/**
 * Copyright 2005-2016 The Kuali Foundation
 *
 * Licensed under the Educational Community License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.opensource.org/licenses/ecl2.php
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.kuali.rice.kim.sesn;

import java.security.SecureRandom;

/**
 * This class generates a random string for creating Distributed Session Tickets 
 * 
 * @author Kuali Rice Team (rice.collab@kuali.org)
 *
 */
public class SessionIdGenerator {

    /** The array of printable characters to be used in our random string. */
    private static final char[] PRINTABLE_CHARACTERS = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ012345679"
        .toCharArray();

    private static final SecureRandom randomizer = new SecureRandom();

    public static String getNewString() {
        final byte[] random = getNewStringAsBytes();

        return convertBytesToString(random);
    }


    private static byte[] getNewStringAsBytes() {
        final byte[] random = new byte[40];

        randomizer.nextBytes(random);
        
        return random;
    }

    private static String convertBytesToString(final byte[] random) {
        final char[] output = new char[random.length];
        for (int i = 0; i < random.length; i++) {
            final int index = Math.abs(random[i] % PRINTABLE_CHARACTERS.length);
            output[i] = PRINTABLE_CHARACTERS[index];
        }

        return new String(output);
    }
}
