/* SPDX-License-Identifier: Apache-2.0
*
* The OpenSearch Contributors require contributions made to
* this file be licensed under the Apache-2.0 license or a
* compatible open source license.
*/
/*
* Modifications Copyright OpenSearch Contributors. See
* GitHub history for details.
*
*  Licensed to Elasticsearch B.V. under one or more contributor
*  license agreements. See the NOTICE file distributed with
*  this work for additional information regarding copyright
*  ownership. Elasticsearch B.V. licenses this file to you under
*  the Apache License, Version 2.0 (the "License"); you may
*  not use this file except in compliance with the License.
*  You may obtain a copy of the License at
*
* 	http://www.apache.org/licenses/LICENSE-2.0
*
*  Unless required by applicable law or agreed to in writing,
*  software distributed under the License is distributed on an
*  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
*  KIND, either express or implied.  See the License for the
*  specific language governing permissions and limitations
*  under the License.
*/

using System;
using OpenSearch.OpenSearch.Xunit.XunitPlumbing;
using FluentAssertions;
using OpenSearch.Client;
using Tests.Core.Extensions;
using Tests.Core.ManagedOpenSearch.Clusters;
using Tests.Domain;
using Tests.Framework.EndpointTests.TestState;

namespace Tests.Aggregations.Metric.MedianAbsoluteDeviation
{
	/**
	 * A single-value aggregation that approximates the median absolute deviation of its search results.
	 *
	 * Median absolute deviation is a measure of variability. It is a robust statistic, meaning that it is
	 * useful for describing data that may have outliers, or may not be normally distributed.
	 * For such data it can be more descriptive than standard deviation.
	 *
	 * It is calculated as the median of each data point's deviation from the median of the
	 * entire sample. That is, for a random variable `X`, the median absolute deviation is `median(|median(X) - Xi|)`.
	 *
	 * Be sure to read the OpenSearch documentation on {ref_current}/search-aggregations-metrics-median-absolute-deviation-aggregation.html[Median Absolute Deviation Aggregation]
	 */
	public class MedianAbsoluteDeviationAggregationUsageTests : AggregationUsageTestBase<ReadOnlyCluster>
	{
		public MedianAbsoluteDeviationAggregationUsageTests(ReadOnlyCluster i, EndpointUsage usage) : base(i, usage) { }

		protected override object AggregationJson => new
		{
			average_commits = new
			{
				avg = new
				{
					field = "numberOfCommits",
				}
			},
			commit_variability = new
			{
				median_absolute_deviation = new
				{
					field = "numberOfCommits"
				}
			}
		};

		protected override Func<AggregationContainerDescriptor<Project>, IAggregationContainer> FluentAggs => a => a
			.Average("average_commits", avg => avg
				.Field(p => p.NumberOfCommits)
			)
			.MedianAbsoluteDeviation("commit_variability", m => m
				.Field(f => f.NumberOfCommits)
			);

		protected override AggregationDictionary InitializerAggs =>
			new AverageAggregation("average_commits", Infer.Field<Project>(p => p.NumberOfCommits)) &&
			new MedianAbsoluteDeviationAggregation("commit_variability", Infer.Field<Project>(p => p.NumberOfCommits));

		protected override void ExpectResponse(ISearchResponse<Project> response)
		{
			response.ShouldBeValid();
			var medianAbsoluteDeviation = response.Aggregations.MedianAbsoluteDeviation("commit_variability");
			medianAbsoluteDeviation.Should().NotBeNull();
			medianAbsoluteDeviation.Value.Should().BeGreaterThan(0);
		}
	}
}