import asyncio
import json
import hashlib
from typing import Any, Callable, Dict, Optional
from functools import wraps
import logging

logger = logging.getLogger(__name__)

# Simple in-memory cache
_cache: Dict[str, Any] = {}
_cache_lock = asyncio.Lock()

def build_cache_key(namespace: str, *args, **kwargs) -> str:
    """Build a cache key from namespace and parameters"""
    key_data = f"{namespace}:{args}:{sorted(kwargs.items())}"
    return hashlib.md5(key_data.encode()).hexdigest()

def cached(expire: int = 300, key_builder: Optional[Callable] = None):
    """
    Cache decorator for FastAPI endpoints
    
    Args:
        expire: Cache expiration time in seconds
        key_builder: Function to build cache key
    """
    def decorator(func: Callable) -> Callable:
        @wraps(func)
        async def wrapper(*args, **kwargs):
            # Build cache key
            if key_builder:
                cache_key = key_builder(func, **kwargs)
            else:
                cache_key = build_cache_key(func.__name__, *args, **kwargs)
            
            # Check cache
            async with _cache_lock:
                if cache_key in _cache:
                    cached_data, timestamp = _cache[cache_key]
                    import time
                    if time.time() - timestamp < expire:
                        logger.debug(f"Cache hit for key: {cache_key}")
                        return cached_data
                    else:
                        # Expired, remove from cache
                        del _cache[cache_key]
            
            # Cache miss, execute function
            logger.debug(f"Cache miss for key: {cache_key}")
            result = await func(*args, **kwargs)
            
            # Store in cache
            async with _cache_lock:
                import time
                _cache[cache_key] = (result, time.time())
            
            return result
        return wrapper
    return decorator

def setup_cache():
    """Setup cache configuration"""
    logger.info("FastAPI cache initialized with in-memory backend")