"""
Copyright 2020 The OneFlow Authors. All rights reserved.

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 numpy as np
import oneflow as flow
import oneflow.typing as tp


def _of_reverse(input, axis, dtype):
    flow.clear_default_session()

    @flow.global_function()
    def reverse(
        input: tp.Numpy.Placeholder(shape=input.shape, dtype=dtype)
    ) -> tp.Numpy:
        return flow.reverse(input, axis)

    return reverse(input)


def _test_reverse(test_case, input, axis, dtype, verbose=False):
    assert isinstance(input, np.ndarray)
    input = input.astype(flow.convert_oneflow_dtype_to_numpy_dtype(dtype))
    slice_list = [slice(None)] * input.ndim
    for a in axis:
        if a < 0:
            a += input.ndim
        assert a >= 0 and a < input.ndim
        slice_list[a] = slice(None, None, -1)

    output = input[tuple(slice_list)]
    of_output = _of_reverse(input, axis, dtype)
    if verbose:
        print("input: {}\n{}\n".format(input.shape, input))
        print("comparing output:\n{}\nvs.\n{}".format(output, of_output))
    test_case.assertTrue(np.array_equal(output, of_output))


def test_reverse_case_1(test_case):
    input = np.arange(1 * 2 * 3 * 4).reshape(1, 2, 3, 4)
    _test_reverse(test_case, input, [3], flow.int32)


def test_reverse_case_2(test_case):
    input = np.arange(1 * 2 * 3 * 4).reshape(1, 2, 3, 4)
    _test_reverse(test_case, input, [-1], flow.int32)


def test_reverse_case_3(test_case):
    input = np.arange(1 * 2 * 3 * 4).reshape(1, 2, 3, 4)
    _test_reverse(test_case, input, [1], flow.int32)


def test_reverse_case_4(test_case):
    input = np.arange(1 * 2 * 3 * 4).reshape(1, 2, 3, 4)
    _test_reverse(test_case, input, [-3], flow.int32)


def test_reverse_case_5(test_case):
    input = np.arange(1 * 2 * 3 * 4).reshape(1, 2, 3, 4)
    _test_reverse(test_case, input, [2], flow.float32)


def test_reverse_case_6(test_case):
    input = np.arange(1 * 2 * 3 * 4).reshape(1, 2, 3, 4)
    _test_reverse(test_case, input, [-2], flow.float32)
