Support DateMath for DateHistogram ExtendedBounds

Non-binary breaking backport of #2829

Closes #2828

(cherry picked from commit f640b05)

Author: russcam

docs/aggregations/bucket/date-histogram/date-histogram-aggregation-usage.asciidoc

@@ -39,7 +39,7 @@ s => s
         .Interval(DateInterval.Month)
         .MinimumDocumentCount(2)
         .Format("yyyy-MM-dd'T'HH:mm:ss")
-        .ExtendedBounds(FixedDate.AddYears(-1), FixedDate.AddYears(1))
+        .ExtendedBoundsDateMath(FixedDate.AddYears(-1), FixedDate.AddYears(1))
         .Order(HistogramOrder.CountAscending)
         .Missing(FixedDate)
         .Aggregations(childAggs => childAggs
@@ -67,7 +67,7 @@ new SearchRequest<Project>
         Interval = DateInterval.Month,
         MinimumDocumentCount = 2,
         Format = "yyyy-MM-dd'T'HH:mm:ss",
-        ExtendedBounds = new ExtendedBounds<DateTime>
+        ExtendedBoundsDateMath = new ExtendedBounds<DateMath>
         {
             Minimum = FixedDate.AddYears(-1),
             Maximum = FixedDate.AddYears(1),

src/Nest/Aggregations/Bucket/DateHistogram/DateHistogramAggregation.cs

@@ -40,16 +40,21 @@ public interface IDateHistogramAggregation : IBucketAggregation
 		[JsonProperty("order")]
 		HistogramOrder Order { get; set; }
 
-		[JsonProperty("extended_bounds")]
+		[JsonIgnore]
+		[Obsolete("Use ExtendedBoundsDateMath that accepts DateMath expressions. Fixed in NEST 6.x")]
 		ExtendedBounds<DateTime> ExtendedBounds { get; set; }
 
+		[JsonProperty("extended_bounds")]
+		ExtendedBounds<DateMath> ExtendedBoundsDateMath { get; set; }
+
 		[JsonProperty("missing")]
 		DateTime? Missing { get; set; }
 	}
 
 	public class DateHistogramAggregation : BucketAggregationBase, IDateHistogramAggregation
 	{
 		private string _format;
+		private ExtendedBounds<DateTime> _extendedBounds;
 		public Field Field { get; set; }
 		public IScript Script { get; set; }
 		public IDictionary<string, object> Params { get; set; }
@@ -59,7 +64,7 @@ public string Format
 		{
 			get => !string.IsNullOrEmpty(_format) &&
 			       !_format.Contains("date_optional_time") &&
-			       (ExtendedBounds != null || Missing.HasValue)
+			       (ExtendedBoundsDateMath != null || Missing.HasValue)
 				? _format + "||date_optional_time"
 				: _format;
 			set => _format = value;
@@ -73,7 +78,24 @@ public string Format
 
 		public string Offset { get; set; }
 		public HistogramOrder Order { get; set; }
-		public ExtendedBounds<DateTime> ExtendedBounds { get; set; }
+
+		[Obsolete("Use ExtendedBoundsDateMath that accepts DateMath expressions. Fixed in NEST 6.x")]
+		public ExtendedBounds<DateTime> ExtendedBounds
+		{
+			get => _extendedBounds;
+			set
+			{
+				_extendedBounds = value;
+				ExtendedBoundsDateMath = new ExtendedBounds<DateMath>
+				{
+					Minimum = value.Minimum,
+					Maximum = value.Maximum
+				};
+			}
+		}
+
+		public ExtendedBounds<DateMath> ExtendedBoundsDateMath { get; set; }
+
 		public DateTime? Missing { get; set; }
 
 		internal DateHistogramAggregation() { }
@@ -89,6 +111,7 @@ public class DateHistogramAggregationDescriptor<T>
 		where T : class
 	{
 		private string _format;
+		private ExtendedBounds<DateTime> _extendedBounds;
 		Field IDateHistogramAggregation.Field { get; set; }
 
 		IScript IDateHistogramAggregation.Script { get; set; }
@@ -101,7 +124,7 @@ string IDateHistogramAggregation.Format
 		{
 			get => !string.IsNullOrEmpty(_format) &&
 			       !_format.Contains("date_optional_time") &&
-			       (Self.ExtendedBounds != null || Self.Missing.HasValue)
+			       (Self.ExtendedBoundsDateMath != null || Self.Missing.HasValue)
 				? _format + "||date_optional_time"
 				: _format;
 			set => _format = value;
@@ -117,7 +140,22 @@ string IDateHistogramAggregation.Format
 
 		HistogramOrder IDateHistogramAggregation.Order { get; set; }
 
-		ExtendedBounds<DateTime> IDateHistogramAggregation.ExtendedBounds { get; set; }
+		[Obsolete("Use ExtendedBoundsDateMath that accepts DateMath expressions. Fixed in NEST 6.x")]
+		ExtendedBounds<DateTime> IDateHistogramAggregation.ExtendedBounds
+		{
+			get => _extendedBounds;
+			set
+			{
+				_extendedBounds = value;
+				Self.ExtendedBoundsDateMath = new ExtendedBounds<DateMath>
+				{
+					Minimum = value.Minimum,
+					Maximum = value.Maximum
+				};
+			}
+		}
+
+		ExtendedBounds<DateMath> IDateHistogramAggregation.ExtendedBoundsDateMath { get; set; }
 
 		DateTime? IDateHistogramAggregation.Missing { get; set; }
 
@@ -155,9 +193,13 @@ public DateHistogramAggregationDescriptor<T> OrderAscending(string key) =>
 		public DateHistogramAggregationDescriptor<T> OrderDescending(string key) =>
 			Assign(a => a.Order = new HistogramOrder { Key = key, Order = SortOrder.Descending });
 
+		[Obsolete("Use ExtendedBoundsDateMath() that accepts DateMath expressions. Fixed in NEST 6.x")]
 		public DateHistogramAggregationDescriptor<T> ExtendedBounds(DateTime min, DateTime max) =>
 			Assign(a=>a.ExtendedBounds = new ExtendedBounds<DateTime> { Minimum = min, Maximum = max });
 
+		public DateHistogramAggregationDescriptor<T> ExtendedBoundsDateMath(DateMath min, DateMath max) =>
+			Assign(a=>a.ExtendedBoundsDateMath = new ExtendedBounds<DateMath> { Minimum = min, Maximum = max });
+
 		public DateHistogramAggregationDescriptor<T> Missing(DateTime missing) => Assign(a => a.Missing = missing);
 	}
 }

src/Tests/Aggregations/Bucket/DateHistogram/DateHistogramAggregationUsageTests.cs

@@ -75,7 +75,7 @@ public DateHistogramAggregationUsageTests(ReadOnlyCluster i, EndpointUsage usage
 					.Interval(DateInterval.Month)
 					.MinimumDocumentCount(2)
 					.Format("yyyy-MM-dd'T'HH:mm:ss")
-					.ExtendedBounds(FixedDate.AddYears(-1), FixedDate.AddYears(1))
+					.ExtendedBoundsDateMath(FixedDate.AddYears(-1), FixedDate.AddYears(1))
 					.Order(HistogramOrder.CountAscending)
 					.Missing(FixedDate)
 					.Aggregations(childAggs => childAggs
@@ -99,7 +99,7 @@ public DateHistogramAggregationUsageTests(ReadOnlyCluster i, EndpointUsage usage
 					Interval = DateInterval.Month,
 					MinimumDocumentCount = 2,
 					Format = "yyyy-MM-dd'T'HH:mm:ss",
-					ExtendedBounds = new ExtendedBounds<DateTime>
+					ExtendedBoundsDateMath = new ExtendedBounds<DateMath>
 					{
 						Minimum = FixedDate.AddYears(-1),
 						Maximum = FixedDate.AddYears(1),