"""
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.
"""

from random import shuffle
import unittest
from collections import OrderedDict

import numpy as np
from oneflow.test_utils.test_util import GenArgList

import oneflow as flow
import oneflow.unittest


def _test_cast_float2int(test_case, device, shape):
    np_arr = np.random.randn(*shape).astype(np.float32)
    input = flow.tensor(np_arr, dtype=flow.float32, device=flow.device(device))
    output = flow.cast(input, flow.int8)
    np_out = np_arr.astype(np.int8)
    test_case.assertTrue(np.array_equal(output.numpy(), np_out))


def _test_cast_int2float(test_case, device, shape):
    np_arr = np.random.randn(*shape).astype(np.int8)
    input = flow.tensor(np_arr, dtype=flow.int8, device=flow.device(device))
    output = flow.cast(input, flow.float32)
    np_out = np_arr.astype(np.float32)
    test_case.assertTrue(np.array_equal(output.numpy(), np_out))


def _test_cast_with_non_contiguous_input(test_case, device, shape):
    np_arr = np.random.randn(*shape).astype(np.int8)
    permute_dims = np.arange(len(shape)).tolist()
    shuffle(permute_dims)
    input = flow.tensor(np_arr, dtype=flow.int8, device=flow.device(device)).permute(
        permute_dims
    )
    output = flow.cast(input, flow.float32)
    np_out = np_arr.astype(np.float32).transpose(permute_dims)
    test_case.assertTrue(np.array_equal(output.numpy(), np_out))
    test_case.assertTrue(input.stride() == output.stride())


def _test_cast_backward(test_case, device, shape):
    np_arr = np.random.randn(*shape).astype(np.float32)
    x = flow.tensor(
        np_arr, dtype=flow.float32, device=flow.device(device), requires_grad=True
    )
    y = flow.cast(x, flow.float64)
    z = y.sum()
    z.backward()
    np_out = np_arr.astype(np.float64)
    test_case.assertTrue(np.array_equal(x.grad.numpy(), np.ones(shape=shape)))


@flow.unittest.skip_unless_1n1d()
class TestCast(flow.unittest.TestCase):
    def test_cast(test_case):
        arg_dict = OrderedDict()
        arg_dict["test_fun"] = [
            _test_cast_float2int,
            _test_cast_int2float,
            _test_cast_backward,
            _test_cast_with_non_contiguous_input,
        ]
        arg_dict["device"] = ["cpu", "cuda"]
        arg_dict["shape"] = [(2, 3), (2, 3, 4), (2, 3, 4, 5)]
        for arg in GenArgList(arg_dict):
            arg[0](test_case, *arg[1:])

    def test_cast_with_0_size_data(test_case):
        arg_dict = OrderedDict()
        arg_dict["test_fun"] = [
            _test_cast_float2int,
            _test_cast_int2float,
        ]
        arg_dict["device"] = ["cpu", "cuda"]
        arg_dict["shape"] = [(2, 3, 0, 5)]
        for arg in GenArgList(arg_dict):
            arg[0](test_case, *arg[1:])


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