from sqlalchemy import Column, String, ForeignKeyConstraint, Integer
from sqlalchemy.ext.declarative import declarative_base, declared_attr


class TableName(object):
    @declared_attr
    def __tablename__(cls):
        return cls.__name__


Base=declarative_base(cls=TableName)


class TMixin(object):

    @declared_attr
    def user(cls):
        return Column(String, primary_key=True)

    @declared_attr
    def timestamp(cls):
        return Column(Integer, autoincrement=False, primary_key=True)


class Timeline(TMixin, Base):

    snaptype = Column(Integer, primary_key=True, autoincrement=False)

    __mapper_args__ = {'polymorphic_on': snaptype}


class CMixin(TMixin):

    @declared_attr
    def __table_args__(cls):
        return (ForeignKeyConstraint(
                    ['user', 'timestamp'],
                    ['Timeline.user', 'Timeline.timestamp']),)

    @declared_attr
    def __mapper_args__(cls):
        return {'polymorphic_identity': CMixin.__subclasses__().index(cls)}


class C(CMixin, Timeline):

    pass