adding multimatch intercepter class

Author: Samiul-TheSoccerFan

x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/InferencePlugin.java

@@ -95,6 +95,7 @@
 import org.elasticsearch.xpack.inference.mapper.SemanticTextFieldMapper;
 import org.elasticsearch.xpack.inference.queries.SemanticKnnVectorQueryRewriteInterceptor;
 import org.elasticsearch.xpack.inference.queries.SemanticMatchQueryRewriteInterceptor;
+import org.elasticsearch.xpack.inference.queries.SemanticMultiMatchQueryRewriteInterceptor;
 import org.elasticsearch.xpack.inference.queries.SemanticQueryBuilder;
 import org.elasticsearch.xpack.inference.queries.SemanticSparseVectorQueryRewriteInterceptor;
 import org.elasticsearch.xpack.inference.rank.random.RandomRankBuilder;
@@ -569,7 +570,8 @@ public List<QueryRewriteInterceptor> getQueryRewriteInterceptors() {
         return List.of(
             new SemanticKnnVectorQueryRewriteInterceptor(),
             new SemanticMatchQueryRewriteInterceptor(),
-            new SemanticSparseVectorQueryRewriteInterceptor()
+            new SemanticSparseVectorQueryRewriteInterceptor(),
+            new SemanticMultiMatchQueryRewriteInterceptor()
         );
     }
 

x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/queries/SemanticMultiMatchQueryRewriteInterceptor.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+
+package org.elasticsearch.xpack.inference.queries;
+
+import org.elasticsearch.index.query.MultiMatchQueryBuilder;
+import org.elasticsearch.index.query.QueryBuilder;
+
+import java.util.Map;
+
+public class SemanticMultiMatchQueryRewriteInterceptor extends SemanticQueryRewriteInterceptor {
+    @Override
+    protected Map<String, Float> getFieldNamesWithBoosts(QueryBuilder queryBuilder) {
+        assert (queryBuilder instanceof MultiMatchQueryBuilder);
+        MultiMatchQueryBuilder multiMatchQueryBuilder = (MultiMatchQueryBuilder) queryBuilder;
+        return multiMatchQueryBuilder.fields();
+    }
+
+    @Override
+    protected String getQuery(QueryBuilder queryBuilder) {
+        assert (queryBuilder instanceof MultiMatchQueryBuilder);
+        MultiMatchQueryBuilder multiMatchQueryBuilder = (MultiMatchQueryBuilder) queryBuilder;
+        return (String) multiMatchQueryBuilder.value();
+    }
+
+    @Override
+    protected QueryBuilder buildInferenceQuery(
+        QueryBuilder queryBuilder,
+        InferenceIndexInformationForField indexInformation,
+        Float fieldBoost
+    ) {
+        return queryBuilder;
+    }
+
+    @Override
+    protected QueryBuilder buildCombinedInferenceAndNonInferenceQuery(
+        QueryBuilder queryBuilder,
+        InferenceIndexInformationForField indexInformation,
+        Float fieldBoost
+    ) {
+        return queryBuilder;
+    }
+
+    @Override
+    public String getQueryName() {
+        return MultiMatchQueryBuilder.NAME;
+    }
+}

x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/queries/SemanticQueryRewriteInterceptor.java

@@ -12,6 +12,7 @@
 import org.elasticsearch.cluster.metadata.InferenceFieldMetadata;
 import org.elasticsearch.index.mapper.IndexFieldMapper;
 import org.elasticsearch.index.query.BoolQueryBuilder;
+import org.elasticsearch.index.query.MultiMatchQueryBuilder;
 import org.elasticsearch.index.query.QueryBuilder;
 import org.elasticsearch.index.query.QueryRewriteContext;
 import org.elasticsearch.index.query.TermsQueryBuilder;
@@ -41,6 +42,12 @@ public QueryBuilder interceptAndRewrite(QueryRewriteContext context, QueryBuilde
             return queryBuilder;
         }
 
+        if (queryBuilder instanceof MultiMatchQueryBuilder) {
+            // This is a placeholder for the actual multi-field handling logic.
+            // Going forward, we will also send fieldNamesWithWeights and resolvedIndices
+            return handleMultiFieldQuery(queryBuilder);
+        }
+
         String fieldName = fieldsWithBoosts.keySet().iterator().next();
         Float fieldBoost = fieldsWithBoosts.get(fieldName);
 
@@ -60,6 +67,13 @@ public QueryBuilder interceptAndRewrite(QueryRewriteContext context, QueryBuilde
         }
     }
 
+    /**
+     * Handle multi-field queries
+     */
+    private QueryBuilder handleMultiFieldQuery(QueryBuilder queryBuilder) {
+        return queryBuilder;
+    }
+
     /**
      * Extracts field names and their associated boost values from the query builder.
      *