from sqlalchemy import create_engine
from sqlalchemy.orm import declarative_base, sessionmaker
from sqlalchemy.exc import OperationalError
from fastapi import HTTPException, status

from .config import settings

DATABASE_URL = settings.DATABASE_URL

connect_args = {}
if DATABASE_URL.startswith("mysql+pymysql://"):
    connect_args["connect_timeout"] = 5

engine = create_engine(
    DATABASE_URL,
    pool_pre_ping=True,
    pool_recycle=3600,
    pool_size=settings.DB_POOL_SIZE if settings.DB_POOL_SIZE else 5,
    max_overflow=settings.DB_POOL_MAX_OVERFLOW if settings.DB_POOL_MAX_OVERFLOW else 10,
    pool_timeout=30,
    future=True,
    connect_args=connect_args,
)
SessionLocal = sessionmaker(bind=engine, autocommit=False, autoflush=False, future=True)
Base = declarative_base()


def get_db():
    db = SessionLocal()
    try:
        yield db
        db.commit()
    except OperationalError as exc:
        db.rollback()
        raise HTTPException(
            status_code=status.HTTP_503_SERVICE_UNAVAILABLE,
            detail="Database unavailable, please check DATABASE_URL / MySQL service.",
        ) from exc
    except Exception:
        db.rollback()
        raise
    finally:
        db.close()