code: /*
   * Copyright (c) 2019 the Eclipse Milo Authors
   *
   * This program and the accompanying materials are made
   * available under the terms of the Eclipse Public License 2.0
   * which is available at https://www.eclipse.org/legal/epl-2.0/
   *
   * SPDX-License-Identifier: EPL-2.0
   */
  
  package org.eclipse.milo.opcua.sdk.server.identity;
  
  import java.util.function.Predicate;
  
  import org.eclipse.milo.opcua.sdk.server.Session;
  import org.jetbrains.annotations.Nullable;
  
  public class UsernameIdentityValidator extends AbstractUsernameIdentityValidator<String> {
  
      private final boolean anonymousAccessAllowed;
      private final Predicate<AuthenticationChallenge> predicate;
  
      public UsernameIdentityValidator(
          boolean anonymousAccessAllowed,
          Predicate<AuthenticationChallenge> predicate
      ) {
  
          this.anonymousAccessAllowed = anonymousAccessAllowed;
          this.predicate = predicate;
      }
  
      @Nullable
      @Override
      protected String authenticateAnonymous(Session session) {
          if (anonymousAccessAllowed) {
              return String.format(
                  "anonymous_%s_%s",
                  session.getSessionName(),
                  session.getSessionId().toParseableString()
              );
          } else {
              return null;
          }
      }
  
      @Nullable
      @Override
      protected String authenticateUsernamePassword(Session session, String username, String password) {
          AuthenticationChallenge challenge =
              new AuthenticationChallenge(username, password);
  
          return predicate.test(challenge) ? username : null;
      }
  
      public static final class AuthenticationChallenge {
  
          private final String username;
          private final String password;
  
          AuthenticationChallenge(String username, String password) {
              this.username = username;
              this.password = password;
          }
  
          public String getUsername() {
              return username;
          }
  
          public String getPassword() {
              return password;
          }
  
      }
  
  }
  