"""数据库连接管理"""
import os
from typing import Generator

from sqlalchemy import create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker, Session

from app.core.config import get_config

# 数据库配置
# 优先使用环境变量 DATABASE_URL
# 格式：mysql+pymysql://user:password@host:port/database
env_url = os.getenv("DATABASE_URL")
if env_url:
    DATABASE_URL = env_url
else:
    # 从 config.json 读取数据库配置
    config = get_config()
    db_config = config.database
    DATABASE_URL = f"mysql+pymysql://{db_config.user}:{db_config.password}@{db_config.host}:{db_config.port}/{db_config.database}"

# 创建数据库引擎
engine = create_engine(
    DATABASE_URL,
    pool_pre_ping=True,
    pool_size=10,
    max_overflow=20,
)

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

# 声明基类
Base = declarative_base()


def get_db() -> Generator[Session, None, None]:
    """获取数据库会话（用于FastAPI依赖注入）"""
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()


def init_db():
    """初始化数据库（创建所有表）"""
    Base.metadata.create_all(bind=engine)