# Copyright (c) 2020 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 paddle.fluid as fluid
import paddle
import numpy as np
import unittest


def infinite_reader():
    num = 0
    while True:
        yield (np.ones([8, 32]) * num).astype('float32'),
        num += 1


class TestDataLoaderEarlyReset(unittest.TestCase):
    def setUp(self):
        self.stop_batch = 10
        self.iterable = True

    def build_network(self):
        y = fluid.layers.fc(self.x, size=10)
        loss = fluid.layers.reduce_mean(y)

        optimizer = fluid.optimizer.SGD(learning_rate=1e-3)
        optimizer.minimize(loss)

    def get_place(self):
        if fluid.is_compiled_with_cuda():
            return fluid.CUDAPlace(0)
        else:
            return fluid.CPUPlace()

    def create_data_loader(self):
        self.x = fluid.data(name='x', shape=[None, 32], dtype='float32')
        return fluid.io.DataLoader.from_generator(
            feed_list=[self.x], capacity=10, iterable=self.iterable)

    def test_main(self):
        with fluid.program_guard(fluid.Program(), fluid.Program()):
            with fluid.scope_guard(fluid.Scope()):
                self.run_network()

    def run_network(self):
        loader = self.create_data_loader()
        self.build_network()

        exe = fluid.Executor(self.get_place())
        exe.run(fluid.default_startup_program())

        prog = fluid.default_main_program()

        loader.set_batch_generator(infinite_reader, places=self.get_place())
        for epoch_id in range(10):
            batch_id = 0
            if loader.iterable:
                for data in loader():
                    x_val, = exe.run(prog, feed=data, fetch_list=[self.x])
                    self.assertTrue(np.all(x_val == batch_id))
                    batch_id += 1
                    if batch_id >= self.stop_batch:
                        break
            else:
                loader.start()
                while True:
                    exe.run(prog, fetch_list=[self.x])
                    batch_id += 1
                    if batch_id >= self.stop_batch:
                        loader.reset()
                        break

            self.assertEqual(batch_id, self.stop_batch)

        if loader.iterable:
            loader._reset()


class TestDataLoaderEarlyReset2(TestDataLoaderEarlyReset):
    def setUp(self):
        self.stop_batch = 20
        self.iterable = False


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