package test2;

/**
 * A class that represents rotations in the 2D plane. A rotation
 * is defined by an angle of rotation and the units used to
 * represent the rotation.
 *
 */
public class Rotation {
	
	/**
	 * String for units in degrees.
	 */
	public static final String DEGREES = "degrees";
	
	/**
	 * String for units in radians.
	 */
	public static final String RADIANS = "radians";

	/**
	 * The angle of the rotation.
	 */
	private double angle;
	
    /**
     * The units of the angle.
     */
    private String units;
	
	/**
	 * Initializes the rotation to 0 radians.
	 */
	public Rotation() {
		this(0.0, Rotation.RADIANS);
	}
	
	/**
	 * Initializes the rotation to the given angle using the given
	 * units.
	 * 
	 * @param angle the angle of the rotation
	 * @param units the units of the angle
	 * @throws IllegalArgumentException if units is not equal
	 * to Rotation.DEGREES or Rotation.RADIANS
 	 */
	public Rotation(double angle, String units) {
		if (units.equals(Rotation.DEGREES) ||
				units.equals(Rotation.RADIANS)) {
			this.angle = angle;
			this.units = units;
		}
		else {
			throw new IllegalArgumentException();
		}
	}
}