queue/Playlist: move code to MoveOrderToCurrent()

src/queue/Playlist.hxx

@@ -356,6 +356,18 @@ public:
 	}
 
 	void SetConsume(bool new_value);
+
+private:
+	/**
+	 * Prepare a manual song change: move the given song to the
+	 * current playback order.  This is done to avoid skipping
+	 * upcoming songs in the order list.  The newly selected song
+	 * shall be inserted in the order list, and the rest shall be
+	 * played after that as previously planned.
+	 *
+	 * @return the new order number of the given song
+	 */
+	unsigned MoveOrderToCurrent(unsigned old_order);
 };
 
 #endif

src/queue/PlaylistControl.cxx

@@ -56,6 +56,24 @@ playlist::Stop(PlayerControl &pc)
 	}
 }
 
+unsigned
+playlist::MoveOrderToCurrent(unsigned old_order)
+{
+	if (!queue.random)
+		/* no-op because there is no order list */
+		return old_order;
+
+	const unsigned destination_order = playing
+		? (unsigned)current
+		: 0;
+
+	/* swap the new song with the previous "current" one, so
+	   playback continues as planned */
+	queue.SwapOrders(old_order, destination_order);
+
+	return destination_order;
+}
+
 void
 playlist::PlayPosition(PlayerControl &pc, int song)
 {
@@ -90,13 +108,7 @@ playlist::PlayPosition(PlayerControl &pc, int song)
 			   number, because random mode is enabled */
 			i = queue.PositionToOrder(song);
 
-		if (!playing)
+		i = MoveOrderToCurrent(i);
-			current = 0;
-
-		/* swap the new song with the previous "current" one,
-		   so playback continues as planned */
-		queue.SwapOrders(i, current);
-		i = current;
 	}
 
 	stop_on_error = false;