fix(admin): fix rescan goroutine lifecycle and race on shared ScanProgress

- Protect adminService scan state (cancel func + progress pointer) with sync.Mutex.
- Allocate fresh ScanProgress per trigger and pass it to the scanner,
  eliminating races on the previously shared progress struct.
- Cancel previous scan context before starting a new one.
- Add tests for cancellation, fresh progress per scan, concurrent triggers,
  and empty progress when never started.
- Fix race-prone tests by polling Running==true before waiting for completion.

1 files changed, 181 insertions, 0 deletions

diff --git a/web/js/lightbox.js b/web/js/lightbox.js
new file mode 100644
index 0000000..876f456
--- /dev/null
+++ b/web/js/lightbox.js
@@ -0,0 +1,181 @@
+let currentMediaList = [];
+let currentIndex = -1;
+let zoomScale = 1;
+let panX = 0;
+let panY = 0;
+let isPanning = false;
+let panStart = { x: 0, y: 0 };
+let slideshowTimer = null;
+let slideshowPausedUntil = 0;
+let onNavigateCallback = null;
+
+export function initLightbox({ onNavigate }) {
+  onNavigateCallback = onNavigate;
+
+  document.getElementById('lb-close')?.addEventListener('click', close);
+  document.getElementById('lb-prev')?.addEventListener('click', prev);
+  document.getElementById('lb-next')?.addEventListener('click', next);
+  document.getElementById('lb-zoom-in')?.addEventListener('click', zoomIn);
+  document.getElementById('lb-zoom-out')?.addEventListener('click', zoomOut);
+  document.getElementById('lb-slideshow')?.addEventListener('click', toggleSlideshow);
+
+  // Close on backdrop click (clicking outside the image/toolbar)
+  document.getElementById('image-lightbox')?.addEventListener('click', (e) => {
+    if (e.target === e.currentTarget) close();
+  });
+
+  const img = document.getElementById('lightbox-image');
+  if (img) {
+    img.addEventListener('mousedown', (e) => {
+      if (zoomScale > 1) {
+        isPanning = true;
+        panStart = { x: e.clientX - panX, y: e.clientY - panY };
+        img.style.cursor = 'grabbing';
+        e.preventDefault();
+      }
+    });
+    img.addEventListener('wheel', (e) => {
+      e.preventDefault();
+      if (e.deltaY < 0) zoomIn();
+      else zoomOut();
+    }, { passive: false });
+  }
+  window.addEventListener('mousemove', (e) => {
+    if (!isPanning) return;
+    panX = e.clientX - panStart.x;
+    panY = e.clientY - panStart.y;
+    applyTransform();
+  });
+  window.addEventListener('mouseup', () => {
+    if (isPanning) {
+      isPanning = false;
+      const img = document.getElementById('lightbox-image');
+      if (img) img.style.cursor = zoomScale > 1 ? 'grab' : 'zoom-in';
+    }
+  });
+}
+
+export function open(mediaArray, startMediaId) {
+  currentMediaList = mediaArray.filter((m) => m.type === 'image');
+  currentIndex = currentMediaList.findIndex((m) => m.id === startMediaId);
+  if (currentIndex === -1) currentIndex = 0;
+  render();
+  document.getElementById('image-lightbox')?.classList.add('open');
+}
+
+export function close() {
+  stopSlideshow();
+  document.getElementById('image-lightbox')?.classList.remove('open');
+  resetZoom();
+  currentMediaList = [];
+  currentIndex = -1;
+}
+
+export function isOpen() {
+  return document.getElementById('image-lightbox')?.classList.contains('open');
+}
+
+export function next() {
+  if (!currentMediaList.length) return;
+  currentIndex = (currentIndex + 1) % currentMediaList.length;
+  render();
+  pauseSlideshow();
+}
+
+export function prev() {
+  if (!currentMediaList.length) return;
+  currentIndex = (currentIndex - 1 + currentMediaList.length) % currentMediaList.length;
+  render();
+  pauseSlideshow();
+}
+
+export function zoomIn() {
+  setZoom(zoomScale * 1.25);
+  pauseSlideshow();
+}
+
+export function zoomOut() {
+  setZoom(zoomScale / 1.25);
+  pauseSlideshow();
+}
+
+export function toggleSlideshow() {
+  if (slideshowTimer) stopSlideshow();
+  else startSlideshow();
+}
+
+export function isSlideshowActive() {
+  return !!slideshowTimer;
+}
+
+function render() {
+  const media = currentMediaList[currentIndex];
+  const img = document.getElementById('lightbox-image');
+  const meta = document.getElementById('lb-meta');
+  const counter = document.getElementById('lb-counter');
+  if (!media || !img) return;
+  img.src = `/api/media/${media.id}/stream`;
+  resetZoom();
+  if (meta) {
+    const size = media.file_size_bytes ? fmtSize(media.file_size_bytes) : '';
+    const res = media.resolution || '';
+    meta.textContent = `${media.file_name}${res ? ' — ' + res : ''}${size ? ' — ' + size : ''}`;
+  }
+  if (counter) {
+    counter.textContent = `${currentIndex + 1} / ${currentMediaList.length}`;
+  }
+}
+
+function setZoom(s) {
+  zoomScale = Math.max(0.5, Math.min(s, 5));
+  applyTransform();
+}
+
+function applyTransform() {
+  const img = document.getElementById('lightbox-image');
+  if (!img) return;
+  img.style.transform = `translate(${panX}px, ${panY}px) scale(${zoomScale})`;
+  img.style.cursor = zoomScale > 1 ? 'grab' : 'zoom-in';
+}
+
+function resetZoom() {
+  zoomScale = 1;
+  panX = 0;
+  panY = 0;
+  applyTransform();
+}
+
+function startSlideshow() {
+  if (slideshowTimer) clearInterval(slideshowTimer);
+  slideshowTimer = setInterval(() => {
+    if (Date.now() < slideshowPausedUntil) return;
+    if (!isOpen()) { stopSlideshow(); return; }
+    next();
+  }, 5000);
+  const btn = document.getElementById('lb-slideshow');
+  if (btn) btn.textContent = '⏸';
+}
+
+function stopSlideshow() {
+  clearInterval(slideshowTimer);
+  slideshowTimer = null;
+  const btn = document.getElementById('lb-slideshow');
+  if (btn) btn.textContent = '⏵';
+}
+
+function pauseSlideshow() {
+  slideshowPausedUntil = Date.now() + 10000;
+}
+
+function fmtSize(bytes) {
+  if (!bytes || bytes <= 0) return '';
+  const kb = bytes / 1024;
+  if (kb < 1024) return Math.round(kb) + ' KB';
+  const mb = kb / 1024;
+  if (mb < 1024) return Math.round(mb * 10) / 10 + ' MB';
+  return Math.round((mb / 1024) * 10) / 10 + ' GB';
+}
+
+function escapeHtml(s) {
+  return (s ?? '').replace(/[&<>"']/g, (c) => ({ '&': '&amp;', '<': '&lt;', '>': '&gt;', '"': '&quot;', "'": '&#39;' }[c]));
+}