import os

from sqlalchemy import create_engine
from sqlalchemy.orm import declarative_base, sessionmaker

# 优先读取环境变量(Docker 部署用)；默认值与原硬编码配置一致，本地开发不受影响
MYSQL_USER = os.getenv("MYSQL_USER", "root")
MYSQL_PASSWORD = os.getenv("MYSQL_PASSWORD", "123456")
MYSQL_HOST = os.getenv("MYSQL_HOST", "localhost")
MYSQL_PORT = os.getenv("MYSQL_PORT", "3306")
MYSQL_DB = os.getenv("MYSQL_DB", "student_manager")

db_url = f"mysql+pymysql://{MYSQL_USER}:{MYSQL_PASSWORD}@{MYSQL_HOST}:{MYSQL_PORT}/{MYSQL_DB}?charset=utf8mb4"
engine = create_engine(db_url, pool_size=5, pool_pre_ping=True)
Base = declarative_base()
SessionLocal = sessionmaker(bind=engine)

def get_db():
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()

def init_db():
    """导入所有模型并建表，避免任何入口文件漏导入"""
    import model  # noqa: F401  —— 触发 model/__init__.py 注册所有类
    Base.metadata.create_all(bind=engine)


def reset_db():
    """开发环境重建所有表"""
    import model  # noqa: F401
    Base.metadata.drop_all(bind=engine)
    Base.metadata.create_all(bind=engine)