# Copyright 2020 MONAI Consortium
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#     http://www.apache.org/licenses/LICENSE-2.0
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import unittest
import numpy as np
from parameterized import parameterized
from monai.transforms import RandAdjustContrast
from tests.utils import NumpyImageTestCase2D

TEST_CASE_1 = [(0.5, 4.5)]

TEST_CASE_2 = [1.5]


class TestRandAdjustContrast(NumpyImageTestCase2D):
    @parameterized.expand([TEST_CASE_1, TEST_CASE_2])
    def test_correct_results(self, gamma):
        adjuster = RandAdjustContrast(prob=1.0, gamma=gamma)
        result = adjuster(self.imt)
        epsilon = 1e-7
        img_min = self.imt.min()
        img_range = self.imt.max() - img_min
        expected = (
            np.power(((self.imt - img_min) / float(img_range + epsilon)), adjuster.gamma_value) * img_range + img_min
        )
        np.testing.assert_allclose(expected, result, rtol=1e-05)


if __name__ == "__main__":
    unittest.main()
