/*
 * Copyright (c) "Neo4j"
 * Neo4j Sweden AB [http://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.neo4j.internal.batchimport.input;

import org.neo4j.values.storable.RandomValues;

/**
 * Distributes the given items so that item[0] converges towards being returned 1/2 of the times,
 * the next item, item[1] 1/4 of the times, item[2] 1/8 and so on.
 */
public class Distribution<T> {
    private final T[] items;

    public Distribution(T[] items) {
        this.items = items;
    }

    public int length() {
        return items.length;
    }

    public T random(RandomValues random) {
        float value = random.nextFloat();
        float comparison = 0.5f;
        for (T item : items) {
            if (value >= comparison) {
                return item;
            }
            comparison /= 2f;
        }
        return items[items.length - 1];
    }
}
