from typing import Dict, Any
from urllib.parse import quote_plus

from sqlalchemy.ext.asyncio import async_sessionmaker, create_async_engine

from core.settings import db_settings


class DBUtil:
    """
    数据库连接管理器
    支持多数据库配置，通过db_name参数切换
    """

    _engines = {}  # 缓存异步引擎
    _session_makers = {}  # 缓存会话工厂

    @classmethod
    def get_db(cls, db_name: str | None = None):
        """
        获取数据库会话

        :param db_name: 数据库名称，如果为None则使用默认数据库
        :return: 数据库会话
        """
        key = db_name or "default"
        db_config = DBConfigLoader.get_db_config(db_name)

        # 获取或创建异步引擎
        if key in cls._engines:
            async_engine = cls._engines[key]
        else:
            async_engine = cls._create_async_engine(db_config)
            cls._engines[key] = async_engine

        # 获取或创建会话工厂
        if key in cls._session_makers:
            async_session_local = cls._session_makers[key]
        else:
            async_session_local = async_sessionmaker(
                autocommit=False, autoflush=False, bind=async_engine
            )
            cls._session_makers[key] = async_session_local

        db = async_session_local()
        try:
            yield db
        finally:
            db.close()

    @staticmethod
    def _create_async_engine(config):
        """根据配置创建异步引擎

        :param config: 数据库配置字典
        :return: 异步引擎实例
        """
        # 使用配置加载器构建连接URL
        url = DBConfigLoader.build_connection_url(config)

        # 获取引擎参数
        engine_params = DBConfigLoader.get_engine_params(config)

        # 创建异步引擎
        return create_async_engine(url, **engine_params)

    def __call__(self, *args, **kwargs):
        return self.get_db(*args, **kwargs)


class DBConfigLoader:
    """
    数据库配置加载器
    负责加载和处理数据库配置，与数据库连接管理分离
    """

    @classmethod
    def get_db_config(cls, db_name: str | None = None) -> Dict[str, Any]:
        """
        获取指定数据库的配置

        :param db_name: 数据库名称，如果为None则返回默认数据库配置
        :return: 数据库配置字典
        """
        return (
            db_settings.databases[db_name]
            if db_name
            else db_settings.databases["default"]
        )

    @classmethod
    def build_connection_url(cls, config: Dict[str, Any]) -> str:
        """
        根据配置构建数据库连接URL

        :param config: 数据库配置字典
        :return: 连接URL字符串
        """
        db_type = config["type"]
        driver = "asyncmy" if db_type == "mysql" else "asyncpg"

        # 构建数据库连接URL
        url = (
            f"{db_type}+{driver}://{config['username']}:{quote_plus(config['password'])}@"
            f"{config['host']}:{config['port']}/{config['database']}"
        )

        return url

    @classmethod
    def get_engine_params(cls, config: Dict[str, Any]) -> Dict[str, Any]:
        """
        获取创建引擎所需的参数

        :param config: 数据库配置字典
        :return: 引擎参数字典
        """
        return {
            "echo": config["echo"],
            "max_overflow": config["max_overflow"],
            "pool_size": config["pool_size"],
            "pool_recycle": config["pool_recycle"],
            "pool_timeout": config["pool_timeout"],
        }