content: /*
   * Copyright © 2018-2025 Commonwealth Scientific and Industrial Research
   * Organisation (CSIRO) ABN 41 687 119 230.
   *
   * 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
   *
   *     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 au.csiro.pathling.fhir;
  
  import au.csiro.pathling.PathlingVersion;
  import ca.uhn.fhir.interceptor.api.Hook;
  import ca.uhn.fhir.interceptor.api.Interceptor;
  import ca.uhn.fhir.interceptor.api.Pointcut;
  import ca.uhn.fhir.rest.client.api.IHttpRequest;
  import jakarta.annotation.Nonnull;
  import jakarta.annotation.Nullable;
  
  /**
   * HTTP interceptor that adds User-Agent header to FHIR client requests.
   */
  @Interceptor
  public class UserAgentInterceptor {
  
    /**
     * The product identifier used in the User-Agent header.
     */
    public static final String PRODUCT_IDENTIFIER = "pathling";
  
    @Nonnull
    private final PathlingVersion version;
  
    /**
     * Creates a new UserAgentInterceptor.
     */
    public UserAgentInterceptor() {
      this.version = new PathlingVersion();
    }
  
    /**
     * Handles client requests by adding the User-Agent header.
     *
     * @param httpRequest the HTTP request to modify
     */
    @SuppressWarnings("unused")
    @Hook(Pointcut.CLIENT_REQUEST)
    public void handleClientRequest(@Nullable final IHttpRequest httpRequest) {
      if (httpRequest != null) {
        final String userAgent = version.getDescriptiveVersion()
            .map(v -> PRODUCT_IDENTIFIER + "/" + v)
            .orElse(PRODUCT_IDENTIFIER);
        httpRequest.removeHeaders("User-Agent");
        httpRequest.addHeader("User-Agent", userAgent);
      }
    }
  
  }
  