(function () {
	var galleries = document.getElementsByClassName('gallery');

	var process_gallery = function (g) {
		var images = g.querySelectorAll('.images img');
		var navs = [];  // computed below
		var gallery_nav = g.querySelector('nav');
		var selected_index = 0;

		var select_image = function (index) {
			// var image = images[index];
			if (selected_index !== index) {
				images[selected_index].style.display = 'none';
				navs[selected_index].classList.remove('selected');
				images[index].style.display = 'block';
				navs[index].classList.add('selected');
				selected_index = index;
			}
		}

		var next_image = function () {
			if (selected_index >= images.length-1) {
				select_image(0);
			} else {
				select_image(selected_index+1);
			}
		}

		var nav_to_image = function () {
			select_image(Array.from(navs).indexOf(this));
		}

		var navHtml = '';

		for (var i=0; i<images.length; ++i) {
			var image = images[i]
			image.addEventListener('click', next_image)
			navHtml += '<i class="' + (i===0? 'selected' : '') + '" data-target="' + image.id + '"></i>'
		}

		gallery_nav.innerHTML = navHtml;

		navs = gallery_nav.querySelectorAll('i');
		for (var i=0; i<navs.length; ++i) {
			var nav = navs[i];
			nav.addEventListener('click', nav_to_image)
		}
	}

	for (var i=0; i<galleries.length; ++i) {
		var g = galleries[i];
		process_gallery(g);
	}
})();