"""
Redis Client Pool — CrowData
Centralized Redis connection management with in-memory LRU fallback.
"""
import asyncio
import json
import logging
import time
from collections import OrderedDict
from typing import Optional
try:
    import redis.asyncio as aioredis
    _REDIS_MODULE_AVAILABLE = True
except ImportError:
    aioredis = None
    _REDIS_MODULE_AVAILABLE = False

from app.config import get_settings

logger = logging.getLogger(__name__)
settings = get_settings()

# Global connection pools
_redis_client = None
_redis_is_available = True
_reconnect_task = None

# In-memory LRU cache fallback
class LRUCache:
    def __init__(self, maxsize: int = 5000):
        self.maxsize = maxsize
        self._cache = OrderedDict()
        self._ttls = {}
        self._lock = asyncio.Lock()

    async def get(self, key: str):
        async with self._lock:
            if key not in self._cache:
                return None
            expire_at = self._ttls.get(key, 0)
            if expire_at and expire_at < time.time():
                # Expired
                self._cache.pop(key, None)
                self._ttls.pop(key, None)
                return None
            # Move to end (most recently used)
            value = self._cache.pop(key)
            self._cache[key] = value
            return value

    async def set(self, key: str, value: dict, ttl: int):
        async with self._lock:
            # Evict if at maxsize
            if len(self._cache) >= self.maxsize and key not in self._cache:
                self._cache.popitem(last=False)  # Remove LRU
            self._cache[key] = value
            self._ttls[key] = time.time() + ttl if ttl > 0 else 0

    async def delete(self, key: str):
        async with self._lock:
            self._cache.pop(key, None)
            self._ttls.pop(key, None)

    async def cleanup_expired(self):
        """Remove expired entries. Called periodically."""
        async with self._lock:
            now = time.time()
            expired = [k for k, exp in self._ttls.items() if exp and exp < now]
            for k in expired:
                self._cache.pop(k, None)
                self._ttls.pop(k, None)

    def __len__(self):
        return len(self._cache)


_in_memory_cache = LRUCache(maxsize=5000)

_redis_client = None
_redis_is_available = _REDIS_MODULE_AVAILABLE  # False si el módulo no está instalado
_reconnect_task = None


async def get_redis():
    global _redis_client
    if not _REDIS_MODULE_AVAILABLE:
        raise RuntimeError("redis module not installed; using in-memory fallback")
    if _redis_client is None:
        from app.config import get_settings
        settings = get_settings()
        _redis_client = await aioredis.from_url(
            settings.redis_url,
            encoding="utf-8",
            decode_responses=True,
            max_connections=getattr(settings, 'redis_max_connections', 20) or 20,
            socket_keepalive=True,
            socket_connect_timeout=5,
            socket_timeout=5,
            retry_on_timeout=True,
        )
    return _redis_client


async def _try_reconnect():
    """Background task to attempt Redis reconnection."""
    global _redis_is_available, _reconnect_task
    while True:
        await asyncio.sleep(30)  # Try every 30 seconds
        if not _redis_is_available:
            try:
                r = await get_redis()
                await r.ping()
                _redis_is_available = True
                logger.info("Redis reconnected successfully")
            except Exception:
                pass


async def _start_reconnect_task():
    global _reconnect_task
    if _reconnect_task is None or _reconnect_task.done():
        _reconnect_task = asyncio.create_task(_try_reconnect())


async def cache_get(key: str):
    global _redis_is_available
    if _redis_is_available:
        try:
            r = await get_redis()
            data = await r.get(key)
            if data:
                return json.loads(data)
        except Exception as e:
            logger.warning(f"Redis GET error for key {key}: {e}. Falling back to in-memory cache.")
            _redis_is_available = False
            # Start background reconnection
            asyncio.create_task(_try_reconnect())

    # In-memory fallback
    return await _in_memory_cache.get(key)


async def cache_set(key: str, value: dict, ttl: int = None):
    global _redis_is_available
    ttl = ttl or 86400
    if _redis_is_available:
        try:
            r = await get_redis()
            await r.setex(key, ttl, json.dumps(value, ensure_ascii=False))
            return
        except Exception as e:
            logger.warning(f"Redis SET error for key {key}: {e}. Saving in memory.")
            _redis_is_available = False
            # Start background reconnection
            asyncio.create_task(_try_reconnect())

    # In-memory LRU fallback
    await _in_memory_cache.set(key, value, ttl=60)


async def cache_delete(key: str):
    global _redis_is_available
    if _redis_is_available:
        try:
            r = await get_redis()
            await r.delete(key)
        except Exception as e:
            logger.warning(f"Redis DELETE error for key {key}: {e}.")
            _redis_is_available = False
            asyncio.create_task(_try_reconnect())

    # In-memory fallback
    await _in_memory_cache.delete(key)


async def cleanup_expired():
    """Periodic cleanup of expired in-memory cache entries."""
    await _in_memory_cache.cleanup_expired()


async def _start_reconnect_task():
    """Start the background reconnection task."""
    pass  # Task is already started at module level


# Module-level initialization - start background tasks
try:
    loop = asyncio.get_running_loop()
    loop.create_task(_try_reconnect())
except RuntimeError:
    # No event loop running, will be created later
    pass