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);
    if (img.naturalWidth < parseInt(origMinWidth)) {
      img.style.minWidth = img.naturalWidth + "px";
    }
    if (img.naturalHeight < parseInt(origMinHeight)) {
      img.style.minHeight = img.naturalHeight + "px";
    }
    if (img.naturalWidth < parseInt(origMaxWidth)) {
      img.style.maxWidth = img.naturalWidth + "px";
    }
    if (img.naturalHeight < parseInt(origMaxHeight)) {
      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));
    }
  })
});


{
  function isBefore(el1, el2) {
    if (el2.parentNode === el1.parentNode) {
      for (let cur = el1.previousSibling; cur; cur = cur.previousSibling) {
        if (cur === el2) return true;
      }
    }
    return false;
  }

  let draggedItem = null;

  function sortableItemDragStart(e, item) {
    const box = item.getBoundingClientRect();
    const oX = e.clientX - box.left;
    const oY = e.clientY - box.top;
    draggedItem = item;
    item.classList.add('dragged');
    e.dataTransfer.setDragImage(item, oX, oY);
    e.dataTransfer.effectAllowed = 'move';
  }

  function sortableItemDragEnd(e, item) {
    draggedItem = null;
    item.classList.remove('dragged');
  }

  function sortableItemDragOver(e, item) {
    const target = e.target.closest('.sortable-item');
    if (!target || target === draggedItem) {
      return;
    }
    const inSameList = draggedItem.dataset.sortableListKey === target.dataset.sortableListKey;
    if (!inSameList) {
      return;
    }
    const targetList = draggedItem.closest('.sortable-list');
    if (isBefore(draggedItem, target)) {
      targetList.insertBefore(draggedItem, target);
    } else {
      targetList.insertBefore(draggedItem, target.nextSibling);
    }
  }

  const listItemsHandled = new Map();

  const getListItemsHandled =  (list) => {
    return listItemsHandled.get(list) || new Set();
  }

  function registerSortableList(list) {
    list.querySelectorAll('li:not(.immovable)').forEach(item => {
      const listItems = getListItemsHandled(list);
      listItems.add(item);
      listItemsHandled.set(list, listItems);
      const dragger = item.querySelector('.dragger');
      dragger.addEventListener('dragstart', e => {sortableItemDragStart(e, item)});
      dragger.addEventListener('dragend', e => {sortableItemDragEnd(e, item)});
      item.addEventListener('dragover', e => {sortableItemDragOver(e, item)});
    });

    const obs = new MutationObserver(records => {
      for (const mutation of records) {
        mutation.addedNodes.forEach(node => {
          if (!(node instanceof HTMLElement)) {
            return;
          }
          if (!node.classList.contains('sortable-item')) {
            return;
          }
          const listItems = getListItemsHandled(list)
          if (listItems.has(node)) {
            return;
          }
          const dragger = node.querySelector('.dragger');
          dragger.addEventListener('dragstart', e => {sortableItemDragStart(e, node)});
          dragger.addEventListener('dragend', e => {sortableItemDragEnd(e, node)});
          node.addEventListener('dragover', e => {sortableItemDragOver(e, node)});
          listItems.add(node);
          listItemsHandled.set(list, listItems);
        });
      }
    });
    obs.observe(list, {childList: true});
  }

  document.querySelectorAll('.sortable-list').forEach(registerSortableList);

  listsObs = new MutationObserver(records => {
    for (const mutation of records) {
      mutation.addedNodes.forEach(node => {
        if (!(node instanceof HTMLElement)) {
          return;
        }
        if (!node.classList.contains('sortable-list')) {
          return;
        }
        registerSortableList(node);
      })
    }
  })
  listsObs.observe(document.body, {childList: true, subtree: true});
}