// Copyright (c) 2016 OPEN CASCADE SAS
//
// This file is part of Open CASCADE Technology software library.
//
// This library is free software; you can redistribute it and/or modify it under
// the terms of the GNU Lesser General Public License version 2.1 as published
// by the Free Software Foundation, with special exception defined in the file
// OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
// distribution for complete text of the license and disclaimer of any warranty.
//
// Alternatively, this file may be used under the terms of Open CASCADE
// commercial license or contractual agreement.

#include <Standard_ArrayStreamBuffer.hxx>

//=================================================================================================

Standard_ArrayStreamBuffer::Standard_ArrayStreamBuffer(const char* theBegin, const size_t theSize)
    : myBegin(theBegin),
      myEnd(theBegin + theSize),
      myCurrent(theBegin)
{
}

//=================================================================================================

Standard_ArrayStreamBuffer::~Standard_ArrayStreamBuffer() = default;

//=================================================================================================

void Standard_ArrayStreamBuffer::Init(const char* theBegin, const size_t theSize)
{
  myBegin   = theBegin;
  myEnd     = theBegin + theSize;
  myCurrent = theBegin;
}

//=================================================================================================

Standard_ArrayStreamBuffer::int_type Standard_ArrayStreamBuffer::underflow()
{
  if (myCurrent == myEnd)
  {
    return traits_type::eof();
  }

  return traits_type::to_int_type(*myCurrent);
}

//=================================================================================================

Standard_ArrayStreamBuffer::int_type Standard_ArrayStreamBuffer::uflow()
{
  if (myCurrent == myEnd)
  {
    return traits_type::eof();
  }

  return traits_type::to_int_type(*myCurrent++);
}

//=================================================================================================

Standard_ArrayStreamBuffer::int_type Standard_ArrayStreamBuffer::pbackfail(int_type ch)
{
  if (myCurrent == myBegin || (ch != traits_type::eof() && ch != myCurrent[-1]))
  {
    return traits_type::eof();
  }

  return traits_type::to_int_type(*--myCurrent);
}

//=================================================================================================

std::streamsize Standard_ArrayStreamBuffer::showmanyc()
{
  if (myCurrent > myEnd)
  {
    // assert
  }
  return myEnd - myCurrent;
}

//=================================================================================================

Standard_ArrayStreamBuffer::pos_type Standard_ArrayStreamBuffer::seekoff(
  off_type                theOff,
  std::ios_base::seekdir  theWay,
  std::ios_base::openmode theWhich)
{
  switch (theWay)
  {
    case std::ios_base::beg: {
      myCurrent = myBegin + theOff;
      if (myCurrent >= myEnd)
      {
        myCurrent = myEnd;
      }
      break;
    }
    case std::ios_base::cur: {
      myCurrent += theOff;
      if (myCurrent >= myEnd)
      {
        myCurrent = myEnd;
      }
      break;
    }
    case std::ios_base::end: {
      myCurrent = myEnd - theOff;
      if (myCurrent < myBegin)
      {
        myCurrent = myBegin;
      }
      break;
    }
    default: {
      break;
    }
  }
  (void)theWhich;
  return myCurrent - myBegin;
}

//=================================================================================================

Standard_ArrayStreamBuffer::pos_type Standard_ArrayStreamBuffer::seekpos(
  pos_type                thePosition,
  std::ios_base::openmode theWhich)
{
  return seekoff(off_type(thePosition), std::ios_base::beg, theWhich);
}

//=================================================================================================

std::streamsize Standard_ArrayStreamBuffer::xsgetn(char* thePtr, std::streamsize theCount)
{
  const char* aCurrent = myCurrent + theCount;
  if (aCurrent >= myEnd)
  {
    aCurrent = myEnd;
  }
  size_t aCopied = aCurrent - myCurrent;
  if (aCopied == 0)
  {
    return 0;
  }
  memcpy(thePtr, myCurrent, aCopied);
  myCurrent = aCurrent;
  return aCopied;
}
