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Smart Card Utils for Better Access.
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/*
 * This file is part of the SCUBA smart card framework.
 *
 * This library 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 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 *
 * Copyright (C) 2009 - 2015  The SCUBA team.
 *
 * $Id: TLVInputState.java 282 2017-02-05 10:02:46Z martijno $
 */

package net.sf.scuba.tlv;

import java.util.Stack;

/**
 * State keeps track of where we are in a TLV stream.
 * 
 * @author The SCUBA team
 * 
 * @version $Revision: 282 $
 */
class TLVInputState implements Cloneable {

  /**
   * Encodes tags, lengths, and number of valueBytes encountered thus far.
   */
  private Stack state;

  /**
   * TFF: ^TLVVVVVV
   * FTF: T^LVVVVVV
   * FFT: TL^VVVVVV
   * FFT: TLVVVV^VV
   * TFF: ^
   */
  private boolean isAtStartOfTag, isAtStartOfLength, isReadingValue;


  public TLVInputState() {
    state = new Stack();
    isAtStartOfTag = true;
    isAtStartOfLength = false;
    isReadingValue = false;
  }

  private TLVInputState(Stack state, boolean isAtStartOfTag, boolean isAtStartOfLength, boolean isReadingValue) {
    this.state = state;
    this.isAtStartOfTag = isAtStartOfTag;
    this.isAtStartOfLength = isAtStartOfLength;
    this.isReadingValue = isReadingValue;
  }

  public boolean isAtStartOfTag() {
    return isAtStartOfTag;
  }

  public boolean isAtStartOfLength() {
    return isAtStartOfLength;
  }

  public boolean isProcessingValue() {
    return isReadingValue;
  }

  public int getTag() {
    if (state.isEmpty()) {
      throw new IllegalStateException("Tag not yet read.");
    }
    TLStruct currentObject = state.peek();
    return currentObject.getTag();
  }

  public int getLength() {
    if (state.isEmpty()) {
      throw new IllegalStateException("Length not yet known.");
    }
    TLStruct currentObject = state.peek();
    int length = currentObject.getLength();
    return length;
  }

  public int getValueBytesProcessed() {
    TLStruct currentObject = state.peek();
    return currentObject.getValueBytesProcessed();
  }

  public int getValueBytesLeft() {
    if (state.isEmpty()) {
      throw new IllegalStateException("Length of value is unknown.");
    }
    TLStruct currentObject = state.peek();
    int currentLength = currentObject.getLength();
    int valueBytesRead = currentObject.getValueBytesProcessed();
    return currentLength - valueBytesRead;
  }

  public void setTagProcessed(int tag, int byteCount) {
    /* Length is set to MAX INT, we will update it when caller calls our setLengthProcessed. */
    TLStruct obj = new TLStruct(tag);
    if (!state.isEmpty()) {
      TLStruct parent = state.peek();
      parent.updateValueBytesProcessed(byteCount);
    }
    state.push(obj);
    isAtStartOfTag = false;
    isAtStartOfLength = true;
    isReadingValue = false;
  }

  public void setDummyLengthProcessed() {
    isAtStartOfTag = false;
    isAtStartOfLength = false;
    isReadingValue = true;		
  }

  public void setLengthProcessed(int length, int byteCount) {
    if (length < 0) {
      throw new IllegalArgumentException("Cannot set negative length (length = " + length + ", 0x" + Integer.toHexString(length) + " for tag " + Integer.toHexString(getTag()) + ").");
    }
    TLStruct obj = state.pop();
    if (!state.isEmpty()) {
      TLStruct parent = state.peek();
      parent.updateValueBytesProcessed(byteCount);
    }
    obj.setLength(length);
    state.push(obj);
    isAtStartOfTag = false;
    isAtStartOfLength = false;
    isReadingValue = true;
  }

  public void updateValueBytesProcessed(int byteCount) {
    if (state.isEmpty()) { return; }
    TLStruct currentObject = state.peek();
    int bytesLeft = currentObject.getLength() - currentObject.getValueBytesProcessed();
    if (byteCount > bytesLeft) {
      throw new IllegalArgumentException("Cannot process " + byteCount + " bytes! Only " + bytesLeft + " bytes left in this TLV object " + currentObject);
    }
    currentObject.updateValueBytesProcessed(byteCount);
    int currentLength = currentObject.getLength();
    if (currentObject.getValueBytesProcessed() == currentLength) {
      state.pop();
      /* Stand back! I'm going to try recursion! Update parent(s)... */
      updateValueBytesProcessed(currentLength);
      isAtStartOfTag = true;
      isAtStartOfLength = false;
      isReadingValue = false;
    } else {
      isAtStartOfTag = false;
      isAtStartOfLength = false;
      isReadingValue = true;
    }
  }

  public Object clone() {
    /* NOTE: simply cloning the state (of type Stack) will only give a spine-deep copy. */
    Stack newState = new Stack();
    for (int i = 0; i < state.size(); i++) {
      TLStruct tlStruct = state.get(i);
      newState.add((TLStruct)tlStruct.clone());
    }
    return new TLVInputState(newState, isAtStartOfTag, isAtStartOfLength, isReadingValue);
  }

  public String toString() {
    return state.toString();
  }

  private class TLStruct implements Cloneable {

    private int tag, length, valueBytesRead;

    public TLStruct(int tag) { this.tag = tag; this.length = Integer.MAX_VALUE; this.valueBytesRead = 0; }

    public void setLength(int length) { this.length = length; }

    public int getTag() { return tag; }

    public int getLength() { return length; }

    public int getValueBytesProcessed() { return valueBytesRead; }

    public void updateValueBytesProcessed(int n) { this.valueBytesRead += n; }

    public Object clone() { TLStruct copy = new TLStruct(tag); copy.length = this.length; copy.valueBytesRead = this.valueBytesRead; return copy; }

    public String toString() { return "[TLStruct " + Integer.toHexString(tag) + ", " + length + ", " + valueBytesRead + "]"; }
  }
}