"""
Redis client initialization and connection management
Provides standardized Redis connection for all services
"""

import ssl
import redis.asyncio as redis
from typing import Optional, Dict, Any
import structlog
from contextlib import asynccontextmanager

logger = structlog.get_logger()


def get_ssl_kwargs_for_url(redis_url: str) -> Dict[str, Any]:
    """
    Get SSL kwargs for redis.from_url() based on the URL scheme.

    Handles self-signed certificates by disabling certificate verification
    when using rediss:// (TLS-enabled) URLs.

    Args:
        redis_url: Redis connection URL (redis:// or rediss://)

    Returns:
        Dict with SSL configuration kwargs
    """
    if redis_url and redis_url.startswith("rediss://"):
        return {
            "ssl_cert_reqs": ssl.CERT_NONE,  # Disable certificate verification
            "ssl_ca_certs": None,             # Don't require CA certificates
            "ssl_certfile": None,             # Don't require client cert
            "ssl_keyfile": None,              # Don't require client key
        }
    return {}


class RedisConnectionManager:
    """
    Manages Redis connections with connection pooling and error handling.
    Thread-safe singleton pattern for sharing connections across service.

    Usage:
        # Option 1: Using class method (recommended for new code)
        manager = await RedisConnectionManager.create(redis_url)
        client = manager.get_client()

        # Option 2: Using instance method
        manager = RedisConnectionManager()
        await manager.initialize(redis_url)
        client = manager.get_client()

        # Don't forget to close when done
        await manager.close()
    """

    def __init__(self):
        self._client: Optional[redis.Redis] = None
        self._pool: Optional[redis.ConnectionPool] = None
        self._redis_url: Optional[str] = None
        self.logger = logger

    @classmethod
    async def create(
        cls,
        redis_url: str,
        db: int = 0,
        max_connections: int = 50,
        decode_responses: bool = False,
        retry_on_timeout: bool = True,
        socket_keepalive: bool = True,
        health_check_interval: int = 30
    ) -> "RedisConnectionManager":
        """
        Factory method to create and initialize a RedisConnectionManager.

        This is the recommended way to create Redis connections across all services.
        Handles SSL/TLS configuration automatically for self-signed certificates.

        Args:
            redis_url: Redis connection URL (redis:// or rediss://)
            db: Database number (0-15)
            max_connections: Maximum connections in pool
            decode_responses: Automatically decode responses to strings
            retry_on_timeout: Retry on timeout errors
            socket_keepalive: Enable TCP keepalive
            health_check_interval: Health check interval in seconds

        Returns:
            Initialized RedisConnectionManager

        Example:
            from shared.redis_utils import RedisConnectionManager

            manager = await RedisConnectionManager.create(settings.REDIS_URL)
            client = manager.get_client()
            await client.ping()
        """
        instance = cls()
        await instance.initialize(
            redis_url=redis_url,
            db=db,
            max_connections=max_connections,
            decode_responses=decode_responses,
            retry_on_timeout=retry_on_timeout,
            socket_keepalive=socket_keepalive,
            health_check_interval=health_check_interval,
        )
        return instance

    async def initialize(
        self,
        redis_url: str,
        db: int = 0,
        max_connections: int = 50,
        decode_responses: bool = True,
        retry_on_timeout: bool = True,
        socket_keepalive: bool = True,
        health_check_interval: int = 30
    ):
        """
        Initialize Redis connection with pool

        Args:
            redis_url: Redis connection URL (redis://[:password]@host:port)
            db: Database number (0-15)
            max_connections: Maximum connections in pool
            decode_responses: Automatically decode responses to strings
            retry_on_timeout: Retry on timeout errors
            socket_keepalive: Enable TCP keepalive
            health_check_interval: Health check interval in seconds
        """
        try:
            self._redis_url = redis_url

            # Create connection pool with SSL handling for self-signed certificates
            connection_kwargs = {
                'db': db,
                'max_connections': max_connections,
                'decode_responses': decode_responses,
                'retry_on_timeout': retry_on_timeout,
                'socket_keepalive': socket_keepalive,
                'health_check_interval': health_check_interval
            }

            # Add SSL kwargs for self-signed certificates (using shared helper)
            connection_kwargs.update(get_ssl_kwargs_for_url(redis_url))

            self._pool = redis.ConnectionPool.from_url(
                redis_url,
                **connection_kwargs
            )

            # Create Redis client with pool
            self._client = redis.Redis(connection_pool=self._pool)

            # Test connection
            await self._client.ping()

            self.logger.info(
                "redis_initialized",
                redis_url=redis_url.split("@")[-1],  # Log only host:port, not password
                db=db,
                max_connections=max_connections
            )

        except Exception as e:
            self.logger.error(
                "redis_initialization_failed",
                error=str(e),
                redis_url=redis_url.split("@")[-1]
            )
            raise

    async def close(self):
        """Close Redis connection and pool"""
        if self._client:
            await self._client.close()
            self.logger.info("redis_client_closed")

        if self._pool:
            await self._pool.disconnect()
            self.logger.info("redis_pool_closed")

    def get_client(self) -> redis.Redis:
        """
        Get Redis client instance

        Returns:
            Redis client

        Raises:
            RuntimeError: If client not initialized
        """
        if self._client is None:
            raise RuntimeError("Redis client not initialized. Call initialize() first.")
        return self._client

    async def health_check(self) -> bool:
        """
        Check Redis connection health

        Returns:
            bool: True if healthy, False otherwise
        """
        try:
            if self._client is None:
                return False

            await self._client.ping()
            return True

        except Exception as e:
            self.logger.error("redis_health_check_failed", error=str(e))
            return False

    async def get_info(self) -> dict:
        """
        Get Redis server information

        Returns:
            dict: Redis INFO command output
        """
        try:
            if self._client is None:
                return {}

            return await self._client.info()

        except Exception as e:
            self.logger.error("redis_info_failed", error=str(e))
            return {}

    async def flush_db(self):
        """
        Flush current database (USE WITH CAUTION)
        Only for development/testing
        """
        try:
            if self._client is None:
                raise RuntimeError("Redis client not initialized")

            await self._client.flushdb()
            self.logger.warning("redis_database_flushed")

        except Exception as e:
            self.logger.error("redis_flush_failed", error=str(e))
            raise


# Global connection manager instance
_redis_manager: Optional[RedisConnectionManager] = None


async def get_redis_manager() -> RedisConnectionManager:
    """
    Get or create global Redis manager instance

    Returns:
        RedisConnectionManager instance
    """
    global _redis_manager
    if _redis_manager is None:
        _redis_manager = RedisConnectionManager()
    return _redis_manager


async def initialize_redis(
    redis_url: str,
    db: int = 0,
    max_connections: int = 50,
    **kwargs
) -> redis.Redis:
    """
    Initialize Redis and return client

    Args:
        redis_url: Redis connection URL
        db: Database number
        max_connections: Maximum connections in pool
        **kwargs: Additional connection parameters

    Returns:
        Redis client instance
    """
    manager = await get_redis_manager()
    await manager.initialize(
        redis_url=redis_url,
        db=db,
        max_connections=max_connections,
        **kwargs
    )
    return manager.get_client()


async def get_redis_client() -> redis.Redis:
    """
    Get initialized Redis client

    Returns:
        Redis client instance

    Raises:
        RuntimeError: If Redis not initialized
    """
    manager = await get_redis_manager()
    return manager.get_client()


async def close_redis():
    """Close Redis connections"""
    global _redis_manager
    if _redis_manager:
        await _redis_manager.close()
        _redis_manager = None


@asynccontextmanager
async def redis_context(redis_url: str, db: int = 0):
    """
    Context manager for Redis connections

    Usage:
        async with redis_context(settings.REDIS_URL) as client:
            await client.set("key", "value")

    Args:
        redis_url: Redis connection URL
        db: Database number

    Yields:
        Redis client
    """
    client = None
    try:
        client = await initialize_redis(redis_url, db=db)
        yield client
    finally:
        if client:
            await close_redis()


# Convenience functions for common operations
async def set_with_ttl(key: str, value: str, ttl: int) -> bool:
    """
    Set key with TTL

    Args:
        key: Redis key
        value: Value to set
        ttl: Time to live in seconds

    Returns:
        bool: True if successful
    """
    try:
        client = await get_redis_client()
        await client.setex(key, ttl, value)
        return True
    except Exception as e:
        logger.error("redis_set_failed", key=key, error=str(e))
        return False


async def get_value(key: str) -> Optional[str]:
    """
    Get value by key

    Args:
        key: Redis key

    Returns:
        Value or None if not found
    """
    try:
        client = await get_redis_client()
        return await client.get(key)
    except Exception as e:
        logger.error("redis_get_failed", key=key, error=str(e))
        return None


async def increment_counter(key: str, amount: int = 1, ttl: Optional[int] = None) -> int:
    """
    Increment counter with optional TTL

    Args:
        key: Redis key
        amount: Amount to increment
        ttl: Time to live in seconds (sets on first increment)

    Returns:
        New counter value
    """
    try:
        client = await get_redis_client()
        new_value = await client.incrby(key, amount)

        # Set TTL if specified and key is new (value == amount)
        if ttl and new_value == amount:
            await client.expire(key, ttl)

        return new_value
    except Exception as e:
        logger.error("redis_increment_failed", key=key, error=str(e))
        return 0


async def get_keys_pattern(pattern: str) -> list:
    """
    Get keys matching pattern

    Args:
        pattern: Redis key pattern (e.g., "quota:*")

    Returns:
        List of matching keys
    """
    try:
        client = await get_redis_client()
        return await client.keys(pattern)
    except Exception as e:
        logger.error("redis_keys_failed", pattern=pattern, error=str(e))
        return []