// ==UserScript==
// @name         Reddit Button: Old → New
// @namespace    https://github.com/hectorlizard
// @version      1.0
// @description  Adds and maintains a ‘New’ button that redirects to the new.reddit.com version of the current page
// @homepageURL  https://github.com/hectorlizard/reddit-button-old-to-new
// @downloadURL  https://raw.githubusercontent.com/hectorlizard/reddit-button-old-to-new/main/reddit-button-old-to-new.user.js
// @updateURL    https://raw.githubusercontent.com/hectorlizard/reddit-button-old-to-new/main/reddit-button-old-to-new.user.js
// @match        https://old.reddit.com/*
// @run-at       document-idle
// ==/UserScript==

(function insertNewRedditLink() {
	const BUTTON_ID = 'new-reddit-link';

	function createListItem() {
		const li = document.createElement('li');
		li.id = BUTTON_ID;

		const a = document.createElement('a');
		a.textContent = 'NR';
		a.style.cssText = `
			padding-right: 6px;
		`;
		a.href = location.href.replace('old.reddit.com', 'www.reddit.com');
		a.style.marginRight = '6px';

		li.appendChild(a);
		return li;
	}

	function tryInject() {
		const ul = document.querySelector('ul.flat-list.sr-bar.hover');
		if (!ul || ul.querySelector(`#${BUTTON_ID}`)) return;

		const newLi = createListItem();
		const firstLi = ul.querySelector('li');
		if (firstLi) {
			ul.insertBefore(newLi, firstLi);
		} else {
			ul.appendChild(newLi);
		}
	}

	tryInject();

	const observer = new MutationObserver(tryInject);
	observer.observe(document.body, {
		childList: true,
		subtree: true
	});
})();