// ==UserScript==
// @name Vector Layout for Wikipedia (Fast)
// @namespace -
// @version 1.1.9
// @description returns old Wikipedia layout. (layout before 2023 redesign of the website)
// @author NotYou
// @match *://wikipedia.org/*
// @match *://*.wikipedia.org/*
// @run-at document-start
// @license GPL-3.0-or-later
// @grant none
// @downloadURL none
// ==/UserScript==

(function() {
    'use strict';

    const MAKE_CLEAN_URL = false; // removes "useskin=vector" after loading

    const IS_DEBUG_MODE = false; // instead of redirecting, logs information in console

    const DEBUG_TITLE = 'DEBUG — Vector Layout for Wikipedia\n';

    const { href } = location;

    redirect(href, true);

    window.addEventListener('click', onClick);

    if(MAKE_CLEAN_URL) {
        let url = new URL(href);
        let searchParams = new URLSearchParams(url.search);

        if(searchParams.get('useskin') === 'vector') {
            searchParams.delete('useskin');

            let _searchParams = searchParams.toString();

            let newPath = url.pathname + (_searchParams ? '?' + _searchParams : _searchParams);

            history.replaceState({}, '', newPath);
        }
    }

    function redirect(inputUrl, replaceHistory) {
        let url;

        try {
            url = new URL(inputUrl);
        } catch(e) {
            throw new Error('"' + inputUrl + '" is not valid URL!');
        }

        const searchParams = new URLSearchParams(url.search);
        const { pathname, origin, hash } = url;
        const cleanURL = origin + pathname;

        if(searchParams.get('useskin') !== 'vector' && url.pathname !== '/') {
            searchParams.set('useskin', 'vector');

            const params = '?' + searchParams.toString();

            const resultURL = cleanURL + params + hash;
            const newPath = pathname + params;

            if(IS_DEBUG_MODE) {
                console.log(DEBUG_TITLE, resultURL, newPath);
            } else {
                history[replaceHistory ? 'replaceState' : 'pushState']({}, '', newPath);
                replaceURL(resultURL);
            }
        }
    }

    function onClick(e) {
        const node = e.target;
        const link = getLink(node);

        if(link && !(e.ctrlKey || e.metaKey)) {
            const url = new URL(link.href);
            const isOrigin = url.hostname.indexOf('wikipedia.org') > -1;
            const isNotAnchor = !link.getAttribute('href').startsWith('#');
            const isOnlyLink = !link.getAttribute('role');

            const isValid = isOrigin && isNotAnchor && isOnlyLink;

            if(isValid) {
                e.preventDefault();

                redirect(url, false);
            }
        }
    }

    function replaceURL(url) {
        if(location.replace) {
            location.replace(url);
        } else {
            location.href = url;
        }
    }

    function getLink(node) {
        if(node.tagName === 'A') {
            return node;
        } else if(node.tagName === 'HTML' || !node.tagName) {
            return null;
        }

        return getLink(node.parentNode);
    }
})();