function openLightbox(post, idx) {
  lightboxCurrentPost = post;
  lightboxCurrentIdx = idx;
  lightboxObj.img.src = lightboxImages.get(post)[idx].src;
  lightboxObj.openOriginalAnchor.href = lightboxImages.get(post)[idx].src
  lightboxObj.prevButton.disabled = lightboxImages.get(post).length === 1
  lightboxObj.nextButton.disabled = lightboxImages.get(post).length === 1
  lightboxObj.imageCount.textContent = `Image ${idx + 1} of ${lightboxImages.get(post).length}`
  
  if (!lightboxObj.dialog.open) {
    lightboxObj.dialog.showModal();
  }
}

const modulo = (n, m) => ((n % m) + m) % m

function lightboxNext() {
  const l = lightboxImages.get(lightboxCurrentPost).length;
  const target = modulo(lightboxCurrentIdx + 1, l);
  openLightbox(lightboxCurrentPost, target);
}

function lightboxPrev() {
  const l = lightboxImages.get(lightboxCurrentPost).length;
  const target = modulo(lightboxCurrentIdx - 1, l);
  openLightbox(lightboxCurrentPost, target);
}

function constructLightbox() {
  const dialog = document.createElement("dialog");
  dialog.classList.add("lightbox-dialog");
  dialog.addEventListener("click", (e) => {
    if (e.target === dialog) {
      dialog.close();
    }
  })
  const dialogInner = document.createElement("div");
  dialogInner.classList.add("lightbox-inner");
  dialog.appendChild(dialogInner);
  const img = document.createElement("img");
  img.classList.add("lightbox-image")
  dialogInner.appendChild(img);
  const openOriginalAnchor = document.createElement("a")
  openOriginalAnchor.text = "Open original in new window"
  openOriginalAnchor.target = "_blank"
  openOriginalAnchor.rel = "noopener noreferrer nofollow"
  dialogInner.appendChild(openOriginalAnchor);
  
  const navSpan = document.createElement("span");
  navSpan.classList.add("lightbox-nav");
  const prevButton = document.createElement("button");
  prevButton.type = "button";
  prevButton.textContent = "Previous";
  prevButton.addEventListener("click", lightboxPrev);
  const nextButton = document.createElement("button");
  nextButton.type = "button";
  nextButton.textContent = "Next";
  nextButton.addEventListener("click", lightboxNext);
  const imageCount = document.createElement("span");
  imageCount.textContent = "Image of ";
  navSpan.appendChild(prevButton);
  navSpan.appendChild(imageCount);
  navSpan.appendChild(nextButton);
  
  dialogInner.appendChild(navSpan);
  return {
    img: img,
    dialog: dialog,
    openOriginalAnchor: openOriginalAnchor,
    prevButton: prevButton,
    nextButton: nextButton,
    imageCount: imageCount,
  }
}

let lightboxImages = new Map(); //.post-inner : Array<Object>
let lightboxObj = null;
let lightboxCurrentPost = null;
let lightboxCurrentIdx = -1;

document.addEventListener("DOMContentLoaded", () => {
  //lightboxes
  lightboxObj = constructLightbox();
  document.body.appendChild(lightboxObj.dialog);

  function setImageMaxSize(img) {
    const {
      maxWidth: origMaxWidth,
      maxHeight: origMaxHeight,
      minWidth: origMinWidth,
      minHeight: origMinHeight,
    } = getComputedStyle(img);
    console.log(img, img.naturalWidth, img.naturalHeight, origMinWidth, origMinHeight, origMaxWidth, origMaxHeight)
    if (img.naturalWidth < parseInt(origMinWidth)) {
      console.log(1)
      img.style.minWidth = img.naturalWidth + "px";
    }
    if (img.naturalHeight < parseInt(origMinHeight)) {
      console.log(2)
      img.style.minHeight = img.naturalHeight + "px";
    }
    if (img.naturalWidth < parseInt(origMaxWidth)) {
      console.log(3)
      img.style.maxWidth = img.naturalWidth + "px";
    }
    if (img.naturalHeight < parseInt(origMaxHeight)) {
      console.log(4)
      img.style.maxHeight = img.naturalHeight + "px";
    }
  }

  const postImages = document.querySelectorAll(".post-inner img.post-image");
  postImages.forEach(postImage => {
    const belongingTo = postImage.closest(".post-inner");
    const images = lightboxImages.get(belongingTo) ?? [];
    images.push({
      src: postImage.src,
      alt: postImage.alt,
    });
    const idx = images.length - 1;
    lightboxImages.set(belongingTo, images);
    postImage.style.cursor = "pointer";
    postImage.addEventListener("click", () => {
      openLightbox(belongingTo, idx);
    });
  });
  const postAndSigImages = document.querySelectorAll("img.post-image");
  postAndSigImages.forEach(image => {
    if (image.complete) {
      setImageMaxSize(image);
    } else {
      image.addEventListener("load", () => setImageMaxSize(image));
    }
  })
});