var currentImage = 0;
var photos;

function checkImageHandlers() {
	var nextButton = document.getElementById("nextImageButton");
	var prevButton = document.getElementById("prevImageButton");
	
	if(!nextButton && !prevButton) return;
	
	if(photos.length == 0) {
		nextButton.style.display = "none";
		prevButton.style.display = "none";
	} else if(currentImage == 0) {
		prevButton.style.visibility = "hidden";
		nextButton.style.visibility = "";
	} else if(currentImage == photos.length - 1) {
		prevButton.style.visibility = "";
		nextButton.style.visibility = "hidden";
	} else {
		prevButton.style.visibility = "";
		nextButton.style.visibility = "";
	}
}

function nextImage() {
	setImageIndex(currentImage+1);
}

function prevImage() {
	setImageIndex(currentImage-1);	
}

function setImageIndex(index) {
	if(index < 0) {
		index = 0;
	} else if(index > photos.length - 1) {
		index = photos.length - 1;
	}
	currentImage = index;
	
	var img = document.getElementById("photoDisplay");	
	var img_onderschrift = document.getElementById("image-onderschrift");
	var img_download = document.getElementById("image-download");
	
	var details = photos[currentImage];
	var title = details.onderschrift;
	
	if(details.vermelding) {
	  title += "\r\n" + details.vermelding;
	}
	
	img.setAttribute("src",details.file);
	img.setAttribute("alt",title);
	img.setAttribute("title",title);
	
	if(img_onderschrift) {
		var onderschrift = details.onderschrift;
		if(details.vermelding) {
			onderschrift += "<br>" + details.vermelding;
		}
	
		img_onderschrift.innerHTML = onderschrift;
	}
	
	if(details.download && img_download) {
		// img_download.innerHTML = '<a href="'+details.download+'">&gt; Download hi-res versie</a>';
		var anchor = document.getElementById('download-link');
		anchor.setAttribute("href",details.download);
	} else if(img_download) {
		hide('image-download');
	}

	checkImageHandlers();
}