/*=========================================================================
 *
 *  Copyright NumFOCUS
 *
 *  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
 *
 *         https://www.apache.org/licenses/LICENSE-2.0.txt
 *
 *  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.
 *
 *=========================================================================*/
#include "itkXMLFile.h"
#include "itksys/SystemTools.hxx"
#include "itkMakeUniqueForOverwrite.h"
#include <fstream>
#include "expat.h"

namespace itk
{
//----------------------------------------------------------------------------
extern "C"
{
  static void
  itkXMLParserStartElement(void * parser, const char * name, const char ** atts)
  {
    // Begin element handler that is registered with the XML_Parser.
    // This just casts the user data to an itkXMLParser and calls
    // StartElement.
    static_cast<XMLReaderBase *>(parser)->StartElement(name, atts);
  }
}

//----------------------------------------------------------------------------
extern "C"
{
  static void
  itkXMLParserEndElement(void * parser, const char * name)
  {
    // End element handler that is registered with the XML_Parser.  This
    // just casts the user data to an itkXMLParser and calls EndElement.
    static_cast<XMLReaderBase *>(parser)->EndElement(name);
  }
}

//----------------------------------------------------------------------------
extern "C"
{
  static void
  itkXMLParserCharacterDataHandler(void * parser, const char * data, int length)
  {
    // Character data handler that is registered with the XML_Parser.
    // This just casts the user data to an itkXMLParser and calls
    // CharacterDataHandler.
    static_cast<XMLReaderBase *>(parser)->CharacterDataHandler(data, length);
  }
}

void
XMLReaderBase::parse()
{
  XML_Parser Parser = XML_ParserCreate(nullptr);

  XML_SetElementHandler(Parser, &itkXMLParserStartElement, &itkXMLParserEndElement);

  XML_SetCharacterDataHandler(Parser, &itkXMLParserCharacterDataHandler);
  XML_SetUserData(Parser, this);

  std::ifstream inputstream;

  inputstream.open(m_Filename.c_str(), std::ios::binary | std::ios::in);
  if (inputstream.fail())
  {
    ExceptionObject exception(__FILE__, __LINE__);
    std::string     message = "Can't open ";
    message += m_Filename;
    message += '\n';
    exception.SetDescription(message.c_str());
    throw exception;
  }

  // Default stream parser just reads a block at a time.
  std::streamsize filesize = itksys::SystemTools::FileLength(m_Filename.c_str());

  const auto buffer = make_unique_for_overwrite<char[]>(filesize);

  inputstream.read(buffer.get(), filesize);

  if (static_cast<std::streamsize>(inputstream.gcount()) != filesize)
  {
    ExceptionObject exception(__FILE__, __LINE__);
    exception.SetDescription("File Read Error");
    throw exception;
  }
  const auto result = XML_Parse(Parser, buffer.get(), inputstream.gcount(), false);
  if (!result)
  {
    ExceptionObject exception(__FILE__, __LINE__);

    std::string message(XML_ErrorString(XML_GetErrorCode(Parser)));
    message += " ";
    message += m_Filename;
    message += '\n';
    exception.SetDescription(message.c_str());
    throw exception;
  }
  XML_ParserFree(Parser);
}

void
XMLReaderBase::GenerateOutputInformation()
{
  this->parse();
}

void
XMLReaderBase::PrintSelf(std::ostream & os, Indent indent) const
{
  Superclass::PrintSelf(os, indent);

  os << indent << "Filename: " << m_Filename << std::endl;
}

} // namespace itk
