# services/orchestrator/app/utils/cache.py
"""
Redis caching utilities for dashboard endpoints
"""

import json
import redis.asyncio as redis
from typing import Optional, Any, Callable
from functools import wraps
import structlog
from app.core.config import settings

logger = structlog.get_logger()

# Redis client instance
_redis_client: Optional[redis.Redis] = None


async def get_redis_client() -> redis.Redis:
    """Get or create Redis client"""
    global _redis_client

    if _redis_client is None:
        try:
            _redis_client = redis.Redis(
                host=getattr(settings, 'REDIS_HOST', 'localhost'),
                port=getattr(settings, 'REDIS_PORT', 6379),
                db=getattr(settings, 'REDIS_DB', 0),
                decode_responses=True,
                socket_connect_timeout=5,
                socket_timeout=5
            )
            # Test connection
            await _redis_client.ping()
            logger.info("Redis client connected successfully")
        except Exception as e:
            logger.warning(f"Failed to connect to Redis: {e}. Caching will be disabled.")
            _redis_client = None

    return _redis_client


async def close_redis():
    """Close Redis connection"""
    global _redis_client
    if _redis_client:
        await _redis_client.close()
        _redis_client = None
        logger.info("Redis connection closed")


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

    Args:
        key: Cache key

    Returns:
        Cached value (deserialized from JSON) or None if not found or error
    """
    try:
        client = await get_redis_client()
        if not client:
            return None

        cached = await client.get(key)
        if cached:
            logger.debug(f"Cache hit: {key}")
            return json.loads(cached)
        else:
            logger.debug(f"Cache miss: {key}")
            return None
    except Exception as e:
        logger.warning(f"Cache get error for key {key}: {e}")
        return None


async def set_cached(key: str, value: Any, ttl: int = 60) -> bool:
    """
    Set cached value with TTL

    Args:
        key: Cache key
        value: Value to cache (will be JSON serialized)
        ttl: Time to live in seconds

    Returns:
        True if successful, False otherwise
    """
    try:
        client = await get_redis_client()
        if not client:
            return False

        serialized = json.dumps(value, default=str)
        await client.setex(key, ttl, serialized)
        logger.debug(f"Cache set: {key} (TTL: {ttl}s)")
        return True
    except Exception as e:
        logger.warning(f"Cache set error for key {key}: {e}")
        return False


async def delete_cached(key: str) -> bool:
    """
    Delete cached value

    Args:
        key: Cache key

    Returns:
        True if successful, False otherwise
    """
    try:
        client = await get_redis_client()
        if not client:
            return False

        await client.delete(key)
        logger.debug(f"Cache deleted: {key}")
        return True
    except Exception as e:
        logger.warning(f"Cache delete error for key {key}: {e}")
        return False


async def delete_pattern(pattern: str) -> int:
    """
    Delete all keys matching pattern

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

    Returns:
        Number of keys deleted
    """
    try:
        client = await get_redis_client()
        if not client:
            return 0

        keys = []
        async for key in client.scan_iter(match=pattern):
            keys.append(key)

        if keys:
            deleted = await client.delete(*keys)
            logger.info(f"Deleted {deleted} keys matching pattern: {pattern}")
            return deleted
        return 0
    except Exception as e:
        logger.warning(f"Cache delete pattern error for {pattern}: {e}")
        return 0


def cache_response(key_prefix: str, ttl: int = 60):
    """
    Decorator to cache endpoint responses

    Args:
        key_prefix: Prefix for cache key (will be combined with tenant_id)
        ttl: Time to live in seconds

    Usage:
        @cache_response("dashboard:health", ttl=30)
        async def get_health(tenant_id: str):
            ...
    """
    def decorator(func: Callable):
        @wraps(func)
        async def wrapper(*args, **kwargs):
            # Extract tenant_id from kwargs or args
            tenant_id = kwargs.get('tenant_id')
            if not tenant_id and args:
                # Try to find tenant_id in args (assuming it's the first argument)
                tenant_id = args[0] if len(args) > 0 else None

            if not tenant_id:
                # No tenant_id, skip caching
                return await func(*args, **kwargs)

            # Build cache key
            cache_key = f"{key_prefix}:{tenant_id}"

            # Try to get from cache
            cached_value = await get_cached(cache_key)
            if cached_value is not None:
                return cached_value

            # Execute function
            result = await func(*args, **kwargs)

            # Cache result
            await set_cached(cache_key, result, ttl)

            return result

        return wrapper
    return decorator


def make_cache_key(prefix: str, tenant_id: str, **params) -> str:
    """
    Create a cache key with optional parameters

    Args:
        prefix: Key prefix
        tenant_id: Tenant ID
        **params: Additional parameters to include in key

    Returns:
        Cache key string
    """
    key_parts = [prefix, tenant_id]
    for k, v in sorted(params.items()):
        if v is not None:
            key_parts.append(f"{k}:{v}")
    return ":".join(key_parts)