package test3;

import java.util.HashMap;
import java.util.Map;

/**
 * A Social Insurance Number card has a number.
 * 
 * @author Franck van Breugel
 */
public class SINCard 
{
    private int number;
    
    private static Map<Integer, SINCard> instance = new HashMap<Integer, SINCard>();

    /**
     * Initializes this card with the given number
     * 
     * @param number the number of this card.
     * @pre. number >= 1000000000 && number <= 999999999
     */
    private SINCard(int number) 
    {
	this.setNumber(number);
    }

    /**
     * Returns the number of this card.
     * 
     * @return the number of this card.
     */
    public int getNumber() 
    {
	return this.number;
    }

    /**
     * Sets the number of this card to the given number.
     * 
     * @param number the new number of this card.
     * @pre. number >= 1000000000 && number <= 999999999
     */
    private void setNumber(int number) 
    {
	this.number = number;
    }
    
    /**
     * Returns a string representation of this card.
     * This string consists of the number of the card.
     * 
     * @return a string representation of this card.
     */
    public String toString()
    {
	return "" + this.getNumber();
    }
    
    /**
     * Tests whether the number of this card is even.
     * 
     * @return true if the number of this card is even,
     * false otherwise.
     */
    public boolean isEven()
    {
	return this.getNumber() % 2 == 0;
    }
    
    /**
     * Returns a SIN card with the given number.
     *
     * @param number the new number of this card.
     * @pre. number >= 1000000000 && number <= 999999999
     * @return a SIN card with the given number.
     */
    public static SINCard getInstance(int number)
    {
	if (!SINCard.instance.containsKey(number))
	{
	    SINCard.instance.put(number, new SINCard(number));
	}
	return SINCard.instance.get(number);
    }
    
    /**
     * Tests whether a card with the given number has been created.
     * 
     * @param number a number.
     * @return true if a card with the given number has been created,
     * false otherwise.
     */
    public static boolean exists(int number)
    {
	return SINCard.instance.containsKey(number);
    }
}