Command refactor

app/src/main/java/chess/controller/commands/MoveCommand.java

@@ -25,6 +25,26 @@ public class MoveCommand extends PlayerCommand {
 
 	@Override
 	public CommandResult execute(Game game, GameListener outputSystem) {
+		CommandResult result = processMove(game, outputSystem);
+
+		switch (result) {
+			case NotAllowed:
+				outputSystem.onMoveNotAllowed(this.move);
+				return result;
+
+			case Moved:
+				outputSystem.onMove(this.move);
+				return result;
+
+			case ActionNeeded:
+			case NotMoved:
+				return result;
+		}
+
+		return null;
+	}
+
+	private CommandResult processMove(Game game, GameListener outputSystem) {
 		final ChessBoard board = game.getBoard();
 
 		// we must promote the pending pawn before
@@ -50,10 +70,12 @@ public class MoveCommand extends PlayerCommand {
 			return CommandResult.NotAllowed;
 		}
 
-		if (board.pawnShouldBePromoted())
+		if (tryPromote(game, outputSystem)) {
 			return CommandResult.ActionNeeded;
+		}
 
 		board.setLastMove(this.move);
+
 		return CommandResult.Moved;
 	}
 
@@ -65,18 +87,14 @@ public class MoveCommand extends PlayerCommand {
 		return CommandResult.Moved;
 	}
 
-	@Override
-	public void postExec(Game game, GameListener outputSystem) {
-		tryPromote(game, outputSystem);
-	}
-
-	private void tryPromote(Game game, GameListener outputSystem) {
+	private boolean tryPromote(Game game, GameListener outputSystem) {
 		Coordinate pawnPos = game.getBoard().pawnPromotePosition();
 
 		if (pawnPos == null)
-			return;
+			return false;
 
-		outputSystem.promotePawn(pawnPos);
+		outputSystem.onPromotePawn(pawnPos);
+		return true;
 	}
 
 }