fix drag and drop

resources/play_queue_song.blp

@@ -3,10 +3,10 @@ using Gtk 4.0;
 template $AudreyUiPlayQueueSong: Box {
   height-request: 48;
   spacing: 12;
-  margin-start: 6;
-  margin-end: 6;
 
   Box {
+    margin-start: 6;
+
     width-request: 36;
     focusable: false;
     homogeneous: true;
@@ -116,6 +116,7 @@ template $AudreyUiPlayQueueSong: Box {
     valign: center;
   }
 
+  Box {
     MenuButton {
       // visible: false;
       focusable: true;
@@ -132,6 +133,9 @@ template $AudreyUiPlayQueueSong: Box {
       };
     }
 
+    margin-end: 6;
+  }
+
   DragSource {
     actions: move;
     propagation-phase: capture;

resources/style.css

@@ -19,6 +19,11 @@
   min-height: 15px;
 }
 
+/* make drag and drop indicator take up entire perimeter */
+#play-queue listview row {
+  padding: 0;
+}
+
 #play-queue .playing label.title {
   font-weight: bold;
 }

src/ui/play_queue/song.rs

@@ -112,8 +112,7 @@ mod imp {
         fn on_drag_prepare(&self, x: f64, y: f64) -> Option<gdk::ContentProvider> {
             if self.draggable.get() {
                 self.drag_pos.replace((x as i32, y as i32));
-                let value = self.obj().to_value();
-                Some(gdk::ContentProvider::for_value(&value))
+                Some(gdk::ContentProvider::for_value(&self.obj().to_value()))
             } else {
                 None
             }
@@ -122,6 +121,7 @@ mod imp {
         #[template_callback]
         fn on_drag_begin(&self, drag: &gdk::Drag) {
             let drag_widget = gtk::ListBox::new();
+            drag_widget.add_css_class("boxed-list");
 
             let drag_row: super::Song = glib::Object::new();
             drag_row.set_draggable(false);
@@ -148,19 +148,23 @@ mod imp {
         }
 
         #[template_callback]
-        fn on_drop(&self, _value: glib::Value, _x: f64, _y: f64) -> bool {
-            /* FIXME: WrongValueType(ValueTypeMismatchError { actual: GValue, requested: AudreyUiPlayQueueSong })
+        // why BoxedValue? see https://discourse.gnome.org/t/gtk-rs-passing-widget-as-gvalue-through-drag-and-drop-with-composite-template/16449/2
+        fn on_drop(&self, value: glib::BoxedValue, _x: f64, _y: f64) -> bool {
             let source: super::Song = value.get().unwrap();
 
             source.imp().drag_widget.set(None);
 
-            self.obj().playbin().move_track(
-                source.displayed_position() - 1,
-                self.obj().displayed_position() - 1,
-            );
+            let from = source.position();
+            let to = self.obj().position();
 
-            true */
-            false
+            // see playlist_move for justification
+            if from < to {
+                self.obj().window().playlist_move(from, to + 1);
+            } else {
+                self.obj().window().playlist_move(from, to);
+            }
+
+            true
         }
 
         fn set_playlist_pos(&self, playlist_pos: i32) {

src/ui/window.rs

@@ -627,4 +627,39 @@ impl Window {
             }
         }
     }
+
+    pub fn playlist_move(&self, from: u32, to: u32) {
+        // NOTE: for mpv, to refers to the "gap" right before i
+        // so playlist-move i 0 makes a track the first
+        // playlist-move i 1 makes a track the second
+        // and playlist-move i playlist-count makes a track the last
+        // (so if to is the position of another track, from is left behind to)
+        self.imp()
+            .mpv
+            .command(["playlist-move", &from.to_string(), &to.to_string()])
+            .unwrap();
+
+        if from < to {
+            // F1234T -> 1234FT
+            let mut spliced = Vec::with_capacity((to - from) as usize);
+            for i in from + 1..to {
+                spliced.push(self.playlist_model().item(i).unwrap());
+            }
+            spliced.push(self.playlist_model().item(from).unwrap());
+
+            self.playlist_model()
+                .splice(from, spliced.len() as u32, &spliced);
+        } else if to < from {
+            // T1234F -> FT1234
+            let mut spliced = Vec::with_capacity((from - to + 1) as usize);
+            spliced.push(self.playlist_model().item(from).unwrap());
+            spliced.push(self.playlist_model().item(to).unwrap());
+            for i in to + 1..from {
+                spliced.push(self.playlist_model().item(i).unwrap());
+            }
+
+            self.playlist_model()
+                .splice(to, spliced.len() as u32, &spliced);
+        }
+    }
 }