/* the next two functions are implicitely thread safe,
   as they are only called by setup() which uses a mutex.
*/
static void setupLocaleMapper()
{
#ifdef Q_OS_WIN32
    localeMapper = QTextCodec::codecForName("System");
#else

#if defined (_XOPEN_UNIX) && !defined(Q_OS_QNX6) && !defined(Q_OS_OSF) && !defined(Q_OS_MAC)
    char *charset = nl_langinfo (CODESET);
    if (charset)
      localeMapper = QTextCodec::codecForName(charset);
#endif

    if (!localeMapper) {
        // Very poorly defined and followed standards causes lots of code
        // to try to get all the cases...

        // Try to determine locale codeset from locale name assigned to
        // LC_CTYPE category.

        // First part is getting that locale name.  First try setlocale() which
        // definitely knows it, but since we cannot fully trust it, get ready
        // to fall back to environment variables.
        char * ctype = qstrdup(setlocale(LC_CTYPE, 0));

        // Get the first nonempty value from $LC_ALL, $LC_CTYPE, and $LANG
        // environment variables.
        char * lang = qstrdup(qgetenv("LC_ALL").constData());
        if (!lang || lang[0] == 0 || strcmp(lang, "C") == 0) {
            if (lang) delete [] lang;
            lang = qstrdup(qgetenv("LC_CTYPE").constData());
        }
        if (!lang || lang[0] == 0 || strcmp(lang, "C") == 0) {
            if (lang) delete [] lang;
            lang = qstrdup(qgetenv("LANG").constData());
        }

        // Now try these in order:
        // 1. CODESET from ctype if it contains a .CODESET part (e.g. en_US.ISO8859-15)
        // 2. CODESET from lang if it contains a .CODESET part
        // 3. ctype (maybe the locale is named "ISO-8859-1" or something)
        // 4. locale (ditto)
        // 5. check for "@euro"
        // 6. guess locale from ctype unless ctype is "C"
        // 7. guess locale from lang

        // 1. CODESET from ctype if it contains a .CODESET part (e.g. en_US.ISO8859-15)
        char * codeset = ctype ? strchr(ctype, '.') : 0;
        if (codeset && *codeset == '.')
            localeMapper = checkForCodec(codeset + 1);

        // 2. CODESET from lang if it contains a .CODESET part
        codeset = lang ? strchr(lang, '.') : 0;
        if (!localeMapper && codeset && *codeset == '.')
            localeMapper = checkForCodec(codeset + 1);

        // 3. ctype (maybe the locale is named "ISO-8859-1" or something)
        if (!localeMapper && ctype && *ctype != 0 && strcmp (ctype, "C") != 0)
            localeMapper = checkForCodec(ctype);

        // 4. locale (ditto)
        if (!localeMapper && lang && *lang != 0)
            localeMapper = checkForCodec(lang);

        // 5. "@euro"
        if (!localeMapper && ctype && strstr(ctype, "@euro") || lang && strstr(lang, "@euro"))
            localeMapper = checkForCodec("ISO 8859-15");

        // 6. guess locale from ctype unless ctype is "C"
        // 7. guess locale from lang
        char * try_by_name = ctype;
        if (ctype && *ctype != 0 && strcmp (ctype, "C") != 0)
            try_by_name = lang;

        // Now do the guessing.
        if (lang && *lang && !localeMapper && try_by_name && *try_by_name) {
            if (try_locale_list(iso8859_15locales, lang))
                localeMapper = QTextCodec::codecForName("ISO 8859-15");
            else if (try_locale_list(iso8859_2locales, lang))
                localeMapper = QTextCodec::codecForName("ISO 8859-2");
            else if (try_locale_list(iso8859_3locales, lang))
                localeMapper = QTextCodec::codecForName("ISO 8859-3");
            else if (try_locale_list(iso8859_4locales, lang))
                localeMapper = QTextCodec::codecForName("ISO 8859-4");
            else if (try_locale_list(iso8859_5locales, lang))
                localeMapper = QTextCodec::codecForName("ISO 8859-5");
            else if (try_locale_list(iso8859_6locales, lang))
                localeMapper = QTextCodec::codecForName("ISO 8859-6");
            else if (try_locale_list(iso8859_7locales, lang))
                localeMapper = QTextCodec::codecForName("ISO 8859-7");
            else if (try_locale_list(iso8859_8locales, lang))
                localeMapper = QTextCodec::codecForName("ISO 8859-8-I");
            else if (try_locale_list(iso8859_9locales, lang))
                localeMapper = QTextCodec::codecForName("ISO 8859-9");
            else if (try_locale_list(iso8859_13locales, lang))
                localeMapper = QTextCodec::codecForName("ISO 8859-13");
            else if (try_locale_list(tis_620locales, lang))
                localeMapper = QTextCodec::codecForName("ISO 8859-11");
            else if (try_locale_list(koi8_ulocales, lang))
                localeMapper = QTextCodec::codecForName("KOI8-U");
            else if (try_locale_list(cp_1251locales, lang))
                localeMapper = QTextCodec::codecForName("CP 1251");
            else if (try_locale_list(pt_154locales, lang))
                localeMapper = QTextCodec::codecForName("PT 154");
            else if (try_locale_list(probably_koi8_rlocales, lang))
                localeMapper = ru_RU_hack(lang);
        }

        delete [] ctype;
        delete [] lang;
    }

    // If everything failed, we default to 8859-1
    // We could perhaps default to 8859-15.
    if (!localeMapper)
        localeMapper = QTextCodec::codecForName("ISO 8859-1");
#endif
}