# 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.
# ============================================================================
"""Tests for Bijector."""

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

# Dependency imports
import numpy as np
from scipy import stats

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 GumbelBijectorTest(tf.test.TestCase):
  """Tests correctness of the Gumbel bijector."""

  def testBijector(self):
    loc = 0.3
    scale = 5.
    bijector = tfb.Gumbel(loc=loc, scale=scale, validate_args=True)
    self.assertEqual("gumbel", bijector.name)
    x = np.array([[[-3.], [0.], [0.5], [4.2], [12.]]], dtype=np.float32)
    # Gumbel distribution
    gumbel_dist = stats.gumbel_r(loc=loc, scale=scale)
    y = gumbel_dist.cdf(x).astype(np.float32)
    self.assertAllClose(y, self.evaluate(bijector.forward(x)))
    self.assertAllClose(x, self.evaluate(bijector.inverse(y)))
    self.assertAllClose(
        np.squeeze(gumbel_dist.logpdf(x), axis=-1),
        self.evaluate(bijector.forward_log_det_jacobian(x, event_ndims=1)))
    self.assertAllClose(
        self.evaluate(-bijector.inverse_log_det_jacobian(y, event_ndims=1)),
        self.evaluate(bijector.forward_log_det_jacobian(x, event_ndims=1)),
        rtol=1e-4,
        atol=0.)

  def testScalarCongruency(self):
    bijector_test_util.assert_scalar_congruency(
        tfb.Gumbel(loc=0.3, scale=20.), lower_x=1., upper_x=100.,
        eval_func=self.evaluate, rtol=0.02)

  def testBijectiveAndFinite(self):
    bijector = tfb.Gumbel(loc=0., scale=3.0, validate_args=True)
    x = np.linspace(-10., 10., num=10).astype(np.float32)
    y = np.linspace(0.01, 0.99, num=10).astype(np.float32)
    bijector_test_util.assert_bijective_and_finite(
        bijector, x, y, eval_func=self.evaluate, event_ndims=0, rtol=1e-3)


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