/*
    * Copyright 2013–2024 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;
  
  import java.nio.ByteBuffer;
  import java.nio.ByteOrder;
  import java.util.Arrays;
  
  /**
   * An immutable class representing a
   * <a href="https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-dtyp/f992ad60-0fe4-4b87-9fed-beb478836861">security identifier</a>
   * from Active Directory.
   */
  public class Sid {
  
  	public static final Sid NULL_SID = new Sid(new byte[] { (byte) 0x01, (byte) 0x01, (byte) 0x00,
  			(byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00,
  			(byte) 0x00, (byte) 0x00, (byte) 0x00 });
  
  	public static final Sid ANONYMOUS_SID = new Sid(new byte[] { (byte) 0x01, (byte) 0x01,
  			(byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x05,
  			(byte) 0x07, (byte) 0x00, (byte) 0x00, (byte) 0x00 });
  
  	private byte[] bytes;
  
  	private int revision;
  	private int subAuthorityCount;
  	private byte[] identifierAuthority;
  	private long[] subAuthorities;
  
  	private String sidString;
  
  	public Sid(byte[] sidBytes) {
  		if (sidBytes == null)
  			throw new NullPointerException("sidBytes cannot be null");
  		if (sidBytes.length < 12)
  			throw new IllegalArgumentException(
  				"SID must be at least 12 bytes long but is " + sidBytes.length);
  
  		ByteBuffer buf = ByteBuffer.wrap(sidBytes);
  		buf.order(ByteOrder.LITTLE_ENDIAN);
  
  		// Always 0x01
  		this.revision = buf.get() & 0xFF;
  		if (this.revision != 0x01)
  			throw new IllegalArgumentException(
  					"SID revision must be 1 but is " + this.revision);
  
  		// At most 15 subauthorities
  		this.subAuthorityCount = buf.get() & 0xFF;
  		if (this.subAuthorityCount > 15)
  			throw new IllegalArgumentException(
  					"SID subauthority count must be at most 15 but is " + this.subAuthorityCount);
  
  		this.identifierAuthority = new byte[6];
  		buf.get(this.identifierAuthority);
  
  		StringBuilder sidStringBuilder = new StringBuilder("S");
  
  		sidStringBuilder.append('-').append(this.revision);
  
  		ByteBuffer iaBuf = ByteBuffer.allocate(Long.SIZE / Byte.SIZE);
  		iaBuf.position(2);
  		iaBuf.put(this.identifierAuthority);
  		iaBuf.flip();
  
  		sidStringBuilder.append('-').append(iaBuf.getLong());
  
  		this.subAuthorities = new long[this.subAuthorityCount];
  		for (byte b = 0; b < this.subAuthorityCount; b++) {
  			this.subAuthorities[b] = buf.getInt() & 0xffffffffL;
  
  			sidStringBuilder.append('-').append(this.subAuthorities[b]);
  		}
  
  		this.bytes = Arrays.copyOf(sidBytes, sidBytes.length);
  		this.sidString = sidStringBuilder.toString();
  	}
  
  	public byte[] getBytes() {
  		return Arrays.copyOf(bytes, bytes.length);
  	}
  
  	@Override
  	public boolean equals(Object obj) {
  		if (obj == null)
 			return false;
 
 		if (!(obj instanceof Sid))
 			return false;
 
 		Sid that = (Sid) obj;
 
 		if (this == that)
 			return true;
 
 		return Arrays.equals(this.bytes, that.bytes);
 	}
 
 	@Override
 	public int hashCode() {
 		return Arrays.hashCode(this.bytes);
 	}
 
 	@Override
 	public String toString() {
 		return sidString;
 	}
 
 }