# Licensed under a 3-clause BSD style license - see LICENSE.rst


__all__ = ['BaseTransform', 'CompositeTransform']


class BaseTransform:
    """
    A transformation object.

    This is used to construct transformations such as scaling, stretching, and
    so on.
    """

    def __add__(self, other):
        return CompositeTransform(other, self)


class CompositeTransform(BaseTransform):
    """
    A combination of two transforms.

    Parameters
    ----------
    transform_1 : :class:`astropy.visualization.BaseTransform`
        The first transform to apply.
    transform_2 : :class:`astropy.visualization.BaseTransform`
        The second transform to apply.
    """

    def __init__(self, transform_1, transform_2):
        super().__init__()
        self.transform_1 = transform_1
        self.transform_2 = transform_2

    def __call__(self, values, clip=True):
        return self.transform_2(self.transform_1(values, clip=clip), clip=clip)

    @property
    def inverse(self):
        return self.__class__(self.transform_2.inverse,
                              self.transform_1.inverse)