/**
 * This version of Rectangle accompanies Chapter 2. Method
 * setLength() now throws an <tt>IllegalArgumentException</tt>
 * if its argument is invalid.
 */
public class Rectangle extends Shape {
    private double length;
    private double height;

    /**
     * Construct a <tt>Rectangle</tt> object using the default size
     * for its dimensions.
     */
    public Rectangle() {
        super( "Rectangle" );
        setLength( super.DEFAULT_SIZE );
        setHeight( Shape.DEFAULT_SIZE );
    }

    /**
     * Construct a <tt>Rectangle</tt> object using the arguments.
     * If an argument is <= 0, the default size specified in
     * <tt>Shape</tt> is used instead.
     * @param theLength the length of this <tt>Rectangle</tt>;
     *        must be > 0
     * @param theHeight the height of this <tt>Rectangle</tt>;
     *        must be > 0
     */
    public Rectangle( double theLength, double theHeight ) {
        super( "Rectangle" );
        setLength( theLength );
        setHeight( theHeight );
    }

    /**
     * Get the surface area of this <tt>Rectangle</tt>.
     * @return the surface area of this <tt>Rectangle</tt>
     */
    public double getSurfaceArea() {
        return this.length * this.height;
    }

    /**
     * Get the perimeter of this <tt>Rectangle</tt>.
     * @return the perimeter of this <tt>Rectangle</tt>
     */
    public double getPerimeter() {
        return this.length + 2 * this.height;
    }

    /**
     * Get the length dimension of this <tt>Rectangle</tt>.
     * @return the length of this <tt>Rectangle</tt>
     */
    public double getLength() {
        return this.length;
    }

    /**
     * Get the height dimension of this <tt>Rectangle</tt>.
     * @return the height of this <tt>Rectangle</tt>
     */
    public double getHeight() {
        return this.height;
    }

    /**
     * Set the length dimension of this <tt>Rectangle</tt>.
     * If <tt>theLength</tt> is <= 0, the dimension is unchanged.
     * @param theLength new length of this <tt>Rectangle</tt>;
     *       must be > 0
     */
    public void setLength( double theLength ) {
        if ( theLength <= 0 ) {
            throw new IllegalArgumentException( "Invalid Rectangle length (" +
                                                theLength + "): must be > 0 " );
        }
        this.length = theLength;
    }

    /**
     * Set the height dimension of this <tt>Rectangle</tt>.
     * If <tt>theHeight</tt> is <= 0, the dimension is unchanged.
     * @param theHeight the new height of this <tt>Rectangle</tt>;
     *   must be > 0
     */
    public void setHeight( double theHeight ) {
        if ( theHeight <= 0 ) {
            return;
        }
        this.height = theHeight;
    }

    /**
     * Returns a <tt>String</tt> object representing this
     * <tt>Rectangle</tt>'s value. Overridden from <tt>Object</tt>.
     * @return a string representation of this object
     */
    public String toString() {
        return this.getShapeName() + ": length = " + this.length
            + ", height = " + this.height;
    }

    /**
     * Returns <tt>true</tt> if and only if the argument is not
     * <tt>null</tt> and is a <tt>Rectangle</tt> object that
     * represents the same rectangle value as this object. The
     * comparison is done based on the dimension's length and
     * height.
     * @param o the object to compare with
     * @return <tt>true</tt> if the <tt>Rectangle</tt> objects
     * represent the same value; <tt>false</tt> otherwise.
     */
    public boolean equals( Object o ) {
        if ( ( o == null ) || ( ! ( o instanceof Rectangle ) ) ) {
            return false;
        }
        return ( ( ( ( Rectangle ) o ).getLength() == getLength() ) &&
                 ( ( ( Rectangle ) o ).getHeight() == getHeight() ) );
    }
}