from functools import partial
import gym
from gym.spaces import Box
import numpy as np
from gym.wrappers import TimeLimit


from envs.multiagentenv import MultiAgentEnv
from envs.mamujoco import obsk

from gym.wrappers import Monitor

# using code from https://github.com/ikostrikov/pytorch-ddpg-naf
class NormalizedActions(gym.ActionWrapper):

    def _action(self, action):
        action = (action + 1) / 2
        action *= (self.action_space.high - self.action_space.low)
        action += self.action_space.low
        return action

    def action(self, action_):
        return self._action(action_)

    def _reverse_action(self, action):
        action -= self.action_space.low
        action /= (self.action_space.high - self.action_space.low)
        action = action * 2 - 1
        return action


class MujocoMulti(MultiAgentEnv):

    def __init__(self, batch_size=None, **kwargs):
        super().__init__(batch_size, **kwargs)
        self.scenario = kwargs["env_args"]["scenario"] # e.g. Ant-v2
        self.agent_conf = kwargs["env_args"]["agent_conf"] # e.g. '2x3'

        self.agent_partitions, self.mujoco_edges, self.mujoco_globals  = obsk.get_parts_and_edges(self.scenario,
                                                                                             self.agent_conf)

        self.n_agents = len(self.agent_partitions)
        self.n_actions = max([len(l) for l in self.agent_partitions])
        self.obs_add_global_pos = kwargs["env_args"].get("obs_add_global_pos", False)

        self.agent_obsk = kwargs["env_args"].get("agent_obsk", None) # if None, fully observable else k>=0 implies observe nearest k agents or joints
        self.agent_obsk_agents = kwargs["env_args"].get("agent_obsk_agents", False)  # observe full k nearest agents (True) or just single joints (False)

        if self.agent_obsk is not None:
            self.k_categories_label = kwargs["env_args"].get("k_categories")
            if self.k_categories_label is None:
                if self.scenario in ["Ant-v2", "manyagent_ant"]:
                    self.k_categories_label = "qpos,qvel,cfrc_ext|qpos"
                elif self.scenario in ["Humanoid-v2", "HumanoidStandup-v2"]:
                    self.k_categories_label = "qpos,qvel,cfrc_ext,cvel,cinert,qfrc_actuator|qpos"
                elif self.scenario in ["Reacher-v2"]:
                    self.k_categories_label = "qpos,qvel,fingertip_dist|qpos"
                if self.scenario in ["coupled_half_cheetah"]:
                    self.k_categories_label = "qpos,qvel,ten_J,ten_length,ten_velocity|qpos"
                else:
                    self.k_categories_label = "qpos,qvel|qpos"

            k_split = self.k_categories_label.split("|")
            self.k_categories = [k_split[k if k < len(k_split) else -1].split(",") for k in range(self.agent_obsk+1)]

            self.global_categories_label = kwargs["env_args"].get("global_categories")
            self.global_categories = self.global_categories_label.split(",") if self.global_categories_label is not None else []

        if self.agent_obsk is not None:
            self.k_dicts = [obsk.get_joints_at_kdist(agent_id,
                                                self.agent_partitions,
                                                self.mujoco_edges,
                                                k=self.agent_obsk,
                                                kagents=False,) for agent_id in range(self.n_agents)]

        # load scenario from script
        self.episode_limit = self.args.episode_limit

        self.env_version = kwargs["env_args"].get("env_version", 2)
        if self.env_version == 2:
            try:
                self.wrapped_env = NormalizedActions(gym.make(self.scenario))
            except gym.error.Error:
                if self.scenario in ["manyagent_ant"]:
                    from .manyagent_ant import ManyAgentAntEnv as this_env
                    self.wrapped_env = NormalizedActions(TimeLimit(this_env(**kwargs["env_args"]), max_episode_steps=self.episode_limit))
                elif self.scenario in ["manyagent_swimmer"]:
                    from .manyagent_swimmer import ManyAgentSwimmerEnv as this_env
                    self.wrapped_env = NormalizedActions(TimeLimit(this_env(**kwargs["env_args"]), max_episode_steps=self.episode_limit))
                elif self.scenario in ["coupled_half_cheetah"]:
                    from .coupled_half_cheetah import CoupledHalfCheetah as this_env
                    self.wrapped_env = NormalizedActions(TimeLimit(this_env(**kwargs["env_args"]), max_episode_steps=self.episode_limit))
                else:
                    # raise NotImplementedError('Custom env not implemented!')
                    from envs import REGISTRY as env_REGISTRY
                    self.wrapped_env = NormalizedActions(TimeLimit(partial(env_REGISTRY[self.scenario],**kwargs["env_args"])(), max_episode_steps=self.episode_limit))
        else:
            assert False,  "not implemented!"

        # use gym wrapper to save video
        if kwargs["env_args"].get("env_monitor", False):
            self.save_video = True
            video_path = kwargs["env_args"].get("video_path", "./video")
            self.wrapped_env = Monitor(self.wrapped_env, video_path, force=True)

            self.timelimit_env = self.wrapped_env.env.env
        else:
            self.save_video = False
            self.timelimit_env = self.wrapped_env.env
        self.timelimit_env._max_episode_steps = self.episode_limit
        self.env = self.timelimit_env.env
        self.timelimit_env.reset()
        self.obs_size = self.get_obs_size()

        # COMPATIBILITY
        self.n = self.n_agents
        self.observation_space = [Box(low=np.array([-10]*self.n_agents), high=np.array([10]*self.n_agents)) for _ in range(self.n_agents)]

        acdims = [len(ap) for ap in self.agent_partitions]
        self.action_space = tuple([Box(self.env.action_space.low[sum(acdims[:a]):sum(acdims[:a+1])],
                                       self.env.action_space.high[sum(acdims[:a]):sum(acdims[:a+1])]) for a in range(self.n_agents)])
        pass

    def step(self, actions):
        flat_actions = np.concatenate([actions[i][:self.action_space[i].low.shape[0]] for i in range(self.n_agents)])
        obs_n, reward_n, done_n, info_n = self.wrapped_env.step(flat_actions)
        self.steps += 1

        info = {}
        info.update(info_n)

        if done_n:
            if self.steps < self.episode_limit:
                info["episode_limit"] = False   # the next state will be masked out
            else:
                info["episode_limit"] = True    # the next state will not be masked out

        return reward_n, done_n, info

    def get_obs(self):
        """ Returns all agent observat3ions in a list """
        obs_n = []
        for a in range(self.n_agents):
            obs_n.append(self.get_obs_agent(a))
        return obs_n

    def get_obs_agent(self, agent_id):
        if self.agent_obsk is None:
            return self.env._get_obs()
        else:
            return obsk.build_obs(self.env,
                                  self.k_dicts[agent_id],
                                  self.k_categories,
                                  self.mujoco_globals,
                                  self.global_categories,
                                  vec_len=getattr(self, "obs_size", None))

    def get_obs_size(self):
        """ Returns the shape of the observation """
        if self.agent_obsk is None:
            return self.get_obs_agent(0).size
        else:
            return max([len(self.get_obs_agent(agent_id)) for agent_id in range(self.n_agents)])

    def get_state(self, team=None):
        return self.env._get_obs()

    def get_state_size(self):
        """ Returns the shape of the state"""
        return len(self.get_state())

    def get_avail_actions(self): # all actions are always available
        return np.ones(shape=(self.n_agents, self.n_actions,))

    def get_avail_agent_actions(self, agent_id):
        """ Returns the available actions for agent_id """
        return np.ones(shape=(self.n_actions,))

    def get_total_actions(self):
        """ Returns the total number of actions an agent could ever take """
        return self.n_actions # CAREFUL! - for continuous dims, this is action space dim rather
        # return self.env.action_space.shape[0]

    def get_stats(self):
        return {}

    def get_agg_stats(self, stats):
        return {}

    def reset(self, **kwargs):
        """ Returns initial observations and states"""
        self.steps = 0
        if self.save_video:
            self.wrapped_env.reset()
        else:
            self.timelimit_env.reset()
        return self.get_obs()

    def render(self, **kwargs):
        self.env.render(**kwargs)

    def close(self):
        return
        # raise NotImplementedError

    def seed(self, args):
        pass

    def get_env_info(self):
        env_info = {"state_shape": self.get_state_size(),
                    "obs_shape": self.get_obs_size(),
                    "n_actions": self.get_total_actions(),
                    "n_agents": self.n_agents,
                    "episode_limit": self.episode_limit,
                    "action_spaces": self.action_space,
                    "obs_spaces": self.observation_space,
                    "actions_dtype": np.float32,
                    "normalise_actions": False
                    }
        return env_info