package org.metricshub.ipmi.core.coding.protocol.encoder;
   
   /*-
    * ╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲
    * IPMI Java Client
    * ჻჻჻჻჻჻
    * Copyright 2023 Verax Systems, MetricsHub
    * ჻჻჻჻჻჻
    * This program is free software: you can redistribute it and/or modify
   * it under the terms of the GNU Lesser General Public License as
   * published by the Free Software Foundation, either version 3 of the
   * License, or (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Lesser Public License for more details.
   *
   * You should have received a copy of the GNU General Lesser Public
   * License along with this program.  If not, see
   * <http://www.gnu.org/licenses/lgpl-3.0.html>.
   * ╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱
   */
  
  import org.metricshub.ipmi.core.coding.protocol.AuthenticationType;
  import org.metricshub.ipmi.core.coding.protocol.IpmiMessage;
  import org.metricshub.ipmi.core.coding.protocol.Ipmiv15Message;
  import org.metricshub.ipmi.core.common.TypeConverter;
  
  import java.security.InvalidKeyException;
  
  /**
   * Encodes IPMI v1.5 message
   */
  public class Protocolv15Encoder extends ProtocolEncoder {
  
  	/**
  	 * @param ipmiMessage
  	 *        - IPMI message to be encoded. Must be {@link Ipmiv15Message}.
  	 * @throws InvalidKeyException
  	 *         - when initiation of the confidentiality algorithm fails
  	 * @throws IllegalArgumentException
  	 *         when IPMI protocol version is incorrect.
  	 * @see Ipmiv15Message
  	 */
  	@Override
  	public byte[] encode(IpmiMessage ipmiMessage) throws InvalidKeyException {
  		if (!(ipmiMessage instanceof Ipmiv15Message)) {
  			throw new IllegalArgumentException("IPMIMessage must be in 1.5 version.");
  		}
  		Ipmiv15Message message = (Ipmiv15Message) ipmiMessage;
  
  		byte[] raw = new byte[getMessageLength(message)];
  
  		raw[0] = encodeAuthenticationType(message.getAuthenticationType());
  
  		int offset = 1;
  
  		encodeSessionSequenceNumber(message.getSessionSequenceNumber(), raw, offset);
  		offset += 4;
  
  		encodeSessionId(message.getSessionID(), raw, offset);
  		offset += 4;
  
  		if (message.getAuthenticationType() != AuthenticationType.None) {
  			encodeAuthenticationCode(message.getAuthCode(), raw, offset);
  			offset += message.getAuthCode().length;
  		}
  
  		byte[] payload = message.getPayload().getEncryptedPayload();
  
  		if (payload == null) {
  			message.getPayload().encryptPayload(message.getConfidentialityAlgorithm());
  			payload = message.getPayload().getEncryptedPayload();
  		}
  
  		encodePayloadLength(payload.length, raw, offset);
  		++offset;
  
  		offset = encodePayload(payload, raw, offset);
  
  		encodeSessionTrailer(raw, offset);
  
  		return raw;
  	}
  
  	private int getMessageLength(IpmiMessage ipmiMessage) {
  		int length = 11
  				+ ipmiMessage.getConfidentialityAlgorithm().getConfidentialityOverheadSize(ipmiMessage.getPayloadLength())
  				+ ipmiMessage.getPayloadLength();
  
  		if (ipmiMessage.getAuthenticationType() != AuthenticationType.None) {
  			length += 16;
  		}
  
  		return length;
  	}
  
  	/**
 	 * Inserts authentication code into message at given offset.
 	 *
 	 * @param authCode
 	 * @param message
 	 *        - message being encoded
 	 * @param offset
 	 * @throws IndexOutOfBoundsException
 	 *         when message is too short to hold value at given offset
 	 */
 	private void encodeAuthenticationCode(byte[] authCode, byte[] message, int offset) {
 		if (authCode.length + offset > message.length) {
 			throw new IndexOutOfBoundsException("Message is too short");
 		}
 		System.arraycopy(authCode, 0, message, offset, authCode.length);
 	}
 
 	@Override
 	protected void encodePayloadLength(int value, byte[] message, int offset) {
 		message[offset] = TypeConverter.intToByte(value);
 	}
 
 	/**
 	 * Creates session trailer. <br>
 	 * Creates an inserts Legacy PAD.
 	 *
 	 * @param message
 	 *        - IPMI message being created
 	 * @param offset
 	 *        - Should point at the beginning of the session trailer.
 	 * @throws IndexOutOfBoundsException
 	 *         when message is too short to hold value at given offset
 	 * @return Offset pointing after Authorization Code
 	 */
 	private int encodeSessionTrailer(byte[] message, int offset) {
 		if (1 + offset > message.length) {
 			throw new IndexOutOfBoundsException("Message is too short");
 		}
 
 		message[offset] = 0;
 
 		return offset + 1;
 	}
 }