/*
    * Copyright 2013–2021 Michael Osipov
    *
    * 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 net.sf.michaelo.tomcat.realm.mapper;
  
  import java.util.Arrays;
  
  import javax.naming.NamingException;
  import javax.naming.directory.DirContext;
  
  import org.apache.commons.lang3.StringUtils;
  import org.ietf.jgss.GSSException;
  import org.ietf.jgss.GSSName;
  import org.ietf.jgss.Oid;
  
  /**
   * A mapper for the AD attribute {@code userPrincipalName}. This mapper maps the GSS name to the AD
   * attribute {@code userPrincipalName} which by default contains the implicit UPN unless it's
   * overwritten by the explicit (enterprise) UPN. In this case, the result will be empty. No
   * assumption is made about the root DN set in the given context, so you can narrow down your search
   * base if you like.
   */
  public class UserPrincipalNameSearchMapper implements UsernameSearchMapper {
  
  	protected final static Oid KRB5_NT_PRINCIPAL;
  	protected final static Oid KRB5_NT_ENTERPRISE_PRINCIPAL;
  	protected final static Oid MS_UPN;
  
  	static {
  		try {
  			KRB5_NT_PRINCIPAL = new Oid("1.2.840.113554.1.2.2.1");
  		} catch (GSSException e) {
  			throw new IllegalStateException("Failed to create OID for KRB5_NT_PRINCIPAL");
  		}
  
  		try {
  			KRB5_NT_ENTERPRISE_PRINCIPAL = new Oid("1.2.840.113554.1.2.2.6");
  		} catch (GSSException e) {
  			throw new IllegalStateException("Failed to create OID for KRB5_NT_ENTERPRISE_PRINCIPAL");
  		}
  
  		try {
  			MS_UPN = new Oid("1.3.6.1.4.1.311.20.2.3");
  		} catch (GSSException e) {
  			throw new IllegalStateException("Failed to create OID for MS_UPN");
  		}
  	}
  
  	private static final Oid[] SUPPORTED_STRING_NAME_TYPES = new Oid[] { MS_UPN, KRB5_NT_ENTERPRISE_PRINCIPAL,
  			KRB5_NT_PRINCIPAL };
  
  	@Override
  	public Oid[] getSupportedStringNameTypes() {
  		return Arrays.copyOf(SUPPORTED_STRING_NAME_TYPES, SUPPORTED_STRING_NAME_TYPES.length);
  	}
  
  	@Override
  	public boolean supportsGssName(GSSName gssName) {
  		try {
  			return gssName.getStringNameType().containedIn(SUPPORTED_STRING_NAME_TYPES);
  		} catch (GSSException e) {
  			// Can this ever happen?
  			return false;
  		}
  	}
  
  	protected static class UserPrincipalNameMappedValues implements MappedValues {
  
  		private String searchUsername;
  
  		protected UserPrincipalNameMappedValues(String searchUsername) {
  			this.searchUsername = searchUsername;
  		}
  
  		@Override
  		public String getSearchBase() {
  			return StringUtils.EMPTY;
  		}
  
  		@Override
  		public String getSearchAttributeName() {
  			return "userPrincipalName";
  		}
  
  		@Override
  		public String getSearchUsername() {
  			return searchUsername;
 		}
 
 	}
 
 	public synchronized MappedValues map(DirContext context, GSSName gssName)
 			throws NamingException {
 		if (!supportsGssName(gssName))
 			throw new IllegalArgumentException("GSS name '" + gssName + "' is not supported");
 
 		return new UserPrincipalNameMappedValues(gssName.toString());
 	}
 
 }