from typing import Any, Dict, Generic, List, Optional, TypeVar, Union, Callable

T = TypeVar('T')

class CacheItem(Generic[T]):
    """Cache item with metadata."""
    def __init__(
        self, 
        key: str, 
        value: T, 
        expires_at: Optional[float] = None, 
        tags: Optional[List[str]] = None, 
        dependencies: Optional[List[str]] = None
    ):
        self.key = key
        self.value = value
        self.expires_at = expires_at
        self.tags = tags or []
        self.dependencies = dependencies or []

class CacheBackend(Generic[T]):
    """Base cache backend interface."""
    async def get(self, key: str) -> Optional[CacheItem[T]]:
        """Get a value from the cache."""
        raise NotImplementedError()
    
    async def set(
        self, 
        key: str, 
        value: T, 
        ttl: Optional[int] = None, 
        tags: Optional[List[str]] = None, 
        dependencies: Optional[List[str]] = None
    ) -> None:
        """Set a value in the cache."""
        raise NotImplementedError()
    
    async def delete(self, key: str) -> None:
        """Delete a value from the cache."""
        raise NotImplementedError()
    
    async def delete_by_tags(self, tags: List[str]) -> None:
        """Delete values with specified tags."""
        raise NotImplementedError()
    
    async def delete_by_dependencies(self, keys: List[str]) -> None:
        """Delete values with specified dependencies."""
        raise NotImplementedError()
    
    async def clear(self) -> None:
        """Clear the entire cache."""
        raise NotImplementedError()

class MemoryCacheBackend(CacheBackend[T]):
    """In-memory cache backend implementation."""
    def __init__(self, max_size: Optional[int] = None):
        self.cache: Dict[str, CacheItem[T]] = {}
        self.max_size = max_size
    
    async def get(self, key: str) -> Optional[CacheItem[T]]:
        """Get a value from the cache."""
        if key not in self.cache:
            return None
        
        item = self.cache[key]
        # Check expiration
        # Implementation details would go here
        
        return item
    
    async def set(
        self, 
        key: str, 
        value: T, 
        ttl: Optional[int] = None, 
        tags: Optional[List[str]] = None, 
        dependencies: Optional[List[str]] = None
    ) -> None:
        """Set a value in the cache."""
        expires_at = None
        if ttl is not None:
            # Calculate expires_at based on ttl
            pass
        
        self.cache[key] = CacheItem(key, value, expires_at, tags, dependencies)
        
        # Handle max_size eviction policy
        if self.max_size and len(self.cache) > self.max_size:
            # Implement eviction strategy
            pass
    
    async def delete(self, key: str) -> None:
        """Delete a value from the cache."""
        if key in self.cache:
            del self.cache[key]
    
    async def delete_by_tags(self, tags: List[str]) -> None:
        """Delete values with specified tags."""
        keys_to_delete = []
        for key, item in self.cache.items():
            if any(tag in item.tags for tag in tags):
                keys_to_delete.append(key)
        
        for key in keys_to_delete:
            await self.delete(key)
    
    async def delete_by_dependencies(self, keys: List[str]) -> None:
        """Delete values with specified dependencies."""
        keys_to_delete = []
        for cache_key, item in self.cache.items():
            if any(key in item.dependencies for key in keys):
                keys_to_delete.append(cache_key)
        
        for key in keys_to_delete:
            await self.delete(key)
    
    async def clear(self) -> None:
        """Clear the entire cache."""
        self.cache.clear()

