import math
import turtle
import random
import time

window = turtle.Screen()
window.setup(1200 + 3, 800 + 3)
window.bgpic("images/background.png")
window.screensize(1200, 800)
# window.tracer(n=2)

BASE_X, BASE_Y = 0, -300


def calc_heading(x1, y1, x2, y2):
    dx = (x2 - x1)
    dy = y2 - y1
    length = (dx ** 2 + dy ** 2) ** .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()
    # missile.forward(500)
    # missile.shape("circle")
    # missile.shapesize(2)
    # missile.shapesize(3)
    # missile.shapesize(4)
    # missile.shapesize(5)
    # missile.clear()
    # missile.hideturtle()

    info = {"missile": missile,
            "target": [x, y],
            "state": "launched",
            "radius": 0}
    our_missiles.append(info)


def enemy_missile():
    missile = turtle.Turtle(visible=False)
    missile.speed(0)
    missile.color('red')
    missile.penup()
    z, c = random.randint(-600, 600), random.randint(300, 400)
    missile.setpos(x=z, y=c)
    missile.pendown()
    heading = calc_heading(x2=BASE_X, y2=BASE_Y, x1=z, y1=c)
    missile.setheading(heading)
    missile.showturtle()
    info = {"missile": missile,
            "target": [BASE_X, BASE_Y],
            "state": "launched",
            "radius": 0}
    our_missiles.append(info)

window.onclick(fire_missile)


our_missiles = []

while True:
    window.update()
    delay_time = random.randrange(120)
    delay = delay_time
    if delay < 1:
        enemy_missile()

    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'])

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