# coding=utf-8
# Copyright 2020 The Google Research Authors.
#
# 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
#
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# distributed under the License is distributed on an "AS IS" BASIS,
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"""DQN Agent with logged replay buffer."""

from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

from batch_rl.baselines.replay_memory import logged_replay_buffer
from dopamine.agents.dqn import dqn_agent


class LoggedDQNAgent(dqn_agent.DQNAgent):
  """An implementation of the DQN agent with replay buffer logging to disk."""

  def __init__(self, sess, num_actions, replay_log_dir, replay_capacity=1000000, **kwargs):
    """Initializes the agent and constructs the components of its graph.

    Args:
      sess: tf.Session, for executing ops.
      num_actions: int, number of actions the agent can take at any state.
      replay_log_dir: str, log Directory to save the replay buffer to disk
        periodically.
      **kwargs: Arbitrary keyword arguments.
    """
    assert replay_log_dir is not None
    # Set replay_log_dir before calling parent's initializer
    self._replay_log_dir = replay_log_dir
    self._replay_capacity = replay_capacity
    super(LoggedDQNAgent, self).__init__(sess, num_actions, **kwargs)

  def log_final_buffer(self):
    self._replay.memory.log_final_buffer()

  def _build_replay_buffer(self, use_staging):
    """Creates the replay buffer used by the agent.

    Args:
      use_staging: bool, if True, uses a staging area to prefetch data for
        faster training.

    Returns:
      A WrapperReplayBuffer object.
    """
    return logged_replay_buffer.WrappedLoggedReplayBuffer(
        log_dir=self._replay_log_dir,
        observation_shape=self.observation_shape,
        stack_size=self.stack_size,
        use_staging=use_staging,
        update_horizon=self.update_horizon,
        gamma=self.gamma,
        observation_dtype=self.observation_dtype.as_numpy_dtype,
        replay_capacity=self._replay_capacity
    )
