dungeon.py 'function' object is not subscriptable

# make monster move
# leave breadcrumbs for rooms you've visited

import os
import random

size = 8 # test size

DUNGEON = []
for x in range(size):
  for y in range(size):
    DUNGEON.append((x,y))


def clear():
  os.system('cls' if os.name == 'nt' else 'clear')


def get_locations():

  monster = random.choice(DUNGEON)
  door = random.choice(DUNGEON)
  player = random.choice(DUNGEON)

  if monster == door or monster == player or door == player:
    return get_locations()
  else:
    return monster, door, player


def move_player(player, move):

  x, y = player

  if move == 'LEFT':
    y -= 1
  elif move == 'RIGHT':
    y += 1
  elif move == 'UP':
    x -= 1
  elif move == 'DOWN':
    x += 1
  return x, y


def avail_monster_moves(monster):

  monster_moves = ['LEFT', 'RIGHT', 'UP', 'DOWN']

  if monster == door:
    return avail_monster_moves(monster)
  if monster[1] == 0:
    monster_moves.remove('LEFT')
  if monster[0] == 0:
    monster_moves.remove('UP')
  if monster[1] == size - 1:
    monster_moves.remove('RIGHT')
  if monster[0] == size - 1:
    monster_moves.remove('DOWN')
  return monster_moves


def move_monster(monster, monster_moves):

  m_move = random.choice(monster_moves)
  x, y = monster

  if m_move == 'LEFT':
    y -= 1
  if m_move == 'RIGHT':
    y += 1
  if m_move == 'UP':
    x -= 1
  if m_move == 'DOWN':
    x += 1
  return x, y



  # monster = random.choice(DUNGEON)

  # if monster == door:
  #   return move_monster()
  # else:
  #   return monster


def get_moves(player):

  moves = ['LEFT', 'RIGHT', 'UP', 'DOWN', 'QUIT']

  if player[1] == 0:
    moves.remove('LEFT')
  if player[0] == 0:
    moves.remove('UP')
  if player[1] == size - 1:
    moves.remove('RIGHT')
  if player[0] == size - 1:
    moves.remove('DOWN')
  return moves


def draw_map(player):

  dungeon_lid = ' _' * size
  print(dungeon_lid)
  tile = '|{}'
  dungeon_array = []

  for i in range(len(DUNGEON)):
    if (i + 1) % (size) == 0:
      dungeon_array.append(i)

  for idx, cell in enumerate(DUNGEON):
    if idx not in dungeon_array:
      if cell == player:
        print(tile.format('X'), end='')
      elif cell == monster:
        print(tile.format('O'), end='')
      elif cell == door:
        print(tile.format('!'), end='')
      else:
        print(tile.format('_'), end='')

    else:
      if cell == player:
        print(tile.format('X|'))
      elif cell == monster:
        print(tile.format('O|'))
      elif cell == door:
        print(tile.format('!|'))
      else:
        print(tile.format('_|'))




monster, door, player = get_locations()
print('Welcome to the dungeon!')


while True:

  moves = get_moves(player)
  print('You are currently in room {}'.format(player))
  draw_map(player)
  print('You can move {}'.format(moves))
#  print('Enter QUIT to quit')

  move = input('> ')
  clear()
  move = move.upper()

  if move not in moves:
    print('Please enter a valid direction')

  else:
    if move == 'QUIT':
      break

    if move in moves:
      player = move_player(player, move)
      monster = avail_monster_moves(move_monster)
    else:
      print('** walls are hard...stop walking into them **')
      continue

    if player == door:
      print("Congratulations, adventuror! You've escaped the dungeon!")
      break
    elif player == monster:
      print("You've been ripped limb from limb by the monster.  Sorry about your life.")
      break