/*
    * Copyright 2024 the original author or authors.
    *
    * 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 org.bremersee.spring.security.ldaptive.authentication;
  
  import java.util.Collection;
  import java.util.Objects;
  import java.util.Optional;
  import java.util.stream.Collectors;
  import java.util.stream.Stream;
  import org.bremersee.ldaptive.LdaptiveEntryMapper;
  import org.ldaptive.dn.Dn;
  import org.ldaptive.dn.NameValue;
  import org.ldaptive.dn.RDn;
  
  /**
   * Converts a username (like 'foobar') into it's bind dn (like
   * 'uid=foobar,ou=people,dc=example,dc=org').
   *
   * @author Christian Bremer
   */
  @FunctionalInterface
  public interface UsernameToBindDnConverter {
  
    /**
     * Converts a username (like 'foobar') into it's bind dn (like
     * 'uid=foobar,ou=people,dc=example,dc=org').
     *
     * @param username the username
     * @return the bind dn
     */
    String convert(String username);
  
    /**
     * The type By user rdn attribute.
     */
    class ByUserRdnAttribute implements UsernameToBindDnConverter {
  
      private final LdaptiveAuthenticationProperties properties;
  
      /**
       * Instantiates a new converter.
       *
       * @param properties the properties
       */
      public ByUserRdnAttribute(LdaptiveAuthenticationProperties properties) {
        this.properties = Objects
            .requireNonNull(properties, "Ldaptive authentication properties are required.");
      }
  
      @Override
      public String convert(String username) {
        return Optional.ofNullable(properties.getUserBaseDn())
            .map(baseDn -> LdaptiveEntryMapper
                .createDn(properties.getUserRdnAttribute(), username, baseDn))
            .orElseThrow(() -> new IllegalStateException(String
                .format("Converting username %s to bind dn is not possible.", username)));
      }
    }
  
    /**
     * Converts a username (like 'foobar') into it's (active directory) bind dn (like
     * 'foobar@example.org').
     *
     * @author Christian Bremer
     */
    class ByDomainEmail implements UsernameToBindDnConverter {
  
      private final LdaptiveAuthenticationProperties properties;
  
      /**
       * Instantiates a new converter.
       *
       * @param properties the properties
       */
      public ByDomainEmail(LdaptiveAuthenticationProperties properties) {
        this.properties = Objects
            .requireNonNull(properties, "Ldaptive authentication properties are required.");
      }
  
      @Override
      public String convert(String username) {
        return Optional.of(extractDomainName(properties.getUserBaseDn()))
            .filter(domain -> !domain.isEmpty())
            .map(domain -> username + "@" + domain)
            .orElseThrow(() -> new IllegalStateException(String
               .format("Converting username %s to bind dn is not possible.", username)));
     }
 
     private static String extractDomainName(String baseDn) {
       return Stream.ofNullable(baseDn)
           .map(Dn::new)
           .map(Dn::getRDns)
           .flatMap(Collection::stream)
           .map(RDn::getNameValue)
           .filter(nameValue -> nameValue.hasName("dc"))
           .map(NameValue::getStringValue)
           .collect(Collectors.joining("."));
     }
 
   }
 
 }