from typing import Optional, Dict, Any
import json
from datetime import datetime, timedelta
import asyncio


class MockCacheClient:
    """Mock cache client that simulates Redis behavior in memory"""
    
    def __init__(self):
        self._cache: Dict[str, Dict[str, Any]] = {}
        
    async def get(self, key: str) -> Optional[str]:
        """Get value from cache if not expired"""
        await asyncio.sleep(0.01)  # Simulate network delay
        
        if key in self._cache:
            entry = self._cache[key]
            if entry['expires_at'] > datetime.utcnow():
                return entry['value']
            else:
                # Remove expired entry
                del self._cache[key]
        return None
    
    async def set(self, key: str, value: Any, ttl: int = 86400) -> bool:
        """Set value in cache with TTL in seconds"""
        await asyncio.sleep(0.01)  # Simulate network delay
        
        self._cache[key] = {
            'value': json.dumps(value) if not isinstance(value, str) else value,
            'expires_at': datetime.utcnow() + timedelta(seconds=ttl),
            'created_at': datetime.utcnow()
        }
        return True
    
    async def setex(self, key: str, ttl: int, value: Any) -> bool:
        """Set with explicit TTL (Redis compatibility)"""
        return await self.set(key, value, ttl)
    
    async def delete(self, key: str) -> bool:
        """Delete key from cache"""
        if key in self._cache:
            del self._cache[key]
            return True
        return False
    
    async def exists(self, key: str) -> bool:
        """Check if key exists and is not expired"""
        if key in self._cache:
            entry = self._cache[key]
            if entry['expires_at'] > datetime.utcnow():
                return True
            else:
                del self._cache[key]
        return False
    
    def clear_all(self):
        """Clear entire cache (for testing)"""
        self._cache.clear()
    
    def get_stats(self) -> Dict[str, Any]:
        """Get cache statistics"""
        total_keys = len(self._cache)
        expired_keys = sum(
            1 for entry in self._cache.values() 
            if entry['expires_at'] <= datetime.utcnow()
        )
        
        return {
            'total_keys': total_keys,
            'active_keys': total_keys - expired_keys,
            'expired_keys': expired_keys,
            'cache_size_bytes': sum(
                len(entry['value']) for entry in self._cache.values()
            )
        }