# MIT License
#
# Copyright (C) 2021. Huawei Technologies Co., Ltd. All rights reserved.
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.
import numpy as np
from torch import nn


class EpsilonExplore:
    def __init__(self, max_epsilon, min_epsilon, decay):
        self.max_epsilon = max_epsilon
        self.min_epsilon = min_epsilon
        self.decay = decay
        self.epsilon = max_epsilon
        self.epsilon_step = 0

    def get_epsilon(self):
        return self.epsilon

    def step(self):
        if isinstance(self.decay, int):
            delta = (self.max_epsilon - self.min_epsilon) / self.decay
            self.epsilon = np.clip(
                self.max_epsilon - delta * self.epsilon_step,
                self.min_epsilon,
                self.max_epsilon,
            )
        else:
            self.epsilon = np.clip(
                self.epsilon * self.decay, self.min_epsilon, self.max_epsilon
            )
        self.epsilon_step += 1
