#region PDFsharp - A .NET library for processing PDF
//
// Authors:
//   Stefan Lange (mailto:Stefan.Lange@pdfsharp.com)
//
// Copyright (c) 2005-2007 empira Software GmbH, Cologne (Germany)
//
// http://www.pdfsharp.com
// http://sourceforge.net/projects/pdfsharp
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 
// DEALINGS IN THE SOFTWARE.
#endregion

using System;
using System.Diagnostics;
using PdfSharp.Internal;
using PdfSharp.Pdf.Internal;

namespace PdfSharp.Pdf.Filters
{
  /// <summary>
  /// Implements the ASCIIHexDecode filter.
  /// </summary>
  public class ASCIIHexDecode : Filter
  {
    public override byte[] Encode(byte[] data)
    {
      if (data == null)
        throw new ArgumentNullException("data");

      int count = data.Length;
      byte[] bytes = new byte[2 * count];
      for (int i = 0, j = 0; i < count; i++)
      {
        byte b = data[i];
        bytes[j++] = (byte)((b >> 4) + ((b >> 4) < 10 ? (byte)'0' : (byte)('A' - 10)));
        bytes[j++] = (byte)((b & 0xF) + ((b & 0xF) < 10 ? (byte)'0' : (byte)('A' - 10)));
      }
      return bytes;
    }

    public override byte[] Decode(byte[] data, FilterParms parms)
    {
      if (data == null)
        throw new ArgumentNullException("data");

      data = RemoveWhiteSpace(data);
      int count = data.Length;
      if (count % 2 == 1)
      {
        count++;
        byte[] temp = data;
        data = new byte[count];
        temp.CopyTo(data, 0);
      }
      count <<= 2;
      byte[] bytes = new byte[count];
      for (int i = 0, j = 0; i < count; i++)
      {
        byte hi = data[j++];
        byte lo = data[j++];
        bytes[i] = (byte)((hi > '9' ? hi - 'A' : hi - '0') * 16 + (lo > '9' ? lo - 'A' : lo - '0'));
      }
      return bytes;
    }
  }
}
