"""
数据库连接管理模块

统一管理所有数据库连接池：
- asyncpg Pool: 用于一般的数据库操作
- psycopg AsyncConnectionPool: 用于 LangGraph Checkpointer
"""
from typing import Optional
import asyncio

import asyncpg
from psycopg_pool import AsyncConnectionPool
from langgraph.checkpoint.postgres.aio import AsyncPostgresSaver

from core.config import settings
from core.graph_metadata import ensure_graph_metadata, reset_graph_metadata
from logger.logging import get_logger

logger = get_logger(__name__)

# 全局数据库连接池
_asyncpg_pool: Optional[asyncpg.Pool] = None
_psycopg_pool: Optional[AsyncConnectionPool] = None
_checkpointer: Optional[AsyncPostgresSaver] = None


async def get_db_pool() -> asyncpg.Pool:
    """
    获取或创建 asyncpg 数据库连接池
    
    用于一般的数据库 CRUD 操作。
    """
    global _asyncpg_pool
    
    if _asyncpg_pool is None:
        logger.info(f"初始化 asyncpg 数据库连接池: {settings.db_user}@{settings.db_host}:{settings.db_port}/{settings.db_name}")
        
        max_retries = 3
        retry_delay = 2  # 秒
        
        for attempt in range(max_retries):
            try:
                _asyncpg_pool = await asyncpg.create_pool(
                    host=settings.db_host,
                    port=settings.db_port,
                    database=settings.db_name,
                    user=settings.db_user,
                    password=settings.db_password,
                    min_size=settings.db_pool_min_size,
                    max_size=settings.db_pool_max_size,
                    command_timeout=settings.db_command_timeout,
                    timeout=30,  # 连接超时 30 秒
                    server_settings={
                        'application_name': 'huoyan-enterprise',
                        'jit': 'off'  # 禁用 JIT 以提高稳定性
                    }
                )
                
                # 测试连接
                async with _asyncpg_pool.acquire() as _conn:
                    await _conn.execute("SELECT 1")
                    await ensure_graph_metadata(_conn)
                
                logger.info("asyncpg 数据库连接池初始化成功")
                break
                
            except Exception as e:
                logger.error(f"asyncpg 数据库连接池初始化失败 (尝试 {attempt + 1}/{max_retries}): {e}")
                
                if _asyncpg_pool is not None:
                    try:
                        await _asyncpg_pool.close()
                    except:
                        pass
                    _asyncpg_pool = None
                
                if attempt < max_retries - 1:
                    logger.info(f"将在 {retry_delay} 秒后重试...")
                    await asyncio.sleep(retry_delay)
                    retry_delay *= 2  # 指数退避
                else:
                    logger.error("数据库连接池初始化失败，已达到最大重试次数")
                    raise
    
    return _asyncpg_pool


async def get_checkpointer() -> AsyncPostgresSaver:
    """
    获取或创建 LangGraph Checkpointer
    
    使用 psycopg AsyncConnectionPool，用于 LangGraph 的状态持久化。
    """
    global _psycopg_pool, _checkpointer
    
    if _checkpointer is None:
        logger.info("初始化 psycopg 连接池和 Checkpointer...")
        
        max_retries = 3
        retry_delay = 2  # 秒
        
        for attempt in range(max_retries):
            try:
                _psycopg_pool = AsyncConnectionPool(
                    conninfo=settings.db_uri_psycopg,
                    max_size=settings.checkpointer_pool_max_size,
                    open=False,
                    timeout=30,  # 连接超时 30 秒
                    kwargs={
                        "autocommit": True,
                        "prepare_threshold": 0
                    },
                )
                await _psycopg_pool.open()
                
                _checkpointer = AsyncPostgresSaver(_psycopg_pool)
                await _checkpointer.setup()
                
                logger.info("Checkpointer 初始化成功")
                break
                
            except Exception as e:
                logger.error(f"Checkpointer 初始化失败 (尝试 {attempt + 1}/{max_retries}): {e}")
                
                if _psycopg_pool is not None:
                    try:
                        await _psycopg_pool.close()
                    except:
                        pass
                    _psycopg_pool = None
                    _checkpointer = None
                
                if attempt < max_retries - 1:
                    logger.info(f"将在 {retry_delay} 秒后重试...")
                    await asyncio.sleep(retry_delay)
                    retry_delay *= 2  # 指数退避
                else:
                    logger.error("Checkpointer 初始化失败，已达到最大重试次数")
                    raise
    
    return _checkpointer


async def close_db_pool():
    """关闭所有数据库连接池"""
    global _asyncpg_pool, _psycopg_pool, _checkpointer
    
    # 关闭 asyncpg 连接池
    if _asyncpg_pool is not None:
        logger.info("关闭 asyncpg 数据库连接池...")
        await _asyncpg_pool.close()
        _asyncpg_pool = None
        reset_graph_metadata()
        logger.info("asyncpg 数据库连接池已关闭")
    
    # 关闭 psycopg 连接池
    if _psycopg_pool is not None:
        logger.info("关闭 psycopg 连接池...")
        await _psycopg_pool.close()
        _psycopg_pool = None
        _checkpointer = None
        logger.info("psycopg 连接池已关闭")


async def get_db_connection():
    """获取数据库连接（用于依赖注入）"""
    pool = await get_db_pool()
    async with pool.acquire() as connection:
        yield connection