from typing import Any, Tuple, List

import numpy as np
from ding.utils import BUFFER_REGISTRY

from lzero.mcts.utils import prepare_observation
from .game_buffer_muzero import MuZeroGameBuffer


@BUFFER_REGISTRY.register('game_buffer_stochastic_muzero')
class StochasticMuZeroGameBuffer(MuZeroGameBuffer):
    """
    Overview:
        The specific game buffer for Stochastic MuZero policy.
    """

    def __init__(self, cfg: dict):
        super().__init__(cfg)
        """
        Overview:
            Use the default configuration mechanism. If a user passes in a cfg with a key that matches an existing key
            in the default configuration, the user-provided value will override the default configuration. Otherwise,
            the default configuration will be used.
        """
        default_config = self.default_config()
        default_config.update(cfg)
        self._cfg = default_config
        assert self._cfg.env_type in ['not_board_games', 'board_games']
        assert self._cfg.action_type in ['fixed_action_space', 'varied_action_space']
        self.replay_buffer_size = self._cfg.replay_buffer_size
        self.batch_size = self._cfg.batch_size
        self._alpha = self._cfg.priority_prob_alpha
        self._beta = self._cfg.priority_prob_beta

        self.keep_ratio = 1
        self.model_update_interval = 10
        self.num_of_collected_episodes = 0
        self.base_idx = 0
        self.clear_time = 0

        self.game_segment_buffer = []
        self.game_pos_priorities = []
        self.game_segment_game_pos_look_up = []

    def _make_batch(self, batch_size: int, reanalyze_ratio: float) -> Tuple[Any]:
        """
        Overview:
            first sample orig_data through ``_sample_orig_data()``,
            then prepare the context of a batch:
                reward_value_context:        the context of reanalyzed value targets
                policy_re_context:           the context of reanalyzed policy targets
                policy_non_re_context:       the context of non-reanalyzed policy targets
                current_batch:                the inputs of batch
        Arguments:
            - batch_size (:obj:`int`): the batch size of orig_data from replay buffer.
            - reanalyze_ratio (:obj:`float`): ratio of reanalyzed policy (value is 100% reanalyzed)
        Returns:
            - context (:obj:`Tuple`): reward_value_context, policy_re_context, policy_non_re_context, current_batch
        """
        # obtain the batch context from replay buffer
        orig_data = self._sample_orig_data(batch_size)
        game_segment_list, pos_in_game_segment_list, batch_index_list, weights_list, make_time_list = orig_data
        batch_size = len(batch_index_list)
        obs_list, action_list, mask_list = [], [], []
        if self._cfg.use_ture_chance_label_in_chance_encoder:
            chance_list = []
        # prepare the inputs of a batch
        for i in range(batch_size):
            game = game_segment_list[i]
            pos_in_game_segment = pos_in_game_segment_list[i]

            actions_tmp = game.action_segment[pos_in_game_segment:pos_in_game_segment +
                                                                  self._cfg.num_unroll_steps].tolist()
            if self._cfg.use_ture_chance_label_in_chance_encoder:
                chances_tmp = game.chance_segment[1 + pos_in_game_segment:1 + pos_in_game_segment +
                                                                          self._cfg.num_unroll_steps].tolist()
            # add mask for invalid actions (out of trajectory)
            mask_tmp = [1. for i in range(len(actions_tmp))]
            mask_tmp += [0. for _ in range(self._cfg.num_unroll_steps - len(mask_tmp))]

            # pad random action
            actions_tmp += [
                np.random.randint(0, game.action_space_size)
                for _ in range(self._cfg.num_unroll_steps - len(actions_tmp))
            ]
            if self._cfg.use_ture_chance_label_in_chance_encoder:
                chances_tmp += [
                    np.random.randint(0, self._cfg.model.chance_space_size)
                    for _ in range(self._cfg.num_unroll_steps - len(chances_tmp))
                ]
            # obtain the input observations
            # pad if length of obs in game_segment is less than stack+num_unroll_steps
            # e.g. stack+num_unroll_steps  4+5
            obs_list.append(
                game_segment_list[i].get_unroll_obs(
                    pos_in_game_segment_list[i], num_unroll_steps=self._cfg.num_unroll_steps, padding=True
                )
            )
            action_list.append(actions_tmp)
            mask_list.append(mask_tmp)
            if self._cfg.use_ture_chance_label_in_chance_encoder:
                chance_list.append(chances_tmp)

        # formalize the input observations
        obs_list = prepare_observation(obs_list, self._cfg.model.model_type)

        # formalize the inputs of a batch
        if self._cfg.use_ture_chance_label_in_chance_encoder:
            current_batch = [obs_list, action_list, mask_list, batch_index_list, weights_list, make_time_list,
                             chance_list]
        else:
            current_batch = [obs_list, action_list, mask_list, batch_index_list, weights_list, make_time_list]
        for i in range(len(current_batch)):
            current_batch[i] = np.asarray(current_batch[i])

        total_transitions = self.get_num_of_transitions()

        # obtain the context of value targets
        reward_value_context = self._prepare_reward_value_context(
            batch_index_list, game_segment_list, pos_in_game_segment_list, total_transitions
        )
        """
        only reanalyze recent reanalyze_ratio (e.g. 50%) data
        if self._cfg.reanalyze_outdated is True, batch_index_list is sorted according to its generated env_steps
        0: reanalyze_num -> reanalyzed policy, reanalyze_num:end -> non reanalyzed policy
        """
        reanalyze_num = int(batch_size * reanalyze_ratio)
        # reanalyzed policy
        if reanalyze_num > 0:
            # obtain the context of reanalyzed policy targets
            policy_re_context = self._prepare_policy_reanalyzed_context(
                batch_index_list[:reanalyze_num], game_segment_list[:reanalyze_num],
                pos_in_game_segment_list[:reanalyze_num]
            )
        else:
            policy_re_context = None

        # non reanalyzed policy
        if reanalyze_num < batch_size:
            # obtain the context of non-reanalyzed policy targets
            policy_non_re_context = self._prepare_policy_non_reanalyzed_context(
                batch_index_list[reanalyze_num:], game_segment_list[reanalyze_num:],
                pos_in_game_segment_list[reanalyze_num:]
            )
        else:
            policy_non_re_context = None

        context = reward_value_context, policy_re_context, policy_non_re_context, current_batch
        return context

    def update_priority(self, train_data: List[np.ndarray], batch_priorities: Any) -> None:
        """
        Overview:
            Update the priority of training data.
        Arguments:
            - train_data (:obj:`Optional[List[Optional[np.ndarray]]]`): training data to be updated priority.
            - batch_priorities (:obj:`batch_priorities`): priorities to update to.
        NOTE:
            train_data = [current_batch, target_batch]
            if self._cfg.use_ture_chance_label_in_chance_encoder:
                obs_batch_orig, action_batch, mask_batch, indices, weights, make_time, chance_batch = current_batch
            else:
                obs_batch_orig, action_batch, mask_batch, indices, weights, make_time = current_batch

        """
        indices = train_data[0][3]
        metas = {'make_time': train_data[0][5], 'batch_priorities': batch_priorities}
        # only update the priorities for data still in replay buffer
        for i in range(len(indices)):
            if metas['make_time'][i] > self.clear_time:
                idx, prio = indices[i], metas['batch_priorities'][i]
                self.game_pos_priorities[idx] = prio
