// Copyright (C) 2024 Artifex Software, Inc.

//

// This file is part of MuPDF.

//

// MuPDF is free software: you can redistribute it and/or modify it under the

// terms of the GNU Affero General Public License as published by the Free

// Software Foundation, either version 3 of the License, or (at your option)

// any later version.

//

// MuPDF is distributed in the hope that it will be useful, but WITHOUT ANY

// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS

// FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more

// details.

//

// You should have received a copy of the GNU Affero General Public License

// along with MuPDF. If not, see <https://www.gnu.org/licenses/agpl-3.0.en.html>

//

// Alternative licensing terms are available from the licensor.

// For commercial licensing, see <https://www.artifex.com/> or contact

// Artifex Software, Inc., 39 Mesa Street, Suite 108A, San Francisco,

// CA 94129, USA, for further information.

#include "mupdf/fitz.h"

#include "mupdf/pdf.h"

static int simple_text_decode_bound(fz_text_decoder *dec, unsigned char *s, int n)

{

  return n * 4 + 1;

}

static int simple_text_decode_size(fz_text_decoder *dec, unsigned char *s, int n)

{

  const unsigned short *table = dec->table1;

  unsigned char *e = s + n;

  int len = 1;

  while (s < e)

    len += fz_runelen(table[*s++]);

  return len;

}

static void simple_text_decode(fz_text_decoder *dec, char *p, unsigned char *s, int n)

{

  const unsigned short *table = dec->table1;

  unsigned char *e = s + n;

  while (s < e)

    p += fz_runetochar(p, table[*s++]);

  *p = 0;

}

static int utf16be_text_decode_bound(fz_text_decoder *dec, unsigned char *s, int n)

{

  return n * 2 + 1;

}

static int utf16le_text_decode_bound(fz_text_decoder *dec, unsigned char *s, int n)

{

  return n * 2 + 1;

}

static int utf16be_text_decode_size(fz_text_decoder *dec, unsigned char *s, int n)

{

  unsigned char *e = s + n;

  int len = 1;

  while (s + 1 < e) {

    len += fz_runelen(s[0] << 8 | s[1]);

    s += 2;

  }

  return len;

}

static int utf16le_text_decode_size(fz_text_decoder *dec, unsigned char *s, int n)

{

  unsigned char *e = s + n;

  int len = 1;

  while (s + 1 < e) {

    len += fz_runelen(s[0] | s[1] << 8);

    s += 2;

  }

  return len;

}

static void utf16be_text_decode(fz_text_decoder *dec, char *p, unsigned char *s, int n)

{

  unsigned char *e = s + n;

  while (s + 1 < e) {

    p += fz_runetochar(p, s[0] << 8 | s[1]);

    s += 2;

  }

  *p = 0;

}

static void utf16le_text_decode(fz_text_decoder *dec, char *p, unsigned char *s, int n)

{

  unsigned char *e = s + n;

  while (s + 1 < e) {

    p += fz_runetochar(p, s[0] | s[1] << 8);

    s += 2;

  }

  *p = 0;

}

static int cjk_text_decode_bound(fz_text_decoder *dec, unsigned char *s, int n)

{

  return n * 4 + 1;

}

static int cjk_text_decode_size(fz_text_decoder *dec, unsigned char *s, int n)

{

  unsigned char *e = s + n;

  pdf_cmap *to_cid = dec->table1;

  pdf_cmap *to_uni = dec->table2;

  unsigned int raw;

  int cid, uni;

  int len = 1;

  while (s < e) {

    s += pdf_decode_cmap(to_cid, s, e, &raw);

    cid = pdf_lookup_cmap(to_cid, raw);

    uni = pdf_lookup_cmap(to_uni, cid);

    if (uni < 0) {

      // ASCII control characters are missing in the CMaps

      if (raw < 32)

        uni = raw;

      else

        uni = FZ_REPLACEMENT_CHARACTER;

    }

    len += fz_runelen(uni);

  }

  return len;

}

static void cjk_text_decode(fz_text_decoder *dec, char *p, unsigned char *s, int n)

{

  unsigned char *e = s + n;

  pdf_cmap *to_cid = dec->table1;

  pdf_cmap *to_uni = dec->table2;

  unsigned int raw;

  int cid, uni;

  while (s < e) {

    s += pdf_decode_cmap(to_cid, s, e, &raw);

    cid = pdf_lookup_cmap(to_cid, raw);

    uni = pdf_lookup_cmap(to_uni, cid);

    if (uni < 0) {

      // ASCII control characters are missing in the CMaps

      if (raw < 32)

        uni = raw;

      else

        uni = FZ_REPLACEMENT_CHARACTER;

    }

    p += fz_runetochar(p, uni);

  }

  *p = 0;

}

static void fz_init_simple_text_decoder(fz_context *ctx, fz_text_decoder *dec, const unsigned short *table)

{

  dec->decode_bound = simple_text_decode_bound;

  dec->decode_size = simple_text_decode_size;

  dec->decode = simple_text_decode;

  dec->table1 = (void*)table;

}

static void fz_init_utf16be_text_decoder(fz_context *ctx, fz_text_decoder *dec)

{

  dec->decode_bound = utf16be_text_decode_bound;

  dec->decode_size = utf16be_text_decode_size;

  dec->decode = utf16be_text_decode;

}

static void fz_init_utf16le_text_decoder(fz_context *ctx, fz_text_decoder *dec)

{

  dec->decode_bound = utf16le_text_decode_bound;

  dec->decode_size = utf16le_text_decode_size;

  dec->decode = utf16le_text_decode;

}

static void fz_init_cjk_text_decoder(fz_context *ctx, fz_text_decoder *dec, const char *to_cid, const char *to_uni)

{

  dec->decode_bound = cjk_text_decode_bound;

  dec->decode_size = cjk_text_decode_size;

  dec->decode = cjk_text_decode;

  dec->table1 = pdf_load_builtin_cmap(ctx, to_cid);

  if (!dec->table1)

    fz_throw(ctx, FZ_ERROR_UNSUPPORTED, "unknown CMap: %s", to_cid);

  dec->table2 = pdf_load_builtin_cmap(ctx, to_uni);

  if (!dec->table2)

    fz_throw(ctx, FZ_ERROR_UNSUPPORTED, "unknown CMap: %s", to_uni);

}

void fz_init_text_decoder(fz_context *ctx, fz_text_decoder *dec, const char *enc)

{

  // Recognize IANA character set identifiers (case insensitive).

  // https://www.iana.org/assignments/character-sets/character-sets.xhtml

  if (!fz_strcasecmp(enc, "utf-16"))

    fz_init_utf16le_text_decoder(ctx, dec);

  else if (!fz_strcasecmp(enc, "utf-16be"))

    fz_init_utf16be_text_decoder(ctx, dec);

  else if (!fz_strcasecmp(enc, "utf-16le"))

    fz_init_utf16le_text_decoder(ctx, dec);

  else if (!fz_strcasecmp(enc, "euc-jp"))

    fz_init_cjk_text_decoder(ctx, dec, "EUC-H", "Adobe-Japan1-UCS2");

  else if (!fz_strcasecmp(enc, "shift_jis") || !fz_strcasecmp(enc, "sjis"))

    fz_init_cjk_text_decoder(ctx, dec, "90msp-H", "Adobe-Japan1-UCS2");

  else if (!fz_strcasecmp(enc, "euc-kr"))

    fz_init_cjk_text_decoder(ctx, dec, "KSCms-UHC-H", "Adobe-Korea1-UCS2");

  else if (!fz_strcasecmp(enc, "euc-cn"))

    fz_init_cjk_text_decoder(ctx, dec, "GB-EUC-H", "Adobe-GB1-UCS2");

  else if (!fz_strcasecmp(enc, "gbk") || !fz_strcasecmp(enc, "gb2312") || !fz_strcasecmp(enc, "gb18030"))

    fz_init_cjk_text_decoder(ctx, dec, "GBK2K-H", "Adobe-GB1-UCS2");

  else if (!fz_strcasecmp(enc, "euc-tw"))

    fz_init_cjk_text_decoder(ctx, dec, "CNS-EUC-H", "Adobe-CNS1-UCS2");

  else if (!fz_strcasecmp(enc, "big5"))

    fz_init_cjk_text_decoder(ctx, dec, "ETen-B5-H", "Adobe-CNS1-UCS2");

  else if (!fz_strcasecmp(enc, "big5-hkscs"))

    fz_init_cjk_text_decoder(ctx, dec, "HKscs-B5-H", "Adobe-CNS1-UCS2");

  else if (!fz_strcasecmp(enc, "iso-8859-1"))

    fz_init_simple_text_decoder(ctx, dec, fz_unicode_from_iso8859_1);

  else if (!fz_strcasecmp(enc, "iso-8859-7"))

    fz_init_simple_text_decoder(ctx, dec, fz_unicode_from_iso8859_7);

  else if (!fz_strcasecmp(enc, "koi8-r"))

    fz_init_simple_text_decoder(ctx, dec, fz_unicode_from_koi8u);

  else if (!fz_strcasecmp(enc, "windows-1250"))

    fz_init_simple_text_decoder(ctx, dec, fz_unicode_from_windows_1250);

  else if (!fz_strcasecmp(enc, "windows-1251"))

    fz_init_simple_text_decoder(ctx, dec, fz_unicode_from_windows_1251);

  else if (!fz_strcasecmp(enc, "windows-1252"))

    fz_init_simple_text_decoder(ctx, dec, fz_unicode_from_windows_1252);

  else

    fz_throw(ctx, FZ_ERROR_UNSUPPORTED, "unknown text encoding: %s", enc);

}