"""
Redis cache management for conversation context
"""
import json
from typing import Any, Optional
from datetime import timedelta

import redis.asyncio as redis

from config import settings, get_redis_url
from .logger import get_logger

logger = get_logger(__name__)


class CacheManager:
    """Redis cache manager for conversation context"""
    
    def __init__(self, redis_url: Optional[str] = None):
        """Initialize cache manager
        
        Args:
            redis_url: Redis connection URL, defaults to settings
        """
        self._redis_url = redis_url or get_redis_url()
        self._client: Optional[redis.Redis] = None
        
    async def connect(self) -> None:
        """Connect to Redis"""
        if self._client is None:
            self._client = redis.from_url(
                self._redis_url,
                encoding="utf-8",
                decode_responses=True
            )
            logger.info("Connected to Redis")
    
    async def disconnect(self) -> None:
        """Disconnect from Redis"""
        if self._client:
            await self._client.close()
            self._client = None
            logger.info("Disconnected from Redis")
    
    async def _ensure_connected(self) -> redis.Redis:
        """Ensure Redis connection is established"""
        if self._client is None:
            await self.connect()
        return self._client
    
    # ============ Conversation Context ============
    
    def _context_key(self, conversation_id: str) -> str:
        """Generate Redis key for conversation context"""
        return f"conversation:{conversation_id}"
    
    async def get_context(self, conversation_id: str) -> Optional[dict[str, Any]]:
        """Get conversation context
        
        Args:
            conversation_id: Unique conversation identifier
            
        Returns:
            Context dictionary or None if not found
        """
        client = await self._ensure_connected()
        key = self._context_key(conversation_id)
        
        data = await client.get(key)
        if data:
            logger.debug("Context retrieved", conversation_id=conversation_id)
            return json.loads(data)
        return None
    
    async def set_context(
        self,
        conversation_id: str,
        context: dict[str, Any],
        ttl: Optional[int] = None
    ) -> None:
        """Set conversation context
        
        Args:
            conversation_id: Unique conversation identifier
            context: Context dictionary
            ttl: Time-to-live in seconds, defaults to settings
        """
        client = await self._ensure_connected()
        key = self._context_key(conversation_id)
        ttl = ttl or settings.conversation_timeout
        
        await client.setex(
            key,
            timedelta(seconds=ttl),
            json.dumps(context, ensure_ascii=False)
        )
        logger.debug("Context saved", conversation_id=conversation_id, ttl=ttl)
    
    async def update_context(
        self,
        conversation_id: str,
        updates: dict[str, Any]
    ) -> dict[str, Any]:
        """Update conversation context with new values
        
        Args:
            conversation_id: Unique conversation identifier
            updates: Dictionary of updates to merge
            
        Returns:
            Updated context dictionary
        """
        context = await self.get_context(conversation_id) or {}
        context.update(updates)
        await self.set_context(conversation_id, context)
        return context
    
    async def delete_context(self, conversation_id: str) -> bool:
        """Delete conversation context
        
        Args:
            conversation_id: Unique conversation identifier
            
        Returns:
            True if deleted, False if not found
        """
        client = await self._ensure_connected()
        key = self._context_key(conversation_id)
        
        result = await client.delete(key)
        if result:
            logger.debug("Context deleted", conversation_id=conversation_id)
        return bool(result)
    
    # ============ Message History ============
    
    def _messages_key(self, conversation_id: str) -> str:
        """Generate Redis key for message history"""
        return f"messages:{conversation_id}"
    
    async def add_message(
        self,
        conversation_id: str,
        role: str,
        content: str,
        max_messages: int = 20
    ) -> None:
        """Add message to conversation history
        
        Args:
            conversation_id: Unique conversation identifier
            role: Message role (user/assistant/system)
            content: Message content
            max_messages: Maximum messages to keep
        """
        client = await self._ensure_connected()
        key = self._messages_key(conversation_id)
        
        message = json.dumps({
            "role": role,
            "content": content
        }, ensure_ascii=False)
        
        # Add to list and trim
        await client.rpush(key, message)
        await client.ltrim(key, -max_messages, -1)
        await client.expire(key, settings.conversation_timeout)
        
        logger.debug(
            "Message added",
            conversation_id=conversation_id,
            role=role
        )
    
    async def get_messages(
        self,
        conversation_id: str,
        limit: int = 20
    ) -> list[dict[str, str]]:
        """Get conversation message history
        
        Args:
            conversation_id: Unique conversation identifier
            limit: Maximum messages to retrieve
            
        Returns:
            List of message dictionaries
        """
        client = await self._ensure_connected()
        key = self._messages_key(conversation_id)
        
        messages = await client.lrange(key, -limit, -1)
        return [json.loads(m) for m in messages]
    
    async def clear_messages(self, conversation_id: str) -> bool:
        """Clear conversation message history
        
        Args:
            conversation_id: Unique conversation identifier
            
        Returns:
            True if cleared, False if not found
        """
        client = await self._ensure_connected()
        key = self._messages_key(conversation_id)
        
        result = await client.delete(key)
        return bool(result)
    
    # ============ Generic Cache Operations ============
    
    async def get(self, key: str) -> Optional[str]:
        """Get value from cache"""
        client = await self._ensure_connected()
        return await client.get(key)
    
    async def set(
        self,
        key: str,
        value: str,
        ttl: Optional[int] = None
    ) -> None:
        """Set value in cache"""
        client = await self._ensure_connected()
        if ttl:
            await client.setex(key, timedelta(seconds=ttl), value)
        else:
            await client.set(key, value)
    
    async def delete(self, key: str) -> bool:
        """Delete key from cache"""
        client = await self._ensure_connected()
        return bool(await client.delete(key))


# Global cache manager instance
cache_manager: Optional[CacheManager] = None


def get_cache_manager() -> CacheManager:
    """Get or create global cache manager instance"""
    global cache_manager
    if cache_manager is None:
        cache_manager = CacheManager()
    return cache_manager