import numpy as np
from gym.spaces import Box

from metaworld.envs.asset_path_utils import full_v2_path_for
from metaworld.envs.mujoco.sawyer_xyz.sawyer_xyz_env import SawyerXYZEnv, _assert_task_is_set


class SawyerDrawerCloseEnvV2(SawyerXYZEnv):
    def __init__(self):

        hand_low = (-0.5, 0.40, 0.05)
        hand_high = (0.5, 1, 0.5)
        obj_low = (-0.1, 0.9, 0.0)
        obj_high = (0.1, 0.9, 0.0)

        super().__init__(
            self.model_name,
            hand_low=hand_low,
            hand_high=hand_high,
        )

        self.init_config = {
            'obj_init_angle': np.array([0.3, ], dtype=np.float32),
            'obj_init_pos': np.array([0., 0.9, 0.0], dtype=np.float32),
            'hand_init_pos': np.array([0, 0.6, 0.2], dtype=np.float32),
            'drawer_init_pos': 0.0 # 0 - 0.15
        }
        self.obj_init_pos = self.init_config['obj_init_pos']
        self.obj_init_angle = self.init_config['obj_init_angle']
        self.hand_init_pos = self.init_config['hand_init_pos']

        goal_low = self.hand_low
        goal_high = self.hand_high

        self.max_path_length = 150

        self._random_reset_space = Box(
            np.array(obj_low),
            np.array(obj_high),
        )
        self.goal_space = Box(np.array(goal_low), np.array(goal_high))

        self.maxDist = self.init_config['drawer_init_pos']
        self.target_reward = 1000 * self.maxDist + 1000 * 2

    @property
    def model_name(self):
        return full_v2_path_for('sawyer_xyz/sawyer_drawer.xml')

    @_assert_task_is_set
    def step(self, action):
        ob = super().step(action)
        reward, reachDist, pullDist = self.compute_reward(action, ob)
        self.curr_path_length += 1
        info = {
            'reachDist': reachDist,
            'goalDist': pullDist,
            'epRew': reward,
            'pickRew': None,
            'success': float(pullDist <= 0.03),
        }

        return ob, reward, False, info

    def _get_pos_objects(self):
        return self.get_body_com('drawer_link') + np.array([.0, -.16, .05])

    def _set_obj_xyz(self, pos):
        qpos = self.data.qpos.flat.copy()
        qvel = self.data.qvel.flat.copy()
        qpos[9] = pos
        self.set_state(qpos, qvel)

    def reset_model(self):
        self._reset_hand()

        # Compute nightstand position
        self.obj_init_pos = self._get_state_rand_vec() if self.random_init \
            else self.init_config['obj_init_pos']
        # Set mujoco body to computed position
        self.sim.model.body_pos[self.model.body_name2id(
            'drawer'
        )] = self.obj_init_pos
        # Set _target_pos to current drawer position (closed)
        self._target_pos = self.obj_init_pos + np.array([.0, -.16, .09])
        # Pull drawer out all the way and mark its starting position
        self.maxDist = self.init_config['drawer_init_pos']
        self.target_reward = 1000 * self.maxDist + 1000 * 2
        self._set_obj_xyz(-self.maxDist)

        return self._get_obs()

    def compute_reward(self, actions, obs):
        del actions
        objPos = obs[3:6]

        rightFinger, leftFinger = self._get_site_pos('rightEndEffector'), self._get_site_pos('leftEndEffector')
        fingerCOM  =  (rightFinger + leftFinger)/2

        pullGoal = self._target_pos[1]

        reachDist = np.linalg.norm(objPos - fingerCOM)

        pullDist = np.abs(objPos[1] - pullGoal)

        c1 = 1000
        c2 = 0.01
        c3 = 0.001

        if reachDist < 0.05:
            pullRew = 1000*(self.maxDist - pullDist) + c1*(np.exp(-(pullDist**2)/c2) + np.exp(-(pullDist**2)/c3))
            pullRew = max(pullRew, 0)
        else:
            pullRew = 0

        reward = -reachDist + pullRew

        return [reward, reachDist, pullDist]
