/*
* Copyright 2008 Federal Chancellery Austria and
* Graz University of Technology
*
* 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 at.gv.egiz.smcc;

import java.nio.ByteBuffer;

import javax.smartcardio.Card;
import javax.smartcardio.CardChannel;
import javax.smartcardio.CardException;
import javax.smartcardio.CommandAPDU;
import javax.smartcardio.ResponseAPDU;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class LogCardChannel extends CardChannel {
  
  private final Logger log = LoggerFactory.getLogger(LogCardChannel.class);
  
  private CardChannel channel;
  
  public LogCardChannel(CardChannel channel) {
    if (channel == null) {
      throw new NullPointerException();
    }
    this.channel = channel;
  }

  @Override
  public void close() throws CardException {
    channel.close();
  }

  @Override
  public Card getCard() {
    return channel.getCard();
  }

  @Override
  public int getChannelNumber() {
    return channel.getChannelNumber();
  }

  @Override
  public ResponseAPDU transmit(CommandAPDU command) throws CardException {
    if (log.isTraceEnabled()) {
      switch (command.getINS()) {
      case 0x20:    // VERIFY
      case 0x21:    // VERIFY
      case 0x24: {  // CHANGE REFERENCE DATA
        // Don't log possibly sensitive command data
        StringBuilder sb = new StringBuilder();
        sb.append(command);
        sb.append("\n-> ");
        byte[] c = new byte[4];
        c[0] = (byte) command.getCLA();
        c[1] = (byte) command.getINS();
        c[2] = (byte) command.getP1();
        c[3] = (byte) command.getP2();
        sb.append(toString(c));
        if (command.getNc() > 0) {
          sb.append(':');
          sb.append(toString(new byte[] {(byte) command.getNc()}));
          for (int i = 0; i < command.getNc(); i++) {
            sb.append(":XX");
          }
        }
        if (command.getNe() > 0) {
          sb.append(':');
          sb.append(toString(new byte[] {(byte) command.getNe()}));
        }
        log.trace(sb.toString());
      }; break;

      default:
        log.trace(command + "\n-> " + toString(command.getBytes()));
      }
      long t0 = System.currentTimeMillis();
      ResponseAPDU response = channel.transmit(command);
      long t1 = System.currentTimeMillis();
      log.trace(response + " [" + (t1 - t0) + "ms]\n<- " + toString(response.getBytes()));
      return response;
    } else {
      return channel.transmit(command);
    }
  }

  @Override
  public int transmit(ByteBuffer command, ByteBuffer response) throws CardException {
    if (log.isTraceEnabled()) {
      long t0 = System.currentTimeMillis();
      int l = channel.transmit(command, response);
      long t1 = System.currentTimeMillis();
      log.trace("[" + (t1 - t0) + "ms]");
      return l;
    } else {
      return channel.transmit(command, response);
    }
  }

  private String toString(byte[] b) {
    StringBuffer sb = new StringBuffer();
    if (b != null && b.length > 0) {
      sb.append(Integer.toHexString((b[0] & 240) >> 4));
      sb.append(Integer.toHexString(b[0] & 15));
    }
    for (int i = 1; i < b.length; i++) {
      sb.append(':');
      sb.append(Integer.toHexString((b[i] & 240) >> 4));
      sb.append(Integer.toHexString(b[i] & 15));
    }
    return sb.toString();
  }
  
}