#
# Copyright (c) 2017 Intel Corporation
#
# 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 typing import List, Dict

import numpy as np

from rl_coach.agents.dqn_agent import DQNAgentParameters
from rl_coach.architectures.tensorflow_components.layers import NoisyNetDense
from rl_coach.base_parameters import AgentParameters, NetworkParameters
from rl_coach.spaces import ActionSpace, BoxActionSpace, DiscreteActionSpace

from rl_coach.core_types import ActionType
from rl_coach.exploration_policies.exploration_policy import ExplorationPolicy, ExplorationParameters


class ParameterNoiseParameters(ExplorationParameters):
    def __init__(self, agent_params: AgentParameters):
        super().__init__()
        if not isinstance(agent_params, DQNAgentParameters):
            raise ValueError("Currently only DQN variants are supported for using an exploration type of "
                             "ParameterNoise.")

        self.network_params = agent_params.network_wrappers

    @property
    def path(self):
        return 'rl_coach.exploration_policies.parameter_noise:ParameterNoise'


class ParameterNoise(ExplorationPolicy):
    def __init__(self, network_params: Dict[str, NetworkParameters], action_space: ActionSpace):
        """
        :param action_space: the action space used by the environment
        :param alpha0:
        """
        super().__init__(action_space)
        self.network_params = network_params
        self._replace_network_dense_layers()

    def get_action(self, action_values: List[ActionType]) -> ActionType:
        if type(self.action_space) == DiscreteActionSpace:
            return np.argmax(action_values)
        elif type(self.action_space) == BoxActionSpace:
            action_values_mean = action_values[0].squeeze()
            action_values_std = action_values[1].squeeze()
            return np.random.normal(action_values_mean, action_values_std)
        else:
            raise ValueError("ActionSpace type {} is not supported for ParameterNoise.".format(type(self.action_space)))

    def get_control_param(self):
        return 0

    def _replace_network_dense_layers(self):
        # replace the dense type for all the networks components (embedders, mw, heads) with a NoisyNetDense

        # NOTE: we are changing network params in a non-params class (an already instantiated class), this could have
        #       been prone to a bug, but since the networks are created very late in the game
        #       (after agent.init_environment_dependent()_modules is called) - then we are fine.

        for network_wrapper_params in self.network_params.values():
            for component_params in list(network_wrapper_params.input_embedders_parameters.values()) + \
                                    [network_wrapper_params.middleware_parameters] + \
                                    network_wrapper_params.heads_parameters:
                component_params.dense_layer = NoisyNetDense

