"""
Rate limiting configuration using slowapi with Redis backend.

This module provides rate limiting functionality to protect against
brute force attacks and DoS attempts on sensitive endpoints.
"""

import logging
import os

from slowapi import Limiter
from slowapi.util import get_remote_address

from app.core.config import settings

logger = logging.getLogger(__name__)


def _get_storage_uri() -> str:
    """
    Determine the appropriate storage URI for rate limiting.

    Priority:
    1. Use memory storage if TESTING environment variable is set
    2. Try Redis if available
    3. Fall back to memory storage if Redis is unavailable (with warning)

    Note: Memory storage is acceptable for development but Redis should
    be used in production for consistent rate limiting across workers.
    """
    # Use memory storage for testing
    testing = os.environ.get("TESTING", "").lower() in ("true", "1", "yes")
    if testing:
        return "memory://"

    # Try to connect to Redis
    redis_url = settings.REDIS_URL
    try:
        import redis
        r = redis.Redis(
            host=settings.REDIS_HOST,
            port=settings.REDIS_PORT,
            db=settings.REDIS_DB,
            socket_connect_timeout=1,
        )
        r.ping()
        logger.info("Rate limiter using Redis storage")
        return redis_url
    except Exception as e:
        logger.warning(
            f"Redis unavailable for rate limiting ({e}). "
            "Falling back to in-memory storage. "
            "Note: In production, Redis should be running for consistent "
            "rate limiting across multiple workers."
        )
        return "memory://"


_storage_uri = _get_storage_uri()

# Create limiter instance with appropriate storage
# Uses the client's remote address (IP) as the key for rate limiting
limiter = Limiter(
    key_func=get_remote_address,
    storage_uri=_storage_uri,
    strategy="fixed-window",  # Fixed window strategy for predictable rate limiting
)