package sample;

import javafx.event.EventHandler;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.canvas.Canvas;
import javafx.scene.canvas.GraphicsContext;
import javafx.scene.image.PixelWriter;
import javafx.scene.input.KeyCode;
import javafx.scene.input.KeyEvent;
import javafx.scene.input.MouseEvent;
import javafx.scene.paint.Color;

import java.net.URL;
import java.util.ResourceBundle;

public class Controller implements Initializable {

    private GraphicsContext gc;
    private PixelWriter pw;

    //параметры окружности
    private int x = 100;
    private int y = 100;
    private int angle = 90;

    @FXML
    private Canvas canvas = new Canvas();

    private void clear() {
        gc.setFill(Color.WHITE);
        gc.fillRect(0, 0, canvas.getWidth(), canvas.getHeight());
    }

    private void update() {
        clear();
        gc.setFill(Color.BLACK);
        int r = 50;
        drawPie(x, y, r, angle);
        gc.fill();
        gc.stroke();
    }

    private void drawPixel(int x, int y) {
        pw.setColor(x, y, Color.BLACK);
    }

    private void drawPie(int x0, int y0, int r, double angle) {
        //проверяем, что угол корректный
        if (angle < 0 || angle > 360)
            throw new IllegalArgumentException();

        double small_angle = angle < 180 ? angle : 360 - angle;
        int sx = (int) (r * Math.sin(small_angle * Math.PI / 360));
        int sy = (int) (r * Math.cos(small_angle * Math.PI / 360));

        int x = 0;
        int y = r;

        if (angle != 360 && angle != 0) {
            gc.strokeLine(x0, y0, x0 + sx, y0 + sy);
            gc.strokeLine(x0, y0, x0 - sx, y0 + sy);
        }

        int delta = 1 - 2 * r;
        int error = 0;

        while (y >= 0) {
            if (angle < 180) {
                if (y >= sy) {
                    drawPixel(x0 + x, y0 + y);
                    drawPixel(x0 - x, y0 + y);
                }
                if (-y >= sy) {
                    drawPixel(x0 + x, y0 - y);
                    drawPixel(x0 - x, y0 - y);
                }
            } else {
                if (y <= sy) {
                    drawPixel(x0 + x, y0 + y);
                    drawPixel(x0 - x, y0 + y);
                }
                if (-y <= sy) {
                    drawPixel(x0 + x, y0 - y);
                    drawPixel(x0 - x, y0 - y);
                }
            }

            error = 2 * (delta + y) - 1;

            if ((delta < 0) && (error <= 0)) {
                delta += 2 * ++x + 1;
                continue;
            }
            if ((delta > 0) && (error > 0)) {
                delta -= 2 * --y + 1;
                continue;
            }
            delta += 2 * (++x - y--);
        }
    }

    @Override
    public void initialize(URL url, ResourceBundle resourceBundle) {
        gc = canvas.getGraphicsContext2D();
        pw = gc.getPixelWriter();

        canvas.setFocusTraversable(true);

        canvas.setOnMouseReleased(new EventHandler<MouseEvent>() {
            @Override
            public void handle(MouseEvent mouseEvent) {
                System.out.print(x + " ");
                System.out.println(y);
                x = (int) mouseEvent.getX();
                y = (int) mouseEvent.getY();
                update();
            }
        });

        canvas.setOnKeyPressed(new EventHandler<KeyEvent>() {

            @Override
            public void handle(KeyEvent event) {
                System.out.println(event.getCode());
                if (event.getCode() == KeyCode.EQUALS) {
                    angle += 3;
                    update();
                }
                if (event.getCode() == KeyCode.MINUS) {
                    angle -= 3;
                    update();
                }
            }
        });


        update();
    }
}