var mastheadCycle = {

    imgs: new Array(),

    interval: 5000,

    currentIndex: 0,

    init: function (images) {

        mastheadCycle.imgs = images;

        if (mastheadCycle.imgs.length > 1) {

            // preload the first  image...
			mastheadCycle.preload(mastheadCycle._image(0));

		}

    },

    // Gives us a circular array.
	_image: function (index) {
		return mastheadCycle.imgs[index % mastheadCycle.imgs.length];
	},

    run: function () {

        var current = mastheadCycle._image(mastheadCycle.currentIndex + 1);

        // alternate fg and bg based on iteration mod 2

        toFadeIn  = $('#map_masthead' + ((mastheadCycle.currentIndex + 1) % 2 != 0 ? '1' : '2') );
        toFadeOut = $('#map_masthead' + ((mastheadCycle.currentIndex + 1) % 2 == 0 ? '1' : '2') );

        $('#caption').fadeOut(500, function() {

            // set source of element to fade in

            toFadeIn.attr('src', current.src);
            toFadeIn.fadeIn(1500);

            toFadeOut.fadeOut(1500, function() {

                $('#caption').html(current.caption);
                $('#caption').fadeIn(500);

                mastheadCycle.currentIndex++;

                // preload next image to set the loop going again...
                var next = mastheadCycle._image(mastheadCycle.currentIndex + 1);

                mastheadCycle.preload(next);

            });

        });

	},

	preload: function(img) {

	    // need to preload?

	    if (img.preloaded) {
	        setTimeout(mastheadCycle.run, mastheadCycle.interval);
	        return;

	    } else {

            image = jQuery("<img>").load(
                function() {
                    setTimeout(mastheadCycle.run, mastheadCycle.interval);
                    img.preloaded = true;
                }
            );

            image.attr("src", img.src);

	    }

	}
}

$(function () {
     mastheadCycle.init(mastheadGallery);
});