from d4rl.gym_minigrid.minigrid import *

def reject_next_to(env, pos):
    """
    Function to filter out object positions that are right next to
    the agent's starting point
    """

    sx, sy = env.agent_pos
    x, y = pos
    d = abs(sx - x) + abs(sy - y)
    return d < 2

class Room:
    def __init__(
        self,
        top,
        size
    ):
        # Top-left corner and size (tuples)
        self.top = top
        self.size = size

        # List of door objects and door positions
        # Order of the doors is right, down, left, up
        self.doors = [None] * 4
        self.door_pos = [None] * 4

        # List of rooms adjacent to this one
        # Order of the neighbors is right, down, left, up
        self.neighbors = [None] * 4

        # Indicates if this room is behind a locked door
        self.locked = False

        # List of objects contained
        self.objs = []

    def rand_pos(self, env):
        topX, topY = self.top
        sizeX, sizeY = self.size
        return env._randPos(
            topX + 1, topX + sizeX - 1,
            topY + 1, topY + sizeY - 1
        )

    def pos_inside(self, x, y):
        """
        Check if a position is within the bounds of this room
        """

        topX, topY = self.top
        sizeX, sizeY = self.size

        if x < topX or y < topY:
            return False

        if x >= topX + sizeX or y >= topY + sizeY:
            return False

        return True

class RoomGrid(MiniGridEnv):
    """
    Environment with multiple rooms and random objects.
    This is meant to serve as a base class for other environments.
    """

    def __init__(
        self,
        room_size=7,
        num_rows=3,
        num_cols=3,
        max_steps=100,
        seed=0
    ):
        assert room_size > 0
        assert room_size >= 3
        assert num_rows > 0
        assert num_cols > 0
        self.room_size = room_size
        self.num_rows = num_rows
        self.num_cols = num_cols

        height = (room_size - 1) * num_rows + 1
        width = (room_size - 1) * num_cols + 1

        # By default, this environment has no mission
        self.mission = ''

        super().__init__(
            width=width,
            height=height,
            max_steps=max_steps,
            see_through_walls=False,
            seed=seed
        )

    def room_from_pos(self, x, y):
        """Get the room a given position maps to"""

        assert x >= 0
        assert y >= 0

        i = x // (self.room_size-1)
        j = y // (self.room_size-1)

        assert i < self.num_cols
        assert j < self.num_rows

        return self.room_grid[j][i]

    def get_room(self, i, j):
        assert i < self.num_cols
        assert j < self.num_rows
        return self.room_grid[j][i]

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

        self.room_grid = []

        # For each row of rooms
        for j in range(0, self.num_rows):
            row = []

            # For each column of rooms
            for i in range(0, self.num_cols):
                room = Room(
                    (i * (self.room_size-1), j * (self.room_size-1)),
                    (self.room_size, self.room_size)
                )
                row.append(room)

                # Generate the walls for this room
                self.grid.wall_rect(*room.top, *room.size)

            self.room_grid.append(row)

        # For each row of rooms
        for j in range(0, self.num_rows):
            # For each column of rooms
            for i in range(0, self.num_cols):
                room = self.room_grid[j][i]

                x_l, y_l = (room.top[0] + 1, room.top[1] + 1)
                x_m, y_m = (room.top[0] + room.size[0] - 1, room.top[1] + room.size[1] - 1)

                # Door positions, order is right, down, left, up
                if i < self.num_cols - 1:
                    room.neighbors[0] = self.room_grid[j][i+1]
                    room.door_pos[0] = (x_m, self._rand_int(y_l, y_m))
                if j < self.num_rows - 1:
                    room.neighbors[1] = self.room_grid[j+1][i]
                    room.door_pos[1] = (self._rand_int(x_l, x_m), y_m)
                if i > 0:
                    room.neighbors[2] = self.room_grid[j][i-1]
                    room.door_pos[2] = room.neighbors[2].door_pos[0]
                if j > 0:
                    room.neighbors[3] = self.room_grid[j-1][i]
                    room.door_pos[3] = room.neighbors[3].door_pos[1]

        # The agent starts in the middle, facing right
        self.agent_pos = (
            (self.num_cols // 2) * (self.room_size-1) + (self.room_size // 2),
            (self.num_rows // 2) * (self.room_size-1) + (self.room_size // 2)
        )
        self.agent_dir = 0

    def place_in_room(self, i, j, obj):
        """
        Add an existing object to room (i, j)
        """

        room = self.get_room(i, j)

        pos = self.place_obj(
            obj,
            room.top,
            room.size,
            reject_fn=reject_next_to,
            max_tries=1000
        )

        room.objs.append(obj)

        return obj, pos

    def add_object(self, i, j, kind=None, color=None):
        """
        Add a new object to room (i, j)
        """

        if kind == None:
            kind = self._rand_elem(['key', 'ball', 'box'])

        if color == None:
            color = self._rand_color()

        # TODO: we probably want to add an Object.make helper function
        assert kind in ['key', 'ball', 'box']
        if kind == 'key':
            obj = Key(color)
        elif kind == 'ball':
            obj = Ball(color)
        elif kind == 'box':
            obj = Box(color)

        return self.place_in_room(i, j, obj)

    def add_door(self, i, j, door_idx=None, color=None, locked=None):
        """
        Add a door to a room, connecting it to a neighbor
        """

        room = self.get_room(i, j)

        if door_idx == None:
            # Need to make sure that there is a neighbor along this wall
            # and that there is not already a door
            while True:
                door_idx = self._rand_int(0, 4)
                if room.neighbors[door_idx] and room.doors[door_idx] is None:
                    break

        if color == None:
            color = self._rand_color()

        if locked is None:
            locked = self._rand_bool()

        assert room.doors[door_idx] is None, "door already exists"

        room.locked = locked
        door = Door(color, is_locked=locked)

        pos = room.door_pos[door_idx]
        self.grid.set(*pos, door)
        door.cur_pos = pos

        neighbor = room.neighbors[door_idx]
        room.doors[door_idx] = door
        neighbor.doors[(door_idx+2) % 4] = door

        return door, pos

    def remove_wall(self, i, j, wall_idx):
        """
        Remove a wall between two rooms
        """

        room = self.get_room(i, j)

        assert wall_idx >= 0 and wall_idx < 4
        assert room.doors[wall_idx] is None, "door exists on this wall"
        assert room.neighbors[wall_idx], "invalid wall"

        neighbor = room.neighbors[wall_idx]

        tx, ty = room.top
        w, h = room.size

        # Ordering of walls is right, down, left, up
        if wall_idx == 0:
            for i in range(1, h - 1):
                self.grid.set(tx + w - 1, ty + i, None)
        elif wall_idx == 1:
            for i in range(1, w - 1):
                self.grid.set(tx + i, ty + h - 1, None)
        elif wall_idx == 2:
            for i in range(1, h - 1):
                self.grid.set(tx, ty + i, None)
        elif wall_idx == 3:
            for i in range(1, w - 1):
                self.grid.set(tx + i, ty, None)
        else:
            assert False, "invalid wall index"

        # Mark the rooms as connected
        room.doors[wall_idx] = True
        neighbor.doors[(wall_idx+2) % 4] = True

    def place_agent(self, i=None, j=None, rand_dir=True):
        """
        Place the agent in a room
        """

        if i == None:
            i = self._rand_int(0, self.num_cols)
        if j == None:
            j = self._rand_int(0, self.num_rows)

        room = self.room_grid[j][i]

        # Find a position that is not right in front of an object
        while True:
            super().place_agent(room.top, room.size, rand_dir, max_tries=1000)
            front_cell = self.grid.get(*self.front_pos)
            if front_cell is None or front_cell.type is 'wall':
                break

        return self.agent_pos

    def connect_all(self, door_colors=COLOR_NAMES, max_itrs=5000):
        """
        Make sure that all rooms are reachable by the agent from its
        starting position
        """

        start_room = self.room_from_pos(*self.agent_pos)

        added_doors = []

        def find_reach():
            reach = set()
            stack = [start_room]
            while len(stack) > 0:
                room = stack.pop()
                if room in reach:
                    continue
                reach.add(room)
                for i in range(0, 4):
                    if room.doors[i]:
                        stack.append(room.neighbors[i])
            return reach

        num_itrs = 0

        while True:
            # This is to handle rare situations where random sampling produces
            # a level that cannot be connected, producing in an infinite loop
            if num_itrs > max_itrs:
                raise RecursionError('connect_all failed')
            num_itrs += 1

            # If all rooms are reachable, stop
            reach = find_reach()
            if len(reach) == self.num_rows * self.num_cols:
                break

            # Pick a random room and door position
            i = self._rand_int(0, self.num_cols)
            j = self._rand_int(0, self.num_rows)
            k = self._rand_int(0, 4)
            room = self.get_room(i, j)

            # If there is already a door there, skip
            if not room.door_pos[k] or room.doors[k]:
                continue

            if room.locked or room.neighbors[k].locked:
                continue

            color = self._rand_elem(door_colors)
            door, _ = self.add_door(i, j, k, color, False)
            added_doors.append(door)

        return added_doors

    def add_distractors(self, i=None, j=None, num_distractors=10, all_unique=True):
        """
        Add random objects that can potentially distract/confuse the agent.
        """

        # Collect a list of existing objects
        objs = []
        for row in self.room_grid:
            for room in row:
                for obj in room.objs:
                    objs.append((obj.type, obj.color))

        # List of distractors added
        dists = []

        while len(dists) < num_distractors:
            color = self._rand_elem(COLOR_NAMES)
            type = self._rand_elem(['key', 'ball', 'box'])
            obj = (type, color)

            if all_unique and obj in objs:
                continue

            # Add the object to a random room if no room specified
            room_i = i
            room_j = j
            if room_i == None:
                room_i = self._rand_int(0, self.num_cols)
            if room_j == None:
                room_j = self._rand_int(0, self.num_rows)

            dist, pos = self.add_object(room_i, room_j, *obj)

            objs.append(obj)
            dists.append(dist)

        return dists
