import numpy
import pprint


class ImageLayer(object):
  """
  Represents a layer of an image
  """
  def __init__(self, x_shape, y_shape, fill_character, left_x, top_y, right_x, bottom_y):
    self.x_shape = x_shape
    self.y_shape = y_shape
    self.fill_character = fill_character
    self.canvas = self._build_canvas(left_x, top_y, right_x, bottom_y)

  def _verify_coords(self, x, y):
    # Check that the co-ordinates are valid
    if x<0 or x>=self.x_shape or y<0 or y>=self.y_shape:
      raise ValueError(f'[{x}, {y}] is outside the bounds')

  def _build_canvas(self, left_x, top_y, right_x, bottom_y):
    self._verify_coords(left_x, top_y)
    self._verify_coords(right_x, bottom_y)
    # Create the initial canvas for the layer
    canvas = numpy.zeros(shape=(self.x_shape, self.y_shape))
    canvas[left_x:right_x+1, top_y:bottom_y+1] = numpy.ones(shape=(right_x-left_x+1, bottom_y-top_y+1))
    return canvas

  def erase_area(self, left_x, top_y, right_x, bottom_y):
    """
    Erase a section of the layer
    """
    self._verify_coords(left_x, top_y)
    self._verify_coords(right_x, bottom_y)
    self.canvas[left_x:right_x+1, top_y:bottom_y+1] = numpy.zeros(shape=(right_x-left_x+1, bottom_y-top_y+1))

  def hit(self, select_x, select_y):
    """
    Check if the layer has any content at these co-ordinates
    """
    self._verify_coords(select_x, select_y)
    return self.canvas[select_x, select_y] == 1

  def drag_and_drop(self, move_x, move_y):
    """
    Roll the canvas to move the position of the rectangle
    """
    # This will wrap rectanges around the maximums
    self.canvas = numpy.roll(self.canvas, move_x, axis=0)
    self.canvas = numpy.roll(self.canvas, move_y, axis=1)


class Image(object):
  """
  Represents an image with multiple layers
  """
  def __init__(self, x_shape=10, y_shape=6):
    self.x_shape = x_shape
    self.y_shape = y_shape
    self.layers = []

  def draw_rectangle(self, fill_character, left_x, top_y, right_x, bottom_y):
    """
    Creates a new layer on top with the specified rectangle on it
    """
    new_layer = ImageLayer(
      self.x_shape,
      self.y_shape,
      fill_character,
      left_x,
      top_y,
      right_x,
      bottom_y
    )
    self.layers = [new_layer] + self.layers

  def erase_area(self, left_x, top_y, right_x, bottom_y):
    """
    Erase the area on all layers
    """
    for layer in self.layers:
      layer.erase_area(left_x, top_y, right_x, bottom_y)

  def drag_and_drop(self, select_x, select_y, release_x, release_y):
    """
    Move the top layer
    """
    for layer in self.layers:
      if layer.hit(select_x, select_y):
        layer.drag_and_drop(release_x-select_x, release_y-select_y)
        return

  def bring_to_front(self, select_x, select_y):
    """
    Move the selected layer to the top of the stack
    """
    for i, layer in enumerate(self.layers):
      if layer.hit(select_x, select_y):
        self.layers.pop(i)
        self.layers = [layer] + self.layers
        return

  def print_canvas(self):
    """
    Return an array of arrays with the rendered content
    """
    canvas = numpy.zeros(shape=(self.x_shape, self.y_shape)).tolist()
    for layer in reversed(self.layers):
      for i in range(self.x_shape):
        for j in range(self.y_shape):
          if layer.canvas[i, j] == 1:
            canvas[i][j] = layer.fill_character

    # This can probably done when initializing the canvas.
    # The solution is somewhere in the numpy docs.
    for i in range(self.x_shape):
      for j in range(self.y_shape):
        if canvas[i][j] == 0:
          canvas[i][j] = ' '
    return canvas


def command_parser():
  # Parses the file in to the format:
  # ["COMMAND", [*command_args]]
  # BELOW IS HARDCODED EXAMPLE I USED FOR DEBUGGING:
  return [
    ['DRAW_RECTANGLE',['L',1,1,4,4]],
    ['DRAW_RECTANGLE',['R',2,1,4,4]],
    ['PRINT_CANVAS',[]],
    ['ERASE_AREA',[3,2,3,3]],
    ['PRINT_CANVAS',[]],
    ['DRAW_RECTANGLE',['#',1,3,8,4]],
    ['DRAG_AND_DROP',[2,2,6,2]],
    ['PRINT_CANVAS',[]],
    ['BRING_TO_FRONT',[1,2]],
    ['BRING_TO_FRONT',[6,2]],
    ['PRINT_CANVAS',[]],
    ['DRAG_AND_DROP',[3,3,3,2]],
    ['PRINT_CANVAS',[]],
  ]


def main():
  # Parse the command list
  command_list = command_parser()
  # create an empty image
  image = Image(10, 6)

  # For each command apply it to the command list
  for command, command_args in command_list:
    if command == 'DRAW_RECTANGLE':
      image.draw_rectangle(*command_args)
    elif command == 'ERASE_AREA':
      image.erase_area(*command_args)
    elif command == 'DRAG_AND_DROP':
      image.drag_and_drop(*command_args)
    elif command == 'BRING_TO_FRONT':
      image.bring_to_front(*command_args)
    elif command == 'PRINT_CANVAS':
      pprint.pprint(image.print_canvas())


if __name__ == '__main__':
  main()