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.firefox;
  
  import static org.openqa.selenium.remote.Browser.FIREFOX;
  
  import com.google.auto.service.AutoService;
  import com.google.common.collect.ImmutableMap;
  import java.io.FileOutputStream;
  import java.io.IOException;
  import java.nio.file.FileVisitResult;
  import java.nio.file.Files;
  import java.nio.file.Path;
  import java.nio.file.Paths;
  import java.nio.file.SimpleFileVisitor;
  import java.nio.file.attribute.BasicFileAttributes;
  import java.util.Base64;
  import java.util.Map;
  import java.util.function.Predicate;
  import java.util.zip.ZipEntry;
  import java.util.zip.ZipOutputStream;
  import org.openqa.selenium.Capabilities;
  import org.openqa.selenium.InvalidArgumentException;
  import org.openqa.selenium.internal.Require;
  import org.openqa.selenium.remote.AdditionalHttpCommands;
  import org.openqa.selenium.remote.AugmenterProvider;
  import org.openqa.selenium.remote.CommandInfo;
  import org.openqa.selenium.remote.ExecuteMethod;
  import org.openqa.selenium.remote.http.HttpMethod;
  
  @AutoService({AdditionalHttpCommands.class, AugmenterProvider.class})
  public class AddHasExtensions implements AugmenterProvider<HasExtensions>, AdditionalHttpCommands {
  
    public static final String INSTALL_EXTENSION = "installExtension";
    public static final String UNINSTALL_EXTENSION = "uninstallExtension";
  
    private static final Map<String, CommandInfo> COMMANDS =
        ImmutableMap.of(
            INSTALL_EXTENSION,
                new CommandInfo("/session/:sessionId/moz/addon/install", HttpMethod.POST),
            UNINSTALL_EXTENSION,
                new CommandInfo("/session/:sessionId/moz/addon/uninstall", HttpMethod.POST));
  
    @Override
    public Map<String, CommandInfo> getAdditionalCommands() {
      return COMMANDS;
    }
  
    @Override
    public Predicate<Capabilities> isApplicable() {
      return FIREFOX::is;
    }
  
    @Override
    public Class<HasExtensions> getDescribedInterface() {
      return HasExtensions.class;
    }
  
    @Override
    public HasExtensions getImplementation(Capabilities capabilities, ExecuteMethod executeMethod) {
      return new HasExtensions() {
        @Override
        public String installExtension(Path path) {
          return installExtension(path, false);
        }
  
        @Override
        public String installExtension(Path path, Boolean temporary) {
          Require.nonNull("Extension Path", path);
          Require.nonNull("Temporary", temporary);
  
          String encoded;
          try {
            if (Files.isDirectory(path)) {
              encoded = Base64.getEncoder().encodeToString(Files.readAllBytes(zipDirectory(path)));
            } else {
              encoded = Base64.getEncoder().encodeToString(Files.readAllBytes(path));
            }
          } catch (IOException e) {
            throw new InvalidArgumentException(path + " is an invalid path", e);
          }
  
          return (String)
              executeMethod.execute(
                  INSTALL_EXTENSION, ImmutableMap.of("addon", encoded, "temporary", temporary));
        }
  
        private Path zipDirectory(Path path) throws IOException {
          Path extZip = Paths.get(path.getFileName().toString() + ".zip");
          try (ZipOutputStream zos = new ZipOutputStream(new FileOutputStream(extZip.toFile()))) {
            Files.walkFileTree(
                path,
                new SimpleFileVisitor<Path>() {
                  @Override
                  public FileVisitResult visitFile(Path file, BasicFileAttributes attrs)
                      throws IOException {
                    zos.putNextEntry(new ZipEntry(path.relativize(file).toString()));
                    Files.copy(file, zos);
                    zos.closeEntry();
                    return FileVisitResult.CONTINUE;
                  }
                });
          }
          return extZip;
        }
  
        @Override
        public void uninstallExtension(String extensionId) {
          Require.nonNull("Extension ID", extensionId);
  
          executeMethod.execute(UNINSTALL_EXTENSION, ImmutableMap.of("id", extensionId));
        }
      };
    }
  }
  