Elasticsearch: Fix top metrics with terms in backend (#65063)

* Elasticsearch: Fix top metrics with terms in backend

* Refactor to remove cyclomatic complexity

pkg/tsdb/elasticsearch/response_parser_test.go

@@ -1484,7 +1484,7 @@ func TestResponseParser(t *testing.T) {
 		})
 	})
 
-	t.Run("With top_metrics", func(t *testing.T) {
+	t.Run("With top_metrics and date_histogram agg", func(t *testing.T) {
 		targets := map[string]string{
 			"A": `{
 				"metrics": [
@@ -1571,6 +1571,76 @@ func TestResponseParser(t *testing.T) {
 		v, _ = frame.FloatAt(1, 1)
 		assert.Equal(t, 2., v)
 	})
+
+	t.Run("With top_metrics and terms agg", func(t *testing.T) {
+		targets := map[string]string{
+			"A": `{
+				"metrics": [
+					{
+						"type": "top_metrics",
+						"settings": {
+							"order": "desc",
+							"orderBy": "@timestamp",
+							"metrics": ["@value", "@anotherValue"]
+						},
+						"id": "1"
+					}
+				],
+				"bucketAggs": [{ "type": "terms", "field": "id", "id": "3" }]
+			}`,
+		}
+		response := `{
+			"responses": [{
+				"aggregations": {
+					"3": {
+						"buckets": [
+							{
+								"key": "id1",
+								"1": {
+									"top": [
+										{ "sort": [10], "metrics": { "@value": 10, "@anotherValue": 2 } }
+									]
+								}
+							},
+							{
+								"key": "id2",
+								"1": {
+									"top": [
+										{ "sort": [5], "metrics": { "@value": 5, "@anotherValue": 2 } }
+									]
+								}
+							}
+						]
+					}
+				}
+			}]
+		}`
+
+		result, err := parseTestResponse(targets, response)
+		assert.Nil(t, err)
+		assert.Len(t, result.Responses, 1)
+		frames := result.Responses["A"].Frames
+		require.Len(t, frames, 1)
+		requireFrameLength(t, frames[0], 2)
+		require.Len(t, frames[0].Fields, 3)
+
+		f1 := frames[0].Fields[0]
+		f2 := frames[0].Fields[1]
+		f3 := frames[0].Fields[2]
+
+		require.Equal(t, "id", f1.Name)
+		require.Equal(t, "Top Metrics @value", f2.Name)
+		require.Equal(t, "Top Metrics @anotherValue", f3.Name)
+
+		requireStringAt(t, "id1", f1, 0)
+		requireStringAt(t, "id2", f1, 1)
+
+		requireFloatAt(t, 10, f2, 0)
+		requireFloatAt(t, 5, f2, 1)
+
+		requireFloatAt(t, 2, f3, 0)
+		requireFloatAt(t, 2, f3, 1)
+	})
 }
 
 func parseTestResponse(tsdbQueries map[string]string, responseBody string) (*backend.QueryDataResponse, error) {