package candy;

import java.util.Random;

/**
 * A machine that dispenses gumballs.
 *
 * @author Samuel A. Rebelsky
 * @version 1.0 of August 2004
 */
public class GumballMachine
	implements CandyMachine
{

// +---------------+-----------------------------------------------------
// | Static Fields |
// +---------------+

	/**
	 * Colors of gumballs.
	 */
	String[] colors = { "Yellow", "White", "Green", "Red", "Blue" };

// +--------+------------------------------------------------------------
// | Fields |
// +--------+

	/**
	 * The number of balls remaining in the machine.
	 */
	int ballsleft;

	/**
	 * A random number generator, used to select balls.
	 */
	Random rng;


// +--------------+------------------------------------------------------
// | Constructors |
// +--------------+

	/**
	 * Build a new Gumball machine with the default number of
	 * balls.
	 */
	public GumballMachine()
	{
		this.rng = new Random();
		// 40 to 50 balls.
		this.ballsleft = 40 + this.rng.nextInt(11);
	} // GumballMachine()

// +----------+----------------------------------------------------------
// | Mutators |
// +----------+

	/**
	 * Get a piece of candy.
	 *
	 * @exception CandyMachineException
	 *   If unable to return a piece of candy (e.g., if empty).
	 */
	public String get()
		throws CandyMachineException
	{
		if (this.ballsleft <= 0)
			throw new EmptyMachineException();
		else {
			--this.ballsleft;
			return colors[this.rng.nextInt(colors.length)];
		} // else
	} // get()

// +-----------+---------------------------------------------------------
// | Observers |
// +-----------+

	/**
	 * Determine if the jar is empty.
	 */
	public boolean isEmpty()
	{
		return (this.ballsleft <= 0);
	} // isEmtpy()

} // interface CandyMachine