# Copyright 2018 The TensorFlow Probability Authors.
#
# 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.
# ============================================================================
"""Exp Tests."""

from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

# Dependency imports
import numpy as np
import tensorflow.compat.v2 as tf
from tensorflow_probability.python import bijectors as tfb

from tensorflow_probability.python.bijectors import bijector_test_util
from tensorflow.python.framework import test_util  # pylint: disable=g-direct-tensorflow-import,g-import-not-at-top


@test_util.run_all_in_graph_and_eager_modes
class Expm1BijectorTest(tf.test.TestCase):
  """Tests correctness of the Y = g(X) = expm1(X) transformation."""

  def testBijector(self):
    bijector = tfb.Expm1()
    self.assertEqual("expm1", bijector.name)
    x = [[[-1.], [1.4]]]
    y = np.expm1(x)
    self.assertAllClose(y, self.evaluate(bijector.forward(x)))
    self.assertAllClose(x, self.evaluate(bijector.inverse(y)))
    self.assertAllClose(
        -np.squeeze(np.log1p(y), axis=-1),
        self.evaluate(bijector.inverse_log_det_jacobian(
            y, event_ndims=1)))
    self.assertAllClose(
        self.evaluate(-bijector.inverse_log_det_jacobian(
            np.expm1(x), event_ndims=1)),
        self.evaluate(bijector.forward_log_det_jacobian(
            x, event_ndims=1)))

  def testMatchesExpm1(self):
    bijector = tfb.Expm1()
    x = np.random.randn(30)
    y = np.expm1(x)
    self.assertAllClose(y, self.evaluate(bijector.forward(x)))
    # Disable caching.
    self.assertAllClose(x, self.evaluate(
        bijector.inverse(tf.identity(y))))

  def testScalarCongruency(self):
    bijector = tfb.Expm1()
    bijector_test_util.assert_scalar_congruency(
        bijector, lower_x=-5., upper_x=2.5, eval_func=self.evaluate,
        rtol=0.05)

  def testBijectiveAndFinite(self):
    bijector = tfb.Expm1()
    x = np.linspace(-5, 5, num=20).astype(np.float32)
    y = np.logspace(-5, 5, num=20).astype(np.float32)
    bijector_test_util.assert_bijective_and_finite(
        bijector, x, y, eval_func=self.evaluate, event_ndims=0)


if __name__ == "__main__":
  tf.test.main()
