var tap = {
	wrapDom: $('#tab_wrap'),
	getPos() {
		var wrapDom = tap.wrapDom;
		var wrap_ntv_dom = document.getElementById('wrap');
		var children = wrapDom.children();
		var index = 0;
		var canSwipe = true;
		var animTime = 500;
		var oldLeft = parseInt(wrapDom.css('left'));
		
		wrap_ntv_dom.addEventListener(
			'touchstart',
			function(ev) {
				tap.startPos = ev.touches[0].pageX;
			},
			{ passive: true }
		);
		wrap_ntv_dom.addEventListener(
			'touchend',
			function(ev) {
				if(canSwipe) {
					var isOver = false;
					var endPos = ev.changedTouches[0].pageX;
					if (endPos - tap.startPos > 80) {
						index--;
						if (index < 0) {
							index = 0;
							isOver = true;
						}
					} else if (endPos - tap.startPos < -80) {
						index++;
						if (index > children.length - 1) {
							index = children.length - 1;
							isOver = true;
						}
					} else {
						return;
					}
					if (canSwipe && !isOver) {
						var deltaValue = -80;
						canSwipe = false;
						wrapDom.animate(
							{
								left: oldLeft + deltaValue * index + 'px'
							},
							animTime,
							function() {
								canSwipe = true;
							}
						);
						children
							.eq(index)
							.removeClass('tobeSmall')
							.addClass('middle-item tobeLarge')
							.siblings()
							.removeClass('middle-item tobeLarge')
							.addClass('tobeSmall');
					} else {
						return;
					}
				}
			},
			{ passive: true }
		);
	}
};

$(function() {
	tap.getPos();
});