/*=========================================================================

  Program:   Insight Segmentation & Registration Toolkit
  Module:    itkStreamingImageIOBase.cxx
  Language:  C++
  Date:      $Date$
  Version:   $Revision$

  Copyright (c) Insight Software Consortium. All rights reserved.
  See ITKCopyright.txt or http://www.itk.org/HTML/Copyright.htm for details.

     This software is distributed WITHOUT ANY WARRANTY; without even
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
     PURPOSE.  See the above copyright notices for more information.

=========================================================================*/
#include "itkStreamingImageIOBase.h"


#include <itksys/SystemTools.hxx>

namespace itk
{

StreamingImageIOBase::StreamingImageIOBase()
  : ImageIOBase()
{
}


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


bool StreamingImageIOBase
::StreamReadBufferAsBinary(std::istream& file, void *_buffer)
{
  itkDebugMacro( << "StreamingReadBufferAsBinary called" );

  char *buffer = static_cast<char*>(_buffer);
  // Offset into file
  std::streampos dataPos = this->GetDataPosition();

  std::streamsize sizeOfRegion = static_cast<std::streamsize>( m_IORegion.GetNumberOfPixels() )
    *this->GetPixelSize();


  // compute the number of continuous bytes to be read
  std::streamsize sizeOfChunk = 1;
  unsigned int movingDirection = 0;
  do
    {
    sizeOfChunk *= m_IORegion.GetSize(movingDirection);
    ++movingDirection;
    }
  while ( movingDirection < m_IORegion.GetImageDimension() &&
          m_IORegion.GetSize(movingDirection-1) == this->GetDimensions(movingDirection-1) );
  sizeOfChunk *= this->GetPixelSize();

  ImageIORegion::IndexType currentIndex = m_IORegion.GetIndex();
  std::streamsize gcount = 0;
  while ( m_IORegion.IsInside(currentIndex) )
    {
    // calculate the position to seek to in the file
    std::streampos seekPos = 0;
    size_t subDimensionQuantity = 1;
    for ( unsigned int i = 0; i < m_IORegion.GetImageDimension(); ++i )
      {
      seekPos = seekPos + static_cast<std::streamoff> (subDimensionQuantity *
                                                       this->GetPixelSize() *
                                                       currentIndex[i]);
      subDimensionQuantity *= this->GetDimensions(i);
      }


    itkDebugMacro(<< "Reading " << sizeOfChunk << " of " << sizeOfRegion << " bytes for " << m_FileName << " at " << dataPos+seekPos << " position in file");

    file.seekg( dataPos+seekPos, std::ios::beg );
    this->ReadBufferAsBinary( file, buffer, sizeOfChunk );

    // increment the buffer pointer
    buffer += sizeOfChunk;
    gcount += file.gcount();

    if ( file.fail() )
      {
      itkExceptionMacro(<<"Fail reading");
      }

    if (movingDirection == m_IORegion.GetImageDimension())
      break;

    // increment index to next chunk
    ++currentIndex[movingDirection];
    for (unsigned int i = movingDirection; i < m_IORegion.GetImageDimension()-1; ++i)
      {
      // when reaching the end of the moving index dimension carry to
      // higher dimensions
      if (static_cast<ImageIORegion::SizeValueType>(currentIndex[i]  - m_IORegion.GetIndex(i)) >= m_IORegion.GetSize(i) )
        {
        currentIndex[i] = m_IORegion.GetIndex(i);
        ++currentIndex[i+1];
        }
      }
    }

  if ( gcount != sizeOfRegion )
    {
    itkExceptionMacro("Data not read completely. Expected = " << sizeOfRegion << ", but only read " <<  gcount <<  " bytes.");
    }

  return true;
}

bool StreamingImageIOBase::ReadBufferAsBinary( std::istream& is, void *buffer, StreamingImageIOBase::SizeType num )
{

  // some systems have a limit of 2GB to be read at once
  const SizeType maxChunk = 1024*1024*1024;

  std::streamsize bytesRemaining = static_cast<std::streamsize>( num );

  while (bytesRemaining)
    {

    std::streamsize bytesToRead = bytesRemaining > maxChunk ? maxChunk : bytesRemaining;

    itkDebugMacro(<< "Reading " << bytesToRead << " of " << bytesRemaining << " bytes for " << m_FileName);

    is.read( static_cast<char *>( buffer ) ,  bytesToRead );

    if ( (is.gcount() != bytesToRead) || is.fail() )
      {
      return false;
      }
    buffer =  static_cast<char *>( buffer ) + bytesToRead;
    bytesRemaining -= bytesToRead;
    }

  return true;
}


bool StreamingImageIOBase::WriteBufferAsBinary( std::ostream& os, const void *buffer, StreamingImageIOBase::SizeType num )
{
  // some systems have a limit of 2GB to be written at once
  const SizeType maxChunk = 1024*1024*1024;

  std::streamsize bytesRemaining = num;
  while (bytesRemaining)
    {

    SizeType bytesToWrite = bytesRemaining > maxChunk ? maxChunk : bytesRemaining;

    itkDebugMacro(<< "Writing " << bytesToWrite << " of " << bytesRemaining << " bytes for " << m_FileName);

    os.write(static_cast<const char*>(buffer) , bytesToWrite);
    if ( os.fail() )
      {
      return false;
      }

    buffer =  static_cast<const char *>( buffer ) + bytesToWrite;
    bytesRemaining -= bytesToWrite;
    }

  return true;
}


bool StreamingImageIOBase::StreamWriteBufferAsBinary(std::ostream& file, const void *_buffer)
{
  itkDebugMacro( << "StreamingWriteBufferAsBinary called" );

  const char *buffer = static_cast< const char* >( _buffer );
  // Offset into file
  std::streampos dataPos = this->GetDataPosition();

  // compute the number of continuous bytes to be written
  std::streamsize sizeOfChunk = 1;
  unsigned int movingDirection = 0;
  do
    {
    sizeOfChunk *= m_IORegion.GetSize(movingDirection);
    ++movingDirection;
    }
  while ( movingDirection < m_IORegion.GetImageDimension() &&
          m_IORegion.GetSize(movingDirection-1) == this->GetDimensions(movingDirection-1) );
  sizeOfChunk *= this->GetPixelSize();


  ImageIORegion::IndexType currentIndex = m_IORegion.GetIndex();
  while ( m_IORegion.IsInside(currentIndex) )
    {
    // calculate the position to seek to in the file
    std::streampos seekPos = 0;
    size_t subDimensionQuantity = 1;
    for ( unsigned int i = 0; i < m_IORegion.GetImageDimension(); ++i )
      {
      seekPos = seekPos + static_cast<std::streamoff> (subDimensionQuantity *
                                                       this->GetPixelSize() *
                                                       currentIndex[i]);
      subDimensionQuantity *= this->GetDimensions(i);
      }

    file.seekp( dataPos+seekPos, std::ios::beg );
    this->WriteBufferAsBinary( file, buffer, sizeOfChunk );

    // increment the buffer pointer
    buffer += sizeOfChunk;


    itkDebugMacro(<< "Writing " << sizeOfChunk << " of " <<  " ?? bytes for " << m_FileName << " at " << dataPos+seekPos << " position in file");


    if ( file.fail() )
      {
      itkExceptionMacro(<<"Fail writing");
      }

    if (movingDirection == m_IORegion.GetImageDimension())
      break;

    // increment index to next chunk
    ++currentIndex[movingDirection];
    for (unsigned int i = movingDirection; i < m_IORegion.GetImageDimension()-1; ++i)
      {
      // when reaching the end of the movingDirection dimension carry to
      // higher dimensions
      if ( static_cast<ImageIORegion::SizeValueType>(currentIndex[i] - m_IORegion.GetIndex(i))
           >=  m_IORegion.GetSize(i) )
        {
        currentIndex[i] = m_IORegion.GetIndex(i);
        ++currentIndex[i+1];
        }
      }
    }


  return true;
}


void StreamingImageIOBase::OpenFileForReading(std::ifstream& os, const char* filename)
{
  // Make sure that we have a file to
  if ( *filename == 0 )
    {
    itkExceptionMacro(<<"A FileName must be specified.");
    }

  // Close file from any previous image
  if ( os.is_open() )
    {
    os.close();
    }

  // Open the new file for reading
  itkDebugMacro(<< "Initialize: opening file " << filename);

  os.open(filename,  std::ios::in | std::ios::binary  );
  if ( os.fail() )
    {
    itkExceptionMacro(<< "Could not open file for reading: " << filename);
    }

}

void StreamingImageIOBase::OpenFileForWriting(std::ofstream& os, const char* filename, bool truncate)
{
  // Make sure that we have a file to
  if ( *filename == 0 )
    {
    itkExceptionMacro(<<"A FileName must be specified.");
    }

  // Close file from any previous image
  if ( os.is_open() )
    {
    os.close();
    }

  // Open the new file for writing
  itkDebugMacro(<< "Initialize: opening file " << filename);

 if (truncate)
    {
    // truncate
    os.open( m_FileName.c_str(), std::ios::out | std::ios::binary | std::ios::trunc );

    }
  else
    {
    os.open( m_FileName.c_str(), std::ios::out | std::ios::binary | std::ios::in );
    }

  if ( os.fail() )
    {
    itkExceptionMacro(<< "Could not open file for writing: " << filename);
    }

}

bool StreamingImageIOBase::CanStreamRead( void )
{
  return true;
}

bool StreamingImageIOBase::CanStreamWrite( void )
{
  return true;
}


unsigned int
StreamingImageIOBase::GetActualNumberOfSplitsForWriting(unsigned int numberOfRequestedSplits,
                                               const ImageIORegion &pasteRegion,
                                               const ImageIORegion &largestPossibleRegion)
{
  if (!itksys::SystemTools::FileExists( m_FileName.c_str() ))
    {
    // file doesn't exits so we don't have potential problems
    }
  else if (pasteRegion != largestPossibleRegion)
    {
    // we are going to be pasting (may be streaming too)

    // need to check to see if the file is compatible
    std::string errorMessage;
    Pointer headerImageIOReader = dynamic_cast<StreamingImageIOBase*>(this->CreateAnother().GetPointer());

    try
      {
      headerImageIOReader->SetFileName(m_FileName.c_str());
      headerImageIOReader->ReadImageInformation();
      }
    catch (...)
      {
      errorMessage = "Unable to read information from file: " + m_FileName;
      }

    // we now need to check that the following match:
    // 2)pixel type
    // 3)dimensions
    // 4)size/origin/spacing
    // 5)direction cosines
    //
    // todo check for byte order

    if (errorMessage.size())
      {
      // 0) Can't read file
      }
    // 2)pixel type
    // this->GetPixelType() is not verified becasue the metaio file format
    // stores all multi-component types as arrays, so it does not
    // distinguish between pixel types. Also as long as the compoent
    // and number of compoents match we should be able to paste, that
    // is the numbers should be the same it is just the interpretation
    // that is not matching
    else if ( headerImageIOReader->GetNumberOfComponents() != this->GetNumberOfComponents() ||
              headerImageIOReader->GetComponentType() != this->GetComponentType() )
      {
      errorMessage = "Component type does not match in file: " + m_FileName;
      }
    // 3)dimensions/size
    else if (headerImageIOReader->GetNumberOfDimensions() != this->GetNumberOfDimensions())
      {
      errorMessage = "Dimensions does not match in file: " + m_FileName;
      }
    else
      {
      for (unsigned int i = 0; i < this->GetNumberOfDimensions(); ++i)
        {
        // 4)size/origin/spacing
        if (headerImageIOReader->GetDimensions(i) != this->GetDimensions(i) ||
            headerImageIOReader->GetSpacing(i) != this->GetSpacing(i) ||
            headerImageIOReader->GetOrigin(i) != this->GetOrigin(i))
          {
          errorMessage = "Size, spacing or origin does not match in file: " + m_FileName;
          break;
          }
        // 5)direction cosines
        if (headerImageIOReader->GetDirection(i) != this->GetDirection(i))
          {
          errorMessage = "Direction cosines does not match in file: " + m_FileName;
          break;
          }
        }
      }

    if (errorMessage.size())
      {
      itkExceptionMacro("Unable to paste because pasting file exists and is different. " << errorMessage);
      }
    else if ( headerImageIOReader->GetPixelType() != this->GetPixelType() )
      {
      // since there is currently poor support for pixel types in
      // MetaIO we will just warn when it does not match
      itkWarningMacro("Pixel types does not match file, but component type and number of components do.");
      }
    }
  else if (numberOfRequestedSplits != 1)
    {
    // we are going be streaming

    // need to remove the file incase the file doesn't match our
    // current header/meta data information
    if (!itksys::SystemTools::RemoveFile(m_FileName.c_str()))
      itkExceptionMacro("Unable to remove file for streaming: " << m_FileName);
    }

  return GetActualNumberOfSplitsForWritingCanStreamWrite(numberOfRequestedSplits, pasteRegion);

}


ImageIORegion StreamingImageIOBase::GenerateStreamableReadRegionFromRequestedRegion( const ImageIORegion & requestedRegion ) const
{
  // This implementation returns the requestedRegion if
  // "UseStreamedReading" is enabled

  ImageIORegion streamableRegion(this->m_NumberOfDimensions);
  if( !m_UseStreamedReading )
    {
    for( unsigned int i=0; i < this->m_NumberOfDimensions; i++ )
      {
      streamableRegion.SetSize( i, this->m_Dimensions[i] );
      streamableRegion.SetIndex( i, 0 );
      }
    }
  else
    {
    streamableRegion = requestedRegion;
    }

  return streamableRegion;
}


bool StreamingImageIOBase::RequestedToStream( void ) const
{
  // we choose the max dimension and then pad the smaller with ones
  //
  // This enables a 2D request from a 3D volume to get the first slice,
  // and a 4D with a 1-sized 4th dimension to equal the 3D volume
  // aswell.
  unsigned int maxNumberOfDimension = vnl_math_max( this->GetNumberOfDimensions(), this->GetIORegion().GetImageDimension() );

  ImageIORegion ioregion( maxNumberOfDimension );
  ImageIORegion largestRegion( maxNumberOfDimension );
  for(unsigned int i=0; i<maxNumberOfDimension; i++)
    {

    largestRegion.SetIndex(i, 0);
    if ( i < this->GetNumberOfDimensions() )
      {
      largestRegion.SetSize( i, this->GetDimensions(i) );
      }
    else
      {
      largestRegion.SetSize( i, 1 );
      }

    if ( i < this->GetIORegion().GetImageDimension() )
      {
      ioregion.SetIndex( i, this->GetIORegion().GetIndex(i) );
      ioregion.SetSize( i, this->GetIORegion().GetSize(i) );
      }
    else
      {
      ioregion.SetIndex( i, 0 );
      ioregion.SetSize( i, 1 );
      }

    }

  return (largestRegion != ioregion);
}

} // namespace itk