# Copyright (c) 2018 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.

from __future__ import print_function

import contextlib
import unittest
import numpy as np
import six

import paddle
import paddle.fluid as fluid
from paddle.fluid import core
from paddle.fluid.optimizer import SGDOptimizer
from paddle.fluid.dygraph.base import to_variable
from test_imperative_base import new_program_scope
from test_imperative_mnist import MNIST


class TestImperativeMnistSortGradient(unittest.TestCase):
    def test_mnist_sort_gradient_float32(self):
        seed = 90
        epoch_num = 1

        with fluid.dygraph.guard():
            fluid.default_startup_program().random_seed = seed
            fluid.default_main_program().random_seed = seed
            backward_strategy = fluid.dygraph.BackwardStrategy()
            backward_strategy.sort_sum_gradient = True

            mnist2 = MNIST("mnist")
            sgd2 = SGDOptimizer(learning_rate=1e-3)
            train_reader2 = paddle.batch(
                paddle.dataset.mnist.train(), batch_size=128, drop_last=True)

            mnist2.train()
            dy_param_init_value2 = {}
            for epoch in range(epoch_num):
                for batch_id, data in enumerate(train_reader2()):
                    dy_x_data2 = np.array(
                        [x[0].reshape(1, 28, 28)
                         for x in data]).astype('float32')
                    y_data2 = np.array(
                        [x[1] for x in data]).astype('int64').reshape(128, 1)

                    img2 = to_variable(dy_x_data2)
                    label2 = to_variable(y_data2)
                    label2.stop_gradient = True

                    cost2 = mnist2(img2)
                    loss2 = fluid.layers.cross_entropy(cost2, label2)
                    avg_loss2 = fluid.layers.mean(loss2)

                    dy_out2 = avg_loss2.numpy()

                    if epoch == 0 and batch_id == 0:
                        for param in mnist2.parameters():
                            dy_param_init_value2[param.name] = param.numpy()

                    avg_loss2.backward(backward_strategy)
                    sgd2.minimize(avg_loss2)
                    mnist2.clear_gradients()

                    dy_param_value2 = {}
                    for param in mnist2.parameters():
                        dy_param_value2[param.name] = param.numpy()
                    if batch_id == 20:
                        break

        with new_program_scope():
            fluid.default_startup_program().random_seed = seed
            fluid.default_main_program().random_seed = seed

            exe = fluid.Executor(fluid.CPUPlace(
            ) if not core.is_compiled_with_cuda() else fluid.CUDAPlace(0))

            mnist = MNIST("mnist")
            sgd = SGDOptimizer(learning_rate=1e-3)
            train_reader = paddle.batch(
                paddle.dataset.mnist.train(), batch_size=128, drop_last=True)

            img = fluid.layers.data(
                name='pixel', shape=[1, 28, 28], dtype='float32')
            label = fluid.layers.data(name='label', shape=[1], dtype='int64')
            cost = mnist(img)
            loss = fluid.layers.cross_entropy(cost, label)
            avg_loss = fluid.layers.mean(loss)
            sgd.minimize(avg_loss)

            # initialize params and fetch them
            static_param_init_value = {}
            static_param_name_list = []
            for param in mnist.parameters():
                static_param_name_list.append(param.name)

            out = exe.run(fluid.default_startup_program(),
                          fetch_list=static_param_name_list)

            for i in range(len(static_param_name_list)):
                static_param_init_value[static_param_name_list[i]] = out[i]

            for epoch in range(epoch_num):
                for batch_id, data in enumerate(train_reader()):
                    static_x_data = np.array(
                        [x[0].reshape(1, 28, 28)
                         for x in data]).astype('float32')
                    y_data = np.array(
                        [x[1] for x in data]).astype('int64').reshape([128, 1])

                    fetch_list = [avg_loss.name]
                    fetch_list.extend(static_param_name_list)
                    out = exe.run(
                        fluid.default_main_program(),
                        feed={"pixel": static_x_data,
                              "label": y_data},
                        fetch_list=fetch_list)

                    static_param_value = {}
                    static_out = out[0]
                    for i in range(1, len(out)):
                        static_param_value[static_param_name_list[i - 1]] = out[
                            i]
                    if batch_id == 20:
                        break

        self.assertTrue(np.allclose(dy_x_data2.all(), static_x_data.all()))

        for key, value in six.iteritems(static_param_init_value):
            self.assertTrue(np.allclose(value, dy_param_init_value2[key]))

        self.assertTrue(np.allclose(static_out, dy_out2))

        for key, value in six.iteritems(static_param_value):
            self.assertTrue(np.allclose(value, dy_param_value2[key], atol=1e-5))


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