"""MySQL database connector.

Manages interactions with Relational Database (MySQL and SQLite).
"""

from functools import wraps

from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker

from asset_file_details import config
from asset_file_details.utils import db as db_utils


_db_engine = db_utils.create_engine(config.DD_DB_URL)
_session_maker = sessionmaker(bind=_db_engine)

BaseModel = declarative_base()


def db_session(function):
    """DB Session Wrappper.

    Creates a new session if one isn't passed in.
    """
    @wraps(function)
    def wrapper(*args, **kwargs):
        session = kwargs.pop('session', None)
        if session:
            return function(*args, session=session, **kwargs)
        else:
            with db_utils.create_session(_session_maker) as session:
                return function(*args, session=session, **kwargs)

    return wrapper