/*
 * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
 * or more contributor license agreements. Licensed under the "Elastic License
 * 2.0", the "GNU Affero General Public License v3.0 only", and the "Server Side
 * Public License v 1"; you may not use this file except in compliance with, at
 * your election, the "Elastic License 2.0", the "GNU Affero General Public
 * License v3.0 only", or the "Server Side Public License, v 1".
 */

package org.elasticsearch.search.aggregations.support;

import org.elasticsearch.test.ESTestCase;

import static org.hamcrest.Matchers.closeTo;
import static org.hamcrest.Matchers.equalTo;

public class SamplingContextTests extends ESTestCase {

    private static SamplingContext randomContext() {
        return new SamplingContext(randomDoubleBetween(1e-6, 0.1, false), randomInt(), randomBoolean() ? null : randomInt());
    }

    public void testScaling() {
        for (int i = 0; i < 20; i++) {
            SamplingContext samplingContext = randomContext();
            long randomLong = randomLongBetween(1_000_000_000L, 100_000_000_000L);
            double randomDouble = randomDouble();
            long rescaled = samplingContext.scaleUp(samplingContext.scaleDown(randomLong));
            assertThat(
                Double.toString(samplingContext.probability()),
                (double) rescaled / randomLong,
                // No matter how you scale `long` values, the inverse back may be a little off due to rounding
                closeTo(1.0, 1e-4)
            );
            assertThat(
                Double.toString(samplingContext.probability()),
                randomDouble,
                closeTo(samplingContext.scaleUp(samplingContext.scaleDown(randomDouble)), 1e-12)
            );
        }
    }

    public void testNoScaling() {
        SamplingContext samplingContext = new SamplingContext(1.0, randomInt(), randomBoolean() ? null : randomInt());
        long randomLong = randomLong();
        double randomDouble = randomDouble();
        assertThat(randomLong, equalTo(samplingContext.scaleDown(randomLong)));
        assertThat(randomDouble, equalTo(samplingContext.scaleDown(randomDouble)));
    }

}