/*
 * ISO-2022-JP-2
 */

/* Specification: RFC 1554 */
/* ESC '(' 'I' for JISX0201 Katakana is an extension not found in RFC 1554 or
   CJK.INF, but implemented in glibc-2.1 and qt-2.0. */

#define ESC 0x1b

/*
 * The state is composed of one of the following values
 */
#define STATE_ASCII             0
#define STATE_JISX0201ROMAN     1
#define STATE_JISX0201KATAKANA  2
#define STATE_JISX0208          3
#define STATE_JISX0212          4
#define STATE_GB2312            5
#define STATE_KSC5601           6
/*
 * and one of the following values, << 8
 */
#define STATE_G2_NONE           0
#define STATE_G2_ISO8859_1      1
#define STATE_G2_ISO8859_7      2

#define SPLIT_STATE \
  unsigned int state1 = state & 0xff, state2 = state >> 8
#define COMBINE_STATE \
  state = (state2 << 8) | state1

static int
iso2022_jp2_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
{
  state_t state = conv->istate;
  SPLIT_STATE;
  int count = 0;
  unsigned char c;
  for (;;) {
    c = *s;
    if (c == ESC) {
      if (n < count+3)
        goto none;
      if (s[1] == '(') {
        if (s[2] == 'B') {
          state1 = STATE_ASCII;
          s += 3; count += 3;
          if (n < count+1)
            goto none;
          continue;
        }
        if (s[2] == 'J') {
          state1 = STATE_JISX0201ROMAN;
          s += 3; count += 3;
          if (n < count+1)
            goto none;
          continue;
        }
        if (s[2] == 'I') {
          state1 = STATE_JISX0201KATAKANA;
          s += 3; count += 3;
          if (n < count+1)
            goto none;
          continue;
        }
        return RET_ILSEQ;
      }
      if (s[1] == '$') {
        if (s[2] == '@' || s[2] == 'B') {
          /* We don't distinguish JIS X 0208-1978 and JIS X 0208-1983. */
          state1 = STATE_JISX0208;
          s += 3; count += 3;
          if (n < count+1)
            goto none;
          continue;
        }
        if (s[2] == 'A') {
          state1 = STATE_GB2312;
          s += 3; count += 3;
          if (n < count+1)
            goto none;
          continue;
        }
        if (s[2] == '(') {
          if (n < count+4)
            goto none;
          if (s[3] == 'D') {
            state1 = STATE_JISX0212;
            s += 4; count += 4;
            if (n < count+1)
              goto none;
            continue;
          }
          if (s[3] == 'C') {
            state1 = STATE_KSC5601;
            s += 4; count += 4;
            if (n < count+1)
              goto none;
            continue;
          }
          return RET_ILSEQ;
        }
        return RET_ILSEQ;
      }
      if (s[1] == '.') {
        if (n < count+3)
          goto none;
        if (s[2] == 'A') {
          state2 = STATE_G2_ISO8859_1;
          s += 3; count += 3;
          if (n < count+1)
            goto none;
          continue;
        }
        if (s[2] == 'F') {
          state2 = STATE_G2_ISO8859_7;
          s += 3; count += 3;
          if (n < count+1)
            goto none;
          continue;
        }
        return RET_ILSEQ;
      }
      if (s[1] == 'N') {
        switch (state2) {
          case STATE_G2_NONE:
            return RET_ILSEQ;
          case STATE_G2_ISO8859_1:
            if (s[2] < 0x80) {
              unsigned char buf = s[2]+0x80;
              int ret = iso8859_1_mbtowc(conv,pwc,&buf,1);
              if (ret == RET_ILSEQ)
                return RET_ILSEQ;
              if (ret != 1) abort();
              COMBINE_STATE;
              conv->istate = state;
              return count+3;
            } else
              return RET_ILSEQ;
          case STATE_G2_ISO8859_7:
            if (s[2] < 0x80) {
              unsigned char buf = s[2]+0x80;
              int ret = iso8859_7_mbtowc(conv,pwc,&buf,1);
              if (ret == RET_ILSEQ)
                return RET_ILSEQ;
              if (ret != 1) abort();
              COMBINE_STATE;
              conv->istate = state;
              return count+3;
            } else
              return RET_ILSEQ;
          default: abort();
        }
      }
      return RET_ILSEQ;
    }
    break;
  }
  switch (state1) {
    case STATE_ASCII:
      if (c < 0x80) {
        int ret = ascii_mbtowc(conv,pwc,s,1);
        if (ret == RET_ILSEQ)
          return RET_ILSEQ;
        if (ret != 1) abort();
        if (*pwc == 0x000a || *pwc == 0x000d)
          state2 = STATE_G2_NONE;
        COMBINE_STATE;
        conv->istate = state;
        return count+1;
      } else
        return RET_ILSEQ;
    case STATE_JISX0201ROMAN:
      if (c < 0x80) {
        int ret = jisx0201_mbtowc(conv,pwc,s,1);
        if (ret == RET_ILSEQ)
          return RET_ILSEQ;
        if (ret != 1) abort();
        if (*pwc == 0x000a || *pwc == 0x000d)
          state2 = STATE_G2_NONE;
        COMBINE_STATE;
        conv->istate = state;
        return count+1;
      } else
        return RET_ILSEQ;
    case STATE_JISX0201KATAKANA:
      if (c < 0x80) {
        unsigned char buf = c+0x80;
        int ret = jisx0201_mbtowc(conv,pwc,&buf,1);
        if (ret == RET_ILSEQ)
          return RET_ILSEQ;
        if (ret != 1) abort();
        COMBINE_STATE;
        conv->istate = state;
        return count+1;
      } else
        return RET_ILSEQ;
    case STATE_JISX0208:
      if (n < count+2)
        goto none;
      if (s[0] < 0x80 && s[1] < 0x80) {
        int ret = jisx0208_mbtowc(conv,pwc,s,2);
        if (ret == RET_ILSEQ)
          return RET_ILSEQ;
        if (ret != 2) abort();
        COMBINE_STATE;
        conv->istate = state;
        return count+2;
      } else
        return RET_ILSEQ;
    case STATE_JISX0212:
      if (n < count+2)
        goto none;
      if (s[0] < 0x80 && s[1] < 0x80) {
        int ret = jisx0212_mbtowc(conv,pwc,s,2);
        if (ret == RET_ILSEQ)
          return RET_ILSEQ;
        if (ret != 2) abort();
        COMBINE_STATE;
        conv->istate = state;
        return count+2;
      } else
        return RET_ILSEQ;
    case STATE_GB2312:
      if (n < count+2)
        goto none;
      if (s[0] < 0x80 && s[1] < 0x80) {
        int ret = gb2312_mbtowc(conv,pwc,s,2);
        if (ret == RET_ILSEQ)
          return RET_ILSEQ;
        if (ret != 2) abort();
        COMBINE_STATE;
        conv->istate = state;
        return count+2;
      } else
        return RET_ILSEQ;
    case STATE_KSC5601:
      if (n < count+2)
        goto none;
      if (s[0] < 0x80 && s[1] < 0x80) {
        int ret = ksc5601_mbtowc(conv,pwc,s,2);
        if (ret == RET_ILSEQ)
          return RET_ILSEQ;
        if (ret != 2) abort();
        COMBINE_STATE;
        conv->istate = state;
        return count+2;
      } else
        return RET_ILSEQ;
    default: abort();
  }

none:
  COMBINE_STATE;
  conv->istate = state;
  return RET_TOOFEW(count);
}

static int
iso2022_jp2_wctomb (conv_t conv, unsigned char *r, ucs4_t wc, int n)
{
  state_t state = conv->ostate;
  SPLIT_STATE;
  unsigned char buf[2];
  int ret;

  /* Try ASCII. */
  ret = ascii_wctomb(conv,buf,wc,1);
  if (ret != RET_ILSEQ) {
    if (ret != 1) abort();
    if (buf[0] < 0x80) {
      int count = (state1 == STATE_ASCII ? 1 : 4);
      if (n < count)
        return RET_TOOSMALL;
      if (state1 != STATE_ASCII) {
        r[0] = ESC;
        r[1] = '(';
        r[2] = 'B';
        r += 3;
        state1 = STATE_ASCII;
      }
      r[0] = buf[0];
      if (wc == 0x000a || wc == 0x000d)
        state2 = STATE_G2_NONE;
      COMBINE_STATE;
      conv->ostate = state;
      return count;
    }
  }

  /* Try ISO-8859-1. */
  ret = iso8859_1_wctomb(conv,buf,wc,1);
  if (ret != RET_ILSEQ) {
    if (ret != 1) abort();
    if (buf[0] >= 0x80) {
      int count = (state2 == STATE_G2_ISO8859_1 ? 3 : 6);
      if (n < count)
        return RET_TOOSMALL;
      if (state2 != STATE_G2_ISO8859_1) {
        r[0] = ESC;
        r[1] = '.';
        r[2] = 'A';
        r += 3;
        state2 = STATE_G2_ISO8859_1;
      }
      r[0] = ESC;
      r[1] = 'N';
      r[2] = buf[0]-0x80;
      COMBINE_STATE;
      conv->ostate = state;
      return count;
    }
  }

  /* Try ISO-8859-7. */
  ret = iso8859_7_wctomb(conv,buf,wc,1);
  if (ret != RET_ILSEQ) {
    if (ret != 1) abort();
    if (buf[0] >= 0x80) {
      int count = (state2 == STATE_G2_ISO8859_7 ? 3 : 6);
      if (n < count)
        return RET_TOOSMALL;
      if (state2 != STATE_G2_ISO8859_7) {
        r[0] = ESC;
        r[1] = '.';
        r[2] = 'F';
        r += 3;
        state2 = STATE_G2_ISO8859_7;
      }
      r[0] = ESC;
      r[1] = 'N';
      r[2] = buf[0]-0x80;
      COMBINE_STATE;
      conv->ostate = state;
      return count;
    }
  }

  /* Try JIS X 0201-1976 Roman and Kana. */
  ret = jisx0201_wctomb(conv,buf,wc,1);
  if (ret != RET_ILSEQ) {
    if (ret != 1) abort();
    if (buf[0] < 0x80) {
      int count = (state1 == STATE_JISX0201ROMAN ? 1 : 4);
      if (n < count)
        return RET_TOOSMALL;
      if (state1 != STATE_JISX0201ROMAN) {
        r[0] = ESC;
        r[1] = '(';
        r[2] = 'J';
        r += 3;
        state1 = STATE_JISX0201ROMAN;
      }
      r[0] = buf[0];
      if (wc == 0x000a || wc == 0x000d)
        state2 = STATE_G2_NONE;
      COMBINE_STATE;
      conv->ostate = state;
      return count;
    } else {
      int count = (state1 == STATE_JISX0201KATAKANA ? 1 : 4);
      if (n < count)
        return RET_TOOSMALL;
      if (state1 != STATE_JISX0201KATAKANA) {
        r[0] = ESC;
        r[1] = '(';
        r[2] = 'I';
        r += 3;
        state1 = STATE_JISX0201KATAKANA;
      }
      r[0] = buf[0]-0x80;
      COMBINE_STATE;
      conv->ostate = state;
      return count;
    }
  }

  /* Try JIS X 0208-1990 in place of JIS X 0208-1978 and JIS X 0208-1983. */
  ret = jisx0208_wctomb(conv,buf,wc,2);
  if (ret != RET_ILSEQ) {
    if (ret != 2) abort();
    if (buf[0] < 0x80 && buf[1] < 0x80) {
      int count = (state1 == STATE_JISX0208 ? 2 : 5);
      if (n < count)
        return RET_TOOSMALL;
      if (state1 != STATE_JISX0208) {
        r[0] = ESC;
        r[1] = '$';
        r[2] = 'B';
        r += 3;
        state1 = STATE_JISX0208;
      }
      r[0] = buf[0];
      r[1] = buf[1];
      COMBINE_STATE;
      conv->ostate = state;
      return count;
    }
  }

  /* Try JIS X 0212-1990. */
  ret = jisx0212_wctomb(conv,buf,wc,2);
  if (ret != RET_ILSEQ) {
    if (ret != 2) abort();
    if (buf[0] < 0x80 && buf[1] < 0x80) {
      int count = (state1 == STATE_JISX0212 ? 2 : 6);
      if (n < count)
        return RET_TOOSMALL;
      if (state1 != STATE_JISX0212) {
        r[0] = ESC;
        r[1] = '$';
        r[2] = '(';
        r[3] = 'D';
        r += 4;
        state1 = STATE_JISX0212;
      }
      r[0] = buf[0];
      r[1] = buf[1];
      COMBINE_STATE;
      conv->ostate = state;
      return count;
    }
  }

  /* Try GB 2312-1980. */
  ret = gb2312_wctomb(conv,buf,wc,2);
  if (ret != RET_ILSEQ) {
    if (ret != 2) abort();
    if (buf[0] < 0x80 && buf[1] < 0x80) {
      int count = (state1 == STATE_GB2312 ? 2 : 5);
      if (n < count)
        return RET_TOOSMALL;
      if (state1 != STATE_GB2312) {
        r[0] = ESC;
        r[1] = '$';
        r[2] = 'A';
        r += 3;
        state1 = STATE_GB2312;
      }
      r[0] = buf[0];
      r[1] = buf[1];
      COMBINE_STATE;
      conv->ostate = state;
      return count;
    }
  }

  /* Try KS C 5601-1992. */
  ret = ksc5601_wctomb(conv,buf,wc,2);
  if (ret != RET_ILSEQ) {
    if (ret != 2) abort();
    if (buf[0] < 0x80 && buf[1] < 0x80) {
      int count = (state1 == STATE_KSC5601 ? 2 : 6);
      if (n < count)
        return RET_TOOSMALL;
      if (state1 != STATE_KSC5601) {
        r[0] = ESC;
        r[1] = '$';
        r[2] = '(';
        r[3] = 'C';
        r += 4;
        state1 = STATE_KSC5601;
      }
      r[0] = buf[0];
      r[1] = buf[1];
      COMBINE_STATE;
      conv->ostate = state;
      return count;
    }
  }

  return RET_ILSEQ;
}

static int
iso2022_jp2_reset (conv_t conv, unsigned char *r, int n)
{
  state_t state = conv->ostate;
  SPLIT_STATE;
  (void)state2;
  if (state1 != STATE_ASCII) {
    if (n < 3)
      return RET_TOOSMALL;
    r[0] = ESC;
    r[1] = '(';
    r[2] = 'B';
    /* conv->ostate = 0; will be done by the caller */
    return 3;
  } else
    return 0;
}

#undef COMBINE_STATE
#undef SPLIT_STATE
#undef STATE_G2_ISO8859_7
#undef STATE_G2_ISO8859_1
#undef STATE_G2_NONE
#undef STATE_KSC5601
#undef STATE_GB2312
#undef STATE_JISX0212
#undef STATE_JISX0208
#undef STATE_JISX0201KATAKANA
#undef STATE_JISX0201ROMAN
#undef STATE_ASCII