const darkModeMediaQuery = window.matchMedia("(prefers-color-scheme: dark)");

/** @param {Event} evt */
function removeEffect({ target }) {
  const effectsLayer = document.querySelector("#effects");
  if (effectsLayer == null) { return };
  const effects = Array.from(effectsLayer.children).filter(
    (e) => e['__effectParent'] === target,
  );
  effects.forEach((e) => {
    e.getAnimations().forEach((anim) => {
      if (+(anim.currentTime ?? 0) < 100) {
        anim.pause();
        effectsLayer.removeChild(e);
        return;
      }
      anim.pause();
      anim.updatePlaybackRate(-0.25);
      anim.play();
      anim.addEventListener("finish", () => {
        if (effectsLayer.contains(e)) {
          effectsLayer.removeChild(e);
        }
      });
    });
  });
}

function isElement(target: EventTarget | null): target is Element {
  return target !== null && typeof target["matches"] === 'function'
}

function addEffect({ target }: UIEvent) {
  const effectsLayer = document.querySelector("#effects");
  if (
    !isElement(target) ||
    !target.matches("a[href],.nav-toggle-button,button,input[type='radio']")
  ) {
    return;
  }
  const color = window.getComputedStyle(target).getPropertyValue('--glowColor');
  const rects = Array.from(target.getClientRects());
  Array.from(target.children).forEach((child) => {
    rects.push(...Array.from(child.getClientRects()));
  });
  rects.forEach((rect) => {
    const { top, left, width, height } = rect;
    const newEffect = document.createElement("div");
    newEffect['__effectParent'] = target;
    newEffect.classList.add("effect-instance");
    const padding = "10rem";
    newEffect.style.top = `calc(${top + window.scrollY}px - ${padding})`;
    newEffect.style.left = `calc(${left + window.scrollX}px - ${padding})`;
    newEffect.style.width = `calc(${width}px + 2 * ${padding})`;
    newEffect.style.height = `calc(${height}px + 2 * ${padding})`;
    newEffect.style.setProperty('--glowColor', color);
    effectsLayer?.appendChild(newEffect);
  });
}

document.addEventListener("mouseenter", addEffect, true);
document.addEventListener("focus", addEffect, true);

document.addEventListener("mouseleave", removeEffect, true);
document.addEventListener("blur", removeEffect, true);