feat: display score & game over, code cleanup

src/main/java/eu/midnightdust/yaytris/Tetris.java

@@ -1,17 +1,20 @@
 package eu.midnightdust.yaytris;
 
 import eu.midnightdust.yaytris.game.Space;
+import eu.midnightdust.yaytris.ui.ScoreMenu;
 import eu.midnightdust.yaytris.ui.TetrisUI;
 
 import javax.swing.*;
 import java.util.Random;
 import java.util.Timer;
+import java.util.TimerTask;
 
 public class Tetris {
     public static final Random random = new Random();
-    public static Space space;
-    public static Timer timer;
-    public static TetrisUI ui;
+    private static Space space;
+    private static Timer timer;
+    private static TetrisUI ui;
+    private static TimerTask gravityTask;
 
     public static void main(String[] args) {
         try {
@@ -23,4 +26,35 @@ public class Tetris {
         space = new Space();
         ui = new TetrisUI();
     }
+
+    public static TetrisUI getUi() {
+        return ui;
+    }
+
+    public static Space getSpace() {
+        return space;
+    }
+
+    public static void resetSpace() {
+        space = new Space();
+    }
+
+    public static void startGame() {
+        space.spawnTetromino();
+        gravityTask = new TimerTask() {
+            @Override
+            public void run() {
+                if (space.getCurrentTetromino() != null) {
+                    space.getCurrentTetromino().fall(1);
+                    ui.getGamePanel().repaint();
+                }
+            }
+        };
+        timer.scheduleAtFixedRate(gravityTask, 1, Settings.difficulty.getTimerPeriod());
+    }
+    public static void stopGame() {
+        gravityTask.cancel();
+        if (ui.getMenuPanel() instanceof ScoreMenu) ((ScoreMenu) Tetris.ui.getMenuPanel()).gameOver();
+        ui.transferFocus();
+    }
 }