from turtle import Turtle
from point import Point


class Shape:
    """
    A Shape shape that can draw itself, move, and
    report area and perimeter.

    === Attributes ===
    @type corners: list[Point]
       corners of this Shape
    """
    def __init__(self, corners):
        """
        Create a new Shape self with corners.

        @type self: Shape
        @type corners: list[Point]
        @rtype: None
        """
        # shallow copy of corners
        self.corners = corners[:]
        self._turtle = Turtle()
        self._set_perimeter()
        self._set_area()

    def _set_perimeter(self):
        """
        Set Shape self's perimeter to the sum of the distances
        between corners.

        @type self: Shape
        @rtype: None
        """
        distance_list = []
        for i in range(len(self.corners)):
            distance_list.append(self.corners[i].distance(
                    self.corners[i - 1]))
        self._perimeter = sum(distance_list)

    def _get_perimeter(self):
        """
        Return the perimeter of this Shape

        @type self: Shape
        @rtype: float
        """
        return self._perimeter

    # perimeter is immutable --- no setter method in property
    perimeter = property(_get_perimeter, None, None,
                         """
                         @type perimeter: float
                             The perimeter of Shape self
                         """)

    def _set_area(self):
        """
        Set the area of Shape self to the Shape of
        its sides.

        @type self: Shape
        @rtype: None
        """
        # impossible area to satisfy PyCharm...
        self._area = -1.0
        raise NotImplementedError

    def _get_area(self):
        """
        Return the area of Shape self.

        @type self: Shape
        @rtype: float

        >>> Shape([Point(1, 1), Point(2, 1), Point(2, 2), Point(1, 2)]).area
        1.0
        """
        return self._area

    # area is immutable --- no setter method in property
    area = property(_get_area, None, None,
                    """
                    @type area: float
                        The area of Shape self.
                    """)

    def move_by(self, offset_point):
        """
        Move Shape self to a new position by adding
        Point offset_point to each corner.

        @type self: Shape
        @type offset_point: Point
        @rtype: None
        """
        # list comprehension
        # see course web page, week 2
        self.corners = [c.add(offset_point) for c in self.corners]
        # equivalent to...
        # new_corners = []
        #  for c in self.corners:
        #     new_corners.append(c.add(offset_point))

    def draw(self):
        """
        Draw Shape self.

        @type self: Shape
        @rtype: None
        """
        self._turtle.penup()
        self._turtle.goto(self.corners[-1].x, self.corners[-1].y)
        self._turtle.pendown()
        for i in range(len(self.corners)):
            self._turtle.goto(self.corners[i].x, self.corners[i].y)
        self._turtle.penup()
        self._turtle.goto(0, 0)


if __name__ == "__main__":
    import doctest
    doctest.testmod()