/*
    * Copyright 2024–2026 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.pac;
  
  import java.util.Objects;
  
  /**
   * A class representing the <a href=
   * "https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-pac/6e95edd3-af93-41d4-8303-6c7955297315">{@code PAC_SIGNATURE_DATA}</a>
   * structure from MS-PAC.
   */
  public class PacSignatureData {
  
  	public enum SignatureType {
  		HMAC_MD5(-138, 16, 23),
  		HMAC_SHA1_96_AES128(15, 12, 17),
  		HMAC_SHA1_96_AES256(16, 12, 18);
  
  		private final int value;
  		private final int size;
  		private final int eType;
  
  		SignatureType(int value, int size, int eType) {
  			this.value = value;
  			this.size = size;
  			this.eType = eType;
  		}
  
  		public int getValue() {
  			return value;
  		}
  
  		public int getSize() {
  			return size;
  		}
  
  		public int getEType() {
  			return eType;
  		}
  	}
  
  	private final SignatureType type;
  	private final byte[] signature;
  
  	/**
  	 * Parses a PAC signature data object from a byte array.
  	 *
  	 * @param sigDataBytes PAC signature data structure encoded as bytes
  	 * @throws NullPointerException if {@code sigDataBytes} is null
  	 * @throws IllegalArgumentException if {@code sigDataBytes} is empty
  	 * @throws IllegalArgumentException if encoded signature type is not supported by {@link SignatureType}
  	 */
  	public PacSignatureData(byte[] sigDataBytes) {
  		Objects.requireNonNull(sigDataBytes, "sigDataBytes cannot be null");
  		if (sigDataBytes.length == 0) throw new IllegalArgumentException("sigDataBytes cannot be empty");
  
  		PacDataBuffer buf = new PacDataBuffer(sigDataBytes);
  
  		// SignatureType
  		int type = buf.getInt();
  		if (type == SignatureType.HMAC_MD5.getValue()) {
  			this.type = SignatureType.HMAC_MD5;
  		} else if (type == SignatureType.HMAC_SHA1_96_AES128.getValue()) {
  			this.type = SignatureType.HMAC_SHA1_96_AES128;
  		} else if (type == SignatureType.HMAC_SHA1_96_AES256.getValue()) {
  			this.type = SignatureType.HMAC_SHA1_96_AES256;
  		} else {
  			throw new IllegalArgumentException("Unsupported signature type " + type);
  		}
  
  		// Signature
  		this.signature = new byte[this.type.getSize()];
  		buf.get(this.signature);
  
  		// RODCIdentifier ignored completely
  	}
  
  	public SignatureType getType() {
  		return type;
  	}
  
  	public byte[] getSignature() {
  		return signature;
  	}
  }