(function () {
  'use strict';

  // Set to true to see debug output in the browser console
  var DEBUG = false;

  var usageCache = {};
  var pendingRequests = {};
  var debounceTimer = null;

  function log() {
    if (DEBUG) console.log.apply(console, ['[image-usage]'].concat(Array.prototype.slice.call(arguments)));
  }

  /**
   * Fetch usage data for a Kirby page ID (slug format, e.g. "community-led/inside").
   * Returns a promise resolving to { filename: boolean }.
   */
  function fetchUsage(pageId) {
    if (pageId in usageCache) return Promise.resolve(usageCache[pageId]);
    if (pageId in pendingRequests) return pendingRequests[pageId];

    // Kirby panel encodes / as + in URLs
    var encoded = encodeURIComponent(pageId.replace(/\//g, '+'));
    log('Fetching usage for page:', pageId, '→', '/api/smart-forests/image-usage/' + encoded);

    var csrf = (window.panel && window.panel.system && window.panel.system.csrf) ? window.panel.system.csrf : false;

    var promise = fetch('/api/smart-forests/image-usage/' + encoded, {
      credentials: 'same-origin',
      headers: {
        'x-csrf': csrf,
        'x-fiber': 'true'
      }
    })
      .then(function (r) {
        if (!r.ok) {
          log('API error', r.status, r.statusText);
          return {};
        }
        return r.json();
      })
      .then(function (data) {
        log('Usage data for', pageId, data);
        usageCache[pageId] = data;
        delete pendingRequests[pageId];
        return data;
      })
      .catch(function (err) {
        log('Fetch failed:', err);
        usageCache[pageId] = {};
        delete pendingRequests[pageId];
        return {};
      });

    pendingRequests[pageId] = promise;
    return promise;
  }

  /**
   * Apply (or refresh) a usage badge on a file item element.
   * Skips DOM writes if the element is already in the correct state,
   * which prevents the MutationObserver from re-triggering indefinitely.
   */
  function applyBadge(item, used) {
    var wantedState = used === true ? 'used' : used === false ? 'unused' : null;
    var currentState = item.dataset.sfUsage || null;

    // Already correct — skip to avoid triggering MutationObserver
    if (currentState === wantedState) return;

    // Remove existing badge
    item.querySelectorAll('.sf-usage-dot').forEach(function (el) { el.remove(); });
    item.classList.remove('sf-is-used', 'sf-is-unused');
    delete item.dataset.sfUsage;

    if (!wantedState) return;

    item.dataset.sfUsage = wantedState;
    item.classList.add('sf-is-' + wantedState);

    var dot = document.createElement('span');
    dot.className = 'sf-usage-dot sf-usage-dot--' + wantedState;
    dot.setAttribute('title', used ? 'Utilisée dans le contenu' : 'Non utilisée dans le contenu');

    var imageArea = item.querySelector('.k-item-image, .k-item-icon');
    if (imageArea) {
      imageArea.appendChild(dot);
    } else {
      item.prepend(dot);
    }
  }

  var IMAGE_EXT = /\.(jpe?g|png|gif|webp|svg|avif)$/i;

  /**
   * Scan current DOM for file items, group by page, fetch usage, paint badges.
   *
   * File items in the panel have data-id = "{kirby-page-slug}/{filename}"
   * e.g. "community-led-forest-technologies/inside/image.jpg"
   */
  function run() {
    // All k-item elements that have a data-id ending in an image extension
    var allItems = document.querySelectorAll('.k-item[data-id]');
    log('Total .k-item[data-id] found:', allItems.length);

    var byPage = {};
    allItems.forEach(function (item) {
      var dataId = item.getAttribute('data-id') || '';
      if (!IMAGE_EXT.test(dataId)) return; // skip non-image items

      var parts = dataId.split('/');
      if (parts.length < 2) return;

      var filename = parts[parts.length - 1];
      var pageId   = parts.slice(0, -1).join('/');

      if (!byPage[pageId]) byPage[pageId] = [];
      byPage[pageId].push({ item: item, filename: filename });
    });

    var pageCount = Object.keys(byPage).length;
    log('Pages with image items:', pageCount, byPage);

    if (!pageCount) return;

    Object.keys(byPage).forEach(function (pageId) {
      fetchUsage(pageId).then(function (usage) {
        byPage[pageId].forEach(function (entry) {
          applyBadge(entry.item, usage[entry.filename]);
        });
      });
    });
  }

  function schedule() {
    clearTimeout(debounceTimer);
    debounceTimer = setTimeout(run, 450);
  }

  new MutationObserver(schedule).observe(document.body, {
    childList: true,
    subtree: true
  });

  schedule();
})();