Help playing 16-puzzle.

How to play the 16-puzzle is not
exactly obvious. Notify the user
by an hopefully helpful message,
if it looks like he is searching
how to play (bad click or keys).

src/base-window.vala

@@ -491,7 +491,7 @@ private class BaseWindow : AdaptativeWindow, AdaptativeWidget
     * * notifications
     \*/
 
-    protected void show_notification (string notification)
+    internal void show_notification (string notification)
     {
         main_view.show_notification (notification);
     }

src/game-window.vala

@@ -128,12 +128,6 @@ private class GameWindow : BaseWindow, AdaptativeWidget
     * * Some public calls
     \*/
 
-    internal void cannot_move ()
-    {
-        /* Translators: notification, as a subtitle of the headerbar; on the 15-Puzzle game, if the user clicks a tile that cannot move */
-        show_notification (_("You can’t move this tile!"));
-    }
-
     internal void move (uint moves_count)
     {
         headerbar.set_moves_count (ref moves_count);

src/taquin-game.vala

@@ -56,8 +56,14 @@ public class Game : Object
     /* signals */
     public signal void complete ();
     public signal void move (bool x_axis, int number, int x_gap, int y_gap, uint moves_count, bool disable_animation);
-    public signal void empty_tile ();
-    public signal void cannot_move (int x, int y);
+    public signal void bad_click (BadClick reason, bool keyboard_call);
+
+    public enum BadClick {
+        EMPTY_TILE,
+        NOT_MOVING,
+        IS_OUTSIDE,
+        USE_ARROWS;
+    }
 
     /*\
     * * Creation / exporting
@@ -131,31 +137,43 @@ public class Game : Object
     * * Game code
     \*/
 
-    public void request_move (int x, int y)
+    public void request_move (int x, int y, bool keyboard_call)
     {
         if (game_type == GameType.FIFTEEN)
+        {
+            if (x < 0 || x >= size || y < 0 || y >= size)
+            {
+                bad_click (BadClick.IS_OUTSIDE, keyboard_call);
+                return;
+            }
+            if (x == x_gap && y == y_gap)
+            {
+                bad_click (BadClick.EMPTY_TILE, keyboard_call);
+                return;
+            }
+            if (x != x_gap && y != y_gap)
+            {
+                bad_click (BadClick.NOT_MOVING, keyboard_call);
+                return;
+            }
             fifteen_move (x, y, /* undoing */ false);
+        }
         else
+        {
+            // TODO real touch support
+            if (x >= 0 && x < size && y >= 0 && y < size)
+            {
+                bad_click (BadClick.USE_ARROWS, keyboard_call);
+                return;
+            }
             sixteen_move (x, y, /* undoing */ false);
+        }
     }
 
     private void fifteen_move (int x, int y, bool undoing = false, bool restarting = false)
         requires (!restarting || undoing)
+        requires ((x >= 0) && (x < size) && (y >= 0) && (y < size))
     {
-        if (x < 0 || x >= size || y < 0 || y >= size)
-            return;
-
-        if (x == x_gap && y == y_gap)
-        {
-            empty_tile ();
-            return;
-        }
-        if (x != x_gap && y != y_gap)
-        {
-            cannot_move (x, y);
-            return;
-        }
-
         /* we do the move before notifying */
         bool was_complete = check_complete ();
 
@@ -193,11 +211,8 @@ public class Game : Object
 
     private void sixteen_move (int x, int y, bool undoing = false, bool restarting = false)
         requires (!restarting || undoing)
+        requires ((x < 0) || (x >= size) || (y < 0) || (y >= size))
     {
-        /* TODO touch */
-        if (x >= 0 && x < size && y >= 0 && y < size)
-            return;
-
         var move_x_axis = false;
         if (x < 0 || x >= size)
         {

src/taquin-main.vala

@@ -249,6 +249,7 @@ private class Taquin : Gtk.Application, BaseApplication
         game = new Game (type, size);
         view.game = (!) game;
         window.move (0);
+        move_done = false;
 
         string filename = "";
         var dirlist = theme_dirlist.copy ();
@@ -263,7 +264,7 @@ private class Taquin : Gtk.Application, BaseApplication
         view.realize ();        // TODO does that help?
 
         ((!) game).complete.connect (game_complete_cb);
-        ((!) game).cannot_move.connect (window.cannot_move);
+        ((!) game).bad_click.connect (bad_click_cb);
         ((!) game).move.connect (move_cb);
     }
 
@@ -276,6 +277,7 @@ private class Taquin : Gtk.Application, BaseApplication
     {
         ((!) game).restart ();
         play_sound ("sliding-n");
+        move_done = false;
     }
 
     private void undo_cb ()
@@ -293,6 +295,7 @@ private class Taquin : Gtk.Application, BaseApplication
     {
         window.move (moves_count);
         play_sound ("sliding-1");       // TODO sliding-n??
+        move_done = true;
     }
 
     private void game_complete_cb ()
@@ -301,6 +304,37 @@ private class Taquin : Gtk.Application, BaseApplication
         play_sound ("gameover");
     }
 
+    private bool move_done = false;
+    private void bad_click_cb (Game.BadClick reason, bool keyboard_call)
+    {
+        switch (reason)
+        {
+            case Game.BadClick.NOT_MOVING:
+                /* Translators: in-window notification; on the 15-Puzzle game, if the user clicks a tile that cannot move */
+                window.show_notification (_("You can’t move this tile!"));
+                return;
+
+            case Game.BadClick.USE_ARROWS:
+                if (move_done)  // do nothing if a move has already been done, a bad click or key press happens; reset on next game
+                    return;
+
+                if (keyboard_call)
+                    /* Translators: in-window notification; on the 16-Puzzle game, help for keyboard use, displayed if the user uses an unmeaningful keyboard key */
+                    window.show_notification (_("Use Shift and an arrow to move tiles!"));
+
+                else
+                    /* Translators: in-window notification; on the 16-Puzzle game, if the user clicks on a tile of the board (the game is played using mouse with arrows around the board) */
+                    window.show_notification (_("Click on the arrows to move tiles!"));
+
+                return;
+
+            case Game.BadClick.IS_OUTSIDE:  // TODO something?
+            case Game.BadClick.EMPTY_TILE:  // TODO something?
+            default:
+                return;
+        }
+    }
+
     /*\
     * * Options of the start-screen
     \*/

src/taquin-view.vala

@@ -482,7 +482,8 @@ public class TaquinView : Gtk.DrawingArea
         {
             draw_lights = false;
             game.request_move ((int) (event.x - x_offset - grid_border_main + tile_size) / tile_size - 1,
-                               (int) (event.y - y_offset - grid_border_main + tile_size) / tile_size - 1);
+                               (int) (event.y - y_offset - grid_border_main + tile_size) / tile_size - 1,
+                               /* keyboard */ false);
         }
         return true;
     }
@@ -496,16 +497,16 @@ public class TaquinView : Gtk.DrawingArea
         if (game.game_type == GameType.SIXTEEN && ((event.state & ModifierType.SHIFT_MASK) > 0 || (event.state & ModifierType.CONTROL_MASK) > 0))
         {
             switch (k_name) {
-                case "Left":  game.request_move (- 1, y_arrow);       break;
-                case "Right": game.request_move (game.size, y_arrow); break;
-                case "Up":    game.request_move (x_arrow, - 1);       break;
-                case "Down":  game.request_move (x_arrow, game.size); break;
+                case "Left":  game.request_move (- 1,       y_arrow,    /* keyboard */ true); break;
+                case "Right": game.request_move (game.size, y_arrow,    /* keyboard */ true); break;
+                case "Up":    game.request_move (x_arrow,   - 1,        /* keyboard */ true); break;
+                case "Down":  game.request_move (x_arrow,   game.size,  /* keyboard */ true); break;
                 default: return false;
             }
         }
         if (k_name == "space" || k_name == "KP_Enter" || k_name == "Return")        // TODO even if game.game_type == GameType.SIXTEEN ??
         {
-            game.request_move (x_arrow, y_arrow);
+            game.request_move (x_arrow, y_arrow, /* keyboard */ true);
             return true;
         }
         switch (k_name) {