// сделано на основе пена http://codepen.io/sitepoint/pen/mweaqm

(function($) {

	var _elements,
		_options;

	var methods = {
		init: function(elements, options) {

			_elements = elements;
			_options = options;

			methods.bind();
		},
		bind: function() {
			$(window).scroll(function() {
				methods.animate(_elements, _options);
			});
			$(window).trigger('scroll');
		},
		animate: function(elements, options) {

			var viewheight = $(window).height(),
				viewtop = $(window).scrolltop(),
				viewbottom = (viewtop + viewheight);

			$.each(elements, function() {
				var elementanimation = $(this).data('animate'),
					elementoffset = $(this).data('offset'),
					elementduration = $(this).data('duration'),
					elementdelay = $(this).data('delay'),
					elementiteration = $(this).data('iteration'),
					elementheight = $(this).outerheight(),
					elementtop = $(this).offset().top,
					elementbottom = (elementtop + elementheight);

				if (elementoffset) {
					elementtop = elementtop + elementoffset;
					elementbottom = elementbottom - elementoffset;
				}

				$(this).css({'-webkit-animation-duration': elementduration, 'animation-duration': elementduration});
				$(this).css({'-webkit-animation-delay': elementdelay, 'animation-delay': elementdelay});
				$(this).css({'-webkit-animation-iteration-count': elementiteration, 'animation-iteration-count': elementiteration});

				if ((elementbottom >= viewtop) && (elementtop <= viewbottom)) {
					$(this).css('visibility', 'visible');
					$(this).addclass('animate__'+elementanimation);
					$(this).addclass('animate__animated');
				}
				else {
					if (options.once === false) {
						$(this).css('visibility', 'hidden');
						$(this).removeclass('animate__'+elementanimation);
						$(this).removeclass('animate__animated');
					}
				}
			});
		}
	};

	jquery.fn.scrolla = function(options) {
		options = $.extend({
			mobile: false,
			once: false
		}, options);

		if (options.mobile === false) {
			if(/android|webos|iphone|ipod|blackberry|iemobile|opera mini/i.test(navigator.useragent)) {
				return false;
			}
		}

		methods.init(this, options);

	};
})(jquery);