/* 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 System.Collections.Generic;
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.Bucket.RareTerms
{
	/**
	 * A multi-bucket value source based aggregation which finds "rare" terms — terms that are at the long-tail of the
	 * distribution and are not frequent. Conceptually, this is like a terms aggregation that is sorted by _count ascending.
	 * As noted in the terms aggregation docs, actually ordering a terms agg by count ascending has unbounded error.
	 * Instead, you should use the rare_terms aggregation.
	 *
	 * See the OpenSearch documentation on {ref_current}/search-aggregations-bucket-rare-terms-aggregation.html[rare terms aggregation] for more detail.
	 */
	public class RareTermsAggregationUsageTests : AggregationUsageTestBase<ReadOnlyCluster>
	{
		public RareTermsAggregationUsageTests(ReadOnlyCluster i, EndpointUsage usage) : base(i, usage) { }

		protected override object AggregationJson => new
		{
			names = new
			{
				meta = new
				{
					foo = "bar"
				},
				rare_terms = new
				{
					field = "name",
					max_doc_count = 5,
					missing = "n/a",
					precision = 0.001
				}
			}
		};

		protected override Func<AggregationContainerDescriptor<Project>, IAggregationContainer> FluentAggs => a => a
			.RareTerms("names", st => st
				.Field(p => p.Name)
				.Missing("n/a")
				.MaximumDocumentCount(5)
				.Precision(0.001)
				.Meta(m => m
					.Add("foo", "bar")
				)
			);

		protected override AggregationDictionary InitializerAggs =>
			new RareTermsAggregation("names")
			{
				Field = Infer.Field<Project>(p => p.Name),
				MaximumDocumentCount = 5,
				Precision = 0.001,
				Missing = "n/a",
				Meta = new Dictionary<string, object> { { "foo", "bar" } }
			};

		protected override void ExpectResponse(ISearchResponse<Project> response)
		{
			response.ShouldBeValid();
			var rareTerms = response.Aggregations.RareTerms("names");
			rareTerms.Should().NotBeNull();
			rareTerms.Buckets.Should().NotBeNull();
			rareTerms.Buckets.Count.Should().BeGreaterThan(0);
			foreach (var item in rareTerms.Buckets)
			{
				item.Key.Should().NotBeNullOrEmpty();
				item.DocCount.Should().BeGreaterOrEqualTo(1);
			}
			rareTerms.Meta.Should().NotBeNull().And.HaveCount(1);
			rareTerms.Meta["foo"].Should().Be("bar");
		}
	}
}