[Rest Api Compatibility] Typed endpoints for search _count api (#73958)

retrofits typed endpoints removed in #42112

relates #51816

rest-api-spec/build.gradle

@@ -76,9 +76,6 @@ tasks.named("yamlRestCompatTest").configure {
   systemProperty 'tests.rest.blacklist', ([
     'cluster.voting_config_exclusions/10_basic/Throw exception when adding voting config exclusion and specifying both node_ids and node_names',
     'cluster.voting_config_exclusions/10_basic/Throw exception when adding voting config exclusion without specifying nodes',
-    'count/11_basic_with_types/count body without query element',
-    'count/11_basic_with_types/count with body',
-    'count/11_basic_with_types/count with empty body',
     'field_caps/30_filter/Field caps with index filter',
     'get_source/11_basic_with_types/Basic with types',
     'get_source/16_default_values_with_types/Default values',

server/src/main/java/org/elasticsearch/rest/action/search/RestCountAction.java

@@ -13,7 +13,9 @@
 import org.elasticsearch.action.support.IndicesOptions;
 import org.elasticsearch.client.node.NodeClient;
 import org.elasticsearch.common.Strings;
+import org.elasticsearch.common.logging.DeprecationLogger;
 import org.elasticsearch.common.xcontent.XContentBuilder;
+import org.elasticsearch.core.RestApiVersion;
 import org.elasticsearch.index.query.QueryBuilder;
 import org.elasticsearch.rest.BaseRestHandler;
 import org.elasticsearch.rest.BytesRestResponse;
@@ -32,14 +34,21 @@
 import static org.elasticsearch.search.internal.SearchContext.DEFAULT_TERMINATE_AFTER;
 
 public class RestCountAction extends BaseRestHandler {
-
+    private final DeprecationLogger deprecationLogger = DeprecationLogger.getLogger(RestCountAction.class);
+    static final String TYPES_DEPRECATION_MESSAGE = "[types removal] Specifying types in count requests is deprecated.";
     @Override
     public List<Route> routes() {
         return List.of(
             new Route(GET, "/_count"),
             new Route(POST, "/_count"),
             new Route(GET, "/{index}/_count"),
-            new Route(POST, "/{index}/_count"));
+            new Route(POST, "/{index}/_count"),
+            Route.builder(GET, "/{index}/{type}/_count")
+                .deprecated(TYPES_DEPRECATION_MESSAGE, RestApiVersion.V_7)
+                .build(),
+            Route.builder(POST, "/{index}/{type}/_count")
+                .deprecated(TYPES_DEPRECATION_MESSAGE, RestApiVersion.V_7)
+                .build());
     }
 
     @Override
@@ -49,6 +58,10 @@ public String getName() {
 
     @Override
     public RestChannelConsumer prepareRequest(final RestRequest request, final NodeClient client) throws IOException {
+        if (request.getRestApiVersion() == RestApiVersion.V_7 && request.hasParam("type")) {
+            deprecationLogger.compatibleApiWarning("count_with_types", TYPES_DEPRECATION_MESSAGE);
+            request.param("type");
+        }
         SearchRequest countRequest = new SearchRequest(Strings.splitStringByCommaToArray(request.param("index")));
         countRequest.indicesOptions(IndicesOptions.fromRequest(request, countRequest.indicesOptions()));
         SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder().size(0).trackTotalHits(true);

server/src/test/java/org/elasticsearch/rest/action/search/RestCountActionTests.java

@@ -0,0 +1,67 @@
+/*
+ * 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 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+package org.elasticsearch.rest.action.search;
+
+
+import org.elasticsearch.action.search.SearchRequest;
+import org.elasticsearch.action.search.SearchResponse;
+import org.elasticsearch.core.RestApiVersion;
+import org.elasticsearch.rest.RestRequest;
+import org.elasticsearch.rest.RestRequest.Method;
+import org.elasticsearch.test.rest.FakeRestRequest;
+import org.elasticsearch.test.rest.RestActionTestCase;
+import org.junit.Before;
+import org.mockito.Mockito;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import static org.hamcrest.Matchers.instanceOf;
+
+public class RestCountActionTests extends RestActionTestCase {
+
+    final List<String> contentTypeHeader = Collections.singletonList(randomCompatibleMediaType(RestApiVersion.V_7));
+
+    @Before
+    public void setUpAction() {
+        controller().registerHandler(new RestCountAction());
+        verifyingClient.setExecuteVerifier((actionType, request) -> {
+            assertThat(request, instanceOf(SearchRequest.class));
+            return Mockito.mock(SearchResponse.class);
+        });
+    }
+
+    public void testTypeInPath() {
+        RestRequest request = new FakeRestRequest.Builder(xContentRegistry())
+            .withHeaders(Map.of("Accept", contentTypeHeader))
+            .withMethod(Method.POST)
+            .withPath("/some_index/some_type/_count")
+            .build();
+
+        dispatchRequest(request);
+        assertWarnings(RestCountAction.TYPES_DEPRECATION_MESSAGE);
+    }
+
+    public void testTypeParameter() {
+        Map<String, String> params = new HashMap<>();
+        params.put("type", "some_type");
+
+        RestRequest request = new FakeRestRequest.Builder(xContentRegistry())
+            .withHeaders(Map.of("Accept", contentTypeHeader))
+            .withMethod(Method.GET)
+            .withPath("/some_index/_count")
+            .withParams(params)
+            .build();
+
+        dispatchRequest(request);
+        assertWarnings(RestCountAction.TYPES_DEPRECATION_MESSAGE);
+    }
+}