class UserGroup(Base):
    """  """
    __tablename__ = 'user_group'
    user_id = Column(Integer, ForeignKey('user.id'), primary_key=True)
    group_id = Column(Integer, ForeignKey('group.id'), primary_key=True)

class GroupPermission(Base):
    """  """
    __tablename__ = 'group_permission'
    group_id = Column(Integer, ForeignKey('group.id'), primary_key=True)
    permission_id = Column(Integer, ForeignKey('permission.id'), primary_key=True)

class Group(Base):
    """  """
    __tablename__ = 'group'
    id = Column(Integer(), primary_key=True)
    name = Column(Unicode(255), unique=True, nullable=False)

    users = relation('User', backref=backref('groups'), secondary=UserGroup.__table__)
    permissions = relation('Permission', backref=backref('groups'), secondary=GroupPermission.__table__)

class Permission(object):
    """  """
    __tablename__ = 'permission'
    id = Column(Integer(), primary_key=True)
    name = Column(Unicode(255), unique=True, nullable=False)

class User(Base):
    """  """
    __tablename__ = 'user'
    id = Column(Integer(), primary_key=True)
    username = Column(Unicode(255), unique=True, nullable=False)
    email = Column(Unicode(255), unique=True, nullable=False)
    password = Column(Unicode(80), nullable=False)
    fullname = Column(Unicode(255), nullable=False)