"""MySQL connector."""
from contextlib import contextmanager
from sqlalchemy import create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import scoped_session
from sqlalchemy.orm import sessionmaker
from label_copy_export import config


BaseModel = declarative_base()


_label_copy_export_history_engine = create_engine(
    config.LCE_DB_CONNECTION_STRING, poolclass=config.DB_POOLCLASS,
    connect_args=config.DB_CONNECT_ARGS)

_label_copy_export_history_factory = sessionmaker(
    bind=_label_copy_export_history_engine, expire_on_commit=False)

Session = scoped_session(_label_copy_export_history_factory)


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

    Taken from http://docs.sqlalchemy.org/en/latest/orm/session_basics.html.
    This handles rollback and closing of session, so there is no need
    to do that throughout the code. Usage:
    with label_copy_export_history_session_scope() as session:
        session.execute(query)
    """
    session = Session()
    try:
        yield session
        session.commit()
    except:
        session.rollback()
        raise
    finally:
        session.close()


_ar_db_engine = create_engine(
    config.AR_DB_CONNECTION_STRING, poolclass=config.DB_POOLCLASS,
    connect_args=config.DB_CONNECT_ARGS)

_ar_db_factory = sessionmaker(
    bind=_ar_db_engine, expire_on_commit=False)

ArSession = scoped_session(_ar_db_factory)


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

    Taken from http://docs.sqlalchemy.org/en/latest/orm/session_basics.html.
    This handles rollback and closing of session, so there is no need
    to do that throughout the code. Usage:
    with label_copy_export_history_session_scope() as session:
        session.execute(query)
    """
    session = ArSession()
    try:
        yield session
        session.commit()
    except:
        session.rollback()
        raise
    finally:
        session.close()