snake.py

from turtle import Turtle

STARTING_POSITIONS = [(0, 0), (-20, 0), (-40, 0)]
MOVEDISTANCE = 20

class Snake():
    
    def __init__(self) -> None:
        self.segments = []
        self.current_dir = 'right'
        self.createSegments()


    def  createSegments(self):

        for position in STARTING_POSITIONS:
            self.add_segment(position)
        self.head = self.segments[0]

    def add_segment(self, position):
        """
        this method is to add new segment"""
        new_segment = Turtle("square")
        new_segment.color("green")
        new_segment.penup()
        new_segment.goto(position)
        self.segments.append(new_segment)

    def moveSnake(self):
        for i in range(len(self.segments) - 1, 0, -1):
            x_new = self.segments[i - 1].xcor()
            y_new = self.segments[i - 1].ycor()
            self.segments[i].goto(x_new, y_new)
        self.head.forward(MOVEDISTANCE)

    def turn_up(self):
        if self.current_dir == 'right' or self.current_dir == 'left':
            self.head.setheading(90)
            self.current_dir = 'up'

    def turn_right(self):
        if self.current_dir == 'up' or self.current_dir == 'down':
            self.head.setheading(0)
            self.current_dir = 'right'

    def turn_down(self):
        if self.current_dir == 'left' or self.current_dir == 'right':
            self.head.setheading(270)
            self.current_dir = 'down'

    def turn_left(self):
        if self.current_dir == 'up' or self.current_dir == 'down':
            self.head.setheading(180)
            self.current_dir = 'left'

    def extend(self):
        """"
        This method is to extend the body of the snake when it get food"""
        self.add_segment(self.segments[-1].position())