Add support for FTS

Fixes #2085

Signed-off-by: Emilien Bevierre <emilien.bevierre@couchbase.com>

Author: emilienbev

src/main/java/org/springframework/data/couchbase/core/CouchbaseTemplate.java

@@ -49,6 +49,7 @@
  * @author Michael Reiche
  * @author Jorge Rodriguez Martin
  * @author Tigran Babloyan
+ * @author Emilien Bevierre
  * @since 3.0
  */
 public class CouchbaseTemplate implements CouchbaseOperations, ApplicationContextAware {
@@ -188,6 +189,11 @@ public <T> ExecutableFindByAnalytics<T> findByAnalytics(Class<T> domainType) {
 		return new ExecutableFindByAnalyticsOperationSupport(this).findByAnalytics(domainType);
 	}
 
+	@Override
+	public <T> ExecutableFindBySearch<T> findBySearch(Class<T> domainType) {
+		return new ExecutableFindBySearchOperationSupport(this).findBySearch(domainType);
+	}
+
 	@Override
 	@Deprecated
 	public ExecutableRemoveById removeById() {

src/main/java/org/springframework/data/couchbase/core/ExecutableFindBySearchOperation.java

@@ -0,0 +1,197 @@
+/*
+ * Copyright 2025-present the original author or authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.couchbase.core;
+
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.stream.Stream;
+
+import org.springframework.dao.IncorrectResultSizeDataAccessException;
+import org.springframework.data.couchbase.core.support.InCollection;
+import org.springframework.data.couchbase.core.support.InScope;
+import org.springframework.data.couchbase.core.support.WithSearchConsistency;
+import org.springframework.data.couchbase.core.support.WithSearchOptions;
+import org.springframework.data.couchbase.core.support.WithSearchQuery;
+import org.jspecify.annotations.Nullable;
+
+import com.couchbase.client.java.search.HighlightStyle;
+import com.couchbase.client.java.search.SearchOptions;
+import com.couchbase.client.java.search.SearchRequest;
+import com.couchbase.client.java.search.SearchScanConsistency;
+import com.couchbase.client.java.search.facet.SearchFacet;
+import com.couchbase.client.java.search.result.SearchRow;
+import com.couchbase.client.java.search.sort.SearchSort;
+
+/**
+ * Full-Text Search (FTS) Operations (Blocking)
+ *
+ * @author Emilien Bevierre
+ * @since 6.2
+ */
+public interface ExecutableFindBySearchOperation {
+
+	/**
+	 * Queries the Full-Text Search (FTS) service.
+	 *
+	 * @param domainType the entity type to use for the results.
+	 */
+	<T> ExecutableFindBySearch<T> findBySearch(Class<T> domainType);
+
+	interface TerminatingFindBySearch<T> {
+
+		/**
+		 * Get exactly zero or one result.
+		 *
+		 * @return {@link Optional#empty()} if no match found.
+		 * @throws IncorrectResultSizeDataAccessException if more than one match found.
+		 */
+		default Optional<T> one() {
+			return Optional.ofNullable(oneValue());
+		}
+
+		/**
+		 * Get exactly zero or one result.
+		 *
+		 * @return {@literal null} if no match found.
+		 * @throws IncorrectResultSizeDataAccessException if more than one match found.
+		 */
+		@Nullable
+		T oneValue();
+
+		/**
+		 * Get the first or no result.
+		 *
+		 * @return {@link Optional#empty()} if no match found.
+		 */
+		default Optional<T> first() {
+			return Optional.ofNullable(firstValue());
+		}
+
+		/**
+		 * Get the first or no result.
+		 *
+		 * @return {@literal null} if no match found.
+		 */
+		@Nullable
+		T firstValue();
+
+		/**
+		 * Get all matching elements, hydrated as entities via KV GET.
+		 *
+		 * @return never {@literal null}.
+		 */
+		List<T> all();
+
+		/**
+		 * Stream all matching elements.
+		 *
+		 * @return a {@link Stream} of results. Never {@literal null}.
+		 */
+		Stream<T> stream();
+
+		/**
+		 * Get the number of matching elements.
+		 *
+		 * @return total number of matching elements.
+		 */
+		long count();
+
+		/**
+		 * Check for the presence of matching elements.
+		 *
+		 * @return {@literal true} if at least one matching element exists.
+		 */
+		boolean exists();
+
+		/**
+		 * Get raw FTS search rows (without entity hydration).
+		 *
+		 * @return never {@literal null}.
+		 */
+		List<SearchRow> rows();
+
+		/**
+		 * Get a combined result including hydrated entities, raw rows, metadata, and facet results.
+		 *
+		 * @return a {@link SearchResult} containing the full response.
+		 */
+		SearchResult<T> result();
+	}
+
+	interface FindBySearchWithQuery<T> extends TerminatingFindBySearch<T>, WithSearchQuery<T> {
+		@Override
+		TerminatingFindBySearch<T> matching(SearchRequest searchRequest);
+	}
+
+	interface FindBySearchWithOptions<T> extends FindBySearchWithQuery<T>, WithSearchOptions<T> {
+		@Override
+		FindBySearchWithQuery<T> withOptions(SearchOptions options);
+	}
+
+	interface FindBySearchInCollection<T> extends FindBySearchWithOptions<T>, InCollection<T> {
+		@Override
+		FindBySearchWithOptions<T> inCollection(String collection);
+	}
+
+	interface FindBySearchInScope<T> extends FindBySearchInCollection<T>, InScope<T> {
+		@Override
+		FindBySearchInCollection<T> inScope(String scope);
+	}
+
+	interface FindBySearchWithConsistency<T> extends FindBySearchInScope<T>, WithSearchConsistency<T> {
+		@Override
+		FindBySearchInScope<T> withConsistency(SearchScanConsistency scanConsistency);
+	}
+
+	interface FindBySearchWithLimit<T> extends FindBySearchWithConsistency<T> {
+		FindBySearchWithConsistency<T> withLimit(int limit);
+	}
+
+	interface FindBySearchWithSkip<T> extends FindBySearchWithLimit<T> {
+		FindBySearchWithLimit<T> withSkip(int skip);
+	}
+
+	interface FindBySearchWithSort<T> extends FindBySearchWithSkip<T> {
+		FindBySearchWithSkip<T> withSort(SearchSort... sort);
+	}
+
+	interface FindBySearchWithHighlight<T> extends FindBySearchWithSort<T> {
+		FindBySearchWithSort<T> withHighlight(HighlightStyle style, String... fields);
+
+		default FindBySearchWithSort<T> withHighlight(String... fields) {
+			return withHighlight(HighlightStyle.SERVER_DEFAULT, fields);
+		}
+	}
+
+	interface FindBySearchWithFacets<T> extends FindBySearchWithHighlight<T> {
+		FindBySearchWithHighlight<T> withFacets(Map<String, SearchFacet> facets);
+	}
+
+	interface FindBySearchWithFields<T> extends FindBySearchWithFacets<T> {
+		FindBySearchWithFacets<T> withFields(String... fields);
+	}
+
+	interface FindBySearchWithProjection<T> extends FindBySearchWithFields<T> {
+		<R> FindBySearchWithFields<R> as(Class<R> returnType);
+	}
+
+	interface FindBySearchWithIndex<T> extends FindBySearchWithProjection<T> {
+		FindBySearchWithProjection<T> withIndex(String indexName);
+	}
+
+	interface ExecutableFindBySearch<T> extends FindBySearchWithIndex<T> {}
+}