//  MeCab -- Yet Another Part-of-Speech and Morphological Analyzer
//
//
//  Copyright(C) 2001-2006 Taku Kudo <taku@chasen.org>
//  Copyright(C) 2004-2006 Nippon Telegraph and Telephone Corporation
#ifndef MECAB_UCS_H
#define MECAB_UCS_H

#ifndef MECAB_USE_UTF8_ONLY
#include "ucstable.h"
#endif

namespace MeCab {

// All internal codes are represented in UCS2,
// if you want to use specific local codes, e.g, big5/euc-kr,
// make a function which maps the local code to the UCS code.

inline unsigned short utf8_to_ucs2(const char *begin, const char *end,
                                   size_t*  mblen) {
  const size_t len = end - begin;

  if (static_cast<unsigned char>(begin[0]) < 0x80) {
    *mblen = 1;
    return static_cast<unsigned char>(begin[0]);

  } else if (len >= 2 && (begin[0] & 0xe0) == 0xc0) {
    *mblen = 2;
    return((begin[0] & 0x1f) << 6) |(begin[1] & 0x3f);

  } else if (len >= 3 && (begin[0] & 0xf0) == 0xe0) {
    *mblen = 3;
    return ((begin[0] & 0x0f) << 12) |
        ((begin[1] & 0x3f) << 6) |(begin[2] & 0x3f);

    /* belows are out of UCS2 */
  } else if (len >= 4 && (begin[0] & 0xf8) == 0xf0) {
    *mblen = 4;
    return 0;

  } else if (len >= 5 && (begin[0] & 0xfc) == 0xf8) {
    *mblen = 5;
    return 0;

  } else if (len >= 6 && (begin[0] & 0xfe) == 0xfc) {
    *mblen = 6;
    return 0;

  } else {
    *mblen = 1;
    return 0;
  }
}

inline unsigned short ascii_to_ucs2(const char *begin, const char *end,
                                    size_t *mblen) {
  return static_cast<unsigned char>(begin[0]);
}

inline unsigned short utf16be_to_ucs2(const char *begin, const char *end,
                                      size_t *mblen) {
  const size_t len = end - begin;
  if (len <= 1) {
    *mblen = 1;
    return 0;
  }
  *mblen = 2;
#if defined WORDS_BIGENDIAN
  return (begin[0] << 8 | begin[1]);
#else
  return (begin[1] << 8 | begin[0]);
#endif
  return 0;
}

inline unsigned short utf16le_to_ucs2(const char *begin, const char *end,
                                      size_t *mblen) {
  const size_t len = end - begin;
  if (len <= 1) {
    *mblen = 1;
    return 0;
  }
  *mblen = 2;
#if defined WORDS_BIGENDIAN
  return (begin[1] << 8 | begin[0]);
#else
  return (begin[0] << 8 | begin[1]);
#endif
}

inline unsigned short utf16_to_ucs2(const char *begin, const char *end,
                                    size_t *mblen) {
#if defined WORDS_BIGENDIAN
  return utf16be_to_ucs2(begin, end, mblen);
#else
  return utf16le_to_ucs2(begin, end, mblen);
#endif
}


#ifndef MECAB_USE_UTF8_ONLY
inline unsigned short euc_to_ucs2(const char *begin, const char *end,
                                  size_t *mblen) {
  const size_t len = end - begin;

  // JISX 0212, 0213
  if (static_cast<unsigned char>(begin[0]) == 0x8f && len >= 3) {
    unsigned short key = (static_cast<unsigned char>(begin[1]) << 8) +
        static_cast<unsigned char>(begin[2]);
    if (key < 0xA0A0) {  // offset  violation
      *mblen = 1;
      return static_cast<unsigned char>(begin[0]);
    }
    *mblen = 3;
    return euc_hojo_tbl[ key - 0xA0A0 ];
    // JISX 0208 + 0201
  } else if ((static_cast<unsigned char>(begin[0]) & 0x80) && len >= 2) {
    *mblen = 2;
    return euc_tbl[(static_cast<unsigned char>(begin[0]) << 8) +
                   static_cast<unsigned char>(begin[1]) ];
  } else {
    *mblen = 1;
    return static_cast<unsigned char>(begin[0]);
  }
}

inline unsigned short cp932_to_ucs2(const char *begin, const char *end,
                                    size_t *mblen) {
  const size_t len = end - begin;

  if ((static_cast<unsigned char>(begin[0]) >= 0xA1 &&
       static_cast<unsigned char>(begin[0]) <= 0xDF)) {
    *mblen = 1;
    return cp932_tbl[static_cast<unsigned char>(begin[0]) ];
  } else if ((static_cast<unsigned char>(begin[0]) & 0x80) && len >= 2) {
    *mblen = 2;
    return cp932_tbl[(static_cast<unsigned char>(begin[0]) << 8)
                     + static_cast<unsigned char>(begin[1]) ];
  } else {
    *mblen = 1;
    return static_cast<unsigned char>(begin[0]);
  }
}
#endif
}

#endif
