function argstr(args) {
	return "?" + Object.keys(args).map(function(key) {
		return encodeURIComponent(key)+"="+encodeURIComponent(args[key]);
	}).join("&");
}

function api(method, args, cb) {
	fetch("/admin/api/"+method+argstr(args), { method: "POST" })
		.then(response => response.json())
		.then(res => cb(res.err, res.obj));
}

function elem(tag, props, children) {
	var e;
	if (tag instanceof HTMLElement)
		e = tag;
	else
		e = document.createElement(tag);

	if (props) {
		for (var i in props) {
			e[i] = props[i];
		}
	}

	if (children) {
		for (var i in children) {
			e.appendChild(children[i]);
		}
	}

	e.appendTo = function(p) {
		p.appendChild(e);
		return e;
	}

	e.on = function(name, fn) {
		e.addEventListener(name, function(evt) {
			fn.call(e, evt);
		}, false);
		return e;
	}

	e.addClass = function(name) {
		if (e.className.indexOf(name) !== -1)
			return e;

		e.className += " "+name;
		return e;
	}

	e.removeClass = function(name) {
		e.className = e.className
			.replace(name, "")
			.trim()
			.replace(/ +/, "");
		return e;
	}

	e.clear = function() {
		var fc;
		while (fc = e.firstChild)
			e.removeChild(fc);
		return e;
	}

	return e;
}

var uploadElId = 0;
function uploadEl(args, cb) {
	var id = uploadElId++;
	var frame;
	var form;
	var fileEl;
	return form = elem("form", {
		className: "uploader",
		action: "/admin/api/slide_file_upload"+argstr(args),
		method: "post",
		enctype: "multipart/form-data",
		target: "upload-form-"+id
	}, [
		frame = elem("iframe", {
			style: "display: none",
			name: "upload-form-"+id
		}).on("load", cb),

		fileEl = elem("input", {
			type: "file",
			style: "display: none",
			name: "file"
		}).on("change", () => {
			form.submit();
		}),

		elem("button", {
			innerHTML: "Upload",
			type: "button"
		}).on("click", () => {
			fileEl.click();
		})
	]);
}

function async(n, cb) {
	var args = [];
	return function(arg) {
		args.push(arg);

		n -= 1;
		if (n === 0)
			cb(args);
	}
}

function debounce(fn, ms) {
	if (ms === undefined)
		ms = 300;

	var timeout;
	return function() {

		if (timeout)
			clearTimeout(timeout);

		timeout = setTimeout(function() {
			fn();
			timeout = null;
		}, ms);
	}
 }

function error(msg) {
	alert(msg);
}

var $$ = function() {
	return elem(document.querySelector.apply(document, arguments));
}