Alternative Hover Tooltips for Fandom Wiki's using the MediaWiki API

WikiHover.user.js

// ==UserScript==
// @name         WikiHover
// @namespace    https://fandom.com
// @version      1.2
// @description  Inline wiki preview on hover for Fandom wikis
// @author       rjf89
// @match        *://warhammer-40000-space-wolf.fandom.com/*
// @match        *://*.lexicanum.com/*
// @match        *://bleach.fandom.com/*
// @match        *://andromeda.fandom.com/*
// @match        *://lastepoch.fandom.com/*
// @match        *://monster-train.fandom.com/*
// @match        *://warhammer40k.fandom.com/*
// @match        *://wildermyth.com/*
// @require      http://ajax.googleapis.com/ajax/libs/jquery/1.11.3/jquery.js
// @updateURL    https://gist.github.com/rf5860/e1f0ca962b000a3effc239ff9176dfcc/raw/WikiHover.user.js
// @downloadURL  https://gist.github.com/rf5860/e1f0ca962b000a3effc239ff9176dfcc/raw/WikiHover.user.js
// @grant        GM_xmlhttpRequest
// @grant        GM_setValue
// @grant        GM_getValue
// @grant        GM_listValues
// ==/UserScript==
const KnownEndpoints = {
  "ageofsigmar.lexicanum.com": "mediawiki/",
  "wildermyth.com": "w/",
}
const Main = document.querySelector('#content, #mw-content, main');
const ComputedStyle = getComputedStyle(Main);
const Color = ComputedStyle ? ComputedStyle.color : "";
const Background = ComputedStyle ? ComputedStyle.background : "";
const BorderImage = ComputedStyle ? ComputedStyle.borderImage : "";
const Border = ComputedStyle ? ComputedStyle.border : "1px solid black";
const $content = $('*[id*=content]').first();
let $popup = $('<div id="wiki-popup"></div>').appendTo('body');

$popup.css({
  "position": 'absolute',
  "display": 'none',
  "maxWidth": '350px',
  "border": '1px solid black',
  "padding": '10px',
  "borderRadius": '5px',
  "zIndex": '9999999',
  "background": Background,
  "borderImage": BorderImage,
  "color": Color
});
const viewportWidth = window.innerWidth;
const viewportHeight = window.innerHeight;
const getPosition = e => {
  const scrollTop = document.documentElement.scrollTop || window.scrollY || document.body.scrollTop;
  const scrollLeft = document.documentElement.scrollLeft || window.scrollX || document.body.scrollLeft;
  let left
  let top
  // Check if the tooltip goes off the right of the viewport
  if (e.pageX + $popup.width() + 10 > viewportWidth) {
    left = `${e.pageX - $popup.width() - 10}px`;
  } else {
    left = `${e.pageX + 10}px`;
  }
  // Check if the tooltip goes off the bottom of the viewport
  if (e.pageY + $popup.height() + 10 > viewportHeight) {
    top = `${e.pageY - $popup.height() - 10}px`;
  } else {
    top = `${e.pageY + 10}px`;
  }
  return { left, top };
}
let shouldDisplayPopup = true;


const displayPopup = (htmlContent, event) => {
  if (shouldDisplayPopup) {
    $popup.html(htmlContent);
    $popup.css(getPosition(event))
    $popup.show();
  }
};

const hidePopup = () => {
  shouldDisplayPopup = false;
  $popup.hide();
};

async function handleHover(event) {
  shouldDisplayPopup = true;
  let content = await getWikiContent($(this).text());
  if (this.className === 'mw-redirect') {
    const link = $($.parseHTML(content)).find('a');
    const otherWiki = link[0].href.split('/')[2];
    const otherTitle = decodeURIComponent(link[0].href.split('/')[4]);
    console.log(`Redirecting to ${otherWiki} ${otherTitle}`);
    content = await getWikiContent(otherTitle, `https://${otherWiki}`);
  }

  displayPopup(content, event);
}

const cache = {};

const getWikiContent = (pageTitle, host = '') => new Promise((resolve, reject) => {
  const cacheKey = `${host}:${pageTitle}`;

  if (cache[cacheKey]) {
    resolve(cache[cacheKey]);
    return;
  }

  const apiUrl = `${host}/${KnownEndpoints[window.location.host] ?? ""}api.php`;
  const params = {
    "action": 'parse',
    "page": pageTitle,
    "prop": 'text',
    "section": 0,
    "format": 'json',
  }
  const urlParams = new URLSearchParams(params).toString();

  GM_xmlhttpRequest({
    method: "GET",
    url: apiUrl + '?' + urlParams,
    onload: response => {
      const content = JSON.parse(response.responseText).parse.text['*'];
      cache[cacheKey] = content;
      GM_setValue(cacheKey, content);
      resolve(content);
    },
    onerror: error => reject(error)
  });
});

$(document).ready(() => {
  // Load cached data from storage
  for (const key in GM_listValues()) {
    cache[key] = GM_getValue(key);
  }

  $('a').hover(handleHover, hidePopup);
});