/*
 * Copyright (C) 2003-2011 eXo Platform SAS.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */
package org.etk.common.utils;

import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Random;
import java.util.Set;

/**
 * Created by The eXo Platform SAS
 * Author : eXoPlatform
 *          thanhvucong.78@google.com
 * Aug 4, 2011  
 */
public class Randomizer extends Random {

  public static Randomizer getInstance() {
    return _instance;
  }

  public Randomizer() {
    super();
  }

  public Randomizer(long seed) {
    super(seed);
  }

  public int[] nextInt(int n, int size) {
    if (size > n) {
      size = n;
    }

    Set<Integer> set = new LinkedHashSet<Integer>();

    for (int i = 0; i < size; i++) {
      while (true) {
        Integer value = new Integer(nextInt(n));

        if (!set.contains(value)) {
          set.add(value);

          break;
        }
      }
    }

    int[] array = new int[set.size()];

    Iterator<Integer> itr = set.iterator();

    for (int i = 0; i < array.length; i++) {
      array[i] = itr.next().intValue();
    }

    return array;
  }

  public void randomize(char array[]) {
    int length = array.length;

    for (int i = 0; i < length - 1; i++) {
      int x = nextInt(length);
      char y = array[i];

      array[i] = array[i + x];
      array[i + x] = y;

      length--;
    }
  }

  public void randomize(int array[]) {
    int length = array.length;

    for (int i = 0; i < length - 1; i++) {
      int x = nextInt(length);
      int y = array[i];

      array[i] = array[i + x];
      array[i + x] = y;

      length--;
    }
  }

  public void randomize(List<Object> list) {
    int size = list.size();

    for (int i = 0; i <= size; i++) {
      Object obj = list.get(i);

      int j = nextInt(size);

      list.set(i, list.get(i + j));
      list.set(i + j, obj);

      size--;
    }
  }

  public void randomize(Object array[]) {
    int length = array.length;

    for (int i = 0; i < length - 1; i++) {
      int x = nextInt(length);
      Object y = array[i];

      array[i] = array[i + x];
      array[i + x] = y;

      length--;
    }
  }

  public String randomize(String s) {
    if (s == null) {
      return null;
    }

    char[] array = s.toCharArray();

    randomize(array);

    return new String(array);
  }

  private static Randomizer _instance = new Randomizer();

}