from machin.frame.buffers.prioritized_buffer import PrioritizedBuffer
from machin.utils.logging import default_logger

# pylint: disable=wildcard-import, unused-wildcard-import
from .ddpg import *


class DDPGPer(DDPG):
    """
    DDPG with prioritized experience replay.

    Warning:
        Your criterion must return a tensor of shape ``[batch_size,1]``
        when given two tensors of shape ``[batch_size,1]``, since we
        need to multiply the loss with importance sampling weight
        element-wise.

        If you are using loss modules given by pytorch. It is always
        safe to use them without any modification.
    """

    def __init__(
        self,
        actor: Union[NeuralNetworkModule, nn.Module],
        actor_target: Union[NeuralNetworkModule, nn.Module],
        critic: Union[NeuralNetworkModule, nn.Module],
        critic_target: Union[NeuralNetworkModule, nn.Module],
        optimizer: Callable,
        criterion,
        *_,
        lr_scheduler: Callable = None,
        lr_scheduler_args: Tuple[Tuple, Tuple] = None,
        lr_scheduler_kwargs: Tuple[Dict, Dict] = None,
        batch_size: int = 100,
        update_rate: float = 0.005,
        update_steps: Union[int, None] = None,
        actor_learning_rate: float = 0.0005,
        critic_learning_rate: float = 0.001,
        discount: float = 0.99,
        gradient_max: float = np.inf,
        replay_size: int = 500000,
        replay_device: Union[str, t.device] = "cpu",
        replay_buffer: Buffer = None,
        visualize: bool = False,
        visualize_dir: str = "",
        **__
    ):
        # DOC INHERITED
        super().__init__(
            actor,
            actor_target,
            critic,
            critic_target,
            optimizer,
            criterion,
            lr_scheduler=lr_scheduler,
            lr_scheduler_args=lr_scheduler_args,
            lr_scheduler_kwargs=lr_scheduler_kwargs,
            batch_size=batch_size,
            update_rate=update_rate,
            update_steps=update_steps,
            actor_learning_rate=actor_learning_rate,
            critic_learning_rate=critic_learning_rate,
            discount=discount,
            gradient_max=gradient_max,
            replay_size=replay_size,
            replay_device=replay_device,
            replay_buffer=(
                PrioritizedBuffer(replay_size, replay_device)
                if replay_buffer is None
                else replay_buffer
            ),
            visualize=visualize,
            visualize_dir=visualize_dir,
        )
        # Must have reduction attribute and value must be None
        if not hasattr(self.criterion, "reduction"):
            raise RuntimeError(
                "Criterion does not have the "
                "'reduction' property, are you using a custom "
                "criterion?"
            )
        else:
            # A loss defined in ``torch.nn.modules.loss``
            if getattr(self.criterion, "reduction") != "none":
                default_logger.warning(
                    "The reduction property of criterion is not 'none', "
                    "automatically corrected."
                )
                self.criterion.reduction = "none"

    def update(
        self,
        update_value=True,
        update_policy=True,
        update_target=True,
        concatenate_samples=True,
        **__
    ):
        # DOC INHERITED
        self.actor.train()
        self.critic.train()
        (
            batch_size,
            (state, action, reward, next_state, terminal, others),
            index,
            is_weight,
        ) = self.replay_buffer.sample_batch(
            self.batch_size,
            concatenate_samples,
            sample_attrs=["state", "action", "reward", "next_state", "terminal", "*"],
        )

        # Update critic network first.
        # Generate value reference :math: `y_i` using target actor and
        # target critic.
        with t.no_grad():
            next_action = self.action_transform_function(
                self._act(next_state, True), next_state, others
            )
            next_value = self._criticize(next_state, next_action, True)
            next_value = next_value.view(batch_size, -1)
            y_i = self.reward_function(
                reward, self.discount, next_value, terminal, others
            )

        # critic loss
        cur_value = self._criticize(state, action)
        value_loss = self.criterion(cur_value, y_i.type_as(cur_value))
        value_loss = value_loss * t.from_numpy(is_weight).view([batch_size, 1]).type_as(
            value_loss
        )
        value_loss = value_loss.mean()

        if self.visualize:
            self.visualize_model(value_loss, "critic", self.visualize_dir)

        if update_value:
            self.critic.zero_grad()
            self._backward(value_loss)
            nn.utils.clip_grad_norm_(self.critic.parameters(), self.gradient_max)
            self.critic_optim.step()

        # actor loss
        cur_action = self.action_transform_function(self._act(state), state, others)
        act_value = self._criticize(state, cur_action)

        # "-" is applied because we want to maximize J_b(u),
        # but optimizer workers by minimizing the target
        act_policy_loss = -act_value.mean()

        # update priority
        abs_error = (
            t.sum(t.abs(act_value - y_i.type_as(act_value)), dim=1)
            .flatten()
            .detach()
            .cpu()
            .numpy()
        )
        self.replay_buffer.update_priority(abs_error, index)

        if self.visualize:
            self.visualize_model(act_policy_loss, "actor", self.visualize_dir)

        if update_policy:
            self.actor.zero_grad()
            self._backward(act_policy_loss)
            nn.utils.clip_grad_norm_(self.actor.parameters(), self.gradient_max)
            self.actor_optim.step()

        # Update target networks
        if update_target:
            if self.update_rate is not None:
                soft_update(self.actor_target, self.actor, self.update_rate)
                soft_update(self.critic_target, self.critic, self.update_rate)
            else:
                self._update_counter += 1
                if self._update_counter % self.update_steps == 0:
                    hard_update(self.actor_target, self.actor)
                    hard_update(self.critic_target, self.critic)

        self.actor.eval()
        self.critic.eval()
        # use .item() to prevent memory leakage
        return -act_policy_loss.item(), value_loss.item()

    @classmethod
    def generate_config(cls, config: Union[Dict[str, Any], Config]):
        config = DDPG.generate_config(config)
        config["frame"] = "DDPGPer"
        return config

    @classmethod
    def init_from_config(
        cls,
        config: Union[Dict[str, Any], Config],
        model_device: Union[str, t.device] = "cpu",
    ):
        f_config = config["frame_config"]
        models = assert_and_get_valid_models(f_config["models"])
        model_args = f_config["model_args"]
        model_kwargs = f_config["model_kwargs"]
        models = [
            m(*arg, **kwarg).to(model_device)
            for m, arg, kwarg in zip(models, model_args, model_kwargs)
        ]
        optimizer = assert_and_get_valid_optimizer(f_config["optimizer"])
        criterion = assert_and_get_valid_criterion(f_config["criterion"])(
            *f_config["criterion_args"], **f_config["criterion_kwargs"]
        )
        criterion.reduction = "none"
        lr_scheduler = f_config["lr_scheduler"] and assert_and_get_valid_lr_scheduler(
            f_config["lr_scheduler"]
        )
        f_config["optimizer"] = optimizer
        f_config["criterion"] = criterion
        f_config["lr_scheduler"] = lr_scheduler
        frame = cls(*models, **f_config)
        return frame
