_limit(f"user:{user_id}", max_requests)