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);
}