"""Basic mapping model connecting a release to a subgenre.

Although the schema allows for a many-to-many relationship between releases
and subgenres, in practice we only allow a release to have one subgenre.
"""

from oto import response
import sqlalchemy

from product_digital.connectors import mysql


class ReleaseSubgenre(mysql.BaseModel):
    """Release-subgenre mapping model."""

    __tablename__ = 'release_subgenre'

    release_subgenre_id = sqlalchemy.Column(
        'id', sqlalchemy.Integer, primary_key=True, autoincrement=True,
        nullable=False)
    upc = sqlalchemy.Column(sqlalchemy.String, nullable=False)
    subgenre_id = sqlalchemy.Column(sqlalchemy.Integer, nullable=False)
    release_id = sqlalchemy.Column(sqlalchemy.Integer, nullable=False)

    def to_dict(self):
        """Create a dictionary of this object's properties."""
        return {
            'release_subgenre_id': self.release_subgenre_id,
            'release_id': self.release_id,
            'subgenre_id': self.subgenre_id}


@mysql.wrap_db_errors
def get_release_subgenre_by_release_id(release_id):
    """Get the release-genre mapping for the given release_id."""
    with mysql.db_session() as session:
        release_subgenre = session.query(ReleaseSubgenre).filter_by(
            release_id=release_id).first()

        if not release_subgenre:
            return response.create_not_found_response(
                'release subgenre mapping not found')

        payload = release_subgenre.to_dict()

    return response.Response(message=payload)


@mysql.wrap_db_errors
def save_release_subgenre(release_subgenre_data):
    """Save a release-subgenre mapping.

    Args:
        release_subgenre_data (dict): data mapping a release to a subgenre.

    Returns:
        response.Response: wrapper indicating the outcome of the save.
    """
    with mysql.db_session() as session:
        # @todo: validate that all required values are given
        release_subgenre = session.query(ReleaseSubgenre).filter_by(
            release_id=release_subgenre_data.get('release_id')).first()

        if not release_subgenre:
            release_subgenre = ReleaseSubgenre()

        release_subgenre.release_id = release_subgenre_data.get('release_id')
        release_subgenre.subgenre_id = release_subgenre_data.get('subgenre_id')
        release_subgenre.upc = release_subgenre_data.get('upc')

        session.add(release_subgenre)
        # flush the session so a new record gets the primary key value
        session.flush()
        payload = release_subgenre.to_dict()

    return response.Response(message=payload)


@mysql.wrap_db_errors
@mysql.db_session_wrap
def delete_release_subgenre(release_id, session):
    """Delete a release-subgenre entry.

    Args:
        release_id (int): The release id of the entry to be deleted.

    Returns:
        response.Response: wrapper indicating the outcome of the deletion.
    """
    existing_release_subgenre = session.query(ReleaseSubgenre).filter_by(
        release_id=release_id).first()

    if existing_release_subgenre:
        session.delete(existing_release_subgenre)
        session.flush()

    return response.Response()