Add support for bounds in geohash_grid aggregation (#4403)

Relates: #4341, elastic/elasticsearch#50002

This commit adds support for supplying bounds on a geohash_grid
aggregation, similar to how bounds are supplied on
geo_bounding_box query.

src/Nest/Aggregations/Bucket/GeoHashGrid/GeoHashGridAggregation.cs

@@ -5,34 +5,74 @@
 
 namespace Nest
 {
+	/// <summary>
+	/// A multi-bucket aggregation that works on geo_point fields and groups points into buckets that represent cells in a grid.
+	/// The resulting grid can be sparse and only contains cells that have matching data.
+	/// Each cell is labeled using a geohash which is of user-definable precision.
+	/// </summary>
 	[InterfaceDataContract]
 	[ReadAs(typeof(GeoHashGridAggregation))]
 	public interface IGeoHashGridAggregation : IBucketAggregation
 	{
+		/// <summary>
+		/// The name of the field indexed with geopoints.
+		/// </summary>
 		[DataMember(Name ="field")]
 		Field Field { get; set; }
 
+		/// <summary>
+		/// The string length of the geohashes used to define cells/buckets in the results.
+		/// Defaults to <see cref="GeoHashPrecision.Precision5"/>.
+		/// </summary>
 		[DataMember(Name ="precision")]
 		GeoHashPrecision? Precision { get; set; }
 
+		/// <summary>
+		/// To allow for more accurate counting of the top cells returned in the final result the aggregation defaults to returning
+		/// <c>max(10,(size x number-of-shards))</c> buckets from each shard. If this heuristic is undesirable,
+		/// the number considered from each shard can be over-ridden using this parameter.
+		/// </summary>
 		[DataMember(Name ="shard_size")]
 		int? ShardSize { get; set; }
 
+		/// <summary>
+		/// The maximum number of geohash buckets to return. Defaults to <c>10,000</c>. When results are trimmed,
+		/// buckets are prioritised based on the volumes of documents they contain.
+		/// </summary>
 		[DataMember(Name ="size")]
 		int? Size { get; set; }
+
+		/// <summary>
+		/// Restricts the points considered to those that fall within the bounds provided.
+		/// <para />
+		/// Available in Elasticsearch 7.6.0+.
+		/// </summary>
+		[DataMember(Name = "bounds")]
+		IBoundingBox Bounds { get; set; }
 	}
 
+	/// <inheritdoc cref="IGeoHashGridAggregation"/>
 	public class GeoHashGridAggregation : BucketAggregationBase, IGeoHashGridAggregation
 	{
 		internal GeoHashGridAggregation() { }
 
 		public GeoHashGridAggregation(string name) : base(name) { }
 
+		/// <inheritdoc cref="IGeoHashGridAggregation.Field"/>
 		public Field Field { get; set; }
+
+		/// <inheritdoc cref="IGeoHashGridAggregation.Precision"/>
 		public GeoHashPrecision? Precision { get; set; }
+
+		/// <inheritdoc cref="IGeoHashGridAggregation.ShardSize"/>
 		public int? ShardSize { get; set; }
+
+		/// <inheritdoc cref="IGeoHashGridAggregation.Size"/>
 		public int? Size { get; set; }
 
+		/// <inheritdoc cref="IGeoHashGridAggregation.Bounds"/>
+		public IBoundingBox Bounds { get; set; }
+
 		internal override void WrapInContainer(AggregationContainer c) => c.GeoHash = this;
 	}
 
@@ -42,22 +82,30 @@ public class GeoHashGridAggregationDescriptor<T>
 		where T : class
 	{
 		Field IGeoHashGridAggregation.Field { get; set; }
-
 		GeoHashPrecision? IGeoHashGridAggregation.Precision { get; set; }
-
 		int? IGeoHashGridAggregation.ShardSize { get; set; }
-
 		int? IGeoHashGridAggregation.Size { get; set; }
+		IBoundingBox IGeoHashGridAggregation.Bounds { get; set; }
 
+		/// <inheritdoc cref="IGeoHashGridAggregation.Field"/>
 		public GeoHashGridAggregationDescriptor<T> Field(Field field) => Assign(field, (a, v) => a.Field = v);
 
+		/// <inheritdoc cref="IGeoHashGridAggregation.Field"/>
 		public GeoHashGridAggregationDescriptor<T> Field<TValue>(Expression<Func<T, TValue>> field) => Assign(field, (a, v) => a.Field = v);
 
+		/// <inheritdoc cref="IGeoHashGridAggregation.Size"/>
 		public GeoHashGridAggregationDescriptor<T> Size(int? size) => Assign(size, (a, v) => a.Size = v);
 
+		/// <inheritdoc cref="IGeoHashGridAggregation.ShardSize"/>
 		public GeoHashGridAggregationDescriptor<T> ShardSize(int? shardSize) => Assign(shardSize, (a, v) => a.ShardSize = v);
 
+		/// <inheritdoc cref="IGeoHashGridAggregation.Precision"/>
+		// TODO: Rename to precision in next major.
 		public GeoHashGridAggregationDescriptor<T> GeoHashPrecision(GeoHashPrecision? precision) =>
 			Assign(precision, (a, v) => a.Precision = v);
+
+		/// <inheritdoc cref="IGeoHashGridAggregation.Bounds"/>
+		public GeoHashGridAggregationDescriptor<T> Bounds(Func<BoundingBoxDescriptor, IBoundingBox> selector) =>
+			Assign(selector, (a, v) => a.Bounds = v?.Invoke(new BoundingBoxDescriptor()));
 	}
 }

tests/Tests/Aggregations/Bucket/GeoHashGrid/GeoHashGridAggregationUsageTests.cs

@@ -1,4 +1,5 @@
 using System;
+using Elastic.Xunit.XunitPlumbing;
 using FluentAssertions;
 using Nest;
 using Tests.Core.Extensions;
@@ -51,4 +52,62 @@ protected override void ExpectResponse(ISearchResponse<Project> response)
 			myGeoHashGrid.Should().NotBeNull();
 		}
 	}
+
+	[SkipVersion("<7.6.0", "bounds introduced in 7.6.0")]
+	// hide
+	public class GeoHashGridAggregationWithBoundsUsageTests : AggregationUsageTestBase
+	{
+		public GeoHashGridAggregationWithBoundsUsageTests(ReadOnlyCluster i, EndpointUsage usage) : base(i, usage) { }
+
+		protected override object AggregationJson => new
+		{
+			my_geohash_grid = new
+			{
+				geohash_grid = new
+				{
+					field = "locationPoint",
+					bounds = new
+					{
+						top_left = new
+						{
+							lat = 90.0,
+							lon = -180.0
+						},
+						bottom_right = new
+						{
+							lat = -90.0,
+							lon = 180.0
+						}
+					}
+				}
+			}
+		};
+
+		protected override Func<AggregationContainerDescriptor<Project>, IAggregationContainer> FluentAggs => a => a
+			.GeoHash("my_geohash_grid", g => g
+				.Field(p => p.LocationPoint)
+				.Bounds(b => b
+					.TopLeft(90,-180)
+					.BottomRight(-90, 180)
+				)
+			);
+
+		protected override AggregationDictionary InitializerAggs =>
+			new GeoHashGridAggregation("my_geohash_grid")
+			{
+				Field = Field<Project>(p => p.LocationPoint),
+				Bounds = new BoundingBox
+				{
+					TopLeft = new GeoLocation(90, -180),
+					BottomRight = new GeoLocation(-90, 180)
+				}
+			};
+
+		protected override void ExpectResponse(ISearchResponse<Project> response)
+		{
+			response.ShouldBeValid();
+			var myGeoHashGrid = response.Aggregations.GeoHash("my_geohash_grid");
+			myGeoHashGrid.Should().NotBeNull();
+		}
+	}
 }