import fcntl
import os
import random
import select
import struct
import sys
import termios
import tty

DIRS = {
  '\x1b[A': (0, -1, [(j, i) for i in range(4) for j in range(4)]),
  '\x1b[B': (0, 1, [(j, i) for i in reversed(range(4)) for j in range(4)]),
  '\x1b[C': (1, 0, [(i, j) for i in reversed(range(4)) for j in range(4)]),
  '\x1b[D': (-1, 0, [(i, j) for i in range(4) for j in range(4)]),
}
CELL = 6
SIZE = 4
BOARD = {}

class Number:
  def __init__(self, i=None, new=1):
    if i is None:
      i = 4 if random.random() > 0.9 else 2
    self.i = i
    self.new = new

  def __unicode__(self):
    attrs = []
    if self.new:
      attrs.append(self.new)
    if self.i > 2000:
      attrs.append(5)
    if self.i > 1000:
      attrs.append(31)
    elif self.i > 100:
      attrs.append(35)
    elif self.i > 10:
      attrs.append(33)
    text = '\033[%sm%d\033[m' % (';'.join(map(str, attrs)), self.i)
    pad = CELL - len(str(self.i))
    return u'%s%s%s' % (' ' * (pad - pad / 2), text, ' ' * (pad / 2))

def reset():
  BOARD.clear()
  add()
  add()

def add():
  free = set([(i, j) for i in range(4) for j in range(4)]) - set(BOARD)
  BOARD[random.choice(list(free))] = Number(new=4)

def move(key):
  dx, dy, order = DIRS[key]
  dirty = False
  for num in BOARD.values():
    num.new = 0
  for cell in order:
    if cell not in BOARD:
      continue
    next = cell
    while True:
      x, y = next
      x += dx
      y += dy
      if x not in range(4) or y not in range(4):
        break
      if (x, y) in BOARD:
        if BOARD[x,y].i == BOARD[cell].i and not BOARD[x,y].new:
          next = (x, y)
          BOARD[cell] = Number(BOARD[cell].i * 2)
        break
      next = (x, y)
    if next != cell:
      BOARD[next] = BOARD.pop(cell)
      dirty = True
  if dirty:
    add()

def show(f):
  winsize = fcntl.ioctl(fd, termios.TIOCGWINSZ, '\0\0\0\0')
  height, width = struct.unpack('HH', winsize[:4])
  total = (CELL + 1) * SIZE + 1
  template = '\033[1;36m\033[%%d;%dH%%s\033[m' % (width - total + 1)
  lines = SIZE * 4 + 1
  f.write('\033[s')
  for i in range(lines):
    if i % 4 == 0:
      part = [u'\u2501' * CELL] * SIZE
      if i / 4 == 0:
        line = u'\u250f%s\u2513' % u'\u2533'.join(part)
      elif i / 4 == SIZE:
        line = u'\u2517%s\u251b' % u'\u253b'.join(part)
      else:
        line = u'\u2523%s\u252b' % u'\u254b'.join(part)
    else:
      part = map(unicode, ((None if i % 2 else BOARD.get((j, i / 4)))
                           or u' ' * CELL for j in range(-1, SIZE + 1)))
      line = u'\033[1;36m\u2503\033[m'.join(part).strip()
    f.write(template % (i + 1, line))
  line = (' \033[1;36mR\033[m \033[1mto reset' +
          (' ' * (total - 21)) +
          '\033[1;36mQ\033[m \033[1mto quit ')
  f.write(template % (lines + 1, line))
  f.write('\033[u')
  f.flush()

fd = sys.stdin.fileno()
attr = termios.tcgetattr(fd)
tty.setcbreak(fd)
fcntl.fcntl(fd, fcntl.F_SETFL, fcntl.fcntl(fd, fcntl.F_GETFL) | os.O_NONBLOCK)
reset()
try:
  while True:
    show(sys.stdout)
    select.select([sys.stdin], [], [])
    key = sys.stdin.read()
    if key in 'qQ\x1b':
      break
    if key in 'rR':
      reset()
    if key in DIRS:
      move(key)
finally:
  termios.tcsetattr(fd, termios.TCSAFLUSH, attr)