package im.status.keycard.io;

import java.io.ByteArrayOutputStream;
import java.io.IOException;

/**
 * ISO7816-4 APDU.
 */
public class APDUCommand {
  protected int cla;
  protected int ins;
  protected int p1;
  protected int p2;
  protected int lc;
  protected byte[] data;
  protected boolean needsLE;

  /**
   * Constructs an APDU with no response data length field. The data field cannot be null, but can be a zero-length array.
   *
   * @param cla class byte
   * @param ins instruction code
   * @param p1 P1 parameter
   * @param p2 P2 parameter
   * @param data the APDU data
   */
  public APDUCommand(int cla, int ins, int p1, int p2, byte[] data) {
    this(cla, ins, p1, p2, data, false);
  }

  /**
   * Constructs an APDU with an optional data length field. The data field cannot be null, but can be a zero-length array.
   * The LE byte, if sent, is set to 0.
   *
   * @param cla class byte
   * @param ins instruction code
   * @param p1 P1 parameter
   * @param p2 P2 parameter
   * @param data the APDU data
   * @param needsLE whether the LE byte should be sent or not
   */
  public APDUCommand(int cla, int ins, int p1, int p2, byte[] data, boolean needsLE) {
    this.cla = cla & 0xff;
    this.ins = ins & 0xff;
    this.p1 = p1 & 0xff;
    this.p2 = p2 & 0xff;
    this.data = data;
    this.needsLE = needsLE;
  }

  /**
   * Serializes the APDU in order to send it to the card.
   *
   * @return the byte array representation of the APDU
   */
  public byte[] serialize() throws IOException {
    ByteArrayOutputStream out = new ByteArrayOutputStream();
    out.write(this.cla);
    out.write(this.ins);
    out.write(this.p1);
    out.write(this.p2);
    out.write(this.data.length);
    out.write(this.data);

    if (this.needsLE) {
      out.write(0); // Response length
    }

    return out.toByteArray();
  }

  /**
   * Returns the CLA of the APDU
   *
   * @return the CLA of the APDU
   */
  public int getCla() {
    return cla;
  }

  /**
   * Returns the INS of the APDU
   *
   * @return the INS of the APDU
   */
  public int getIns() {
    return ins;
  }

  /**
   * Returns the P1 of the APDU
   *
   * @return the P1 of the APDU
   */
  public int getP1() {
    return p1;
  }

  /**
   * Returns the P2 of the APDU
   *
   * @return the P2 of the APDU
   */
  public int getP2() {
    return p2;
  }

  /**
   * Returns the data field of the APDU
   *
   * @return the data field of the APDU
   */
  public byte[] getData() {
    return data;
  }

  /**
   * Returns whether LE is sent or not.
   *
   * @return whether LE is sent or not
   */
  public boolean getNeedsLE() {
    return this.needsLE;
  }
}