/*
 * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
 * Date: 2022-04-14
 * Description: Circle class inherit from Shape class
 */

public class Circle extends Shape {
	private double radius;

	/**
	 * Constructor.
	 *
	 * @param x      the x coordinate of the center of the circle
	 * @param y      the y coordinate of the center of the circle
	 * @param radius the radius of the circle, must be positive
	 * @throws BadRadiusException if the radius is negative
	 */
	public Circle(double x, double y, double radius) throws BadRadiusException {
		super(x, y);
		this.radius = radius;

		if (radius < 0) {
			throw new BadRadiusException("Radius must be positive!");
		}
	}

	/**
	 * Calculates the area of the circle.
	 *
	 * @return the area of the circle
	 */
	@Override
	public double area() {
		return Math.PI * radius * radius;
	}

	/**
	 * Resizing a circle cahnges its radius to be newRadius.
	 *
	 * @param newRadius
	 */
	@Override
	public void resize(double newRadius) throws BadRadiusException {
		if (newRadius < 0) {
			throw new BadRadiusException("Radius must be positive!");
		}
		radius = newRadius;
	}

	/**
	 * Test.
	 */
	public static void testCircle() {
		// Create a circle with a positive radius.
		// No exception is thrown until we resize with a
		// negative radius.
		try {
			Circle c = new Circle(1.2, 3.4, 4.0);
			// getX, getY, and move are inherited from Shape.
			// area and resize come from Circle itself.
			System.out.println(c.getX() == 1.2);
			System.out.println(c.getY() == 3.4);
			System.out.println(c.area() == Math.PI * 16.0);
			// Move the circle. The area does not change.
			c.move(7.8, 9.0);
			System.out.println(c.getX() == 9.0);
			System.out.println(c.getY() == 12.4);
			System.out.println(c.area() == Math.PI * 16.0);
			// Resize the circle. The area changes but not the position.
			c.resize(8.0);
			System.out.println(c.getX() == 9.0);
			System.out.println(c.getY() == 12.4);
			System.out.println(c.area() == Math.PI * 64.0);
			// Resize the circle with a negative radius.
			// An exception is thrown, caught, and tested.
			c.resize(-12.3);
			System.out.println(c.getX() == 9.0); // Unreachable.
			System.out.println(c.getY() == 12.4);
			System.out.println(c.area() == Math.PI * 64.0);
		} catch (BadRadiusException ex) {
			System.out.println(ex.getMessage() == "Radius must be positive!");
		}
		// Create a circle with a positive radius.
		// Resize the circle with a zero radius.
		// No exception is thrown.
		try {
			Circle c = new Circle(1.2, 3.4, 4.0);
			c.resize(0.0);
			// The area is now zero, the position does not change.
			System.out.println(c.getX() == 1.2);
			System.out.println(c.getY() == 3.4);
			System.out.println(c.area() == 0.0);
		} catch (BadRadiusException ex) {
			System.out.println("BUG! This must never happen!");
		}
		// Try to create a circle with a negative radius.
		// An exception is thrown, caught, and tested.
		try {
			Circle c2 = new Circle(1.2, 3.4, -5.6);
		} catch (BadRadiusException ex) {
			System.out.println(ex.getMessage() == "Radius must be positive!");
		}
		// Create a circle with a zero radius.
		// No exception is thrown.
		try {
			Circle c3 = new Circle(1.2, 3.4, 0.0);
			System.out.println(c3.getX() == 1.2);
			System.out.println(c3.getY() == 3.4);
			System.out.println(c3.area() == 0.0);
		} catch (BadRadiusException ex) {
			System.out.println("BUG! This must never happen!");
		}

	}
}