Generic header mechanism using RequestOption interface

Author: technige

java-client/src/main/java/co/elastic/clients/base/Header.java

@@ -0,0 +1,92 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you 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
+ *
+ *     http://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 co.elastic.clients.base;
+
+import org.elasticsearch.client.RequestOptions;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Objects;
+
+import static java.util.Arrays.asList;
+import static java.util.Collections.unmodifiableList;
+
+/**
+ * HTTP header field, consisting of a string key ('field') plus one
+ * or more values. This implements the {@link RequestOption} interface,
+ * allowing it to be applied to a low-level request as required.
+ */
+public class Header implements RequestOption {
+
+    public static Header header(String field, String... values) {
+        return new Header(field, values);
+    }
+
+    static final String VALUE_DELIMITER = ", ";
+
+    private final String field;
+    private final List<String> values;
+
+    Header(String field, String... values) {
+        this.field = field;
+        this.values = asList(values);
+    }
+
+    public String field() {
+        return field;
+    }
+
+    public String value() {
+        if (values == null || values.isEmpty()) {
+            return null;
+        } else if (values.size() == 1) {
+            return values.get(0);
+        } else {
+            return String.join(VALUE_DELIMITER, values);
+        }
+    }
+
+    public List<String> values() {
+        return values;
+    }
+
+    @Override
+    public boolean equals(Object other) {
+        if (this == other) return true;
+        if (!(other instanceof Header)) return false;
+        Header header = (Header) other;
+        return field.equalsIgnoreCase(header.field()) && Objects.equals(values(), header.values());
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(field(), values());
+    }
+
+    public String toString() {
+        return String.format("%s: %s", field(), value());
+    }
+
+    @Override
+    public void apply(final RequestOptions.Builder builder) {
+        builder.addHeader(field(), value());
+    }
+
+}

java-client/src/main/java/co/elastic/clients/base/RequestOption.java

@@ -0,0 +1,36 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you 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
+ *
+ *     http://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 co.elastic.clients.base;
+
+import org.elasticsearch.client.RequestOptions;
+
+/**
+ * An option that can be applied to an HTTP request.
+ */
+public interface RequestOption {
+
+    /**
+     * Apply the option to an existing builder object.
+     *
+     * @param builder builder to which to apply the option
+     */
+    void apply(final RequestOptions.Builder builder);
+
+}

java-client/src/main/java/co/elastic/clients/base/Transport.java

@@ -23,6 +23,7 @@
 
 import java.io.Closeable;
 import java.io.IOException;
+import java.util.Map;
 import java.util.concurrent.CompletableFuture;
 
 /**
@@ -42,5 +43,6 @@ <RequestT, ResponseT, ErrorT> CompletableFuture<ResponseT> performRequestAsync(
 
     JsonpMapper jsonpMapper();
 
-    String userAgent();
+    Map<String, Header> headers();
+
 }

java-client/src/main/java/co/elastic/clients/base/UserAgent.java

@@ -26,10 +26,10 @@
 import java.util.Properties;
 
 /**
- * Models a user agent, consisting of a name, version,
+ * Models a user agent header, consisting of a name, version,
  * and optional key-value metadata.
  */
-public class UserAgent {
+public class UserAgent extends Header {
 
     static final String DEFAULT_NAME = "elasticsearch-java";
 
@@ -64,6 +64,7 @@ public class UserAgent {
     private final Map<String, String> metadata;
 
     public UserAgent(String name, String version, Map<String, String> metadata) {
+        super("User-Agent", buildValueString(name, version, metadata));
         this.name = name;
         this.version = version;
         this.metadata = metadata;
@@ -73,8 +74,19 @@ public UserAgent(String repoName, String version) {
         this(repoName, version, Collections.emptyMap());
     }
 
-    @Override
-    public String toString() {
+    public String name() {
+        return name;
+    }
+
+    public String version() {
+        return version;
+    }
+
+    public Map<String, String> metadata() {
+        return metadata;
+    }
+
+    private static String buildValueString(String name, String version, Map<String, String> metadata) {
         if (metadata.isEmpty()) {
             return String.format("%s/%s", name, version);
         }

java-client/src/main/java/co/elastic/clients/base/rest_client/RestClientTransport.java

@@ -24,14 +24,15 @@
 import co.elastic.clients.base.BooleanResponse;
 import co.elastic.clients.base.ElasticsearchCatRequest;
 import co.elastic.clients.base.Endpoint;
+import co.elastic.clients.base.Header;
+import co.elastic.clients.base.RequestOption;
 import co.elastic.clients.base.Transport;
 import co.elastic.clients.base.UserAgent;
 import co.elastic.clients.json.JsonpDeserializer;
 import co.elastic.clients.json.JsonpMapper;
 import co.elastic.clients.json.NdJsonpSerializable;
 import jakarta.json.stream.JsonGenerator;
 import jakarta.json.stream.JsonParser;
-import org.apache.http.Header;
 import org.apache.http.entity.ByteArrayEntity;
 import org.apache.http.entity.ContentType;
 import org.elasticsearch.client.Cancellable;
@@ -45,38 +46,35 @@
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
+import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 import java.util.concurrent.CompletableFuture;
-import java.util.function.Function;
+
+import static co.elastic.clients.base.Header.header;
+import static java.util.Collections.singletonList;
 
 public class RestClientTransport implements Transport {
 
+    private static final List<RequestOption> DEFAULT_REQUEST_OPTIONS = singletonList(UserAgent.DEFAULT);
+
     private final RestClient restClient;
     private final JsonpMapper mapper;
     private final RequestOptions requestOptions;
 
-    public RestClientTransport(RestClient restClient, JsonpMapper mapper, @Nullable RequestOptions options,
-                               @Nullable UserAgent userAgent) {
-        this.restClient = restClient;
-        this.mapper = mapper;
-        RequestOptions baseOptions = options == null ? RequestOptions.DEFAULT : options;
-        String manualUserAgent = findUserAgentIn(baseOptions);
-        if (manualUserAgent == null && userAgent == null) {
-            this.requestOptions = baseOptions.toBuilder().addHeader("User-Agent", UserAgent.DEFAULT.toString()).build();
-        }
-        else if (manualUserAgent == null) {
-            this.requestOptions = baseOptions.toBuilder().addHeader("User-Agent", userAgent.toString()).build();
-        }
-        else if (userAgent == null) {
-            this.requestOptions = baseOptions;
-        }
-        else {
-            throw new IllegalArgumentException("Multiple user agents specified");
+    private static void applyRequestOptions(final RequestOptions.Builder builder, Iterable<RequestOption> options) {
+        if (options != null) {
+            options.forEach(option -> option.apply(builder));
         }
     }
 
-    public RestClientTransport(RestClient restClient, JsonpMapper mapper, @Nullable RequestOptions options) {
-        this(restClient, mapper, options, null);
+    public RestClientTransport(RestClient restClient, JsonpMapper mapper, @Nullable Iterable<RequestOption> options) {
+        this.restClient = restClient;
+        this.mapper = mapper;
+        final RequestOptions.Builder builder = RequestOptions.DEFAULT.toBuilder();
+        applyRequestOptions(builder, DEFAULT_REQUEST_OPTIONS);
+        applyRequestOptions(builder, options);
+        this.requestOptions = builder.build();
     }
 
     public RestClientTransport(RestClient restClient, JsonpMapper mapper) {
@@ -86,59 +84,28 @@ public RestClientTransport(RestClient restClient, JsonpMapper mapper) {
     /**
      * Creates a new {@link #RestClientTransport} with specific request options.
      */
-    public RestClientTransport withRequestOptions(@Nullable RequestOptions options) {
+    public RestClientTransport withRequestOptions(@Nullable Iterable<RequestOption> options) {
         return new RestClientTransport(this.restClient, this.mapper, options);
     }
 
-    /**
-     * Creates a new {@link #RestClientTransport} with specific request options, inheriting existing options.
-     *
-     * @param fn a function taking an options builder initialized with the current request options, or initialized
-     *           with default values.
-     */
-    public RestClientTransport withRequestOptions(Function<RequestOptions.Builder, RequestOptions.Builder> fn) {
-        RequestOptions.Builder builder = requestOptions == null ?
-            RequestOptions.DEFAULT.toBuilder() :
-            requestOptions.toBuilder();
-
-        return withRequestOptions(fn.apply(builder).build());
-    }
-
-    public RestClientTransport withUserAgent(UserAgent userAgent) {
-        return new RestClientTransport(this.restClient, this.mapper, this.requestOptions, userAgent);
-    }
-
     @Override
     public JsonpMapper jsonpMapper() {
         return mapper;
     }
 
-    /**
-     * Find and return the first header value which is keyed under any
-     * case-insensitive variant of "User-Agent".
-     *
-     * @return user agent string
-     */
     @Override
-    public String userAgent() {
-        return findUserAgentIn(requestOptions);
+    public Map<String, Header> headers() {
+        Map<String, Header> headers = new HashMap<>();
+        requestOptions.getHeaders().forEach(header ->
+                headers.put(header.getName(), header(header.getName(), header.getValue())));
+        return headers;
     }
 
     @Override
     public void close() throws IOException {
         this.restClient.close();
     }
 
-    private static String findUserAgentIn(RequestOptions options) {
-        // TODO: move this into RequestOptions?
-        for (Header header : options.getHeaders()) {
-            if (header.getName().equalsIgnoreCase("User-Agent")) {
-                return header.getValue();
-            }
-        }
-        return null;
-    }
-
     public <RequestT, ResponseT, ErrorT> ResponseT performRequest(
         RequestT request,
         Endpoint<RequestT, ResponseT, ErrorT> endpoint

java-client/src/test/java/co/elastic/clients/base/HeaderTest.java

@@ -0,0 +1,51 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you 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
+ *
+ *     http://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 co.elastic.clients.base;
+
+import org.junit.Test;
+
+import static co.elastic.clients.base.Header.header;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+
+public class HeaderTest {
+
+    @Test
+    public void testSimple() {
+        Header header = header("Content-Type", "application/json");
+        assertEquals("Content-Type", header.field());
+        assertEquals("application/json", header.value());
+    }
+
+    @Test
+    public void testMulti() {
+        Header header = header("Cache-Control", "no-cache", "no-store");
+        assertEquals("Cache-Control", header.field());
+        assertEquals("no-cache, no-store", header.value());
+    }
+
+    @Test
+    public void testEmpty() {
+        Header header = header("Content-Length");
+        assertEquals("Content-Length", header.field());
+        assertNull(header.value());
+    }
+
+}