import logging
from typing import Any, Dict

import numpy as np
import tensorflow as tf
import horovod.tensorflow as hvd

from mlagents.envs.exception import UnityException
from mlagents.envs.policy import Policy
from mlagents.envs.action_info import ActionInfo
from tensorflow.python.platform import gfile
from tensorflow.python.framework import graph_util
from mlagents.trainers import tensorflow_to_barracuda as tf2bc
from mlagents.envs.brain import BrainInfo


logger = logging.getLogger("mlagents.trainers")


class UnityPolicyException(UnityException):
    """
    Related to errors with the Trainer.
    """

    pass


class TFPolicy(Policy):
    """
    Contains a learning model, and the necessary
    functions to interact with it to perform evaluate and updating.
    """

    possible_output_nodes = [
        "action",
        "value_estimate",
        "action_probs",
        "recurrent_out",
        "memory_size",
        "version_number",
        "is_continuous_control",
        "action_output_shape",
    ]

    def __init__(self, seed, brain, trainer_parameters):
        """
        Initialized the policy.
        :param seed: Random seed to use for TensorFlow.
        :param brain: The corresponding Brain for this policy.
        :param trainer_parameters: The trainer parameters.
        """
        self.m_size = None
        self.model = None
        self.inference_dict = {}
        self.update_dict = {}
        self.sequence_length = 1
        self.seed = seed
        self.brain = brain
        self.use_recurrent = trainer_parameters["use_recurrent"]
        self.normalize = trainer_parameters.get("normalize", False)
        self.use_continuous_act = brain.vector_action_space_type == "continuous"
        self.model_path = trainer_parameters["model_path"]
        self.keep_checkpoints = trainer_parameters.get("keep_checkpoints", 5)
        config = tf.ConfigProto()
        config.gpu_options.visible_device_list = str(hvd.local_rank())
        config.gpu_options.allow_growth = True
        # For multi-GPU training, set allow_soft_placement to True to allow
        # placing the operation into an alternative device automatically
        # to prevent from exceptions if the device doesn't suppport the operation
        # or the device does not exist
        config.allow_soft_placement = True
        self.graph = tf.Graph()
        self.sess = tf.Session(config=config, graph=self.graph)
        self.saver = None
        if self.use_recurrent:
            self.m_size = trainer_parameters["memory_size"]
            self.sequence_length = trainer_parameters["sequence_length"]
            if self.m_size == 0:
                raise UnityPolicyException(
                    "The memory size for brain {0} is 0 even "
                    "though the trainer uses recurrent.".format(brain.brain_name)
                )
            elif self.m_size % 4 != 0:
                raise UnityPolicyException(
                    "The memory size for brain {0} is {1} "
                    "but it must be divisible by 4.".format(
                        brain.brain_name, self.m_size
                    )
                )

    def _initialize_graph(self):
        with self.graph.as_default():
            self.saver = tf.train.Saver(max_to_keep=self.keep_checkpoints)
            init = tf.global_variables_initializer()
            self.sess.run(init)
            self.sess.run(hvd.broadcast_global_variables(0))

    def _load_graph(self):
        with self.graph.as_default():
            self.saver = tf.train.Saver(max_to_keep=self.keep_checkpoints)
            logger.info("Loading Model for brain {}".format(self.brain.brain_name))
            ckpt = tf.train.get_checkpoint_state(self.model_path)
            if ckpt is None:
                logger.info(
                    "The model {0} could not be found. Make "
                    "sure you specified the right "
                    "--run-id".format(self.model_path)
                )
            self.saver.restore(self.sess, ckpt.model_checkpoint_path)

    def evaluate(self, brain_info: BrainInfo) -> Dict[str, Any]:
        """
        Evaluates policy for the agent experiences provided.
        :param brain_info: BrainInfo input to network.
        :return: Output from policy based on self.inference_dict.
        """
        raise UnityPolicyException("The evaluate function was not implemented.")

    def get_action(self, brain_info: BrainInfo) -> ActionInfo:
        """
        Decides actions given observations information, and takes them in environment.
        :param brain_info: A dictionary of brain names and BrainInfo from environment.
        :return: an ActionInfo containing action, memories, values and an object
        to be passed to add experiences
        """
        if len(brain_info.agents) == 0:
            return ActionInfo([], [], [], None, None)

        run_out = self.evaluate(brain_info)
        return ActionInfo(
            action=run_out.get("action"),
            memory=run_out.get("memory_out"),
            text=None,
            value=run_out.get("value"),
            outputs=run_out,
        )

    def update(self, mini_batch, num_sequences):
        """
        Performs update of the policy.
        :param num_sequences: Number of experience trajectories in batch.
        :param mini_batch: Batch of experiences.
        :return: Results of update.
        """
        raise UnityPolicyException("The update function was not implemented.")

    def _execute_model(self, feed_dict, out_dict):
        """
        Executes model.
        :param feed_dict: Input dictionary mapping nodes to input data.
        :param out_dict: Output dictionary mapping names to nodes.
        :return: Dictionary mapping names to input data.
        """
        network_out = self.sess.run(list(out_dict.values()), feed_dict=feed_dict)
        run_out = dict(zip(list(out_dict.keys()), network_out))
        return run_out

    def fill_eval_dict(self, feed_dict, brain_info):
        for i, _ in enumerate(brain_info.visual_observations):
            feed_dict[self.model.visual_in[i]] = brain_info.visual_observations[i]
        if self.use_vec_obs:
            feed_dict[self.model.vector_in] = brain_info.vector_observations
        if not self.use_continuous_act:
            feed_dict[self.model.action_masks] = brain_info.action_masks
        return feed_dict

    def make_empty_memory(self, num_agents):
        """
        Creates empty memory for use with RNNs
        :param num_agents: Number of agents.
        :return: Numpy array of zeros.
        """
        return np.zeros((num_agents, self.m_size))

    def get_current_step(self):
        """
        Gets current model step.
        :return: current model step.
        """
        step = self.sess.run(self.model.global_step)
        return step

    def increment_step(self, n_steps):
        """
        Increments model step.
        """
        out_dict = {
            "global_step": self.model.global_step,
            "increment_step": self.model.increment_step,
        }
        feed_dict = {self.model.steps_to_increment: n_steps}
        return self.sess.run(out_dict, feed_dict=feed_dict)["global_step"]

    def get_inference_vars(self):
        """
        :return:list of inference var names
        """
        return list(self.inference_dict.keys())

    def get_update_vars(self):
        """
        :return:list of update var names
        """
        return list(self.update_dict.keys())

    def save_model(self, steps):
        """
        Saves the model
        :param steps: The number of steps the model was trained for
        :return:
        """
        if hvd.rank() != 0:
            return

        with self.graph.as_default():
            last_checkpoint = self.model_path + "/model-" + str(steps) + ".cptk"
            self.saver.save(self.sess, last_checkpoint)
            tf.train.write_graph(
                self.graph, self.model_path, "raw_graph_def.pb", as_text=False
            )

    def export_model(self):
        """
        Exports latest saved model to .nn format for Unity embedding.
        """
        if hvd.rank() != 0:
            return

        with self.graph.as_default():
            target_nodes = ",".join(self._process_graph())
            graph_def = self.graph.as_graph_def()
            output_graph_def = graph_util.convert_variables_to_constants(
                self.sess, graph_def, target_nodes.replace(" ", "").split(",")
            )
            frozen_graph_def_path = self.model_path + "/frozen_graph_def.pb"
            with gfile.GFile(frozen_graph_def_path, "wb") as f:
                f.write(output_graph_def.SerializeToString())
            tf2bc.convert(frozen_graph_def_path, self.model_path + ".nn")
            logger.info("Exported " + self.model_path + ".nn file")

    def _process_graph(self):
        """
        Gets the list of the output nodes present in the graph for inference
        :return: list of node names
        """
        all_nodes = [x.name for x in self.graph.as_graph_def().node]
        nodes = [x for x in all_nodes if x in self.possible_output_nodes]
        logger.info("List of nodes to export for brain :" + self.brain.brain_name)
        for n in nodes:
            logger.info("\t" + n)
        return nodes

    def update_normalization(self, vector_obs: np.ndarray) -> None:
        """
        If this policy normalizes vector observations, this will update the norm values in the graph.
        :param vector_obs: The vector observations to add to the running estimate of the distribution.
        """
        if self.use_vec_obs and self.normalize:
            self.sess.run(
                self.model.update_normalization,
                feed_dict={self.model.vector_in: vector_obs},
            )

    @property
    def vis_obs_size(self):
        return self.model.vis_obs_size

    @property
    def vec_obs_size(self):
        return self.model.vec_obs_size

    @property
    def use_vis_obs(self):
        return self.model.vis_obs_size > 0

    @property
    def use_vec_obs(self):
        return self.model.vec_obs_size > 0