Enable reordering of websearches with drap and drop

Plugins/Flow.Launcher.Plugin.WebSearch/SettingsControl.xaml

@@ -52,6 +52,10 @@
             MouseDoubleClick="MouseDoubleClickItem"
             SelectedItem="{Binding Settings.SelectedSearchSource}"
             SizeChanged="ListView_SizeChanged"
+            PreviewMouseLeftButtonDown="ListView_PreviewMouseLeftButtonDown"
+            PreviewMouseMove="ListView_PreviewMouseMove"
+            AllowDrop="True"
+            Drop="ListView_Drop"
             Style="{StaticResource {x:Static GridView.GridViewStyleKey}}">
             <ListView.View>
                 <GridView>
@@ -68,7 +72,7 @@
                         </GridViewColumn.CellTemplate>
                     </GridViewColumn>
 
                     <!--  Margin="0 6" is a workaround to set this TextBlock to vertially center  -->
                     <GridViewColumn Width="135" Header="{DynamicResource flowlauncher_plugin_websearch_action_keyword}">
                         <GridViewColumn.CellTemplate>
                             <DataTemplate>
@@ -102,7 +106,7 @@
                         </GridViewColumn.CellTemplate>
                     </GridViewColumn>
 
                     <!--  CheckBox is vertially center by default  -->
                     <GridViewColumn Width="123" Header="{DynamicResource flowlauncher_plugin_websearch_private_mode_label}">
                         <GridViewColumn.CellTemplate>
                             <DataTemplate>

Plugins/Flow.Launcher.Plugin.WebSearch/SettingsControl.xaml.cs

@@ -1,7 +1,10 @@
-using System.Windows;
-using System.Windows.Controls;
+using System;
 using System.ComponentModel;
+using System.Windows;
+using System.Windows.Controls;
 using System.Windows.Data;
+using System.Windows.Input;
+using System.Windows.Media;
 
 namespace Flow.Launcher.Plugin.WebSearch
 {
@@ -12,6 +15,7 @@
     {
         private readonly Settings _settings;
         private readonly PluginInitContext _context;
+        private Point _dragStartPoint;
 
         public SettingsControl(PluginInitContext context, SettingsViewModel viewModel)
         {
@@ -163,5 +167,78 @@
             gView.Columns[3].Width = workingWidth * col4;
             gView.Columns[4].Width = workingWidth * col5;
         }
+
+        private void ListView_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
+        {
+            _dragStartPoint = e.GetPosition(null);
+        }
+
+        private void ListView_PreviewMouseMove(object sender, MouseEventArgs e)
+        {
+            Point mousePos = e.GetPosition(null);
+            Vector diff = _dragStartPoint - mousePos;
+
+            if (e.LeftButton == MouseButtonState.Pressed &&
+                (Math.Abs(diff.X) > SystemParameters.MinimumHorizontalDragDistance ||
+                 Math.Abs(diff.Y) > SystemParameters.MinimumVerticalDragDistance))
+            {
+                var listView = (ListView)sender;
+                ListViewItem listViewItem = FindAncestor<ListViewItem>((DependencyObject)e.OriginalSource);
+
+                if (listViewItem == null) return;
+
+                SearchSource item = (SearchSource)listView.ItemContainerGenerator.ItemFromContainer(listViewItem);
+                if (item == null) return;
+
+                DragDrop.DoDragDrop(listViewItem, item, DragDropEffects.Move);
+            }
+        }
+
+        private void ListView_Drop(object sender, DragEventArgs e)
+        {
+            if (e.Data.GetDataPresent(typeof(SearchSource)))
+            {
+                SearchSource droppedData = e.Data.GetData(typeof(SearchSource)) as SearchSource;
+                var listView = (ListView)sender;
+                var target = GetNearestContainer(e.OriginalSource);
+
+                if (target == null)
+                    return;
+
+                SearchSource targetData = (SearchSource)listView.ItemContainerGenerator.ItemFromContainer(target);
+
+                if (targetData == null)
+                    return;
+
+                var items = _settings.SearchSources;
+                int removedIdx = items.IndexOf(droppedData);
+                int targetIdx = items.IndexOf(targetData);
+
+                if (removedIdx == targetIdx)
+                    return;
+
+                items.Move(removedIdx, targetIdx);
+            }
+        }
+
+        private ListViewItem GetNearestContainer(object source)
+        {
+            var element = source as UIElement;
+            while (element != null && !(element is ListViewItem))
+                element = VisualTreeHelper.GetParent(element) as UIElement;
+
+            return element as ListViewItem;
+        }
+
+        private static T FindAncestor<T>(DependencyObject current) where T : DependencyObject
+        {
+            while (current != null)
+            {
+                if (current is T)
+                    return (T)current;
+                current = VisualTreeHelper.GetParent(current);
+            }
+            return null;
+        }
     }
 }