Lesson 1

import math
import turtle
import random

WINDOW_WIDTH, WINDOW_HEIGHT = 1200, 800
BASE_X, BASE_Y = 0, -300

window = turtle.Screen()
window.setup(WINDOW_WIDTH + 3, WINDOW_HEIGHT + 3)
window.bgpic("images/background.png")
window.screensize(WINDOW_WIDTH, WINDOW_HEIGHT)
# window.tracer(n=2)


def calc_heading(x1, y1, x2, y2):
    dx = x2 - x1
    dy = y2 - y1
    length = (dx ** 2 + dy ** 2) ** 0.5
    cos_alpha = dx / length
    alpha = math.acos(cos_alpha)
    alpha = math.degrees(alpha)
    if dy < 0:
        alpha = -alpha
    return alpha


def fire_missile(x, y):
    missile = turtle.Turtle(visible=False)
    missile.speed(0)
    missile.color('white')
    missile.penup()
    missile.setpos(x=BASE_X, y=BASE_Y)
    missile.pendown()
    heading = calc_heading(x1=BASE_X, y1=BASE_Y, x2=x, y2=y)
    missile.setheading(heading)
    missile.showturtle()
    info = {'missile': missile, 'target': [x, y],
            'state': 'launched', 'radius': 0}
    our_missiles.append(info)


def fire_enemy_missile(x, y):
    missile = turtle.Turtle(visible=False)
    missile.speed(0)
    missile.color('red')
    missile.penup()
    missile.setpos(x=x, y=y)
    missile.pendown()
    heading = calc_heading(x1=x, y1=y, x2=BASE_X, y2=BASE_Y)
    missile.setheading(heading)
    missile.showturtle()
    enemy_missile_info = {'missile': missile, 'target': [BASE_X, BASE_Y], 'state': 'launched', 'radius': 0}
    enemy_missiles.append(enemy_missile_info)


window.onclick(fire_missile)

our_missiles = []
enemy_missiles = []

for num in range(5):
    enemy_x = random.randint(0, WINDOW_WIDTH)
    fire_enemy_missile(enemy_x - WINDOW_WIDTH/2, WINDOW_HEIGHT/2)

while True:
    window.update()

    for info in our_missiles:
        state = info['state']
        missile = info['missile']
        if state == 'launched':
            missile.forward(4)
            target = info['target']
            if missile.distance(x=target[0], y=target[1]) < 20:
                info['state'] = 'explode'
                missile.shape('circle')
        elif state == 'explode':
            info['radius'] += 1
            if info['radius'] > 5:
                missile.clear()
                missile.hideturtle()
                info['state'] = 'dead'
            else:
                missile.shapesize(info['radius'])

    for enemy_missiles_info in enemy_missiles:
        state = enemy_missiles_info['state']
        missile = enemy_missiles_info['missile']
        if state == 'launched':
            missile.forward(4)
            target = enemy_missiles_info['target']
            if missile.distance(x=target[0], y=target[1]) < 20:
                enemy_missiles_info['state'] = 'explode'
                missile.shape('circle')
        elif state == 'explode':
            enemy_missiles_info['radius'] += 1
            if enemy_missiles_info['radius'] > 5:
                missile.clear()
                missile.hideturtle()
                enemy_missiles_info['state'] = 'dead'
            else:
                missile.shapesize(enemy_missiles_info['radius'])

    dead_missiles = [info for info in our_missiles if info['state'] == 'dead']
    for dead in dead_missiles:
        our_missiles.remove(dead)

    dead_enemy_missiles = [enemy_missiles_info for enemy_missiles_info in enemy_missiles if enemy_missiles_info['state'] == 'dead']
    for dead_enemy in dead_enemy_missiles:
        enemy_missiles.remove(dead_enemy)