// - Noel Delgado | @pixelia_me


var nodes  = document.querySelectorAll('li'),
    _nodes = [].slice.call(nodes, 0);

var getDirection = function (ev, obj) {
    var w = obj.offsetWidth,
        h = obj.offsetHeight,
        x = (ev.pageX - obj.offsetLeft - (w / 2) * (w > h ? (h / w) : 1)),
        y = (ev.pageY - obj.offsetTop - (h / 2) * (h > w ? (w / h) : 1)),
        d = Math.round( Math.atan2(y, x) / 1.57079633 + 5 ) % 4;
  
    return d;
};

var addClass = function ( ev, obj, state ) {
    var direction = getDirection( ev, obj ),
        class_suffix = "";
    
    obj.className = "";
    
    switch ( direction ) {
        case 0 : class_suffix = '-top';    break;
        case 1 : class_suffix = '-right';  break;
        case 2 : class_suffix = '-bottom'; break;
        case 3 : class_suffix = '-left';   break;
    }
    
    obj.classList.add( state + class_suffix );
};

// bind events
_nodes.forEach(function (el) {
    el.addEventListener('mouseover', function (ev) {
        addClass( ev, this, 'in' );
    }, false);

    el.addEventListener('mouseout', function (ev) {
        addClass( ev, this, 'out' );
    }, false);
});