import turtle

print('Program Dragon Curve')

laki = turtle.Turtle()

# Setting
iteration = 10
length = 8
pencolor = 'red'
pensize = 4
speed = 20

# prepare to display the graphics
laki.color(pencolor)
laki.hideturtle()
laki.pensize(pensize)
laki.speed(speed)
laki.penup()
laki.goto(0,100)
laki.pendown()

# make variables for the right and left containg 'r' and 'l'
# not really necesessary, but may held understanding
r = 'r'
l = 'l'

# assign our first iteration a right so we can build off of it
old = r
new = old

# set the number of times we have been creating the next iteration as the first
cycle=1

# keep on generating the next iteration until desired iteration is reached
while cycle < iteration:

# add a right to the end of the old iteration and save it to the new
    new = (old) + (r)

# flip the old iteration around(as in the the first charicter becomes last)
    old = old[::-1]

# cycling through each character in the flipped old iteration:        
    for char in range(0,len(old)):
        # if the character is a right:
        if old[char] == r:
            # change it to a left
            old = (old[:char])+ (l) + (old[char+1:])
        # otherwise, if it's a left:
        elif old[char] == l:
            # change it to a right
            old = (old[:char]) + (r) + (old[char+1:])

# add the modified old to the new iteration
    new = (new) + (old)
    # save the new iteration to old as well for use next cycle
    old = new

# advance cycle variable to keep track of the number of times it's been done
    cycle=cycle+1

# input, whether or not to display the r and l form of the iteration
printans='n'
# if yes, print the iteration
if printans=='y':
    print(new)

# display segment of desired length to build off of
laki.forward(length)

# cycling through all the characters in the iteration
for char in range(0,len(new)):
    # if the character is a right:
    if new[char] == (r):
        # turn right at a right angle 
        laki.right(90)
        # go forward desired length
        laki.forward(length)
    # otherwise, if the character is a left:
    elif new[char] == (l):
        # turn left at a right angle
        laki.left(90)
        # go forward desired length
        laki.forward(length)

print('End')

# Code credits: http://www.instructables.com/id/Dragon-Curve-Using-Python/