from typing import Union

from ray.rllib.models.action_dist import ActionDistribution
from ray.rllib.utils.annotations import override
from ray.rllib.utils.exploration.exploration import Exploration
from ray.rllib.utils.framework import TensorType


class ThompsonSampling(Exploration):
    @override(Exploration)
    def get_exploration_action(self,
                               action_distribution: ActionDistribution,
                               timestep: Union[int, TensorType],
                               explore: bool = True):
        if self.framework == "torch":
            return self._get_torch_exploration_action(action_distribution,
                                                      explore)
        else:
            raise NotImplementedError

    def _get_torch_exploration_action(self, action_dist, explore):
        if explore:
            return action_dist.inputs.argmax(dim=-1), None
        else:
            scores = self.model.predict(self.model.current_obs())
            return scores.argmax(dim=-1), None


class UCB(Exploration):
    @override(Exploration)
    def get_exploration_action(self,
                               action_distribution: ActionDistribution,
                               timestep: Union[int, TensorType],
                               explore: bool = True):
        if self.framework == "torch":
            return self._get_torch_exploration_action(action_distribution,
                                                      explore)
        else:
            raise NotImplementedError

    def _get_torch_exploration_action(self, action_dist, explore):
        if explore:
            return action_dist.inputs.argmax(dim=-1), None
        else:
            scores = self.model.value_function()
            return scores.argmax(dim=-1), None
