/* global window, document */

(function () {
  'use strict';

  var Luxtools = window.Luxtools || (window.Luxtools = {});

  // ============================================================
  // Lightbox Module
  // ============================================================
  Luxtools.Lightbox = (function () {
    var lb = null;
    var img = null;
    var cap = null;
    var items = [];
    var index = 0;

    // Zoom/pan state
    var scale = 1;
    var panX = 0;
    var panY = 0;
    var minScale = 1;
    var maxScale = 5;
    var isPanning = false;
    var panStartX = 0;
    var panStartY = 0;

    // History state
    var pushedHistory = false;
    var closingFromPopstate = false;

    function ensureElement() {
      if (lb) return;

      lb = document.createElement('div');
      lb.className = 'luxtools-lightbox';
      lb.setAttribute('role', 'dialog');
      lb.setAttribute('aria-modal', 'true');
      lb.setAttribute('aria-hidden', 'true');

      lb.innerHTML =
        '<div class="luxtools-lightbox-backdrop" data-luxtools-action="close"></div>' +
        '<div class="luxtools-lightbox-stage">' +
          '<button type="button" class="luxtools-lightbox-close" data-luxtools-action="close" aria-label="Close">×</button>' +
          '<button type="button" class="luxtools-lightbox-zone luxtools-lightbox-zone-prev" data-luxtools-action="prev" aria-label="Previous"></button>' +
          '<button type="button" class="luxtools-lightbox-zone luxtools-lightbox-zone-next" data-luxtools-action="next" aria-label="Next"></button>' +
          '<div class="luxtools-lightbox-media">' +
            '<img class="luxtools-lightbox-img" alt="" />' +
          '</div>' +
          '<div class="luxtools-lightbox-caption"></div>' +
        '</div>';

      document.body.appendChild(lb);
      img = lb.querySelector('img.luxtools-lightbox-img');
      cap = lb.querySelector('.luxtools-lightbox-caption');

      lb.addEventListener('click', onClick);
    }

    function clampIndex(n) {
      if (n < 0) return items.length - 1;
      if (n >= items.length) return 0;
      return n;
    }

    function applyTransform() {
      if (scale <= 1 && panX === 0 && panY === 0) {
        img.style.transform = '';
      } else {
        img.style.transform = 'scale(' + scale + ') translate(' + panX + 'px, ' + panY + 'px)';
      }
      img.style.cursor = scale > 1 ? 'grab' : '';
    }

    function resetZoom() {
      scale = 1;
      panX = 0;
      panY = 0;
      applyTransform();
    }

    function render() {
      var it = items[index];
      img.src = it.full;
      img.setAttribute('data-luxtools-index', String(index));
      if (cap) cap.textContent = (it.name || '').trim();
      resetZoom();
    }

    function next() {
      index = clampIndex(index + 1);
      render();
    }

    function prev() {
      index = clampIndex(index - 1);
      render();
    }

    // Event handlers
    function onWheel(e) {
      e.preventDefault();
      var delta = e.deltaY > 0 ? -0.15 : 0.15;
      scale = Math.max(minScale, Math.min(maxScale, scale + delta));
      if (scale <= 1) { panX = 0; panY = 0; }
      applyTransform();
    }

    function onDblClick(e) {
      e.preventDefault();
      if (scale > 1) {
        scale = 1;
        panX = 0;
        panY = 0;
      } else {
        scale = 2.5;
      }
      applyTransform();
    }

    function onMouseDown(e) {
      if (scale > 1 && e.button === 0) {
        isPanning = true;
        panStartX = e.clientX - panX * scale;
        panStartY = e.clientY - panY * scale;
        img.style.cursor = 'grabbing';
        e.preventDefault();
      }
    }

    function onMouseMove(e) {
      if (isPanning && scale > 1) {
        panX = (e.clientX - panStartX) / scale;
        panY = (e.clientY - panStartY) / scale;
        applyTransform();
        img.style.cursor = 'grabbing';
      }
    }

    function onMouseUp() {
      isPanning = false;
      img.style.cursor = scale > 1 ? 'grab' : '';
    }

    function onKeyDown(e) {
      if (!lb || !lb.classList.contains('is-open')) return;
      var key = e.key || '';
      if (key === 'Escape') {
        e.preventDefault();
        close();
      } else if (key === 'ArrowRight') {
        e.preventDefault();
        next();
      } else if (key === 'ArrowLeft') {
        e.preventDefault();
        prev();
      }
    }

    function onPopState() {
      if (!lb || !lb.classList.contains('is-open')) return;
      closingFromPopstate = true;
      try { close(); } finally { closingFromPopstate = false; }
    }

    function onClick(e) {
      var t = e.target;
      if (!t || !t.getAttribute) return;
      var action = t.getAttribute('data-luxtools-action') || '';
      if (action === 'close') { e.preventDefault(); close(); return; }
      if (action === 'next') { e.preventDefault(); next(); return; }
      if (action === 'prev') { e.preventDefault(); prev(); return; }

      if (t.closest && t.closest('button.luxtools-lightbox-zone')) return;
      if (t.closest && t.closest('img.luxtools-lightbox-img')) return;
      e.preventDefault();
      close();
    }

    function attachListeners() {
      document.addEventListener('keydown', onKeyDown, true);
      window.addEventListener('popstate', onPopState, true);
      img.addEventListener('wheel', onWheel, { passive: false });
      img.addEventListener('dblclick', onDblClick);
      img.addEventListener('mousedown', onMouseDown);
      document.addEventListener('mousemove', onMouseMove);
      document.addEventListener('mouseup', onMouseUp);
    }

    function detachListeners() {
      document.removeEventListener('keydown', onKeyDown, true);
      window.removeEventListener('popstate', onPopState, true);
      img.removeEventListener('wheel', onWheel);
      img.removeEventListener('dblclick', onDblClick);
      img.removeEventListener('mousedown', onMouseDown);
      document.removeEventListener('mousemove', onMouseMove);
      document.removeEventListener('mouseup', onMouseUp);
    }

    function open(galleryEl, startEl) {
      var links = galleryEl.querySelectorAll('a.luxtools-gallery-item[data-luxtools-full]');
      items = [];
      links.forEach(function (a) {
        var full = a.getAttribute('data-luxtools-full') || a.getAttribute('href') || '';
        var name = a.getAttribute('data-luxtools-name') || a.getAttribute('title') || '';
        if (!full) return;
        items.push({ el: a, full: full, name: name });
      });
      if (!items.length) return;

      index = 0;
      for (var i = 0; i < items.length; i++) {
        if (items[i].el === startEl) { index = i; break; }
      }

      ensureElement();
      pushedHistory = false;
      closingFromPopstate = false;

      lb.classList.add('is-open');
      lb.setAttribute('aria-hidden', 'false');
      try { document.documentElement.classList.add('luxtools-noscroll'); } catch (e) {}
      try { document.body.style.overflow = 'hidden'; } catch (e) {}

      attachListeners();

      try {
        if (window.history && window.history.pushState) {
          window.history.pushState({ luxtoolsLightbox: 1 }, '', window.location.href);
          pushedHistory = true;
        }
      } catch (e) {}

      render();
    }

    function close() {
      if (!lb) return;

      lb.classList.remove('is-open');
      lb.setAttribute('aria-hidden', 'true');
      try { document.documentElement.classList.remove('luxtools-noscroll'); } catch (e) {}
      try { document.body.style.overflow = ''; } catch (e) {}
      img.src = '';
      resetZoom();

      detachListeners();

      if (pushedHistory && !closingFromPopstate) {
        try {
          if (window.history && window.history.state && window.history.state.luxtoolsLightbox === 1) {
            window.history.back();
          }
        } catch (e) {}
      }

      items = [];
    }

    return {
      open: open,
      close: close
    };
  })();
})();