import os
import pymysql
from sqlalchemy import create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
from sqlalchemy.exc import OperationalError

# ── 数据库配置 ──────────────────────────────────────────────────────────────
DB_HOST = os.getenv("DB_HOST", "mysql1.rdsmbk3ednsgnnt.rds.bj.baidubce.com")
DB_PORT = os.getenv("DB_PORT", "3306")
DB_NAME = os.getenv("DB_NAME", "case_platform")
DB_USER = os.getenv("DB_USER", "root_dev")
DB_PASS = os.getenv("DB_PASS", "Kdse89sd")

MYSQL_URL = f"mysql+pymysql://{DB_USER}:{DB_PASS}@{DB_HOST}:{DB_PORT}/{DB_NAME}?charset=utf8mb4"
SQLITE_URL = "sqlite:///./quantum_test.db"

def get_engine():
    try:
        # 尝试连接 MySQL
        engine = create_engine(
            MYSQL_URL,
            pool_pre_ping=True,
            pool_recycle=1800,
            pool_size=10,
            max_overflow=20,
        )
        # 测试连接
        with engine.connect() as conn:
            pass
        print("✅ 成功连接到 MySQL (百度云 RDS)")
        return engine
    except Exception as e:
        print(f"⚠️ MySQL 连接失败 (IP白名单限制或凭证错误) - {e}")
        print("🔄 自动降级：使用本地 SQLite 数据库以保证应用正常运行...")
        engine = create_engine(
            SQLITE_URL,
            connect_args={"check_same_thread": False}
        )
        return engine

engine = get_engine()

SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)

Base = declarative_base()


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