2048

import curses
from random import randrange,choice
from collections import defaultdict

letter_codes =['W','A','S','D','R','Q','w','a','s','d','r','q']
actions = ['Up','Left','Down','Right',
          'Restart','Exit']

actions_dict = dict(zip(letter_codes, actions * 2))



def transpose(field):
    return [list(row) for row in zip(*field)]

def invert(field):
    return [row[::-1] for row in field]

class GameField(object):
    def __init__(self,height=4,width=4,win=2048):
        self.height = height
        self.width = width
        self.win_value = win
        self.score = 0
        self.highscore = 0
        self.reset()

    def get_user_action(self,keyboard):
        char = 'N'
        while char not in actions_dict:
            char = keyboard.getkey()
        return actions_dict[char]

    def draw(self, screen):
        help_string1 = '(W)Up (S)Down (A)Left (D)Right'
        help_string2 = '     (R)Restart (Q)Exit'
        gameover_string = '           GAME OVER'
        win_string = '          YOU WIN!'

        def cast(string):
            screen.addstr(string+'\n')

        def draw_hor_separator():
            line = '+' + ('+------' * self.width + '+')[1:]
            cast(line)

        def draw_row(row):
            cast(''.join('|{: ^5} '.format(num) if num > 0 else '|      ' for num in row) + '|')

        screen.clear()
        cast('SCORE:'+str(self.score))
        if 0!=self.highscore:
            cast('HIGHSCORE:'+str(self.highscore))

        for row in self.field:
            draw_hor_separator()
            draw_row(row)
        draw_hor_separator()

        if self.is_win():
            cast(win_string)

        else:
            if self.is_gameover():
                cast(gameover_string)
            else:
                cast(help_string1)
        cast(help_string2)



    def spawn(self):
        new_element = 4 if randrange(100) > 60 else 2
        (i,j) = (i,j) = choice([(i,j) for i in range(self.width) for j in range(self.height) if self.field[i][j] == 0])
        self.field[i][j]=new_element

    def is_win(self):
        return any(any(i>=self.win_value for i in row) for row in self.field)

    def is_gameover(self):

        return not any(self.move_is_possible(move) for move in actions)


    def move(self,direction):

        def move_row_left(row):
            def tighten(row):
                new_row = [ i for i in row if i!=0]
                new_row += [0 for i in range(len(row)-len(new_row))]
                return new_row

            def merge(row):
                pair = False
                new_row=[]
                for i in range(len(row)):
                    if pair:
                        new_row.append(2*row[i])
                        self.score += 2 *row[i]
                        pair=False


                    else:
                        if i+1< len(row) and row[i]==row[i+1]:
                            pair= True
                            new_row.append(0)
                        else:
                            new_row.append(row[i])
                assert len(new_row) == len(row)
                return new_row
            return tighten(merge(tighten(row)))

        moves={}
        moves['Left']= lambda field:[move_row_left(row) for row in field]
        moves['Right'] = lambda field: invert(moves['Left'](invert(field)))
        moves['Up'] = lambda field: transpose(moves['Left'](transpose(field)))
        moves['Down'] = lambda field: transpose(moves['Right'](transpose(field)))

        if direction in moves:
            if self.move_is_possible(direction):
                self.field = moves[direction](self.field)
                self.spawn()
                return True
            else:
                return False

    def move_is_possible(self,direction):
        def row_is_left_movable(row):
            def change(i):
                if row[i]==0 and row[i+1]!=0:
                    return True
                if row[i]!=0 and row[i+1] == row[i]:
                    return True
                return False
            return any(change(i) for i in range(len(row)-1))

        check = {}

        check['Left'] = lambda field: any(row_is_left_movable(row) for row in field)

        check['Right'] = lambda field: check['Left'](invert(field))

        check['Up'] = lambda field: check['Left'](transpose(field))

        check['Down'] = lambda field: check['Right'](transpose(field))

        if direction in check:
            return check[direction](self.field)
        else:
            return False


    def reset(self):
        if self.score > self.highscore:
            self.highscore = self.score
        self.score = 0
        self.field = [[0 for i in range(self.width) ] for j in range(self.height)]
        self.spawn()
        self.spawn()


def main(stdscr):
    game_field = GameField(win=68)

    def init():
        game_field.reset()
        return 'Game'



    def game():
      game_field.draw(stdscr)
      action = game_field.get_user_action(stdscr)

      if action == 'Restart':
          return 'Init'
      if action == 'Exit':
          return 'Exit'
      if game_field.move(action):
          if game_field.is_win():
              return 'Win'
          if game_field.is_gameover():
              return 'Gameover'
      return 'Game'

    def not_game(state):
        game_field.draw(stdscr)
        action = game_field.get_user_action(stdscr)
        responses = defaultdict(lambda:state)
        responses['Restart'], responses['Exit'] = 'Init','Exit'
        return responses[action]

    state_action ={
        'Init': init,
        'Win': lambda: not_game('Win'),
        'Gameover': lambda: not_game('Gameover'),
        'Game': game

    }

    curses.use_default_colors()

    state = 'Init'
    while state !='Exit':
        state=state_action[state]()


curses.wrapper(main)