# Copyright (c) 2021 PaddlePaddle 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 unittest

import numpy as np

import paddle
import paddle.fluid.dygraph as dg


class TestTensorBackward(unittest.TestCase):
    def setUp(self):
        self._dtypes = ["float32", "float64"]
        self._places = [paddle.CPUPlace()]
        if paddle.is_compiled_with_cuda():
            self._places.append(paddle.CUDAPlace(0))

    def test_tensor_backward(self):
        for dtype in self._dtypes:
            x = np.random.random([2, 100]).astype(dtype)
            y = np.random.random([100, 2]).astype(dtype)
            z = np.matmul(x, y)
            grad = np.random.random(z.shape).astype(dtype)
            for place in self._places:
                with dg.guard(place):
                    x_tensor = paddle.to_tensor(x, stop_gradient=False)
                    y_tensor = paddle.to_tensor(y)
                    z_tensor = paddle.matmul(x_tensor, y_tensor)

                    grad_tensor = paddle.to_tensor(grad)
                    z_tensor.backward(grad_tensor)

                    x_grad = np.matmul(grad, y.T)

                    np.testing.assert_allclose(
                        x_grad, x_tensor.grad.numpy(), rtol=1e-05
                    )


class TestBackwardAPI(unittest.TestCase):
    def setUp(self):
        self._dtypes = ["float32", "float64"]
        self._places = [paddle.CPUPlace()]
        if paddle.is_compiled_with_cuda():
            self._places.append(paddle.CUDAPlace(0))

    def test_backward_api(self):
        for dtype in self._dtypes:
            x = np.random.random([2, 2]).astype(dtype)
            y = np.random.random([2, 2]).astype(dtype)
            z = np.matmul(x, y)
            grad = np.random.random(z.shape).astype(dtype)
            for place in self._places:
                with dg.guard(place):
                    x_tensor = paddle.to_tensor(x, stop_gradient=False)
                    y_tensor = paddle.to_tensor(y)
                    z_tensor1 = paddle.matmul(x_tensor, y_tensor)
                    z_tensor2 = paddle.matmul(x_tensor, y_tensor)

                    grad_tensor = paddle.to_tensor(grad)
                    paddle.autograd.backward(
                        [z_tensor1, z_tensor2], [grad_tensor, grad_tensor], True
                    )

                    x_grad = np.matmul(grad, y.T)

                    np.testing.assert_allclose(
                        x_grad * 2, x_tensor.grad.numpy(), rtol=1e-05
                    )

    def test_backward_single_tensor(self):
        for dtype in self._dtypes:
            x = np.random.random([2, 2]).astype(dtype)
            y = np.random.random([2, 2]).astype(dtype)
            z = np.matmul(x, y)
            grad = np.random.random(z.shape).astype(dtype)
            for place in self._places:
                with dg.guard(place):
                    x_tensor = paddle.to_tensor(x, stop_gradient=False)
                    y_tensor = paddle.to_tensor(y)
                    z_tensor1 = paddle.matmul(x_tensor, y_tensor)

                    grad_tensor = paddle.to_tensor(grad)
                    paddle.autograd.backward(z_tensor1, grad_tensor, True)

                    x_grad = np.matmul(grad, y.T)

                    np.testing.assert_allclose(
                        x_grad, x_tensor.grad.numpy(), rtol=1e-05
                    )

    def test_backward_none_grad_tensor(self):
        for dtype in self._dtypes:
            x = np.random.random([2, 2]).astype(dtype)
            y = np.random.random([2, 2]).astype(dtype)
            z = np.matmul(x, y)
            grad = np.ones(z.shape).astype(dtype)
            for place in self._places:
                with dg.guard(place):
                    x_tensor = paddle.to_tensor(x, stop_gradient=False)
                    y_tensor = paddle.to_tensor(y)
                    z_tensor1 = paddle.matmul(x_tensor, y_tensor)

                    paddle.autograd.backward(z_tensor1, None)

                    x_grad = np.matmul(grad, y.T)

                    np.testing.assert_allclose(
                        x_grad, x_tensor.grad.numpy(), rtol=1e-05
                    )

    def test_backward_accumulator_with_init_grad(self):
        for dtype in self._dtypes:
            x = np.random.random(
                [
                    10,
                ]
            ).astype(dtype)
            y_grad = np.random.random(
                [
                    10,
                ]
            ).astype(dtype)
            z_grad = np.random.random(
                [
                    10,
                ]
            ).astype(dtype)
            self._places = [paddle.CPUPlace()]
            for place in self._places:
                with dg.guard(place):
                    x_tensor = paddle.to_tensor(x, stop_gradient=False)
                    y_tensor = x_tensor**2
                    z_tensor = y_tensor**3

                    y_grad_tensor = paddle.to_tensor(y_grad)
                    z_grad_tensor = paddle.to_tensor(z_grad)
                    paddle.autograd.backward(
                        [y_tensor, z_tensor], [y_grad_tensor, z_grad_tensor]
                    )

                    y = x**2
                    z = x**3
                    x_grad = 2 * x * (y_grad + 3 * y * y * z_grad)

                    np.testing.assert_allclose(
                        x_grad, x_tensor.grad.numpy(), rtol=1e-05
                    )


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