var timer;
var interval;
var total_slides;
var current_slide = 1;
var upcoming_slide;
var slideshow_mode = 1;	// 0 = pause,  1 = play
var num_of_clicks = 0;


function previous_slide() {
	num_of_clicks++;
	if (num_of_clicks == 1) {
		upcoming_slide = current_slide - 1;
		
		if (upcoming_slide < 1) {
			current_slide = 1;
			upcoming_slide = total_slides;
		}
		
		run_slideshow();
	}
}

function next_slide() {
	num_of_clicks++;
	if (num_of_clicks == 1) {
		upcoming_slide = current_slide + 1;
		
		if (upcoming_slide > total_slides) {
			// current_slide = total_slides;
			upcoming_slide = 1;
		}
		run_slideshow();
	}
}


function run_slideshow() {
	// reset zindex
	for (var num=1;num<=total_slides;num++) {
		if (num == upcoming_slide) {
			$('slide_'+upcoming_slide).style.zIndex = 1;
		} else if (num == current_slide) {
			$('slide_'+current_slide).style.zIndex = 2;
		} else {
			$('slide_'+num).style.display = 'block';
			$('slide_'+num).style.zIndex = 0;
		}
	}
	
	// Drop current slide	
	Effect.DropOut('slide_'+current_slide, {  afterFinish: 
		function() {
			// upcoming slide should have higher zindex
			$('slide_'+upcoming_slide).style.zIndex = total_slides + 1;
				
			// reset zindex
			for (var num=1;num<=total_slides;num++) {
				if (num != upcoming_slide) {
					$('slide_'+num).style.display = 'block';
					$('slide_'+num).style.zIndex = 0;
				}
			}
				
			current_slide = upcoming_slide;
			// Reset number of clicks
			num_of_clicks = 0;
		}
	})	
}


function pause_play_slide() {
	if (slideshow_mode == 0) {
		// Resume slideshow
		slideshow_mode = 1;
		$('slidePausePlay').alt="Pause";
		$('slidePausePlay').src="../../../images/slideshow/pause.gif";
		timer = setInterval('next_slide()', interval );
		
	} else if (slideshow_mode == 1) {
		// Pause slideshow
		$('slidePausePlay').alt="Play";
		$('slidePausePlay').src="../../../images/slideshow/play.gif";
		slideshow_mode = 0;
		clearTimeout(timer);
	}
}