Add search filter to the admin menu player tab (#28030)

Content.Client/UserInterface/Controls/SearchListContainer.cs

@@ -0,0 +1,68 @@
+using System.Linq;
+using Robust.Client.UserInterface.Controls;
+
+namespace Content.Client.UserInterface.Controls;
+
+public sealed class SearchListContainer : ListContainer
+{
+    private LineEdit? _searchBar;
+    private List<ListData> _unfilteredData = new();
+
+    /// <summary>
+    /// The <see cref="LineEdit"/> that is used to filter the list data.
+    /// </summary>
+    public LineEdit? SearchBar
+    {
+        get => _searchBar;
+        set
+        {
+            if (_searchBar is not null)
+                _searchBar.OnTextChanged -= FilterList;
+
+            _searchBar = value;
+
+            if (_searchBar is null)
+                return;
+
+            _searchBar.OnTextChanged += FilterList;
+        }
+    }
+
+    /// <summary>
+    /// Runs over the ListData to determine if it should pass the filter.
+    /// </summary>
+    public Func<string, ListData, bool>? DataFilterCondition = null;
+
+    public override void PopulateList(IReadOnlyList<ListData> data)
+    {
+        _unfilteredData = data.ToList();
+        FilterList();
+    }
+
+    private void FilterList(LineEdit.LineEditEventArgs obj)
+    {
+        FilterList();
+    }
+
+    private void FilterList()
+    {
+        var filterText = SearchBar?.Text;
+
+        if (DataFilterCondition is null || string.IsNullOrEmpty(filterText))
+        {
+            base.PopulateList(_unfilteredData);
+            return;
+        }
+
+        var filteredData = new List<ListData>();
+        foreach (var data in _unfilteredData)
+        {
+            if (!DataFilterCondition(filterText, data))
+                continue;
+
+            filteredData.Add(data);
+        }
+
+        base.PopulateList(filteredData);
+    }
+}