Add client-side filtering to dashboard

Filter bar with Status, Brand, Size, Storage Location dropdowns and text
search. Select-all and bulk toolbar respect visible rows so users can filter
to a group (e.g. a storage location) and bulk-action them in one step.

templates/dashboard.html

@@ -43,6 +43,37 @@
     </div>
   </div>
 
+  <div id="filter-bar" style="display:flex;gap:0.5rem;flex-wrap:wrap;align-items:center;margin-bottom:0.75rem;">
+    <select id="filter-status" onchange="applyFilters()" style="padding:0.25rem 0.5rem;font-size:0.85rem;border:1px solid #cbd5e1;border-radius:4px;">
+      <option value="">All Statuses</option>
+      <option value="available">Available</option>
+      <option value="installed">Installed</option>
+      <option value="retired">Retired</option>
+    </select>
+    <select id="filter-brand" onchange="applyFilters()" style="padding:0.25rem 0.5rem;font-size:0.85rem;border:1px solid #cbd5e1;border-radius:4px;">
+      <option value="">All Brands</option>
+      {% for b in batteries|map(attribute='brand')|unique|sort %}
+      <option value="{{ b }}">{{ b }}</option>
+      {% endfor %}
+    </select>
+    <select id="filter-size" onchange="applyFilters()" style="padding:0.25rem 0.5rem;font-size:0.85rem;border:1px solid #cbd5e1;border-radius:4px;">
+      <option value="">All Sizes</option>
+      {% for s in batteries|map(attribute='size')|select|unique|sort %}
+      <option value="{{ s }}">{{ s }}</option>
+      {% endfor %}
+    </select>
+    <select id="filter-storage" onchange="applyFilters()" style="padding:0.25rem 0.5rem;font-size:0.85rem;border:1px solid #cbd5e1;border-radius:4px;">
+      <option value="">All Locations</option>
+      {% for loc in storage_locations %}
+      <option value="{{ loc }}">{{ loc }}</option>
+      {% endfor %}
+    </select>
+    <input type="text" id="filter-text" oninput="applyFilters()" placeholder="Search…"
+           style="padding:0.25rem 0.5rem;font-size:0.85rem;border:1px solid #cbd5e1;border-radius:4px;width:140px;">
+    <button type="button" onclick="resetFilters()" class="btn btn-sm btn-secondary" id="filter-reset" style="display:none;">✕ Reset</button>
+    <span id="filter-count" style="font-size:0.8rem;color:#64748b;"></span>
+  </div>
+
   <form method="post" action="{{ url_for('battery_bulk_action') }}" id="bulk-form">
 
     <div id="bulk-toolbar" style="display:none;margin-bottom:0.75rem;padding:0.6rem 0.75rem;background:#f1f5f9;border-radius:6px;display:none;align-items:center;gap:0.5rem;flex-wrap:wrap;">
@@ -104,7 +135,7 @@
         </thead>
         <tbody>
           {% for b in batteries %}
-          <tr>
+          <tr data-brand="{{ b.brand }}" data-size="{{ b.size or '' }}" data-status="{{ b.status }}" data-storage="{{ b.storage_location or '' }}">
             <td><input type="checkbox" name="battery_ids" value="{{ b.id }}" class="row-cb"></td>
             <td><a href="{{ url_for('battery_detail', battery_id=b.id) }}"><strong>{{ b.label }}</strong></a></td>
             <td>{{ b.brand }}</td>
@@ -161,27 +192,70 @@
 </div>
 
 <script>
-(function () {
+var selectAll = document.getElementById('select-all');
-  var cbs = document.querySelectorAll('.row-cb');
+var toolbar = document.getElementById('bulk-toolbar');
-  var selectAll = document.getElementById('select-all');
+var countEl = document.getElementById('selected-count');
-  var toolbar = document.getElementById('bulk-toolbar');
-  var countEl = document.getElementById('selected-count');
 
-  function updateToolbar() {
+function visibleCbs() {
-    var checked = document.querySelectorAll('.row-cb:checked');
+  return Array.prototype.filter.call(
-    var n = checked.length;
+    document.querySelectorAll('.row-cb'),
-    toolbar.style.display = n > 0 ? 'flex' : 'none';
+    function(cb) { return cb.closest('tr').style.display !== 'none'; }
-    countEl.textContent = n + ' selected';
+  );
-    selectAll.indeterminate = n > 0 && n < cbs.length;
+}
-    selectAll.checked = cbs.length > 0 && n === cbs.length;
-  }
 
-  cbs.forEach(function (cb) { cb.addEventListener('change', updateToolbar); });
+function updateToolbar() {
-  selectAll.addEventListener('change', function () {
+  var checked = document.querySelectorAll('.row-cb:checked');
-    cbs.forEach(function (cb) { cb.checked = selectAll.checked; });
+  var vis = visibleCbs();
-    updateToolbar();
+  var n = checked.length;
+  toolbar.style.display = n > 0 ? 'flex' : 'none';
+  countEl.textContent = n + ' selected';
+  var visChecked = vis.filter(function(cb) { return cb.checked; });
+  selectAll.indeterminate = visChecked.length > 0 && visChecked.length < vis.length;
+  selectAll.checked = vis.length > 0 && visChecked.length === vis.length;
+}
+
+document.querySelectorAll('.row-cb').forEach(function(cb) {
+  cb.addEventListener('change', updateToolbar);
+});
+selectAll.addEventListener('change', function() {
+  visibleCbs().forEach(function(cb) { cb.checked = selectAll.checked; });
+  updateToolbar();
+});
+
+function applyFilters() {
+  var status  = document.getElementById('filter-status').value;
+  var brand   = document.getElementById('filter-brand').value;
+  var size    = document.getElementById('filter-size').value;
+  var storage = document.getElementById('filter-storage').value;
+  var text    = document.getElementById('filter-text').value.trim().toLowerCase();
+  var anyActive = status || brand || size || storage || text;
+  document.getElementById('filter-reset').style.display = anyActive ? '' : 'none';
+
+  var rows = document.querySelectorAll('tbody tr[data-brand]');
+  var visible = 0;
+  rows.forEach(function(row) {
+    var show = true;
+    if (status  && row.dataset.status  !== status)  show = false;
+    if (brand   && row.dataset.brand   !== brand)   show = false;
+    if (size    && row.dataset.size    !== size)     show = false;
+    if (storage && row.dataset.storage !== storage)  show = false;
+    if (text    && row.textContent.toLowerCase().indexOf(text) === -1) show = false;
+    row.style.display = show ? '' : 'none';
+    if (show) visible++;
   });
-}());
+
+  var fc = document.getElementById('filter-count');
+  fc.textContent = anyActive ? (visible + ' of ' + rows.length + ' shown') : '';
+  updateToolbar();
+}
+
+function resetFilters() {
+  ['filter-status','filter-brand','filter-size','filter-storage'].forEach(function(id) {
+    document.getElementById(id).value = '';
+  });
+  document.getElementById('filter-text').value = '';
+  applyFilters();
+}
 
 function updateBulkField(sel) {
   var field = sel.value;