#!/usr/bin/env python3
"""
数据库基类模块
提供统一的数据库连接管理和上下文管理器
"""
import os
import sqlite3
from contextlib import contextmanager
from typing import Generator, Optional, Any
from pathlib import Path

from src.config import config
from src.logging_config import get_logger

logger = get_logger(__name__)


class DatabaseConnectionError(Exception):
    """数据库连接错误"""
    pass


class DatabaseBase:
    """数据库基类，提供统一的连接管理"""
    
    def __init__(self, db_path: Optional[str] = None):
        """
        初始化数据库基类
        
        参数:
            db_path: 数据库文件路径，如果为None则使用默认配置
        """
        self.db_path = db_path or config.DATABASE_PATH
        self._connection: Optional[sqlite3.Connection] = None
        self._ensure_directory()
    
    def _ensure_directory(self):
        """确保数据库目录存在"""
        data_dir = os.path.dirname(self.db_path)
        if data_dir and not os.path.exists(data_dir):
            os.makedirs(data_dir)
            logger.info(f"创建数据库目录: {data_dir}")
    
    def _connect(self) -> sqlite3.Connection:
        """
        创建数据库连接
        
        返回:
            sqlite3.Connection 对象
        
        异常:
            DatabaseConnectionError: 连接失败时抛出
        """
        try:
            conn = sqlite3.connect(self.db_path)
            conn.row_factory = sqlite3.Row
            logger.debug(f"数据库连接已建立: {self.db_path}")
            return conn
        except sqlite3.Error as e:
            error_msg = f"数据库连接失败: {self.db_path}, 错误: {e}"
            logger.error(error_msg)
            raise DatabaseConnectionError(error_msg) from e
    
    @contextmanager
    def get_connection(self) -> Generator[sqlite3.Connection, None, None]:
        """
        获取数据库连接的上下文管理器
        
        使用示例:
            with self.get_connection() as conn:
                cursor = conn.cursor()
                cursor.execute(...)
        
        返回:
            数据库连接对象
        """
        conn = None
        try:
            conn = self._connect()
            yield conn
        except sqlite3.Error as e:
            logger.error(f"数据库操作失败: {e}")
            raise
        finally:
            if conn:
                conn.close()
                logger.debug("数据库连接已关闭")
    
    def execute_query(self, query: str, params: tuple = ()) -> list:
        """
        执行查询并返回结果
        
        参数:
            query: SQL查询语句
            params: 查询参数
        
        返回:
            查询结果列表
        """
        with self.get_connection() as conn:
            cursor = conn.cursor()
            cursor.execute(query, params)
            return [dict(row) for row in cursor.fetchall()]
    
    def execute_update(self, query: str, params: tuple = ()) -> int:
        """
        执行更新操作
        
        参数:
            query: SQL更新语句
            params: 更新参数
        
        返回:
            受影响的行数
        """
        with self.get_connection() as conn:
            cursor = conn.cursor()
            cursor.execute(query, params)
            conn.commit()
            return cursor.rowcount
    
    def execute_many(self, query: str, params_list: list) -> int:
        """
        批量执行操作
        
        参数:
            query: SQL语句
            params_list: 参数列表
        
        返回:
            受影响的总行数
        """
        with self.get_connection() as conn:
            cursor = conn.cursor()
            cursor.executemany(query, params_list)
            conn.commit()
            return cursor.rowcount
    
    def table_exists(self, table_name: str) -> bool:
        """
        检查表是否存在
        
        参数:
            table_name: 表名
        
        返回:
            表是否存在
        """
        query = """
            SELECT name FROM sqlite_master 
            WHERE type='table' AND name=?
        """
        result = self.execute_query(query, (table_name,))
        return len(result) > 0
    
    def get_table_info(self, table_name: str) -> list:
        """
        获取表结构信息
        
        参数:
            table_name: 表名
        
        返回:
            表结构信息列表
        """
        with self.get_connection() as conn:
            cursor = conn.cursor()
            cursor.execute(f"PRAGMA table_info({table_name})")
            return [dict(row) for row in cursor.fetchall()]
    
    def vacuum(self):
        """执行数据库整理"""
        with self.get_connection() as conn:
            conn.execute("VACUUM")
            logger.info("数据库整理完成")
    
    def backup(self, backup_path: Optional[str] = None):
        """
        备份数据库
        
        参数:
            backup_path: 备份文件路径，如果为None则使用默认路径
        """
        if backup_path is None:
            backup_dir = "backups"
            os.makedirs(backup_dir, exist_ok=True)
            timestamp = os.path.getmtime(self.db_path)
            from datetime import datetime
            dt = datetime.fromtimestamp(timestamp)
            backup_path = os.path.join(
                backup_dir, 
                f"backup_{dt.strftime('%Y%m%d_%H%M%S')}.db"
            )
        
        try:
            with self.get_connection() as src_conn:
                dest_conn = sqlite3.connect(backup_path)
                src_conn.backup(dest_conn)
                dest_conn.close()
            logger.info(f"数据库备份完成: {backup_path}")
        except sqlite3.Error as e:
            logger.error(f"数据库备份失败: {e}")
            raise


# 全局数据库连接池（可选，用于高性能场景）
class ConnectionPool:
    """简单的数据库连接池"""
    
    def __init__(self, db_path: str, max_connections: int = 5):
        self.db_path = db_path
        self.max_connections = max_connections
        self._connections: list[sqlite3.Connection] = []
        self._in_use: set[sqlite3.Connection] = set()
    
    @contextmanager
    def get_connection(self) -> Generator[sqlite3.Connection, None, None]:
        """从连接池获取连接"""
        conn = None
        try:
            if self._connections:
                conn = self._connections.pop()
            elif len(self._in_use) < self.max_connections:
                conn = sqlite3.connect(self.db_path)
                conn.row_factory = sqlite3.Row
            else:
                raise DatabaseConnectionError("连接池已满")
            
            self._in_use.add(conn)
            yield conn
        finally:
            if conn:
                self._in_use.remove(conn)
                self._connections.append(conn)


if __name__ == '__main__':
    # 测试数据库基类
    db = DatabaseBase()
    
    # 测试连接
    with db.get_connection() as conn:
        cursor = conn.cursor()
        cursor.execute("SELECT sqlite_version()")
        version = cursor.fetchone()[0]
        print(f"SQLite版本: {version}")
    
    # 测试查询
    if db.table_exists("sqlite_master"):
        print("sqlite_master表存在")
    
    # 测试备份
    try:
        db.backup("test_backup.db")
        print("备份测试完成")
    except Exception as e:
        print(f"备份测试失败: {e}")