/**
 * Copyright (c) 2010, Sebastian Sdorra
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 3. Neither the name of SCM-Manager; nor the names of its
 *    contributors may be used to endorse or promote products derived from this
 *    software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * http://bitbucket.org/sdorra/scm-manager
 *
 */


package sonia.scm.cli.config;

import com.google.common.annotations.VisibleForTesting;
import sonia.scm.security.KeyGenerator;

import java.security.SecureRandom;
import java.util.Locale;

/**
 * Create keys by using {@link SecureRandom}. The SecureRandomKeyGenerator produces aes compatible keys.
 * Warning the class is not thread safe.
 *
 * @author Sebastian Sdorra
 * @since 1.60
 */
public class SecureRandomKeyGenerator implements KeyGenerator {

  private SecureRandom random = new SecureRandom();

  // key length 16 for aes128
  @VisibleForTesting
  static final int KEY_LENGTH = 16;

  private static final String UPPER = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
  private static final String LOWER = UPPER.toLowerCase(Locale.ENGLISH);
  private static final String DIGITS = "0123456789";
  private static final char[] ALL = (UPPER + LOWER + DIGITS).toCharArray();

  @Override
  public String createKey() {
    char[] key = new char[KEY_LENGTH];
    for (int idx = 0; idx < KEY_LENGTH; ++idx) {
      key[idx] = ALL[random.nextInt(ALL.length)];
    }
    return new String(key);
  }
}
