/* === This file is part of Calamares - <https://github.com/calamares> ===
 *
 *   Copyright 2016, Teo Mrnjavac <teo@kde.org>
 *   Copyright 2017, Adriaan de Groot <groot@kde.org>
 *
 *   Calamares is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, either version 3 of the License, or
 *   (at your option) any later version.
 *
 *   Calamares 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 General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with Calamares. If not, see <http://www.gnu.org/licenses/>.
 */

#include "LocaleConfiguration.h"
#include <QLocale>

LocaleConfiguration::LocaleConfiguration()
    : explicit_lang( false )
    , explicit_lc( false )
{
}


LocaleConfiguration
LocaleConfiguration::createDefault()
{
    LocaleConfiguration lc = LocaleConfiguration();
    lc.lang = lc.lc_numeric = lc.lc_time = lc.lc_monetary = lc.lc_paper = lc.lc_name
            = lc.lc_address = lc.lc_telephone = lc.lc_measurement
            = lc.lc_identification = "en_US.UTF-8";
    return lc;
}


LocaleConfiguration
LocaleConfiguration::fromLanguageAndLocation( const QString& languageLocale,
                                              const QStringList& availableLocales,
                                              const QString& countryCode )
{
    LocaleConfiguration lc;

    // Note that the documentation how this works is in packages.conf
    QString language = languageLocale.split( '_' ).first();
    lc.myLanguageLocaleBcp47 = QLocale(language).bcp47Name().toLower();

    QStringList linesForLanguage;
    for ( const QString &line : availableLocales )
    {
        if ( line.startsWith( language ) )
            linesForLanguage.append( line );
    }

    QString lang;
    if ( linesForLanguage.length() == 0 || languageLocale.isEmpty() )
        lang = "en_US.UTF-8";
    else if ( linesForLanguage.length() == 1 )
        lang = linesForLanguage.first();
    else
    {
        QStringList linesForLanguageUtf;
        // FIXME: this might be useless if we already filter out non-UTF8 locales
        foreach ( QString line, linesForLanguage )
        {
            if ( line.contains( "UTF-8", Qt::CaseInsensitive ) ||
                 line.contains( "utf8", Qt::CaseInsensitive ) )
                linesForLanguageUtf.append( line );
        }

        if ( linesForLanguageUtf.length() == 1 )
            lang = linesForLanguageUtf.first();
    }

    // lang could still be empty if we found multiple locales that satisfy myLanguage

    // The following block was inspired by Ubiquity, scripts/localechooser-apply.
    // No copyright statement found in file, assuming GPL v2 or later.
    /*  # In the special cases of Portuguese and Chinese, selecting a
        # different location may imply a different dialect of the language.
        # In such cases, make LANG reflect the selected language (for
        # messages, character types, and collation) and make the other
        # locale categories reflect the selected location. */
    if ( language == "pt" || language == "zh" )
    {
        QString proposedLocale = QString( "%1_%2" ).arg( language )
                                                   .arg( countryCode );
        foreach ( QString line, linesForLanguage )
        {
            if ( line.contains( proposedLocale ) )
            {
                lang = line;
                break;
            }
        }
    }

    // If we found no good way to set a default lang, do a search with the whole
    // language locale and pick the first result, if any.
    if ( lang.isEmpty() )
    {
        for ( const QString &line : availableLocales )
        {
            if ( line.startsWith( languageLocale ) )
            {
                lang = line;
                break;
            }
        }

    }

    // Else we have an unrecognized or unsupported locale, all we can do is go with
    // en_US.UTF-8 UTF-8. This completes all default language setting guesswork.
    if ( lang.isEmpty() )
        lang = "en_US.UTF-8";


    // The following block was inspired by Ubiquity, scripts/localechooser-apply.
    // No copyright statement found in file, assuming GPL v2 or later.
    /*  # It is relatively common for the combination of language and location (as
        # selected on the timezone page) not to identify a supported combined
        # locale.  For example, this happens when the user is a migrant, or when
        # they prefer to use a different language to interact with their computer
        # because that language is better-supported.
        #
        # In such cases, we would like to be able to use a locale reflecting the
        # selected language in LANG for messages, character types, and collation,
        # and to make the other locale categories reflect the selected location.
        # This means that we have to guess at a suitable locale for the selected
        # location, and we do not want to ask yet another locale-related question.
        # Nevertheless, some cases are ambiguous: a user who has asked for the
        # English language and identifies their location as Switzerland will get
        # different numeric representation depending on which Swiss locale we pick.
        #
        # The goal of identifying a reasonable default for migrants makes things
        # easier: it is reasonable to default to French for France despite the
        # existence of several minority languages there, because anyone who prefers
        # those languages will probably already have selected them and won't arrive
        # here.  However, in some cases we're unsure, and in some cases we actively
        # don't want to pick a "preferred" language: selecting either Greek or
        # Turkish as the default language for migrants to Cyprus would probably
        # offend somebody!  In such cases we simply punt to the old behaviour of not
        # setting up a locale reflecting the location, which is suboptimal but is at
        # least unlikely to give offence.
        #
        # Our best shot at general criteria for selecting a default language in
        # these circumstances are as follows:
        #
        #  * Exclude special-purpose (e.g. en_DK) and artificial (e.g. la_AU,
        #    tlh_GB) locales.
        #  * If there is a language specific to or very strongly associated with the
        #    country in question, prefer it unless it has rather few native
        #    speakers.
        #  * Exclude minority languages that are relatively unlikely to be spoken by
        #    migrants who have not already selected them as their preferred language
        #    earlier in the installer.
        #  * If there is an official national language likely to be seen in print
        #    media, road signs, etc., then prefer that.
        #  * In cases of doubt, selecting no default language is safe. */

    // We make a proposed locale based on the UI language and the timezone's country. There is no
    // guarantee that this will be a valid, supported locale (often it won't).
    QString lc_formats;
    QString combined = QString( "%1_%2" ).arg( language )
                                         .arg( countryCode );
    // We look up if it's a supported locale.
    for ( const QString &line : availableLocales )
    {
        if ( line.startsWith( combined ) )
        {
            lang = line;
            lc_formats = line;
            break;
        }
    }

    if ( lc_formats.isEmpty() )
    {
        QStringList available;
        for ( const QString &line : availableLocales )
        {
            if ( line.contains( QString( "_%1" ).arg( countryCode ) ) )
            {
                available.append( line );
            }
        }
        available.sort();
        if ( available.count() == 1 )
        {
            lc_formats = available.first();
        }
        else
        {
            QMap< QString, QString > countryToDefaultLanguage {
                { "AU", "en" },
                { "CN", "zh" },
                { "DE", "de" },
                { "DK", "da" },
                { "DZ", "ar" },
                { "ES", "es" },
                // Somewhat unclear: Oromo has the greatest number of
                // native speakers; English is the most widely spoken
                // language and taught in secondary schools; Amharic is
                // the official language and was taught in primary
                // schools.
                { "ET", "am" },
                { "FI", "fi" },
                { "FR", "fr" },
                { "GB", "en" },
                // Irish (Gaelic) is strongly associated with Ireland,
                // but nearly all its native speakers also speak English,
                // and migrants are likely to use English.
                { "IE", "en" },
                { "IT", "it" },
                { "MA", "ar" },
                { "MK", "mk" },
                { "NG", "en" },
                { "NL", "nl" },
                { "NZ", "en" },
                { "IL", "he" },
                // Filipino is a de facto version of Tagalog, which is
                // also spoken; English is also an official language.
                { "PH", "fil" },
                { "PK", "ur" },
                { "PL", "pl" },
                { "RU", "ru" },
                // Chinese has more speakers, but English is the "common
                // language of the nation" (Wikipedia) and official
                // documents must be translated into English to be
                // accepted.
                { "SG", "en" },
                { "SN", "wo" },
                { "TR", "tr" },
                { "TW", "zh" },
                { "UA", "uk" },
                { "US", "en" },
                { "ZM", "en" }
            };
            if ( countryToDefaultLanguage.contains( countryCode ) )
            {
                QString combinedLocale =
                        QString( "%1_%2" ).arg( countryToDefaultLanguage.value( countryCode ) )
                                          .arg( countryCode );

                for ( const QString &line : availableLocales )
                {
                    if ( line.startsWith( combinedLocale ) )
                    {
                        lc_formats = line;
                        break;
                    }
                }
            }
        }
    }

    // If we cannot make a good choice for a given country we go with the LANG
    // setting, which defaults to en_US.UTF-8 UTF-8 if all else fails.
    if ( lc_formats.isEmpty() )
        lc_formats = lang;

    lc.lang = lang;
    lc.lc_address = lc.lc_identification = lc.lc_measurement = lc.lc_monetary
                  = lc.lc_name = lc.lc_numeric = lc.lc_paper = lc.lc_telephone
                  = lc.lc_time = lc_formats;

    return lc;
}


bool
LocaleConfiguration::isEmpty() const
{
    return lang.isEmpty() &&
         lc_numeric.isEmpty() &&
         lc_time.isEmpty() &&
         lc_monetary.isEmpty() &&
         lc_paper.isEmpty() &&
         lc_name.isEmpty() &&
         lc_address.isEmpty() &&
         lc_telephone.isEmpty() &&
         lc_measurement.isEmpty() &&
         lc_identification.isEmpty();
}


QMap< QString, QString >
LocaleConfiguration::toMap() const
{
    QMap< QString, QString > map;

    if ( !lang.isEmpty() )
        map.insert( "LANG", lang );

    if ( !lc_numeric.isEmpty() )
        map.insert( "LC_NUMERIC", lc_numeric );

    if ( !lc_time.isEmpty() )
        map.insert( "LC_TIME", lc_time );

    if ( !lc_monetary.isEmpty() )
        map.insert( "LC_MONETARY", lc_monetary );

    if ( !lc_paper.isEmpty() )
        map.insert( "LC_PAPER", lc_paper );

    if ( !lc_name.isEmpty() )
        map.insert( "LC_NAME", lc_name );

    if ( !lc_address.isEmpty() )
        map.insert( "LC_ADDRESS", lc_address );

    if ( !lc_telephone.isEmpty() )
        map.insert( "LC_TELEPHONE", lc_telephone );

    if ( !lc_measurement.isEmpty() )
        map.insert( "LC_MEASUREMENT", lc_measurement );

    if ( !lc_identification.isEmpty() )
        map.insert( "LC_IDENTIFICATION", lc_identification );

    return map;
}

QString
LocaleConfiguration::toBcp47() const
{
    return myLanguageLocaleBcp47;
}