# -*- coding: utf-8 -*-
"""
Created on Mon Oct  1 23:57:09 2018

What to learn in this sample:

Encapsulation:
    Wrapping a piece of code up in a function is called encapsulation. One of the benefits of
    encapsulation is that it attaches a name to the code, which serves as a kind of documentation.

Generalization:
    make a attribute/behavior more general by adding parameters in a function

Refactoring:
    The process in which you rearrange a program in order to improve the following two things:
        * interfaces
        * code re-use

@author: sam
"""
import turtle
import math

# for both polygon and arc
# Refactoring: extract the common parts from polygon(..) and arc(..)
def polyline(t, len, sides, angle):
    # we have a number of sides, but it might not be complete to form a polygon
    # for each side, we know how long it should be by len
    # and we know after each side, how many angle we should turn by angle
    for side in range(sides):
        t.lt(angle) # improvement: to let the circle turn first
        t.fd(len)


# draw a polygon with flexible side and length
# generalization for sides_arc sides and length
def polygon(t, len, sides):
    angle_for_each_side = 360.0 / sides # to see how many angle is assigned to each side
    polyline(t, len, sides, angle_for_each_side)

# draw a square with a fixed length
def square(t):
    square(t, 50)

# draw a square with flexible length
# generalization for len
def square(t, len):
    polygon(t, len, 4)

# draw an arc
def arc(t, r, angle):
    circumference = 2*math.pi*r
    arc_length = circumference * (angle/360)
    sides = int(arc_length/3) + 3 # get an approximate sides according to the arc_length
    len = arc_length/sides
    angle_for_each_side = angle / sides
    polyline(t, len, sides, angle_for_each_side)

# draw an approximate circle
def circle(t, r):
    arc(t, r, 360)




"""
Use cases
"""

bob = turtle.Turtle()

# draw a square use a turtle
# square(bob)

# draw a square use a turtle with a specific length
#square(bob, 10)
#square(bob, 150)

# draw a n-sided polygon
# polygon(bob, 100, 6)

# draw an approximate circle
circle(bob, 100)

# draw an arc
# using keyword arguments
# arc(bob,r=25,angle=270)
# arc(bob,r=75,angle=270)

# wait for the user to close the window
turtle.mainloop()


# bob.pd() # ???