//
// Sep-27 Fri: basic GUI frame for GalleryApp, 
//             can load images, use prev/next buttons to navigate images
//
// Sep-30 Mon: animate through the images using Timeline (KeyFrame, Duration, Animation)
//             prev() and next() methods for modular design
//             HBox as control panel with play/stop buttons 

import javafx.animation.Animation;
import javafx.animation.KeyFrame;
import javafx.animation.Timeline;
import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.HBox;
import javafx.stage.Stage;
import javafx.util.Duration;

public class GalleryApp extends Application {
    
    public static final int APP_WIDTH  = 500;
    public static final int APP_HEIGHT = 600;
    public static final int N_IMAGES   =  30;
    public static final double INTERVAL= 0.5;  // seconds
    
    private BorderPane  mainPane;
    private HBox        hbox;
    private Button      bnPrev, bnNext;
    private Button      bnPlay, bnStop;
    private Label       lbImage;
    private Image[]     imgArray;
    private ImageView[] ivArray;
    
    private Timeline    timeline;
    
    private int currentIndex;
    
    @Override
    public void start(Stage stage) {
        
        setupImages();
        setupPane();
        setupControls();
        setupControlPanel();
        setupTimeline();
        
        Scene scene = new Scene(mainPane, APP_WIDTH, APP_HEIGHT);
        
        // stage setup: title, scene, show
        stage.setTitle("CS112 F24 GalleryApp");
        stage.setScene(scene);
        
        stage.show();
    }
    
    private void setupControlPanel() {
        hbox = new HBox();  // TODO: improve visual
        
        bnPlay = new Button("Play");
        bnStop = new Button("Stop");
        
        bnPlay.setOnAction(e -> {
            timeline.play(); 
        });
        
        bnStop.setOnAction(e -> {
            timeline.stop();
        });
        
        hbox.getChildren().addAll(bnPlay, bnStop);
        
        mainPane.setTop(hbox);
    }
    
    private void setupTimeline() {
        KeyFrame frame = new KeyFrame(Duration.seconds(INTERVAL), 
                                      e -> { next(); });
        
        timeline = new Timeline(frame);
        timeline.setCycleCount(Animation.INDEFINITE);
    }
    
    private void setupImages() {
        
        imgArray = new Image[N_IMAGES];
        ivArray  = new ImageView[N_IMAGES];
        
        String prefix = "file:f";
        
        for (int i = 0; i < N_IMAGES; ++i) {
            String fname = prefix + (i + 1) + ".png";
            imgArray[i] = new Image(fname);
            ivArray[i]  = new ImageView(imgArray[i]);
        }
        
        // Q. do we need imgArray (Image[])
    }
    
    private void setupPane() {
        mainPane = new BorderPane();
    }
    
    private void setupControls() {
        lbImage = new Label(); // Label("Text"); Label(imgView)
        lbImage.setGraphic(ivArray[currentIndex]);
        
        bnPrev = new Button("<");
        bnNext = new Button(">");
        
        bnPrev.setPrefHeight(APP_HEIGHT);
        bnNext.setPrefHeight(APP_HEIGHT);
        
        // action listener
        bnPrev.setOnAction(e -> {            
            prev();            
        });
        
        bnNext.setOnAction(e -> {                    
            next();
        });
        
        mainPane.setCenter(lbImage);
        mainPane.setLeft(bnPrev);
        mainPane.setRight(bnNext);
    }

    private void prev() {
        --currentIndex;    
        
        // wrap-around
        if (currentIndex < 0) {
            currentIndex = N_IMAGES - 1;
        }
        
        lbImage.setGraphic(ivArray[currentIndex]);
    }
    
    private void next() {

        ++currentIndex;
        
        // wrap-around
        if (currentIndex == N_IMAGES) {
            currentIndex = 0;
        }
        
        lbImage.setGraphic(ivArray[currentIndex]);
    }
    
    public static void main(String[] args) {
        launch(args);
    }

}