/*****************************************************************************

 * dvb-text.h:

 *****************************************************************************

 * Copyright (C) 2007-2011 VLC authors and VideoLAN

 *

 * This program is free software; you can redistribute it and/or modify it

 * under the terms of the GNU Lesser General Public License as published by

 * the Free Software Foundation; either version 2.1 of the License, or

 * (at your option) any later version.

 *

 * This program 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 Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public License

 * along with this program; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.

 *****************************************************************************/

/**

 * Converts a DVB SI text item to UTF-8.

 * Refer to EN 800 486 annex A.

 * @return a heap-allocation nul-terminated UTF-8 string or NULL on error.

 */

static char *vlc_from_EIT (const void *buf, size_t length)

{

    if (unlikely(length == 0))

        return NULL;

    char encbuf[12];

    const char *encoding = encbuf;

    const char *in = buf;

    size_t offset = 1;

    unsigned char c = *in;

    if (c >= 0x20)

    {

        offset = 0;

        encoding = "ISO_6937";

    }

    else if ((1 << c) & 0x0EFE) /* 1-7, 9-11 -> ISO 8859-(c+4) */

    {

        snprintf (encbuf, sizeof (encbuf), "ISO_8859-%u", 4u + c);

    }

    else switch (c)

    {

        case 0x10: /* two more bytes */

            offset = 3;

            if (length < 3 || in[1] != 0x00)

                return NULL;

            c = in[2];

            if ((1 << c) & 0xEFFE) /* 1-11, 13-15 -> ISO 8859-(c) */

               snprintf (encbuf, sizeof (encbuf), "ISO_8859-%hhu", c);

           else

               return NULL;

           break;

        case 0x11: /* the BMP */

        case 0x14: /* Big5 subset of the BMP */

            encoding = "UCS-2BE";

            break;

        case 0x12:

            /* DVB has no clue about Korean. KS X 1001 (a.k.a. KS C 5601) is a

             * character set, not a character encoding... So we assume EUC-KR.

             * It is an encoding of KS X 1001. In practice, I guess nobody uses

             * this in any real DVB system. */

            encoding = "EUC-KR";

            break;

        case 0x13: /* GB-2312-1980 */

            encoding = "GB2312";

            break;

        case 0x15:

            encoding = "UTF-8";

            break;

#if 0

        case 0x1F: /* operator-specific(?) */

            offset = 2;

#endif

        default:

            return NULL;

    }

    in += offset;

    length -= offset;

    char *out = FromCharset (encoding, in, length);

    if (out == NULL)

    {   /* Fallback... */

        out = strndup (in, length);

        if (unlikely(out == NULL))

            return NULL;

        EnsureUTF8 (out);

    }

    length = strlen(out);

    /* Convert control codes */

    for (char *p = strchr (out, '\xC2'); p; p = strchr (p + 1, '\xC2'))

    {

        /* We have valid UTF-8, to 0xC2 is followed by a continuation byte. */

        /* 0x80-0x85,0x88-0x89 are reserved.

         * 0x86-0x87 are identical to Unicode and Latin-1.

         * 0x8A is CR/LF.

         * 0x8B-0x9F are unspecified. */

        if (p[1] == '\x8A')

            memcpy (p, "\r\n", 2);

        /* Strip character emphasis */

        if (p[1] == '\x86' || p[1] == '\x87') {

            const size_t n = p - out;

            memmove (p, p+2, length - n);

            length -= 2;

            out[length] = '\0';

            if (length == n)

                break;

        }

    }

    /* Private use area */

    for (char *p = strchr (out, '\xEE'); p; p = strchr (p + 1, '\xEE'))

    {

        /* Within UTF-8, 0xEE is followed by a two continuation bytes. */

        if (p[1] != '\x82')

            continue;

        if (p[2] == '\x8A')

            memcpy (p, "\r\r\n", 3); /* we need three bytes, so to CRs ;) */

        /* Strip character emphasis */

        if (p[2] == '\x86' || p[2] == '\x87') {

            const size_t n = p - out;

            memmove (p, p+3, length - n);

            length -= 3;

            out[length] = '\0';

            if (length == n)

                break;

        }

    }

    return out;

}