#   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 unittest
import numpy as np
import paddle.fluid as fluid


class TestExponentialMovingAverage(unittest.TestCase):
    def setUp(self):
        self._places = [fluid.CPUPlace()]
        if fluid.core.is_compiled_with_cuda():
            self._places.append(fluid.CUDAPlace(0))
        self._ema_decay = 0.999
        self._param_name = "fc.weight"

        self._train_program = fluid.Program()
        self._startup_prog = fluid.Program()
        with fluid.program_guard(self._train_program, self._startup_prog):
            with fluid.unique_name.guard():
                data = fluid.data(name='x', shape=[-1, 5], dtype='float32')
                hidden = fluid.layers.fc(input=data,
                                         size=10,
                                         param_attr=self._param_name)
                cost = fluid.layers.mean(hidden)

                self._test_program = fluid.default_main_program().clone(
                    for_test=True)

                optimizer = fluid.optimizer.Adam(learning_rate=0.001)
                optimizer.minimize(cost)

                self._ema = fluid.optimizer.ExponentialMovingAverage(
                    self._ema_decay)
                self._ema.update()

    def train(self, place):
        exe = fluid.Executor(place)
        exe.run(self._startup_prog)

        params = []
        for pass_id in range(2):
            for batch_id in range(3):
                data = np.random.random(size=(10, 5)).astype('float32')
                tmp_param = np.array(fluid.global_scope().find_var(
                    self._param_name).get_tensor())
                exe.run(program=self._train_program, feed={'x': data})
                tmp_param = np.array(fluid.global_scope().find_var(
                    self._param_name).get_tensor())
                params.append(tmp_param)

        with self._ema.apply(exe):
            final_ema = np.array(fluid.global_scope().find_var(self._param_name)
                                 .get_tensor())
            data = np.random.random(size=(10, 5)).astype('float32')
            exe.run(program=self._test_program, feed={'x': data})
        return params, final_ema

    def test_check_ema(self):
        for place in self._places:
            params, final_ema = self.train(place)
            manu_ema = np.zeros_like(final_ema)
            if len(params) > 0:
                for param in params:
                    manu_ema = self._ema_decay * manu_ema + (1 - self._ema_decay
                                                             ) * param
                manu_ema = manu_ema / (1.0 - self._ema_decay**len(params))
            self.assertTrue(np.allclose(manu_ema, final_ema))


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