// Copyright (c) 1994 James Clark, 2000 Matthias Clasen

// See the file COPYING for copying permission.

#include "splib.h"

#ifdef SP_MULTI_BYTE

#include "UnicodeCodingSystem.h"

#include "UTF16CodingSystem.h"

#include "macros.h"

#include "Owner.h"

#include <stddef.h>

#include <string.h>

#ifdef DECLARE_MEMMOVE

extern "C" {

  void *memmove(void *, const void *, size_t);

}

#endif

#ifdef SP_NAMESPACE

namespace SP_NAMESPACE {

#endif

const unsigned short byteOrderMark = 0xfeff;

const unsigned short swappedByteOrderMark = 0xfffe;

class UnicodeDecoder : public Decoder {

public:

  UnicodeDecoder(const InputCodingSystem *sub);

  size_t decode(Char *to, const char *from, size_t fromLen,

		const char **rest);

  Boolean convertOffset(unsigned long &offset) const;

private:

  PackedBoolean hadByteOrderMark_;

  PackedBoolean swapBytes_;

  Owner<Decoder> subDecoder_;

  const InputCodingSystem *subCodingSystem_;

};

class UnicodeEncoder : public Encoder {

public:

  UnicodeEncoder();

  void output(const Char *, size_t, OutputByteStream *);

  void startFile(OutputByteStream *);

private:

  Owner<Encoder> subEncoder_;

};

UnicodeCodingSystem::UnicodeCodingSystem(const InputCodingSystem *sub)

: sub_(sub)

{

}

Decoder *UnicodeCodingSystem::makeDecoder() const

{

  return new UnicodeDecoder(sub_);

}

Encoder *UnicodeCodingSystem::makeEncoder() const

{

  return new UnicodeEncoder;

}

UnicodeDecoder::UnicodeDecoder(const InputCodingSystem *subCodingSystem)

: Decoder(subCodingSystem ? 1 : 2), subCodingSystem_(subCodingSystem),

  hadByteOrderMark_(0), swapBytes_(0)

{

}

size_t UnicodeDecoder::decode(Char *to, const char *from, size_t fromLen,

			      const char **rest)

{

  union U {

    unsigned short word;

    char bytes[2];

  };

  if (subDecoder_)

    return subDecoder_->decode(to, from, fromLen, rest);

    if (fromLen < 2) {

      *rest = from;

      return 0;

    }

    minBytesPerChar_ = 2;

    U u;

    u.bytes[0] = from[0];

    u.bytes[1] = from[1];

    if (u.word == byteOrderMark) {

      hadByteOrderMark_ = 1;

      from += 2;

      fromLen -= 2;

    }

    else if (u.word == swappedByteOrderMark) {

      hadByteOrderMark_ = 1;

      from += 2;

      fromLen -= 2;

      swapBytes_ = 1;

    }

  if (hadByteOrderMark_ || !subCodingSystem_)

    subCodingSystem_ = new UTF16CodingSystem;

  subDecoder_ = subCodingSystem_->makeDecoder(swapBytes_);

      minBytesPerChar_ = subDecoder_->minBytesPerChar();

      return subDecoder_->decode(to, from, fromLen, rest);

}

Boolean UnicodeDecoder::convertOffset(unsigned long &n) const

{

  subDecoder_->convertOffset(n);

  if (hadByteOrderMark_)

    n += 2;

  return true;

}

UnicodeEncoder::UnicodeEncoder()

{

  UTF16CodingSystem utf16;

  subEncoder_ = utf16.makeEncoder();

}

void UnicodeEncoder::startFile(OutputByteStream *sb)

{

  const unsigned short n = byteOrderMark;

  sb->sputn((char *)&n, 2);

}

void UnicodeEncoder::output(const Char *s, size_t n, OutputByteStream *sb)

{

  subEncoder_->output(s, n, sb);

}

#ifdef SP_NAMESPACE

}

#endif

#else /* not SP_MULTI_BYTE */

#ifndef __GNUG__

static char non_empty_translation_unit;	// sigh

#endif

#endif /* not SP_MULTI_BYTE */