from tkinter import *
from random import randint

root = Tk()

field = [[None] * 4 for i in range(4)]

for i in range(4):
    Label(root, text = "        ", font = "Arial 48").grid(row = 4, column = i)
    Label(root, text = " ", font = "Arial 48").grid(row = i, column = 4)


def add_tile(event):
    i = randint(0,3)
    j = randint(0,3)
    if not field[i][j]:
        field[i][j] = Label(root, text = "2", font = "Arial 48", bg="lightblue")
        field[i][j].grid(row = i, column = j)
    else:
        add_tile(event)

def left(event):
    for i in range(4):
        for j in range(1,4):
            if field[i][j]:
                k = j - 1
                while k >= 0 and field[i][k] == None:
                    k -= 1
                if k == -1:
                    field[i][j], field[i][0] = field[i][0], field[i][j]
                    field[i][0].grid(row = i, column = 0)
                elif field[i][j]["text"] == field[i][k]["text"]:
                    field[i][k]["text"] = str(int(field[i][k]["text"]) * 2)
                    field[i][j].destroy()
                    field[i][j] = None
                else:
                    field[i][j], field[i][k + 1] = field[i][k + 1], field[i][j]
                    field[i][k + 1].grid(row = i, column = k + 1)

    add_tile(event)


def top(event):
    for j in range(4):
        for i in range(1,4):
            if field[i][j]:
                k = i - 1
                while k >= 0 and field[k][j] == None:
                    k -= 1
                if k == -1:
                    field[i][j], field[0][j] = field[0][j], field[i][j]
                    field[0][j].grid(row = 0, column = j)
                elif field[i][j]["text"] == field[k][j]["text"]:
                    field[k][j]["text"] = str(int(field[k][j]["text"]) * 2)
                    field[i][j].destroy()
                    field[i][j] = None
                else:
                    field[i][j], field[k + 1][j] = field[k + 1][j], field[i][j]
                    field[k + 1][j].grid(row = k + 1, column = j)

    add_tile(event)


def right(enent):
    pass


root.bind("<Left>", left)
root.bind("<Up>", top)
root.bind("<Right>", right)
root.bind("<Down>", down)
root.mainloop()