(() => {
  "use strict";

  const VERSION = "0.2.3";
  const ROOT_CLASS = "lildra-active";
  const STYLE_ID = "lildra-layout-style";
  const HEADER_ID = "lildra-page-header";
  const FOOTER_ID = "lildra-product-footer";

  function removeLildra() {
    document.documentElement.classList.remove(ROOT_CLASS);
    document.getElementById(STYLE_ID)?.remove();
    document.getElementById(HEADER_ID)?.remove();
    document.getElementById(FOOTER_ID)?.remove();
  }

  // Toggle off when run a second time.
  if (document.documentElement.classList.contains(ROOT_CLASS)) {
    removeLildra();
    return;
  }

  function getPageTitle() {
    const candidates = [
      document.querySelector("#breadcrumbs [aria-current='page'] .ellipsible")?.textContent,
      document.querySelector("#breadcrumbs [aria-current='page']")?.textContent,
      document.querySelector(".mobile-header-title div:last-child")?.textContent,
      document.querySelector("#wiki_page_show .page-title")?.textContent,
      document.querySelector("#content h1.page-title")?.textContent
    ];

    const found = candidates
      .map((value) => value?.trim())
      .find((value) => value && value.length > 0);

    if (found) return found;

    // Canvas document titles normally end with ": Course name".
    const browserTitle = document.title.trim();
    const separator = browserTitle.lastIndexOf(":");
    return separator > 0 ? browserTitle.slice(0, separator).trim() : browserTitle;
  }

  const style = document.createElement("style");
  style.id = STYLE_ID;
  style.textContent = `
    /* Hide Canvas/QLearn navigation only. */
    html.${ROOT_CLASS} #header,
    html.${ROOT_CLASS} #mobile-header,
    html.${ROOT_CLASS} #mobileContextNavContainer,
    html.${ROOT_CLASS} .ic-app-nav-toggle-and-crumbs,
    html.${ROOT_CLASS} #left-side {
      display: none !important;
    }

    /* Remove navigation offsets while keeping a normal, centred reading width. */
    html.${ROOT_CLASS} #wrapper {
      margin-left: 0 !important;
      padding-top: 42px !important;
    }

    html.${ROOT_CLASS} body.primary-nav-expanded #wrapper,
    html.${ROOT_CLASS} body.course-menu-expanded #wrapper,
    html.${ROOT_CLASS} body.with-left-side #wrapper {
      margin-left: 0 !important;
    }

    html.${ROOT_CLASS} #main {
      display: block !important;
      width: 100% !important;
      max-width: none !important;
      margin: 0 !important;
    }

    html.${ROOT_CLASS} #not_right_side {
      display: block !important;
      width: min(1100px, calc(100% - 32px)) !important;
      max-width: 1100px !important;
      margin: 0 auto !important;
      float: none !important;
    }

    html.${ROOT_CLASS} #content-wrapper,
    html.${ROOT_CLASS} #content {
      width: 100% !important;
      max-width: none !important;
      margin-left: 0 !important;
      margin-right: 0 !important;
    }

    /* Small fixed title bar. */
    html.${ROOT_CLASS} #${HEADER_ID} {
      position: fixed !important;
      top: 0 !important;
      left: 0 !important;
      right: 0 !important;
      z-index: 2147483646 !important;
      box-sizing: border-box !important;
      height: 42px !important;
      display: flex !important;
      align-items: center !important;
      justify-content: center !important;
      padding: 0 18px !important;
      margin: 0 !important;
      overflow: hidden !important;
      white-space: nowrap !important;
      text-overflow: ellipsis !important;
      text-align: center !important;
      background: #ffffff !important;
      border-bottom: 1px solid rgba(0, 0, 0, 0.14) !important;
      box-shadow: 0 1px 3px rgba(0, 0, 0, 0.07) !important;
      color: #1d2733 !important;
      font-family: Lato, "Helvetica Neue", Helvetica, Arial, sans-serif !important;
      font-size: 16px !important;
      font-weight: 700 !important;
      line-height: 1 !important;
    }

    html.${ROOT_CLASS} #${FOOTER_ID} {
      position: fixed !important;
      right: 14px !important;
      bottom: 9px !important;
      z-index: 2147483646 !important;
      padding: 4px 7px !important;
      border-radius: 4px !important;
      background: rgba(255, 255, 255, 0.9) !important;
      color: #5f259f !important;
      font-family: Lato, "Helvetica Neue", Helvetica, Arial, sans-serif !important;
      font-size: 12px !important;
      font-weight: 700 !important;
      line-height: 1 !important;
      pointer-events: none !important;
      box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1) !important;
    }

    @media (max-width: 700px) {
      html.${ROOT_CLASS} #wrapper {
        padding-top: 38px !important;
      }

      html.${ROOT_CLASS} #${HEADER_ID} {
        height: 38px !important;
        padding: 0 12px !important;
        font-size: 14px !important;
      }
    }
  `;

  const header = document.createElement("div");
  header.id = HEADER_ID;
  header.setAttribute("role", "banner");
  header.textContent = getPageTitle();

  const footer = document.createElement("div");
  footer.id = FOOTER_ID;
  footer.textContent = `Lildra v${VERSION}`;

  document.documentElement.appendChild(style);
  document.body.appendChild(header);
  document.body.appendChild(footer);
  document.documentElement.classList.add(ROOT_CLASS);
})();