backend/cache_utils.py

import time
from typing import Dict, Any, Optional


from backend.credentials import setup_google_credentials
setup_google_credentials()

# Simple in-memory cache
user_cache: Dict[str, Dict[str, Any]] = {}
routing_cache: Dict[str, str] = {}
CACHE_DURATION = 30  # 30 seconds
ROUTING_CACHE_DURATION = 1800  # 30 minutes for routing

def get_cache_key(user_id: str) -> str:
    """Generate cache key for user data"""
    return f"user_data:{user_id}"

def is_cache_valid(cache_entry: Dict[str, Any], duration: int = CACHE_DURATION) -> bool:
    """Check if cache entry is still valid"""
    current_time = time.time()
    return current_time - cache_entry['timestamp'] < duration

def get_cached_user_data(user_id: str) -> Optional[Dict[str, Any]]:
    """Retrieve cached user data if valid"""
    cache_key = get_cache_key(user_id)
    
    if cache_key in user_cache:
        cache_entry = user_cache[cache_key]
        if is_cache_valid(cache_entry):
            return cache_entry['data']
        else:
            # Remove expired entry
            del user_cache[cache_key]
    
    return None

def cache_user_data(user_id: str, data: Dict[str, Any]) -> None:
    """Cache user data with timestamp"""
    cache_key = get_cache_key(user_id)
    user_cache[cache_key] = {
        'data': data,
        'timestamp': time.time()
    }
    print(f"[CACHE] Cached user data for user: {user_id}")

def get_cached_route(user_message: str) -> Optional[str]:
    """Get cached routing decision"""
    # Create a simple hash of the message for caching
    import hashlib
    message_hash = hashlib.md5(user_message.lower().strip().encode()).hexdigest()
    
    if message_hash in routing_cache:
        cache_entry = routing_cache[message_hash]
        if is_cache_valid(cache_entry, ROUTING_CACHE_DURATION):
            return cache_entry['route']
        else:
            del routing_cache[message_hash]
    
    return None

def cache_route(user_message: str, route: str) -> None:
    """Cache routing decision"""
    import hashlib
    message_hash = hashlib.md5(user_message.lower().strip().encode()).hexdigest()
    routing_cache[message_hash] = {
        'route': route,
        'timestamp': time.time()
    }
    print(f"[CACHE] Cached route '{route}' for message hash: {message_hash[:8]}...")

def clear_user_cache(user_id: str = None) -> None:
    """Clear cache for specific user or all users"""
    global user_cache
    
    if user_id:
        cache_key = get_cache_key(user_id)
        user_cache.pop(cache_key, None)
        print(f"[CACHE] Cleared cache for user: {user_id}")
    else:
        user_cache.clear()
        print("[CACHE] Cleared all user cache")

def get_cache_stats() -> Dict[str, Any]:
    """Get cache statistics"""
    current_time = time.time()
    valid_user_entries = 0
    expired_user_entries = 0
    valid_routing_entries = 0
    expired_routing_entries = 0
    
    # User cache stats
    for entry in user_cache.values():
        if current_time - entry['timestamp'] < CACHE_DURATION:
            valid_user_entries += 1
        else:
            expired_user_entries += 1
    
    # Routing cache stats
    for entry in routing_cache.values():
        if current_time - entry['timestamp'] < ROUTING_CACHE_DURATION:
            valid_routing_entries += 1
        else:
            expired_routing_entries += 1
    
    return {
        "user_cache": {
            "total_entries": len(user_cache),
            "valid_entries": valid_user_entries,
            "expired_entries": expired_user_entries,
            "cache_duration_seconds": CACHE_DURATION
        },
        "routing_cache": {
            "total_entries": len(routing_cache),
            "valid_entries": valid_routing_entries,
            "expired_entries": expired_routing_entries,
            "cache_duration_seconds": ROUTING_CACHE_DURATION
        }
    }

def cleanup_expired_cache() -> Dict[str, int]:
    """Remove expired cache entries and return count removed"""
    global user_cache, routing_cache
    current_time = time.time()
    
    # Clean user cache
    expired_user_keys = []
    for key, entry in user_cache.items():
        if current_time - entry['timestamp'] >= CACHE_DURATION:
            expired_user_keys.append(key)
    
    for key in expired_user_keys:
        del user_cache[key]
    
    # Clean routing cache
    expired_routing_keys = []
    for key, entry in routing_cache.items():
        if current_time - entry['timestamp'] >= ROUTING_CACHE_DURATION:
            expired_routing_keys.append(key)
    
    for key in expired_routing_keys:
        del routing_cache[key]
    
    if expired_user_keys or expired_routing_keys:
        print(f"[CACHE] Cleaned up {len(expired_user_keys)} user entries and {len(expired_routing_keys)} routing entries")
    
    return {
        "user_entries_removed": len(expired_user_keys),
        "routing_entries_removed": len(expired_routing_keys)
    }