"""MySQL connector."""
from contextlib import contextmanager

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

from handle_user_changes import config


if config.ENABLE_USER_DATA_UPDATE or config.ENABLE_DEACTIVATE_USER_DEVICES:
    engine = create_engine('mysql+pymysql://{user}:{password}@{host}:{port}/{database_name}'.format(
        user=config.DB_USER,
        password=config.DB_PASS,
        host=config.DB_HOST,
        port=config.DB_PORT,
        database_name=config.DB_NAME),
        pool_recycle=config.DB_POOL_RECYCLE, pool_size=config.DB_POOL_SIZE
    )
    _session_factory = scoped_session(sessionmaker(bind=engine))
    _session = _session_factory()


@contextmanager
def session_scope():
    """Provide a transactional scope around a series of operations.

    """
    try:
        yield _session
        _session.commit()
    except Exception:
        _session.rollback()
        raise
    finally:
        _session.close()