package net.sourceforge.solexatools.util;

import java.security.SecureRandom;

/**
 * <p>
 * RandomInvitationCode class.
 * </p>
 * 
 * @author boconnor
 * @version $Id: $Id
 */
public class RandomInvitationCode {
    private static final int SIZE_BLOCK = 5;
    private static final int SIZE_SYMBOLS_IN_BLOCK = 5;
    private static final String DELIMITER = "-";
    private static final char[] SYMBOLS = new char[36];

    static {
        for (int idx = 0; idx < 10; ++idx)
            SYMBOLS[idx] = (char) ('0' + idx);
        for (int idx = 10; idx < 36; ++idx)
            SYMBOLS[idx] = (char) ('a' + idx - 10);
    }

    private SecureRandom random = new SecureRandom();
    private final char[] buf = new char[SIZE_SYMBOLS_IN_BLOCK];

    /**
     * <p>
     * Constructor for RandomInvitationCode.
     * </p>
     */
    public RandomInvitationCode() {
    }

    private String nextString() {
        for (int idx = 0; idx < buf.length; ++idx)
            buf[idx] = SYMBOLS[random.nextInt(SYMBOLS.length)];
        return new String(buf);
    }

    /**
     * <p>
     * nextInvitationCode.
     * </p>
     * 
     * @return a {@link java.lang.String} object.
     */
    public String nextInvitationCode() {
        String invitationCode = "";
        for (int i = 0; i < SIZE_BLOCK; i++) {
            invitationCode += nextString();
            if (i < SIZE_BLOCK - 1) {
                invitationCode += DELIMITER;
            }
        }
        return invitationCode;
    }
}