# Copyright (c) 2019 Maxime Chevalier-Boisvert.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0

from gym_minigrid.minigrid import *

from envs.registration import register as register


class FourRoomsEnv(MiniGridEnv):
    """
    Classic 4 rooms gridworld environment.
    Can specify agent and goal position, if not it set at random.
    """

    def __init__(self, agent_pos=None, goal_pos=None):
        self._agent_default_pos = agent_pos
        self._goal_default_pos = goal_pos
        super().__init__(
            grid_size=19, 
            max_steps=100,
            agent_view_size=5)

        direction_obs_space = gym.spaces.Box(
            low=0, high=3, shape=(1,), dtype='uint8')

        self.observation_space = spaces.Dict({
            'image': self.observation_space['image'],
            'direction': direction_obs_space
        })

    def _gen_grid(self, width, height):
        # Create the grid
        self.grid = Grid(width, height)

        # Generate the surrounding walls
        self.grid.horz_wall(0, 0)
        self.grid.horz_wall(0, height - 1)
        self.grid.vert_wall(0, 0)
        self.grid.vert_wall(width - 1, 0)

        room_w = width // 2
        room_h = height // 2

        # For each row of rooms
        for j in range(0, 2):

            # For each column
            for i in range(0, 2):
                xL = i * room_w
                yT = j * room_h
                xR = xL + room_w
                yB = yT + room_h

                # Bottom wall and door
                if i + 1 < 2:
                    self.grid.vert_wall(xR, yT, room_h)
                    pos = (xR, self._rand_int(yT + 1, yB))
                    self.grid.set(*pos, None)

                # Bottom wall and door
                if j + 1 < 2:
                    self.grid.horz_wall(xL, yB, room_w)
                    pos = (self._rand_int(xL + 1, xR), yB)
                    self.grid.set(*pos, None)

        # Randomize the player start position and orientation
        if self._agent_default_pos is not None:
            self.agent_pos = self._agent_default_pos
            self.grid.set(*self._agent_default_pos, None)
            self.agent_dir = self._rand_int(0, 4)  # assuming random start direction
        else:
            self.place_agent()

        if self._goal_default_pos is not None:
            goal = Goal()
            self.put_obj(goal, *self._goal_default_pos)
            goal.init_pos, goal.cur_pos = self._goal_default_pos
        else:
            self.place_obj(Goal())

        self.mission = 'Reach the goal'

    def step(self, action):
        obs, rewards, done, info = super().step(action)

        del obs['mission']
        obs['image'] = obs['image']
        obs['direction'] = [self.agent_dir]

        return obs, rewards, done, info

    def reset(self):
        obs = super().reset()

        del obs['mission']
        obs['image'] = obs['image']
        obs['direction'] = [self.agent_dir]

        return obs


if hasattr(__loader__, 'name'):
  module_path = __loader__.name
elif hasattr(__loader__, 'fullname'):
  module_path = __loader__.fullname

register(
    id='MiniGrid-FourRooms-v0',
    entry_point=module_path+':FourRoomsEnv'
)
