code: // Licensed to the Software Freedom Conservancy (SFC) under one
  // or more contributor license agreements.  See the NOTICE file
  // distributed with this work for additional information
  // regarding copyright ownership.  The SFC 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 org.openqa.selenium.devtools;
  
  import static org.openqa.selenium.remote.http.Contents.utf8String;
  
  import java.util.Map;
  import java.util.Optional;
  import org.openqa.selenium.WebDriver;
  import org.openqa.selenium.internal.Require;
  import org.openqa.selenium.remote.http.Filter;
  import org.openqa.selenium.remote.http.HttpHandler;
  import org.openqa.selenium.remote.http.HttpMethod;
  import org.openqa.selenium.remote.http.HttpRequest;
  import org.openqa.selenium.remote.http.HttpResponse;
  import org.openqa.selenium.remote.http.Routable;
  import org.openqa.selenium.remote.http.Route;
  
  /**
   * Provides a mechanism for stubbing out responses to requests in drivers which implement {@link
   * HasDevTools}. Usage is done by specifying a {@link Route}, which will be checked for every
   * request to see if that request should be handled or not. Note that the URLs given to the {@code
   * Route} will be fully qualified.
   *
   * <p>Example usage:
   *
   * <p>
   *
   * <pre><code>
   *   Route route = Route.matching(req -&gt; GET == req.getMethod() &amp;&amp; req.getUri().endsWith("/example"))
   *     .to(() -&gt; req -&gt; new HttpResponse().setContent(Contents.utf8String("Hello, World!")));
   *
   *   try (NetworkInterceptor interceptor = new NetworkInterceptor(driver, route)) {
   *     // Your code here.
   *   }
   * </code></pre>
   *
   * <p>It is also possible to intercept and modify responses that the browser will receive. Do this
   * by calling {@link #NetworkInterceptor(WebDriver, Filter)}.
   */
  public class NetworkInterceptor implements AutoCloseable {
  
    /**
     * Return this from a {@link Routable} in order to have the browser continue the request
     * unmodified.
     */
    public static final HttpResponse PROCEED_WITH_REQUEST =
        new HttpResponse()
            .addHeader("Selenium-Interceptor", "Continue")
            .setContent(utf8String("Original request should proceed"));
  
    private final DevTools tools;
  
    public NetworkInterceptor(WebDriver driver, HttpHandler handler) {
      this(driver, (Filter) next -> handler);
    }
  
    public NetworkInterceptor(WebDriver driver, Routable routable) {
      this(
          driver,
          (Filter)
              next ->
                  req -> {
                    if (routable.matches(req)) {
                      return routable.execute(req);
                    }
                    return next.execute(req);
                  });
    }
  
    public NetworkInterceptor(WebDriver driver, Filter filter) {
      Require.nonNull("WebDriver", driver);
      Require.nonNull("HTTP filter", filter);
  
      if (!(driver instanceof HasDevTools)) {
        throw new IllegalArgumentException("WebDriver instance must implement HasDevTools");
      }
  
      this.tools = ((HasDevTools) driver).getDevTools();
      tools.createSessionIfThereIsNotOne(driver.getWindowHandle());
  
      tools.getDomains().network().interceptTrafficWith(filter);
    }
  
    @Override
    public void close() {
      tools.getDomains().network().resetNetworkFilter();
      tools.getDomains().network().markNetworkInterceptorClosed();
    }
  
    protected HttpMethod convertFromCdpHttpMethod(String method) {
      Require.nonNull("HTTP Method", method);
      try {
        return HttpMethod.valueOf(method.toUpperCase());
      } catch (IllegalArgumentException e) {
        // Spam in a reasonable value
        return HttpMethod.GET;
      }
    }
  
    protected HttpRequest createHttpRequest(
        String cdpMethod, String url, Map<String, Object> headers, Optional<String> postData) {
      HttpRequest req = new HttpRequest(convertFromCdpHttpMethod(cdpMethod), url);
      headers.forEach((key, value) -> req.addHeader(key, String.valueOf(value)));
      postData.ifPresent(data -> req.setContent(utf8String(data)));
  
      return req;
    }
  }
  