var tardisWidth = 60;
var tardisWidth_min = 30;
var flightWay = 650;
var sizer = 0;
var speed_def = 2;
var speed = speed_def;



var move = null;
var posX = window.innerWidth/2-tardisWidth/2;
var posY = 0;
var backward = false;


function startTardis() {
    move = window.setInterval('moveTardis()', 30);    
}

function moveTardis() {
    
    if(posX >= window.innerWidth/2 + tardisWidth/2) sizer-=0.25;
    if(posX <= window.innerWidth/2 - tardisWidth/2) sizer+=0.25;
    
    document.getElementById("tardisImage").style.width = (tardisWidth+sizer)+"px";
    if(document.getElementById("tardisImage").style.width >= tardisWidth) {
        document.getElementById("tardisImage").style.width = tardisWidth+"px";
        sizer=0;   
    }
    if(document.getElementById("tardisImage").style.width <= tardisWidth_min) document.getElementById("tardisImage").style.width = tardisWidth_min+"px";
    
    
    if(posX >= window.innerWidth/2+flightWay/2-tardisWidth || posX <= window.innerWidth/2-flightWay/2+tardisWidth) {
        speed = speed_def/2;
    } else speed = speed_def;
        
    
    if(posX >= window.innerWidth/2+flightWay/2-tardisWidth/2) {
        backward = true;
        document.getElementById("tardis").style.zIndex = 99;
    }
    if(posX <= window.innerWidth/2-flightWay/2+tardisWidth/2) {
        backward = false;
        document.getElementById("tardis").style.zIndex = 101;
    }
    if(!backward) posX += speed;
    else posX -= speed;
    document.getElementById("tardis").style.left = posX+"px";
    
}

function tardisClick() {
    if(move==null) startTardis();
    else stopTardis();
}

function stopTardis() {
    window.clearInterval(move);
    move = null;
}