from typing import Optional

import numpy as np
from stable_baselines3 import PPO, A2C
from stable_baselines3.ppo import MlpPolicy as PPOMlp

from primaite import getLogger
from primaite.agents.agent import AgentSessionABC
from primaite.common.enums import AgentIdentifier, AgentFramework
from primaite.environment.primaite_env import Primaite

_LOGGER = getLogger(__name__)


class SB3Agent(AgentSessionABC):
    def __init__(
            self,
            training_config_path,
            lay_down_config_path
    ):
        super().__init__(training_config_path, lay_down_config_path)
        if not self._training_config.agent_framework == AgentFramework.SB3:
            msg = (f"Expected SB3 agent_framework, "
                   f"got {self._training_config.agent_framework}")
            _LOGGER.error(msg)
            raise ValueError(msg)
        if self._training_config.agent_identifier == AgentIdentifier.PPO:
            self._agent_class = PPO
        elif self._training_config.agent_identifier == AgentIdentifier.A2C:
            self._agent_class = A2C
        else:
            msg = ("Expected PPO or A2C agent_identifier, "
                   f"got {self._training_config.agent_identifier.value}")
            _LOGGER.error(msg)
            raise ValueError(msg)

        self._tensorboard_log_path = self.session_path / "tensorboard_logs"
        self._tensorboard_log_path.mkdir(parents=True, exist_ok=True)
        self._setup()
        _LOGGER.debug(
            f"Created {self.__class__.__name__} using: "
            f"agent_framework={self._training_config.agent_framework}, "
            f"agent_identifier="
            f"{self._training_config.agent_identifier}"
        )

    def _setup(self):
        super()._setup()
        self._env = Primaite(
            training_config_path=self._training_config_path,
            lay_down_config_path=self._lay_down_config_path,
            transaction_list=[],
            session_path=self.session_path,
            timestamp_str=self.timestamp_str
        )
        self._agent = self._agent_class(
            PPOMlp,
            self._env,
            verbose=self.output_verbose_level,
            n_steps=self._training_config.num_steps,
            tensorboard_log=self._tensorboard_log_path
        )

    def _save_checkpoint(self):
        checkpoint_n = self._training_config.checkpoint_every_n_episodes
        episode_count = self._env.episode_count
        if checkpoint_n > 0 and episode_count > 0:
            if (
                    (episode_count % checkpoint_n == 0)
                    or (episode_count == self._training_config.num_episodes)
            ):
                self._agent.save(
                    self.checkpoints_path / f"sb3ppo_{episode_count}.zip")

    def _get_latest_checkpoint(self):
        pass

    def learn(
            self,
            time_steps: Optional[int] = None,
            episodes: Optional[int] = None,
            **kwargs
    ):
        if not time_steps:
            time_steps = self._training_config.num_steps

        if not episodes:
            episodes = self._training_config.num_episodes
        for i in range(episodes):
            self._agent.learn(total_timesteps=time_steps)
            self._save_checkpoint()

        self._env.close()
        super().learn()

    def evaluate(
            self,
            time_steps: Optional[int] = None,
            episodes: Optional[int] = None,
            deterministic: bool = True,
            **kwargs
    ):
        if not time_steps:
            time_steps = self._training_config.num_steps

        if not episodes:
            episodes = self._training_config.num_episodes

        for episode in range(episodes):
            obs = self._env.reset()

            for step in range(time_steps):
                action, _states = self._agent.predict(
                    obs,
                    deterministic=deterministic
                )
                if isinstance(action, np.ndarray):
                    action = np.int64(action)
                obs, rewards, done, info = self._env.step(action)

    @classmethod
    def load(self):
        raise NotImplementedError

    def save(self):
        raise NotImplementedError

    def export(self):
        raise NotImplementedError