'''lecture_36_recursion_turtle_tree.py
Uses recursion and turtle to draw trees
Oliver W. Layton
CS 151: Computational Thinking: Visual Media
Fall 2020
'''

import turtle


class Tree:
    def __init__(self, start_x, start_y):
        '''
        Get turtle ready and in-position to draw an upright tree.
        Show animations (but fast ones) with speed of 7
        '''
        self.screen = turtle.Screen()
        self.turt = turtle.Turtle()
        self.turt.setheading(90)
        self.turt.speed(7)
        self.turt.color('purple')
        self.goto(start_x, start_y)

        # self.screen.tracer(False)

    def goto(self, x, y):
        self.turt.penup()
        self.turt.goto(x, y)
        self.turt.pendown()

    def hold(self):
        self.screen.exitonclick()

    def drawTree(self, distance):
        '''Draw a tree recursively with initial trunk/branch length `distance`.
        - Draw branches that look like "forks": straight part then left and right offshots
            +/-20 deg offset from straight.
        - Stop drawing branches when the branch distance is <= 5
        - After drawing left, right, and straight portions, always restore the turtle position
            to what it was before drawing the "fork".
        '''
        if distance <= 5:
            return

        # Draw "straight ahead" trunk
        self.turt.forward(distance)

        # Before drawing left branch, save position so we know where to go back to
        # when going to draw thr right branch
        x, y = self.turt.position()
        # head = self.turt.heading()

        # Draw left branch
        self.turt.left(20)
        self.drawTree(distance/2)  # took care of left branch
        
        # Get ready to draw right branch
        self.turt.setheading(head)
        # self.turt.right(20)
        self.turt.right(40)
        self.turt.setposition(x, y)
        
        # Draw right branch
        self.drawTree(distance/2)

        # Restore turtle to before drawing right branch
        self.turt.left(20) # Facing north again
        self.turt.setposition(x, y)


if __name__ == '__main__':
    tree = Tree(0, -400)
    tree.drawTree(250)
    tree.hold()