import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.HBox;
import javafx.stage.Stage;

public class DemoFX extends Application {
    
    // constants: placeholders (names) that hold a value
    //            once initialized, it cannot change
    //            naming convention is all CAPS, underscore between words
    //            keywords: static final
    public static final int APP_WIDTH  = 400;
    public static final int APP_HEIGHT = 300;
    
    // GUI variables
    private HBox   hbox;
    private Button bnOK, bnLeft, bnRight;
    
    // non-GUI, functional variables
    // note: global variables are initialized at declaration
    //       to a value as close to 0 as possible for the type
    //       boolean: false, numbers: 0, Object: null
    private int countOK;
    
    
    public void start(Stage stage) {
        
        setupLayout();
        setupButtons();
        
        Scene scene = new Scene(hbox, APP_WIDTH, APP_HEIGHT);
        
        stage.setScene(scene);
        stage.setTitle("CS112 Demo FX");
        stage.show();
    }
    
    private void setupLayout() {
        hbox = new HBox();
    }
    
    private void setupButtons() {
        bnOK = new Button("OK");
        countOK = 0;
        
        bnLeft = new Button("Left");
        
        bnRight = new Button("Right");
        
        // event listener: ActionEvent
        bnOK.setOnAction(e -> {
            ++countOK; 
            
            System.out.printf("OK clicked %d times\n", countOK);
        });
        
        bnLeft.setOnAction(e -> {
            System.out.printf("LEFT clicked\n");
        });
        
        bnRight.setOnAction(e -> {
            System.out.printf("RIGHT clicked\n");
        });
            
        
        // add buttons to hbox
        hbox.getChildren().addAll(bnLeft, bnOK, bnRight);
        
    }
    
    public static void main(String[] args) {
        launch(args);
    }

}