// Copyright (C) 2022 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only

#include "qlocale_p.h"

#include "qstringbuilder.h"
#include "qdatetime.h"
#include "qstringlist.h"
#include "qvariant.h"
#include "qreadwritelock.h"

QT_BEGIN_NAMESPACE

using namespace Qt::StringLiterals;

#ifndef QT_NO_SYSTEMLOCALE
struct QSystemLocaleData
{
    QSystemLocaleData()
        : lc_numeric(QLocale::C)
         ,lc_time(QLocale::C)
         ,lc_monetary(QLocale::C)
         ,lc_messages(QLocale::C)
    {
        readEnvironment();
    }

    void readEnvironment();

    QReadWriteLock lock;

    QLocale lc_numeric;
    QLocale lc_time;
    QLocale lc_monetary;
    QLocale lc_messages;
    QByteArray lc_messages_var;
    QByteArray lc_measurement_var;
    QByteArray lc_collate_var;
    QStringList uiLanguages;
};

void QSystemLocaleData::readEnvironment()
{
    QWriteLocker locker(&lock);

    // See https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_02
    // for the semantics of each of these:
    QByteArray all = qgetenv("LC_ALL");
    QByteArray numeric  = all.isEmpty() ? qgetenv("LC_NUMERIC") : all;
    QByteArray time     = all.isEmpty() ? qgetenv("LC_TIME") : all;
    QByteArray monetary = all.isEmpty() ? qgetenv("LC_MONETARY") : all;
    lc_messages_var     = all.isEmpty() ? qgetenv("LC_MESSAGES") : all;
    lc_measurement_var  = all.isEmpty() ? qgetenv("LC_MEASUREMENT") : all;
    lc_collate_var      = all.isEmpty() ? qgetenv("LC_COLLATE") : all;
    QByteArray lang = qgetenv("LANG");
    if (lang.isEmpty())
        lang = QByteArray("C");
    if (numeric.isEmpty())
        numeric = lang;
    if (time.isEmpty())
        time = lang;
    if (monetary.isEmpty())
        monetary = lang;
    if (lc_messages_var.isEmpty())
        lc_messages_var = lang;
    if (lc_measurement_var.isEmpty())
        lc_measurement_var = lang;
    if (lc_collate_var.isEmpty())
        lc_collate_var = lang;
    lc_numeric = QLocale(QString::fromLatin1(numeric));
    lc_time = QLocale(QString::fromLatin1(time));
    lc_monetary = QLocale(QString::fromLatin1(monetary));
    lc_messages = QLocale(QString::fromLatin1(lc_messages_var));
}

Q_GLOBAL_STATIC(QSystemLocaleData, qSystemLocaleData)

#endif

#ifndef QT_NO_SYSTEMLOCALE

static bool contradicts(QStringView maybe, const QString &known)
{
    if (maybe.isEmpty())
        return false;

    /*
      If \a known (our current best shot at deciding which language to use)
      provides more information (e.g. script, country) than \a maybe (a
      candidate to replace \a known) and \a maybe agrees with \a known in what
      it does provide, we keep \a known; this happens when \a maybe comes from
      LANGUAGE (usually a simple language code) and LANG includes script and/or
      country.  A textual comparison won't do because, for example, bn (Bengali)
      isn't a prefix of ben_IN, but the latter is a refinement of the former.
      (Meanwhile, bn is a prefix of bnt, Bantu; and a prefix of ben is be,
      Belarusian.  There are many more such prefixings between two- and
      three-letter codes.)
     */
    QLocaleId knownId = QLocaleId::fromName(known);
    QLocaleId maybeId = QLocaleId::fromName(maybe);
    return !(maybeId.acceptLanguage(knownId.language_id) && maybeId.acceptScriptTerritory(knownId));
}

QLocale QSystemLocale::fallbackLocale() const
{
    // See man 7 locale for precedence - LC_ALL beats LC_MESSAGES beats LANG:
    QString lang = qEnvironmentVariable("LC_ALL");
    if (lang.isEmpty())
        lang = qEnvironmentVariable("LC_MESSAGES");
    if (lang.isEmpty())
        lang = qEnvironmentVariable("LANG");
    // if the locale is the "C" locale, then we can return the language we found here:
    if (lang.isEmpty() || lang == "C"_L1 || lang == "POSIX"_L1)
        return QLocale(lang);

    // ... otherwise, if the first part of LANGUAGE says more than or
    // contradicts what we have, use that:
    for (const auto &language : qEnvironmentVariable("LANGUAGE").tokenize(u':')) {
        if (contradicts(language, lang))
            return QLocale(language);
        break; // We only look at the first entry.
    }

    return QLocale(lang);
}

QVariant QSystemLocale::query(QueryType type, QVariant in) const
{
    QSystemLocaleData *d = qSystemLocaleData();

    if (type == LocaleChanged) {
        d->readEnvironment();
        return QVariant();
    }

    QReadLocker locker(&d->lock);

    const QLocale &lc_numeric = d->lc_numeric;
    const QLocale &lc_time = d->lc_time;
    const QLocale &lc_monetary = d->lc_monetary;
    const QLocale &lc_messages = d->lc_messages;

    switch (type) {
    case DecimalPoint:
        return lc_numeric.decimalPoint();
    case GroupSeparator:
        return lc_numeric.groupSeparator();
    case ZeroDigit:
        return lc_numeric.zeroDigit();
    case NegativeSign:
        return lc_numeric.negativeSign();
    case DateFormatLong:
        return lc_time.dateFormat(QLocale::LongFormat);
    case DateFormatShort:
        return lc_time.dateFormat(QLocale::ShortFormat);
    case TimeFormatLong:
        return lc_time.timeFormat(QLocale::LongFormat);
    case TimeFormatShort:
        return lc_time.timeFormat(QLocale::ShortFormat);
    case DayNameLong:
        return lc_time.dayName(in.toInt(), QLocale::LongFormat);
    case DayNameShort:
        return lc_time.dayName(in.toInt(), QLocale::ShortFormat);
    case DayNameNarrow:
        return lc_time.dayName(in.toInt(), QLocale::NarrowFormat);
    case StandaloneDayNameLong:
        return lc_time.standaloneDayName(in.toInt(), QLocale::LongFormat);
    case StandaloneDayNameShort:
        return lc_time.standaloneDayName(in.toInt(), QLocale::ShortFormat);
    case StandaloneDayNameNarrow:
        return lc_time.standaloneDayName(in.toInt(), QLocale::NarrowFormat);
    case MonthNameLong:
        return lc_time.monthName(in.toInt(), QLocale::LongFormat);
    case MonthNameShort:
        return lc_time.monthName(in.toInt(), QLocale::ShortFormat);
    case MonthNameNarrow:
        return lc_time.monthName(in.toInt(), QLocale::NarrowFormat);
    case StandaloneMonthNameLong:
        return lc_time.standaloneMonthName(in.toInt(), QLocale::LongFormat);
    case StandaloneMonthNameShort:
        return lc_time.standaloneMonthName(in.toInt(), QLocale::ShortFormat);
    case StandaloneMonthNameNarrow:
        return lc_time.standaloneMonthName(in.toInt(), QLocale::NarrowFormat);
    case DateToStringLong:
        return lc_time.toString(in.toDate(), QLocale::LongFormat);
    case DateToStringShort:
        return lc_time.toString(in.toDate(), QLocale::ShortFormat);
    case TimeToStringLong:
        return lc_time.toString(in.toTime(), QLocale::LongFormat);
    case TimeToStringShort:
        return lc_time.toString(in.toTime(), QLocale::ShortFormat);
    case DateTimeFormatLong:
        return lc_time.dateTimeFormat(QLocale::LongFormat);
    case DateTimeFormatShort:
        return lc_time.dateTimeFormat(QLocale::ShortFormat);
    case DateTimeToStringLong:
        return lc_time.toString(in.toDateTime(), QLocale::LongFormat);
    case DateTimeToStringShort:
        return lc_time.toString(in.toDateTime(), QLocale::ShortFormat);
    case PositiveSign:
        return lc_numeric.positiveSign();
    case AMText:
        return lc_time.amText();
    case PMText:
        return lc_time.pmText();
    case FirstDayOfWeek:
        return lc_time.firstDayOfWeek();
    case CurrencySymbol:
        return lc_monetary.currencySymbol(QLocale::CurrencySymbolFormat(in.toUInt()));
    case CurrencyToString: {
        switch (in.userType()) {
        case QMetaType::Int:
            return lc_monetary.toCurrencyString(in.toInt());
        case QMetaType::UInt:
            return lc_monetary.toCurrencyString(in.toUInt());
        case QMetaType::Double:
            return lc_monetary.toCurrencyString(in.toDouble());
        case QMetaType::LongLong:
            return lc_monetary.toCurrencyString(in.toLongLong());
        case QMetaType::ULongLong:
            return lc_monetary.toCurrencyString(in.toULongLong());
        default:
            break;
        }
        return QString();
    }
    case MeasurementSystem: {
        const QString meas_locale = QString::fromLatin1(d->lc_measurement_var);
        if (meas_locale.compare("Metric"_L1, Qt::CaseInsensitive) == 0)
            return QLocale::MetricSystem;
        if (meas_locale.compare("Other"_L1, Qt::CaseInsensitive) == 0)
            return QLocale::MetricSystem;
        return QVariant((int)QLocale(meas_locale).measurementSystem());
    }
    case Collation:
        return QString::fromLatin1(d->lc_collate_var);
    case UILanguages: {
        if (!d->uiLanguages.isEmpty())
            return d->uiLanguages;
        QString languages = QString::fromLatin1(qgetenv("LANGUAGE"));
        QStringList lst;
        if (languages.isEmpty())
            lst.append(QString::fromLatin1(d->lc_messages_var));
        else
            lst = languages.split(u':');

        for (int i = 0; i < lst.size(); ++i) {
            QStringView language, script, territory;
            if (qt_splitLocaleName(lst.at(i), &language, &script, &territory)) {
                QString joined = language.isEmpty() ? u"und"_s : language.toString();
                if (!script.isEmpty())
                    joined += u'-' + script;
                if (!territory.isEmpty())
                    joined += u'-' + territory;
                d->uiLanguages.append(joined);
            }
        }
        return d->uiLanguages.isEmpty() ? QVariant() : QVariant(d->uiLanguages);
    }
    case StringToStandardQuotation:
        return lc_messages.quoteString(qvariant_cast<QStringView>(in));
    case StringToAlternateQuotation:
        return lc_messages.quoteString(qvariant_cast<QStringView>(in), QLocale::AlternateQuotation);
    case ListToSeparatedString:
        return lc_messages.createSeparatedList(in.toStringList());
    case LocaleChanged:
        Q_ASSERT(false);
    default:
        break;
    }
    return QVariant();
}
#endif // QT_NO_SYSTEMLOCALE

QT_END_NAMESPACE