/*

 * Copyright 2009 Google Inc.  All Rights Reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code 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 General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 */

import java.util.Random;

import java.math.BigInteger;

public enum ArrayBuilder {

    // These seven are from  Tim's paper (listsort.txt)

    RANDOM_INT {

        public Object[] build(int len) {

            Integer[] result = new Integer[len];

            for (int i = 0; i < len; i++)

                result[i] = rnd.nextInt();

            return result;

        }

    },

    DESCENDING_INT {

        public Object[] build(int len) {

            Integer[] result = new Integer[len];

            for (int i = 0; i < len; i++)

                result[i] = len - i;

            return result;

        }

    },

    ASCENDING_INT {

        public Object[] build(int len) {

            Integer[] result = new Integer[len];

            for (int i = 0; i < len; i++)

                result[i] = i;

            return result;

        }

    },

    ASCENDING_3_RND_EXCH_INT {

        public Object[] build(int len) {

            Integer[] result = new Integer[len];

            for (int i = 0; i < len; i++)

                result[i] = i;

            for (int i = 0; i < 3; i++)

                swap(result, rnd.nextInt(result.length),

                             rnd.nextInt(result.length));

            return result;

        }

    },

    ASCENDING_10_RND_AT_END_INT {

        public Object[] build(int len) {

            Integer[] result = new Integer[len];

            int endStart = len - 10;

            for (int i = 0; i < endStart; i++)

                result[i] = i;

            for (int i = endStart; i < len; i++)

                result[i] = rnd.nextInt(endStart + 10);

            return result;

        }

    },

    ALL_EQUAL_INT {

        public Object[] build(int len) {

            Integer[] result = new Integer[len];

            for (int i = 0; i < len; i++)

                result[i] = 666;

            return result;

        }

    },

    DUPS_GALORE_INT {

        public Object[] build(int len) {

            Integer[] result = new Integer[len];

            for (int i = 0; i < len; i++)

                result[i] = rnd.nextInt(4);

            return result;

        }

    },

    RANDOM_WITH_DUPS_INT {

        public Object[] build(int len) {

            Integer[] result = new Integer[len];

            for (int i = 0; i < len; i++)

                result[i] = rnd.nextInt(len);

            return result;

        }

    },

    PSEUDO_ASCENDING_STRING {

        public String[] build(int len) {

            String[] result = new String[len];

            for (int i = 0; i < len; i++)

                result[i] = Integer.toString(i);

            return result;

        }

    },

    RANDOM_BIGINT {

        public BigInteger[] build(int len) {

            BigInteger[] result = new BigInteger[len];

            for (int i = 0; i < len; i++)

                result[i] = HUGE.add(BigInteger.valueOf(rnd.nextInt(len)));

            return result;

        }

    };

    public abstract Object[] build(int len);

    public void resetRandom() {

        rnd = new Random(666);

    }

    private static Random rnd = new Random(666);

    private static void swap(Object[] a, int i, int j) {

        Object t = a[i];

        a[i] = a[j];

        a[j] = t;

    }

    private static BigInteger HUGE = BigInteger.ONE.shiftLeft(100);

}