/* ============================================================================
   SillyLaird scroll-to-top (network-wide).

   Injected by nginx before </body> on HTML responses across *.sillylaird.ca
   (see /etc/nginx/snippets/sillylaird-visit-counter.conf). Also loaded as a
   fallback from site.js / nav.js. Runs once (window.__slScrollTopInit).

   Shows a fixed "▲ TOP" control after the page has been scrolled, and only
   when the document is actually taller than the viewport. Works without the
   host page loading site.css (styles come from scroll-to-top.css).
   ============================================================================ */
(function () {
  "use strict";

  if (window.__slScrollTopInit) return;
  window.__slScrollTopInit = true;

  // Embedded forms / comments / changelog iframe: the parent page owns scroll.
  try {
    if (window.self !== window.top) return;
  } catch (_) {
    return;
  }

  var path = location.pathname || "/";
  if (/\/(admin|api|login|logout|auth|captcha|relay|meta|submit)(\/|$|\.)/i.test(path)) {
    return;
  }
  if (/\.(xml|json|m3u|pls|css|js|map|ico|png|jpe?g|gif|webp|svg|woff2?|mp3|flac|webm|mp4)(\?|$)/i.test(path)) {
    return;
  }

  var CSS_HREF = "https://www.sillylaird.ca/assets/css/scroll-to-top.css?v=20260821b";
  var THRESHOLD = 280;
  var MIN_OVERFLOW = 240;

  function labelForLang() {
    var lang = (document.documentElement.lang || "").toLowerCase();
    if (lang.indexOf("ja") === 0) return "先頭へ戻る";
    if (lang.indexOf("zh") === 0) return "回到顶部";
    return "Scroll to top";
  }

  function prefersReducedMotion() {
    return window.matchMedia && window.matchMedia("(prefers-reduced-motion: reduce)").matches;
  }

  function scrollY() {
    return window.pageYOffset || document.documentElement.scrollTop || document.body.scrollTop || 0;
  }

  function overflowPx() {
    var el = document.scrollingElement || document.documentElement;
    return (el ? el.scrollHeight : 0) - (window.innerHeight || 0);
  }

  function ensureCss() {
    var links = document.getElementsByTagName("link");
    var i;
    for (i = 0; i < links.length; i++) {
      if (links[i].rel === "stylesheet" && (links[i].href || "").indexOf("scroll-to-top.css") !== -1) {
        return;
      }
    }
    var l = document.createElement("link");
    l.rel = "stylesheet";
    l.href = CSS_HREF;
    document.head.appendChild(l);
  }

  function ensureTopTarget() {
    if (document.getElementById("top")) return;
    document.documentElement.id = "top";
  }

  function dodgeVisitCounter() {
    var c = document.getElementById("site-visit-counter");
    if (!c) return;
    var pos = (c.style && c.style.position) || "";
    var computed = window.getComputedStyle ? window.getComputedStyle(c).position : "";
    if (pos === "fixed" || computed === "fixed") {
      c.setAttribute("data-stt-docked", "1");
      // Inline bottom from visit-counter.js wins over the stylesheet, so
      // move it here or the two chips sit on top of each other.
      c.style.bottom = "4.65rem";
    }
  }

  function ensureButton() {
    var existing = document.getElementById("scroll-to-top");
    if (existing) return existing;

    var a = document.createElement("a");
    a.id = "scroll-to-top";
    a.className = "scroll-to-top";
    a.href = "#top";
    var label = labelForLang();
    a.setAttribute("aria-label", label);
    a.title = label;

    var caret = document.createElement("span");
    caret.className = "scroll-to-top-caret";
    caret.setAttribute("aria-hidden", "true");
    caret.appendChild(document.createTextNode("\u25B2"));

    var text = document.createElement("span");
    text.className = "scroll-to-top-label";
    text.setAttribute("aria-hidden", "true");
    text.appendChild(document.createTextNode("TOP"));

    a.appendChild(caret);
    a.appendChild(text);
    document.body.appendChild(a);
    return a;
  }

  function goTop(e) {
    if (e) e.preventDefault();
    if (prefersReducedMotion() || typeof window.scrollTo !== "function") {
      if (typeof window.scrollTo === "function") {
        window.scrollTo(0, 0);
      } else {
        document.documentElement.scrollTop = 0;
        document.body.scrollTop = 0;
      }
      return;
    }
    try {
      window.scrollTo({ top: 0, behavior: "smooth" });
    } catch (_) {
      window.scrollTo(0, 0);
    }
  }

  function init() {
    ensureCss();
    ensureTopTarget();
    var btn = ensureButton();
    if (!btn) return;

    document.body.className = (document.body.className ? document.body.className + " " : "") + "has-scroll-to-top";
    dodgeVisitCounter();
    window.setTimeout(dodgeVisitCounter, 50);
    window.setTimeout(dodgeVisitCounter, 400);

    var ticking = false;
    function update() {
      ticking = false;
      var show = overflowPx() > MIN_OVERFLOW && scrollY() > THRESHOLD;
      if (show) {
        if (btn.className.indexOf("is-visible") === -1) {
          btn.className += " is-visible";
        }
      } else {
        btn.className = btn.className.replace(/\s*is-visible\b/g, "");
      }
    }

    function onScroll() {
      if (ticking) return;
      ticking = true;
      if (window.requestAnimationFrame) {
        window.requestAnimationFrame(update);
      } else {
        window.setTimeout(update, 16);
      }
    }

    window.addEventListener("scroll", onScroll, false);
    window.addEventListener("resize", onScroll, false);
    btn.addEventListener("click", goTop);
    update();
  }

  if (document.readyState === "loading") {
    document.addEventListener("DOMContentLoaded", init);
  } else {
    init();
  }
})();