var slideshow_speed = 5000; //slide changing speed, milliseconds
var slideshowTimer;
var slide;
var slideshowActive = false;

(function(jQuery) {
  jQuery.slideshow = function() {

  }
})(jQuery);

var slideshowStart = function() {
	if (slideImages.length >= 2) { //if less than 2 additional (not default) slides, it does not make sense to start slideshow
		if (!slideshowActive) {
			slideshowTimer = setInterval(slides_update, slideshow_speed);
			slideshowActive = true;
		}
		
		return true;
	}
	return false; //prevent default click action
};

var slideshowStop = function() {
	clearInterval(slideshowTimer);
	slideshowActive = false;
	return false;
};

var slide_counter = 0;
var slide_is_ready = true;
var changeSlide  = 'last';

function slides_update() {
	if (slide_is_ready) {
		slide_is_ready = true;
		slide_counter++;
		var slide;
		if (slide_counter == slideImages.length) slide_counter = 0;
		
		if (changeSlide == 'last') {
			jQuery("#backgroundImage > img.last").attr('src', slideImages[slide_counter].src);
			jQuery("#backgroundImage > img.first").fadeOut('slow');
			changeSlide = 'first';
		} else {
			jQuery("#backgroundImage > img.first").attr('src', slideImages[slide_counter].src);
			jQuery("#backgroundImage > img.first").fadeIn('slow');
			changeSlide = 'last';
		} 
		
		
		//
	}
};