from sqlalchemy import create_engine, text
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker, Session
from sqlalchemy.pool import QueuePool
from app.config.settings import settings
from typing import Generator

# 数据库引擎
engine = create_engine(
    settings.database_url,
    poolclass=QueuePool,
    pool_size=10,
    max_overflow=20,
    pool_pre_ping=True,
    pool_recycle=3600,
    echo=settings.config.debug  # 在调试模式下打印SQL
)

# 会话工厂
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)

# 基础模型类
Base = declarative_base()


def get_db() -> Generator[Session, None, None]:
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()


class DatabaseUtils:
    """数据库工具类"""
    
    @staticmethod
    def test_connection() -> dict:
        """测试数据库连接"""
        try:
            with engine.connect() as conn:
                result = conn.execute(text("SELECT 1 as test"))
                row = result.fetchone()
                return {
                    "status": "success",
                    "message": "数据库连接正常",
                    "test_result": row[0] if row else None,
                    "database_url": settings.database_url.replace(settings.config.database.password, "****")
                }
        except Exception as e:
            return {
                "status": "error",
                "message": f"数据库连接失败: {str(e)}"
            }
    
    @staticmethod
    def get_all_tables() -> dict:
        """获取所有表名"""
        try:
            with engine.connect() as conn:
                result = conn.execute(text("SHOW TABLES"))
                tables = [row[0] for row in result.fetchall()]
                return {
                    "status": "success",
                    "tables": tables,
                    "count": len(tables)
                }
        except Exception as e:
            return {
                "status": "error",
                "message": f"获取表名失败: {str(e)}"
            }
    
    @staticmethod
    def execute_query(query: str, limit: int = 100) -> dict:
        """执行查询语句"""
        try:
            with engine.connect() as conn:
                # 添加LIMIT限制
                if "LIMIT" not in query.upper():
                    query = f"{query} LIMIT {limit}"
                
                result = conn.execute(text(query))
                
                # 获取列名
                columns = list(result.keys()) if result.keys() else []
                
                # 获取数据
                rows = result.fetchall()
                data = [dict(zip(columns, row)) for row in rows]
                
                return {
                    "status": "success",
                    "columns": columns,
                    "data": data,
                    "count": len(data)
                }
        except Exception as e:
            return {
                "status": "error",
                "message": f"查询执行失败: {str(e)}"
            }


# 初始化数据库连接
def init_database():
    """初始化数据库"""
    try:
        # 测试连接
        test_result = DatabaseUtils.test_connection()
        if test_result["status"] == "success":
            print(f"✓ 数据库连接成功 - 环境: {settings.environment}")
            print(f"✓ 数据库: {settings.config.database.host}:{settings.config.database.port}/{settings.config.database.database}")
        else:
            print(f"✗ 数据库连接失败: {test_result['message']}")
    except Exception as e:
        print(f"✗ 数据库初始化错误: {str(e)}")


def close_database():
    """关闭数据库连接"""
    engine.dispose()
    print("数据库连接已关闭")