fetch("test.xml")
	.then((res) => res.text())
	.then((data) => {
		parseDocument(data);
	});

const parseDocument = function (data) {
	const parser = new DOMParser();
	const doc = parser.parseFromString(data, "application/xml");

	const container = document.querySelector("#container");
	const levels = document.querySelector("#controller");
	container.innerHTML = "";
	levels.innerHTML = "";

	const errorNode = doc.querySelector("parsererror");
	if (errorNode) {
		let error = document.createElement("span");
		error.style.color = "tomato";
		error.innerHTML = "Error while parsing the XML file! Check if the document is well formed";
		levels.appendChild(error);
	} else {
		controller(layers(doc));
		display(doc);
	}
};

const layers = function (xml) {
	return new Set([...xml.querySelectorAll("*")].map((node) => node.tagName));
};

const controller = function (levels) {
	const controller = document.querySelector("#controller");
	for (const level of levels) {
		let check = document.createElement("input");
		check.type = "checkbox";
		check.checked = true;
		check.value = level;

		let label = document.createElement("label");
		label.for = level;
		label.innerHTML = level;

		controller.appendChild(check);
		controller.appendChild(label);

		check.addEventListener("change", (el) => {
			console.log(check.checked);
			setVisibility(check.checked, level);
		});
	}
};

const setVisibility = function (visibility, selector) {
	let elements = document.getElementsByClassName(selector);
	for (const el of elements) {
		el.style.display = visibility ? "initial" : "none";
	}
};

const display = function (doc) {
	const container = document.querySelector("#container");

	traverse(doc.documentElement, (el) => {
		let block = document.createElement("span");
		block.classList.add(el.parentNode.tagName);
		block.innerHTML = el.textContent;
		container.appendChild(block);
	});
};

const traverse = function (el, callback) {
	if (el.childNodes.length) {
		for (const child of el.childNodes) {
			traverse(child, callback);
		}
	} else {
		if (typeof callback == "function") {
			callback(el);
		}
	}
};

const fileSelector = document.getElementById("file-selector");
fileSelector.addEventListener("change", (event) => {
	const file = event.target.files[0];

	const reader = new FileReader();
	reader.addEventListener("load", (event) => {
		parseDocument(event.target.result);
	});

	reader.readAsText(file);
});