import turtle
import os
import math
#screensetup
wn = turtle.Screen()
wn.bgcolor("black")
wn.title("space invaders")

#drawborder
border_pen = turtle.Turtle()
border_pen.speed(0)
border_pen.color("white")
border_pen.penup()
border_pen.setposition(-300,-300)
border_pen.pensize(3)
for side in range(4):
        border_pen.fd(600)
        border_pen.lt(90)
border_pen.hideturtle()

#create the player
player = turtle.Turtle()
player.color("blue")
player.shape("triangle")
player.penup()
player.speed(0)
player.setposition(0, -250)
player.setheading(90)

playerspeed = 15

#create the enemy
enemy = turtle.Turtle()
enemy.color("pink")
enemy.shape("circle")
enemy.penup()
enemy.speed(0)
enemy.setposition(-250, 200)

enemyspeed = 2

#create the bullet
bullet = turtle.Turtle()
bullet.color("yellow")
bullet.shape("triangle")
bullet.penup()
bullet.speed(0)
bullet.setheading(90)
bullet.shapesize(0.5, 0.5)
bullet.hideturtle()

bulletspeed = 20

#define bullet state
#ready - ready to fire
#fire - bullet is firing
bulletstate = "ready"
#move the player left and right
def move_left():
        x = player.xcor()
        x -= playerspeed
        if x < -280:
                x = - 280
        player.setx(x

def move_right():
        x = player.xcor()
        x += playerspeed
        if x > 280:
               x = 280
     player.setx(x)

#bulletstuff
def fire_bullet():
    #declare bulletstate as a global variable
        global bulletstate
        if bulletstate == "ready":
                bulletstate = "fire"
#move the bullet above player
                x = player.xcor()
                y = player.ycor() + 10
                bullet.setposition(x,y)
                bullet.showturtle()

def isCollision(t1, t2):
        distance = math.sqrt(math.pow(t1.xcor()-t2.xcor(),2)+math.pow(t1.ycor()-t2.ycor(),2))
        if distance < 15:
                return True
    else:
        return False
#keyboard bindings
turtle.listen()
turtle.onkey(move_left, "Left")
turtle.onkey(move_right, "Right")
turtle.onkey(fire_bullet, "space")




#main game loop
while True:
#move the enemy
        x = enemy.xcor()
        x += enemyspeed
        enemy.setx(x)

#move the enemy back and down
        if enemy.xcor() > 280:
                y = enemy.ycor()
                y -= 40
                enemyspeed *= -1
                enemy.sety(y)

        if enemy.xcor() < -280:
                y = enemy.ycor()
                y -= 40
                enemyspeed *= -1
                enemy.sety(y)

                #move the bullet
        if bulletstate == "fire":
            y = bullet.ycor()
            y += bulletspeed
            bullet.sety(y)
                #check to see if the bullet has gone to the top
        if bullet.ycor() > 275:
                bullet.hideturtle()
                bulletstate = "ready"

    #collision checker
        if isCollision(bullet, enemy):
        #reset the bullet
                bullet.hideturtle()
                bulletstate = "ready"
                bullet.setposition(0,-400)
    #enemy reset
                enemy.setposition(-200, 250)

        if isCollision(player, enemy):
                player.hideturtle()
                enemy.hideturtle()
                print ("Game Over")
                break


delay = raw_input("press enter to finish")