class Screen:
  def _check(self, x, o, name):
    if not isinstance(x, int):
      raise TypeError("{} is not an int object".format(name))
    elif x < 1:
      raise ValueError("{} is lower than 1".format(name))
    if o is None:
      o = 0
    elif x > o and o:
      raise ValueError("{} is greater than the height of this object: {} > {}".
        format(name, x, o))

  def __init__(self, width=21, height=6, patern=" ", copy=None):
    if isinstance(copy, Screen):
      self._width = copy._width
      self._height = copy._height
      self._mat = copy._mat
    else:
      self._check(width, None, "width")
      self._check(height, None, "height")
      if not isinstance(patern, str):
        raise TypeError("patern is not a string")
      elif len(patern) > 1:
        raise ValueError("patern is too long (length = {})".format(len(patern)))
      self._width = width
      self._height = height
      self.fill(patern)

  def locate(self, x, y, string):
    self._check(x, self._width, "x")
    self._check(y, self._height, "y")
    string = str(string)
    i = -1
    for char in string:
      if i + x < self._width:
        self._mat[y - 1][x + i] = char
      i += 1

  def locate_v(self, x, y, string):
    self._check(x, self._width, "x")
    self._check(y, self._height, "y")
    string = str(string)
    i = -1
    for char in string:
      if i + y < self._height:
        self._mat[y + i][x - 1] = char
      i += 1

  def fill(self, patern=" "):
    self._mat = [[patern[0] for i in range(self._width)] for i in range(self._height)]

  def refresh(self, ask_for_input=True, endl="\n"):
    to_print = str()
    for line in self._mat:
      for cell in line:
        to_print += cell
      to_print += "\n"
    to_print = to_print[:-1]
    print(to_print)
    if ask_for_input:
      return input("> ")
    else:
      print("", end=endl)
      return None

  def get_cell(self, x, y):
    self._check(x, self._width, "x")
    self._check(y, self._width, "y")
    return self._mat[y - 1][x - 1]

  def get_dim(self):
    return self._width, self._height

  def export(self):
    result = str()
    for line in self._mat:
      for cell in line:
        result += cell
    return result

  def load(self, string):
    if type(string) is not str:
      raise TypeError("string is not a string type")
    if len(string) != self._width * self._height:
      raise ValueError("string lenght isn't equal to {}".format(self._width * self._height))
    i = 0
    s = 0
    while i != self._height:
      self._mat[i] = list(string[s:s + self._width])
      i += 1
      s += self._width
  
  get_cell_content = get_cell # For retro-compability

class Pad(Screen):
  def refresh(self, x=1, y=1, width=21, height=6, ask_for_input=True, endl="\n"):
    if width > self._width:
      width = self._width
    if height > self._height:
      height = self._height
    if x < 1:
      x = 1
    if y < 1:
      y = 1
    x -= 1
    y -= 1
    if x + width > self._width:
      x = self._width - width
    if y + height > self._height:
      y = self._height - height
    to_print = str()
    for dy in range(y, height+y):
      dy = dy
      for dx in range(x, width+x):
        print(dx, dy)
        to_print += self._mat[dy][dx]
      to_print += "\n"
    to_print = to_print[:-1]
    print(to_print)
    if ask_for_input:
      return input("> ")
    else:
      print("", end=endl)
      return None