import javafx.application.Application;
import javafx.stage.Stage;
import javafx.scene.Scene;
import javafx.scene.layout.StackPane;
import javafx.scene.canvas.*;
import javafx.scene.paint.Color;
import javafx.animation.AnimationTimer;
import javafx.scene.input.KeyCode;

import java.util.*;

public class Primes extends Application{
	private static final int WIDTH = 800;
	private static final int HEIGHT = 600;
	private static final int FPS = 40;

	private int squareSize = 5;
	private int cameraX, cameraY;
	private HashMap<KeyCode, Boolean> keys = new HashMap<>();

	private int frames, fps;

	@Override
	public void start(Stage stage){
		StackPane pane = new StackPane();
		Canvas canvas = new Canvas(WIDTH, HEIGHT);
		pane.getChildren().add(canvas);
		GraphicsContext gc = canvas.getGraphicsContext2D();

		canvas.setOnScroll(e -> {
			if (e.getDeltaY() > 0){
				this.squareSize += 1;
			} else if (e.getDeltaY() < 0){
				this.squareSize -= 1;
			}

			this.squareSize = Math.min(150, Math.max(this.squareSize, 1));
		});

		canvas.setFocusTraversable(true);
		canvas.setOnKeyPressed(e -> this.keys.put(e.getCode(), true));
		canvas.setOnKeyReleased(e -> this.keys.put(e.getCode(), false));

		AnimationTimer timer = new AnimationTimer(){
			@Override
			public void handle(long time){
				update(gc);
				Primes.this.frames++;
				stage.setTitle("Prime numbers - FPS:"+Primes.this.fps); // Set FPS title
			}
		};
		timer.start();

		Thread fpsCounter = new Thread(() -> {
			while (true){
				try {
					this.fps = this.frames;
					this.frames = 0;
					Thread.sleep(1000);
				} catch (InterruptedException ex){
					ex.printStackTrace();
				}
			}
		});
		fpsCounter.setDaemon(true);
		fpsCounter.start();

		Scene scene = new Scene(pane, WIDTH, HEIGHT);
		stage.setScene(scene);
		stage.setResizable(false);
		stage.show();
	}

	private void update(GraphicsContext gc){
		gc.clearRect(0, 0, WIDTH, HEIGHT);
		gc.setFill(Color.BLACK);
		gc.fillRect(0, 0, WIDTH, HEIGHT);

		final int cameraSpeed = 4;
		if (this.keys.getOrDefault(KeyCode.W, false)){
			this.cameraY -= cameraSpeed;
			this.keys.put(KeyCode.W, false);
		} else if (this.keys.getOrDefault(KeyCode.A, false)){
			this.cameraX -= cameraSpeed;
			this.keys.put(KeyCode.A, false);
		} else if (this.keys.getOrDefault(KeyCode.S, false)){
			this.cameraY += cameraSpeed;
			this.keys.put(KeyCode.S, false);
		} else if (this.keys.getOrDefault(KeyCode.D, false)){
			this.cameraX += cameraSpeed;
			this.keys.put(KeyCode.D, false);
		} else if (this.keys.getOrDefault(KeyCode.ESCAPE, false)){
			System.exit(0);
		}
		
		for (int i = 0; i < WIDTH; i += squareSize){
			for (int j = 0; j < HEIGHT; j += squareSize){
				int xpos = i/squareSize+this.cameraX;
				int ypos = j/squareSize+this.cameraY;
				if (xpos < 0 || ypos < 0) continue;
				int id = xpos ^ ypos; //xpos+ypos*WIDTH;
				if (isPrime(id)){
					for (int x = 0; x < squareSize; x++){
						for (int y = 0; y < squareSize; y++){
							gc.getPixelWriter().setColor(i+x, j+y, getColor(id));
						}
					}
				}
			}
		}
	}

	private static Color getColor(int prime){
		Random random = new Random(prime);
		return Color.color(random.nextDouble(), random.nextDouble(), random.nextDouble());
	}

	private static boolean isPrime(int num){
		for (int i = 2; i <= Math.sqrt(num); i++){
			if (num % i == 0){
				return false;
			}
		}

		return true;
	}

	public static void main(String[] args){
		launch(args);
	}
}