# -*- coding: utf-8 -*-
# @Time    : 2024/6/7
# @Author  : 魏志亮

import os
import traceback
from typing import Any, Dict, List, Tuple, Union

import pandas as pd
import pymysql
from pymysql.cursors import DictCursor
from sqlalchemy import create_engine
from sqlalchemy.engine import Engine

from utils.conf.read_conf import load_yaml_config
from utils.log.trans_log import error, info, debug


class MySQLDatabase:
    """MySQL数据库连接管理类"""

    # 类级别的引擎缓存，避免重复创建
    _engine_cache = {}

    def __init__(self, connection_name: str):
        """
        初始化MySQL数据库连接
        
        Args:
            connection_name: 配置文件中对应的连接名称
        """
        # 获取配置文件路径
        config_path = os.environ.get('ETL_CONF')
        if not config_path:
            raise ValueError("环境变量 ETL_CONF 未设置")

        # 加载配置
        self.yaml_data = load_yaml_config(config_path)
        self.connection_name = connection_name

        # 验证配置是否存在
        if connection_name not in self.yaml_data:
            raise KeyError(f"配置中不存在连接名称: {connection_name}")

        self.config = self.yaml_data[connection_name]
        self.database = self.config.get('database', '')

        # 验证必要配置项
        required_keys = ['host', 'user', 'password', 'database']
        missing_keys = [key for key in required_keys if key not in self.config]
        if missing_keys:
            raise KeyError(f"连接配置缺少必要项: {missing_keys}")

    def get_connection(self) -> pymysql.Connection:
        """
        从连接池中获取一个连接
        
        Returns:
            pymysql连接对象
        """
        # 创建连接配置副本，避免修改原配置
        conn_config = self.config.copy()
        # 移除可能不需要的配置项（如果有）
        conn_config.pop('charset', None)  # pymysql连接时charset参数可能会冲突

        return pymysql.connect(
            cursorclass=DictCursor,
            charset='utf8mb4',
            **conn_config
        )

    def execute_query(self, sql: str, params: Union[Tuple, List, Dict] = None) -> List[Dict[str, Any]]:
        """
        执行SQL查询并返回结果
        
        Args:
            sql: SQL语句
            params: SQL参数，可以是元组、列表或字典
            
        Returns:
            查询结果列表，每个元素为字典形式
            
        Raises:
            Exception: SQL执行错误时抛出
        """
        params = params or ()
        conn = None
        cursor = None

        try:
            conn = self.get_connection()
            cursor = conn.cursor()

            # 执行SQL
            cursor.execute(sql, params)
            debug("开始执行SQL:\n", cursor._executed)

            # 提交事务
            conn.commit()

            # 获取结果
            result = cursor.fetchall()
            return result

        except Exception as e:
            error(f"执行SQL出错: {sql}")
            error(f"错误信息: {e}")
            error(traceback.format_exc())

            if conn:
                conn.rollback()
            raise e

        finally:
            # 确保资源被释放
            if cursor:
                cursor.close()
            if conn:
                conn.close()

    def execute_update(self, sql: str, params: Union[Tuple, List, Dict] = None) -> int:
        """
        执行更新操作（INSERT, UPDATE, DELETE）
        
        Args:
            sql: SQL语句
            params: SQL参数
            
        Returns:
            影响的行数
        """
        params = params or ()
        conn = None
        cursor = None

        try:
            conn = self.get_connection()
            cursor = conn.cursor()

            cursor.execute(sql, params)
            debug("开始执行SQL:", cursor._executed)

            conn.commit()
            return cursor.rowcount

        except Exception as e:
            error(f"执行更新SQL出错: {sql}")
            error(f"错误信息: {e}")
            error(traceback.format_exc())

            if conn:
                conn.rollback()
            raise e

        finally:
            if cursor:
                cursor.close()
            if conn:
                conn.close()

    def get_engine(self) -> Engine:
        """
        获取SQLAlchemy引擎，使用缓存避免重复创建
        
        Returns:
            SQLAlchemy引擎对象
        """
        # 构建缓存键
        config = self.config
        cache_key = f"{config['host']}:{config['port']}:{config['user']}:{config['database']}"

        # 检查缓存中是否已有引擎
        if cache_key not in self._engine_cache:
            username = config['user']
            password = config['password']
            host = config['host']
            port = config['port']
            dbname = config['database']

            # 构建连接URL
            connection_url = f'mysql+pymysql://{username}:{password}@{host}:{port}/{dbname}?charset=utf8mb4'

            # 创建引擎并缓存
            self._engine_cache[cache_key] = create_engine(
                connection_url,
                pool_size=10,  # 增加连接池大小
                pool_recycle=3600,
                pool_pre_ping=True,  # 连接池预ping，确保连接有效
                echo=False  # 设置为True可打印SQL日志
            )

        return self._engine_cache[cache_key]

    def save_dataframe(self, df: pd.DataFrame, table_name: str, chunk_size: int = 10000,
                       if_exists: str = 'append') -> None:
        """
        将DataFrame保存到数据库表
        
        Args:
            df: pandas DataFrame对象
            table_name: 目标表名
            chunk_size: 每批写入的行数
            if_exists: 表存在时的处理方式：'fail', 'replace', 'append'
        """
        try:
            df.to_sql(
                table_name,
                self.get_engine(),
                index=False,
                if_exists=if_exists,
                chunksize=chunk_size,
                method='multi'  # 使用多值插入提高性能
            )
            info(f"成功保存 {len(df)} 条数据到表 {table_name}")

        except Exception as e:
            error(f"保存DataFrame到表 {table_name} 失败: {e}")
            error(traceback.format_exc())
            raise e

    def read_sql_to_dataframe(self, sql: str) -> pd.DataFrame:
        """
        执行SQL查询并返回DataFrame
        
        Args:
            sql: SQL查询语句
            
        Returns:
            查询结果的DataFrame
        """
        try:
            df = pd.read_sql_query(sql, self.get_engine())
            debug(f"查询返回 {len(df)} 行数据")
            return df

        except Exception as e:
            error(f"执行SQL查询失败: {sql}")
            error(f"错误信息: {e}")
            error(traceback.format_exc())
            raise e

    # 为了保持向后兼容，保留原方法名（可选）
    get_conn = get_connection
    execute = execute_query
    execute_df_save = save_dataframe
    read_sql_to_df = read_sql_to_dataframe