import easygui, random
yhp = 1000
ehp = 1000
easygui.msgbox("Welcome to the battle field!\nGet ready!!")
while True:
    if yhp <= 0:
        easygui.msgbox("You lost the battle!!")
        break

    weapon = easygui.buttonbox("Your turn to attack, please choose your weapon",
                               choices = ['gun', 'missile'])

    if weapon == 'gun':
        damage = random.randint(1, 100)
        easygui.msgbox("You chose " + weapon + ", deal " + str(damage) + " damage",
                       image = 'gun.gif')
        ehp -= damage
        
    elif weapon == 'missile':
        # homework
        pass

    if ehp <= 0:
        easygui.msgbox("You Won the battle!!")
        break

    damage = random.randint(20, 150)
    easygui.msgbox("Enemy's turn to attack, you got " + str(damage) +
                   " damage and have " + str(yhp) + " HP left")