Add AggregationResultBucket

alerting/src/main/kotlin/org/opensearch/alerting/model/AggregationResultBucket.kt

@@ -0,0 +1,93 @@
+/*
+ * 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.
+ */
+
+package org.opensearch.alerting.model
+
+import org.opensearch.common.ParsingException
+import org.opensearch.common.io.stream.StreamInput
+import org.opensearch.common.io.stream.StreamOutput
+import org.opensearch.common.io.stream.Writeable
+import org.opensearch.common.xcontent.ToXContent
+import org.opensearch.common.xcontent.ToXContentObject
+import org.opensearch.common.xcontent.XContentBuilder
+import org.opensearch.common.xcontent.XContentParser
+import org.opensearch.common.xcontent.XContentParser.Token
+import org.opensearch.common.xcontent.XContentParserUtils.ensureExpectedToken
+import java.io.IOException
+import java.util.Locale
+
+data class AggregationResultBucket(
+    val parentBucketPath: String?,
+    val bucketKeys: List<String>,
+    val bucket: Map<String, Any>? // TODO: Should reduce contents to only top-level to not include sub-aggs here
+) : Writeable, ToXContentObject {
+
+    @Throws(IOException::class)
+    constructor(sin: StreamInput) : this(sin.readString(), sin.readStringList(), sin.readMap())
+
+    override fun writeTo(out: StreamOutput) {
+        out.writeString(parentBucketPath)
+        out.writeStringCollection(bucketKeys)
+        out.writeMap(bucket)
+    }
+
+    override fun toXContent(builder: XContentBuilder, params: ToXContent.Params): XContentBuilder {
+        builder.startObject()
+        innerXContent(builder)
+        return builder.endObject()
+    }
+
+    fun innerXContent(builder: XContentBuilder): XContentBuilder {
+        builder.startObject(CONFIG_NAME)
+            .field(PARENTS_BUCKET_PATH, parentBucketPath)
+            .field(BUCKET_KEYS, bucketKeys.toTypedArray())
+            .field(BUCKET, bucket)
+            .endObject()
+        return builder
+    }
+
+    companion object {
+        const val CONFIG_NAME = "agg_alert_content"
+        const val PARENTS_BUCKET_PATH = "parent_bucket_path"
+        const val BUCKET_KEYS = "bucket_keys"
+        private const val BUCKET = "bucket"
+
+        fun parse(xcp: XContentParser): AggregationResultBucket {
+            var parentBucketPath: String? = null
+            var bucketKeys = mutableListOf<String>()
+            var bucket: MutableMap<String, Any>? = null
+            ensureExpectedToken(XContentParser.Token.START_OBJECT, xcp.currentToken(), xcp)
+
+            if (CONFIG_NAME != xcp.currentName()) {
+                throw ParsingException(xcp.tokenLocation,
+                    String.format(
+                        Locale.ROOT, "Failed to parse object: expecting token with name [%s] but found [%s]",
+                        CONFIG_NAME, xcp.currentName())
+                )
+            }
+            while (xcp.nextToken() != Token.END_OBJECT) {
+                val fieldName = xcp.currentName()
+                xcp.nextToken()
+                when (fieldName) {
+                    PARENTS_BUCKET_PATH -> parentBucketPath = xcp.text()
+                    BUCKET_KEYS -> {
+                        ensureExpectedToken(Token.START_ARRAY, xcp.currentToken(), xcp)
+                        while (xcp.nextToken() != Token.END_ARRAY) {
+                            bucketKeys.add(xcp.text())
+                        }
+                    }
+                    BUCKET -> bucket = xcp.map()
+                }
+            }
+            return AggregationResultBucket(parentBucketPath, bucketKeys, bucket)
+        }
+    }
+}

alerting/src/main/kotlin/org/opensearch/alerting/util/AlertingUtils.kt

@@ -30,6 +30,7 @@ import inet.ipaddr.IPAddressString
 import org.opensearch.OpenSearchStatusException
 import org.opensearch.action.ActionListener
 import org.opensearch.alerting.destination.message.BaseMessage
+import org.opensearch.alerting.model.AggregationResultBucket
 import org.opensearch.alerting.model.destination.Destination
 import org.opensearch.alerting.settings.DestinationSettings
 import org.opensearch.commons.authuser.User
@@ -139,3 +140,9 @@ fun <T : Any> checkUserFilterByPermissions(
     }
     return true
 }
+
+/**
+ * Since buckets can have multi-value keys, this converts the bucket key values to a string that can be used
+ * as the key for a HashMap to easily retrieve [AggregationResultBucket] based on the bucket key values.
+ */
+fun AggregationResultBucket.getBucketKeysHash(): String = this.bucketKeys.joinToString(separator = "#")