#   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.

import parl

__all__ = ['ES']


class ES(parl.Algorithm):
    def __init__(self, model):
        """ES algorithm.
        
        Since parameters of the model is updated in the numpy level, `learn` function is not needed
        in this algorithm.

        Args:
            model(`parl.Model`): policy model of ES algorithm.
        """
        self.model = model

    def predict(self, obs):
        """Use the policy model to predict actions of observations.

        Args:
            obs(layers.data):  data layer of observations.

        Returns:
            tensor of predicted actions.
        """
        return self.model(obs)