Update: Translations from eints

[openttd-github.git] / src / strings.cpp

/*
 * This file is part of OpenTTD.
 * OpenTTD 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, version 2.
 * OpenTTD 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 OpenTTD. If not, see <http://www.gnu.org/licenses/>.
 */

/** @file strings.cpp Handling of translated strings. */

#include "stdafx.h"
#include "currency.h"
#include "station_base.h"
#include "town.h"
#include "waypoint_base.h"
#include "depot_base.h"
#include "industry.h"
#include "newgrf_text.h"
#include "fileio_func.h"
#include "signs_base.h"
#include "fontdetection.h"
#include "error.h"
#include "error_func.h"
#include "strings_func.h"
#include "rev.h"
#include "core/endian_func.hpp"
#include "timer/timer_game_calendar.h"
#include "vehicle_base.h"
#include "engine_base.h"
#include "language.h"
#include "townname_func.h"
#include "string_func.h"
#include "company_base.h"
#include "smallmap_gui.h"
#include "window_func.h"
#include "debug.h"
#include "game/game_text.hpp"
#include "network/network_content_gui.h"
#include "newgrf_engine.h"
#include "core/backup_type.hpp"
#include "gfx_layout.h"
#include <stack>
#include <charconv>

#include "table/strings.h"
#include "table/control_codes.h"
#include "3rdparty/fmt/std.h"

#include "strings_internal.h"

#include "safeguards.h"

std::string _config_language_file;                ///< The file (name) stored in the configuration.
LanguageList _languages;                          ///< The actual list of language meta data.
const LanguageMetadata *_current_language = nullptr; ///< The currently loaded language.

TextDirection _current_text_dir; ///< Text direction of the currently selected language.

#ifdef WITH_ICU_I18N
std::unique_ptr<icu::Collator> _current_collator;    ///< Collator for the language currently in use.
#endif /* WITH_ICU_I18N */

ArrayStringParameters<20> _global_string_params;

/**
 * Prepare the string parameters for the next formatting run. This means
 * resetting the type information and resetting the offset to the begin.
 */
void StringParameters::PrepareForNextRun()
{
        for (auto &param : this->parameters) param.type = 0;
        this->offset = 0;
}


/**
 * Get the next parameter from our parameters.
 * This updates the offset, so the next time this is called the next parameter
 * will be read.
 * @return The next parameter.
 */
const StringParameter &StringParameters::GetNextParameterReference()
{
        assert(this->next_type == 0 || (SCC_CONTROL_START <= this->next_type && this->next_type <= SCC_CONTROL_END));
        if (this->offset >= this->parameters.size()) {
                throw std::out_of_range("Trying to read invalid string parameter");
        }

        auto &param = this->parameters[this->offset++];
        if (param.type != 0 && param.type != this->next_type) {
                this->next_type = 0;
                throw std::out_of_range("Trying to read string parameter with wrong type");
        }
        param.type = this->next_type;
        this->next_type = 0;
        return param;
}


/**
 * Set a string parameter \a v at index \a n in the global string parameter array.
 * @param n Index of the string parameter.
 * @param v Value of the string parameter.
 */
void SetDParam(size_t n, uint64_t v)
{
        _global_string_params.SetParam(n, v);
}

/**
 * Get the current string parameter at index \a n from the global string parameter array.
 * @param n Index of the string parameter.
 * @return Value of the requested string parameter.
 */
uint64_t GetDParam(size_t n)
{
        return std::get<uint64_t>(_global_string_params.GetParam(n));
}

/**
 * Set DParam n to some number that is suitable for string size computations.
 * @param n Index of the string parameter.
 * @param max_value The biggest value which shall be displayed.
 *                  For the result only the number of digits of \a max_value matter.
 * @param min_count Minimum number of digits independent of \a max.
 * @param size  Font of the number
 */
void SetDParamMaxValue(size_t n, uint64_t max_value, uint min_count, FontSize size)
{
        uint num_digits = 1;
        while (max_value >= 10) {
                num_digits++;
                max_value /= 10;
        }
        SetDParamMaxDigits(n, std::max(min_count, num_digits), size);
}

/**
 * Set DParam n to some number that is suitable for string size computations.
 * @param n Index of the string parameter.
 * @param count Number of digits which shall be displayable.
 * @param size  Font of the number
 */
void SetDParamMaxDigits(size_t n, uint count, FontSize size)
{
        uint front = 0;
        uint next = 0;
        GetBroadestDigit(&front, &next, size);
        uint64_t val = count > 1 ? front : next;
        for (; count > 1; count--) {
                val = 10 * val + next;
        }
        SetDParam(n, val);
}

/**
 * Copy the parameters from the backup into the global string parameter array.
 * @param backup The backup to copy from.
 */
void CopyInDParam(const std::span<const StringParameterData> backup)
{
        for (size_t i = 0; i < backup.size(); i++) {
                _global_string_params.SetParam(i, backup[i]);
        }
}

/**
 * Copy \a num string parameters from the global string parameter array to the \a backup.
 * @param backup The backup to write to.
 * @param num Number of string parameters to copy.
 */
void CopyOutDParam(std::vector<StringParameterData> &backup, size_t num)
{
        backup.resize(num);
        for (size_t i = 0; i < backup.size(); i++) {
                backup[i] = _global_string_params.GetParam(i);
        }
}

/**
 * Checks whether the global string parameters have changed compared to the given backup.
 * @param backup The backup to check against.
 * @return True when the parameters have changed, otherwise false.
 */
bool HaveDParamChanged(const std::span<const StringParameterData> backup)
{
        for (size_t i = 0; i < backup.size(); i++) {
                if (backup[i] != _global_string_params.GetParam(i)) return true;
        }
        return false;
}

static void StationGetSpecialString(StringBuilder &builder, StationFacility x);
static void GetSpecialTownNameString(StringBuilder &builder, int ind, uint32_t seed);
static void GetSpecialNameString(StringBuilder &builder, int ind, StringParameters &args);

static void FormatString(StringBuilder &builder, const char *str, StringParameters &args, uint case_index = 0, bool game_script = false, bool dry_run = false);

struct LanguagePack : public LanguagePackHeader {
        char data[]; // list of strings
};

struct LanguagePackDeleter {
        void operator()(LanguagePack *langpack)
        {
                /* LanguagePack is in fact reinterpreted char[], we need to reinterpret it back to free it properly. */
                delete[] reinterpret_cast<char*>(langpack);
        }
};

struct LoadedLanguagePack {
        std::unique_ptr<LanguagePack, LanguagePackDeleter> langpack;

        std::vector<char *> offsets;

        std::array<uint, TEXT_TAB_END> langtab_num;   ///< Offset into langpack offs
        std::array<uint, TEXT_TAB_END> langtab_start; ///< Offset into langpack offs
};

static LoadedLanguagePack _langpack;

static bool _scan_for_gender_data = false;  ///< Are we scanning for the gender of the current string? (instead of formatting it)


const char *GetStringPtr(StringID string)
{
        switch (GetStringTab(string)) {
                case TEXT_TAB_GAMESCRIPT_START: return GetGameStringPtr(GetStringIndex(string));
                /* 0xD0xx and 0xD4xx IDs have been converted earlier. */
                case TEXT_TAB_OLD_NEWGRF: NOT_REACHED();
                case TEXT_TAB_NEWGRF_START: return GetGRFStringPtr(GetStringIndex(string));
                default: return _langpack.offsets[_langpack.langtab_start[GetStringTab(string)] + GetStringIndex(string)];
        }
}

/**
 * Get a parsed string with most special stringcodes replaced by the string parameters.
 * @param builder     The builder of the string.
 * @param string      The ID of the string to parse.
 * @param args        Arguments for the string.
 * @param case_index  The "case index". This will only be set when FormatString wants to print the string in a different case.
 * @param game_script The string is coming directly from a game script.
 */
void GetStringWithArgs(StringBuilder &builder, StringID string, StringParameters &args, uint case_index, bool game_script)
{
        if (string == 0) {
                GetStringWithArgs(builder, STR_UNDEFINED, args);
                return;
        }

        uint index = GetStringIndex(string);
        StringTab tab = GetStringTab(string);

        switch (tab) {
                case TEXT_TAB_TOWN:
                        if (index >= 0xC0 && !game_script) {
                                try {
                                        GetSpecialTownNameString(builder, index - 0xC0, args.GetNextParameter<uint32_t>());
                                } catch (const std::runtime_error &e) {
                                        Debug(misc, 0, "GetStringWithArgs: {}", e.what());
                                        builder += "(invalid string parameter)";
                                }
                                return;
                        }
                        break;

                case TEXT_TAB_SPECIAL:
                        if (index >= 0xE4 && !game_script) {
                                try {
                                        GetSpecialNameString(builder, index - 0xE4, args);
                                } catch (const std::runtime_error &e) {
                                        Debug(misc, 0, "GetStringWithArgs: {}", e.what());
                                        builder += "(invalid string parameter)";
                                }
                                return;
                        }
                        break;

                case TEXT_TAB_OLD_CUSTOM:
                        /* Old table for custom names. This is no longer used */
                        if (!game_script) {
                                FatalError("Incorrect conversion of custom name string.");
                        }
                        break;

                case TEXT_TAB_GAMESCRIPT_START: {
                        FormatString(builder, GetGameStringPtr(index), args, case_index, true);
                        return;
                }

                case TEXT_TAB_OLD_NEWGRF:
                        NOT_REACHED();

                case TEXT_TAB_NEWGRF_START: {
                        FormatString(builder, GetGRFStringPtr(index), args, case_index);
                        return;
                }

                default:
                        break;
        }

        if (index >= _langpack.langtab_num[tab]) {
                if (game_script) {
                        return GetStringWithArgs(builder, STR_UNDEFINED, args);
                }
                FatalError("String 0x{:X} is invalid. You are probably using an old version of the .lng file.\n", string);
        }

        FormatString(builder, GetStringPtr(string), args, case_index);
}


/**
 * Resolve the given StringID into a std::string with all the associated
 * DParam lookups and formatting.
 * @param string The unique identifier of the translatable string.
 * @return The std::string of the translated string.
 */
std::string GetString(StringID string)
{
        _global_string_params.PrepareForNextRun();
        return GetStringWithArgs(string, _global_string_params);
}

/**
 * Get a parsed string with most special stringcodes replaced by the string parameters.
 * @param string The ID of the string to parse.
 * @param args   Arguments for the string.
 * @return The parsed string.
 */
std::string GetStringWithArgs(StringID string, StringParameters &args)
{
        std::string result;
        StringBuilder builder(result);
        GetStringWithArgs(builder, string, args);
        return result;
}

/**
 * This function is used to "bind" a C string to a OpenTTD dparam slot.
 * @param n slot of the string
 * @param str string to bind
 */
void SetDParamStr(size_t n, const char *str)
{
        _global_string_params.SetParam(n, str);
}

/**
 * This function is used to "bind" the C string of a std::string to a OpenTTD dparam slot.
 * The caller has to ensure that the std::string reference remains valid while the string is shown.
 * @param n slot of the string
 * @param str string to bind
 */
void SetDParamStr(size_t n, const std::string &str)
{
        _global_string_params.SetParam(n, str);
}

/**
 * This function is used to "bind" the std::string to a OpenTTD dparam slot.
 * Contrary to the other \c SetDParamStr functions, this moves the string into
 * the parameter slot.
 * @param n slot of the string
 * @param str string to bind
 */
void SetDParamStr(size_t n, std::string &&str)
{
        _global_string_params.SetParam(n, std::move(str));
}

static const char *GetDecimalSeparator()
{
        const char *decimal_separator = _settings_game.locale.digit_decimal_separator.c_str();
        if (StrEmpty(decimal_separator)) decimal_separator = _langpack.langpack->digit_decimal_separator;
        return decimal_separator;
}

/**
 * Format a number into a string.
 * @param builder   the string builder to write to
 * @param number    the number to write down
 * @param separator the thousands-separator to use
 */
static void FormatNumber(StringBuilder &builder, int64_t number, const char *separator)
{
        static const int max_digits = 20;
        uint64_t divisor = 10000000000000000000ULL;
        int thousands_offset = (max_digits - 1) % 3;

        if (number < 0) {
                builder += '-';
                number = -number;
        }

        uint64_t num = number;
        uint64_t tot = 0;
        for (int i = 0; i < max_digits; i++) {
                uint64_t quot = 0;
                if (num >= divisor) {
                        quot = num / divisor;
                        num = num % divisor;
                }
                if ((tot |= quot) || i == max_digits - 1) {
                        builder += '0' + quot; // quot is a single digit
                        if ((i % 3) == thousands_offset && i < max_digits - 1) builder += separator;
                }

                divisor /= 10;
        }
}

static void FormatCommaNumber(StringBuilder &builder, int64_t number)
{
        const char *separator = _settings_game.locale.digit_group_separator.c_str();
        if (StrEmpty(separator)) separator = _langpack.langpack->digit_group_separator;
        FormatNumber(builder, number, separator);
}

static void FormatNoCommaNumber(StringBuilder &builder, int64_t number)
{
        fmt::format_to(builder, "{}", number);
}

static void FormatZerofillNumber(StringBuilder &builder, int64_t number, int count)
{
        fmt::format_to(builder, "{:0{}d}", number, count);
}

static void FormatHexNumber(StringBuilder &builder, uint64_t number)
{
        fmt::format_to(builder, "0x{:X}", number);
}

/**
 * Format a given number as a number of bytes with the SI prefix.
 * @param builder the string builder to write to
 * @param number  the number of bytes to write down
 */
static void FormatBytes(StringBuilder &builder, int64_t number)
{
        assert(number >= 0);

        /*                                   1   2^10  2^20  2^30  2^40  2^50  2^60 */
        const char * const iec_prefixes[] = {"", "Ki", "Mi", "Gi", "Ti", "Pi", "Ei"};
        uint id = 1;
        while (number >= 1024 * 1024) {
                number /= 1024;
                id++;
        }

        if (number < 1024) {
                id = 0;
                fmt::format_to(builder, "{}", number);
        } else if (number < 1024 * 10) {
                fmt::format_to(builder, "{}{}{:02}", number / 1024, GetDecimalSeparator(), (number % 1024) * 100 / 1024);
        } else if (number < 1024 * 100) {
                fmt::format_to(builder, "{}{}{:01}", number / 1024, GetDecimalSeparator(), (number % 1024) * 10 / 1024);
        } else {
                assert(number < 1024 * 1024);
                fmt::format_to(builder, "{}", number / 1024);
        }

        assert(id < lengthof(iec_prefixes));
        fmt::format_to(builder, NBSP "{}B", iec_prefixes[id]);
}

static void FormatYmdString(StringBuilder &builder, TimerGameCalendar::Date date, uint case_index)
{
        TimerGameCalendar::YearMonthDay ymd = TimerGameCalendar::ConvertDateToYMD(date);

        auto tmp_params = MakeParameters(ymd.day + STR_DAY_NUMBER_1ST - 1, STR_MONTH_ABBREV_JAN + ymd.month, ymd.year);
        FormatString(builder, GetStringPtr(STR_FORMAT_DATE_LONG), tmp_params, case_index);
}

static void FormatMonthAndYear(StringBuilder &builder, TimerGameCalendar::Date date, uint case_index)
{
        TimerGameCalendar::YearMonthDay ymd = TimerGameCalendar::ConvertDateToYMD(date);

        auto tmp_params = MakeParameters(STR_MONTH_JAN + ymd.month, ymd.year);
        FormatString(builder, GetStringPtr(STR_FORMAT_DATE_SHORT), tmp_params, case_index);
}

static void FormatTinyOrISODate(StringBuilder &builder, TimerGameCalendar::Date date, StringID str)
{
        TimerGameCalendar::YearMonthDay ymd = TimerGameCalendar::ConvertDateToYMD(date);

        /* Day and month are zero-padded with ZEROFILL_NUM, hence the two 2s. */
        auto tmp_params = MakeParameters(ymd.day, 2, ymd.month + 1, 2, ymd.year);
        FormatString(builder, GetStringPtr(str), tmp_params);
}

static void FormatGenericCurrency(StringBuilder &builder, const CurrencySpec *spec, Money number, bool compact)
{
        /* We are going to make number absolute for printing, so
         * keep this piece of data as we need it later on */
        bool negative = number < 0;

        number *= spec->rate;

        /* convert from negative */
        if (number < 0) {
                builder.Utf8Encode(SCC_PUSH_COLOUR);
                builder.Utf8Encode(SCC_RED);
                builder += '-';
                number = -number;
        }

        /* Add prefix part, following symbol_pos specification.
         * Here, it can can be either 0 (prefix) or 2 (both prefix and suffix).
         * The only remaining value is 1 (suffix), so everything that is not 1 */
        if (spec->symbol_pos != 1) builder += spec->prefix;

        StringID number_str = STR_NULL;

        /* For huge numbers, compact the number. */
        if (compact) {
                /* Take care of the thousand rounding. Having 1 000 000 k
                 * and 1 000 M is inconsistent, so always use 1 000 M. */
                if (number >= Money(1'000'000'000'000'000) - 500'000'000) {
                        number = (number + Money(500'000'000'000)) / Money(1'000'000'000'000);
                        number_str = STR_CURRENCY_SHORT_TERA;
                } else if (number >= Money(1'000'000'000'000) - 500'000) {
                        number = (number + 500'000'000) / 1'000'000'000;
                        number_str = STR_CURRENCY_SHORT_GIGA;
                } else if (number >= 1'000'000'000 - 500) {
                        number = (number + 500'000) / 1'000'000;
                        number_str = STR_CURRENCY_SHORT_MEGA;
                } else if (number >= 1'000'000) {
                        number = (number + 500) / 1'000;
                        number_str = STR_CURRENCY_SHORT_KILO;
                }
        }

        const char *separator = _settings_game.locale.digit_group_separator_currency.c_str();
        if (StrEmpty(separator)) separator = GetCurrency().separator.c_str();
        if (StrEmpty(separator)) separator = _langpack.langpack->digit_group_separator_currency;
        FormatNumber(builder, number, separator);
        if (number_str != STR_NULL) {
                auto tmp_params = ArrayStringParameters<0>();
                FormatString(builder, GetStringPtr(number_str), tmp_params);
        }

        /* Add suffix part, following symbol_pos specification.
         * Here, it can can be either 1 (suffix) or 2 (both prefix and suffix).
         * The only remaining value is 1 (prefix), so everything that is not 0 */
        if (spec->symbol_pos != 0) builder += spec->suffix;

        if (negative) {
                builder.Utf8Encode(SCC_POP_COLOUR);
        }
}

/**
 * Determine the "plural" index given a plural form and a number.
 * @param count       The number to get the plural index of.
 * @param plural_form The plural form we want an index for.
 * @return The plural index for the given form.
 */
static int DeterminePluralForm(int64_t count, int plural_form)
{
        /* The absolute value determines plurality */
        uint64_t n = abs(count);

        switch (plural_form) {
                default:
                        NOT_REACHED();

                /* Two forms: singular used for one only.
                 * Used in:
                 *   Danish, Dutch, English, German, Norwegian, Swedish, Estonian, Finnish,
                 *   Greek, Hebrew, Italian, Portuguese, Spanish, Esperanto */
                case 0:
                        return n != 1 ? 1 : 0;

                /* Only one form.
                 * Used in:
                 *   Hungarian, Japanese, Turkish */
                case 1:
                        return 0;

                /* Two forms: singular used for 0 and 1.
                 * Used in:
                 *   French, Brazilian Portuguese */
                case 2:
                        return n > 1 ? 1 : 0;

                /* Three forms: special cases for 0, and numbers ending in 1 except when ending in 11.
                 * Note: Cases are out of order for hysterical reasons. '0' is last.
                 * Used in:
                 *   Latvian */
                case 3:
                        return n % 10 == 1 && n % 100 != 11 ? 0 : n != 0 ? 1 : 2;

                /* Five forms: special cases for 1, 2, 3 to 6, and 7 to 10.
                 * Used in:
                 *   Gaelige (Irish) */
                case 4:
                        return n == 1 ? 0 : n == 2 ? 1 : n < 7 ? 2 : n < 11 ? 3 : 4;

                /* Three forms: special cases for numbers ending in 1 except when ending in 11, and 2 to 9 except when ending in 12 to 19.
                 * Used in:
                 *   Lithuanian */
                case 5:
                        return n % 10 == 1 && n % 100 != 11 ? 0 : n % 10 >= 2 && (n % 100 < 10 || n % 100 >= 20) ? 1 : 2;

                /* Three forms: special cases for numbers ending in 1 except when ending in 11, and 2 to 4 except when ending in 12 to 14.
                 * Used in:
                 *   Croatian, Russian, Ukrainian */
                case 6:
                        return n % 10 == 1 && n % 100 != 11 ? 0 : n % 10 >= 2 && n % 10 <= 4 && (n % 100 < 10 || n % 100 >= 20) ? 1 : 2;

                /* Three forms: special cases for 1, and numbers ending in 2 to 4 except when ending in 12 to 14.
                 * Used in:
                 *   Polish */
                case 7:
                        return n == 1 ? 0 : n % 10 >= 2 && n % 10 <= 4 && (n % 100 < 10 || n % 100 >= 20) ? 1 : 2;

                /* Four forms: special cases for numbers ending in 01, 02, and 03 to 04.
                 * Used in:
                 *   Slovenian */
                case 8:
                        return n % 100 == 1 ? 0 : n % 100 == 2 ? 1 : n % 100 == 3 || n % 100 == 4 ? 2 : 3;

                /* Two forms: singular used for numbers ending in 1 except when ending in 11.
                 * Used in:
                 *   Icelandic */
                case 9:
                        return n % 10 == 1 && n % 100 != 11 ? 0 : 1;

                /* Three forms: special cases for 1, and 2 to 4
                 * Used in:
                 *   Czech, Slovak */
                case 10:
                        return n == 1 ? 0 : n >= 2 && n <= 4 ? 1 : 2;

                /* Two forms: cases for numbers ending with a consonant, and with a vowel.
                 * Korean doesn't have the concept of plural, but depending on how a
                 * number is pronounced it needs another version of a particle.
                 * As such the plural system is misused to give this distinction.
                 */
                case 11:
                        switch (n % 10) {
                                case 0: // yeong
                                case 1: // il
                                case 3: // sam
                                case 6: // yuk
                                case 7: // chil
                                case 8: // pal
                                        return 0;

                                case 2: // i
                                case 4: // sa
                                case 5: // o
                                case 9: // gu
                                        return 1;

                                default:
                                        NOT_REACHED();
                        }

                /* Four forms: special cases for 1, 0 and numbers ending in 02 to 10, and numbers ending in 11 to 19.
                 * Used in:
                 *  Maltese */
                case 12:
                        return (n == 1 ? 0 : n == 0 || (n % 100 > 1 && n % 100 < 11) ? 1 : (n % 100 > 10 && n % 100 < 20) ? 2 : 3);
                /* Four forms: special cases for 1 and 11, 2 and 12, 3 .. 10 and 13 .. 19, other
                 * Used in:
                 *  Scottish Gaelic */
                case 13:
                        return ((n == 1 || n == 11) ? 0 : (n == 2 || n == 12) ? 1 : ((n > 2 && n < 11) || (n > 12 && n < 20)) ? 2 : 3);

                /* Three forms: special cases for 1, 0 and numbers ending in 01 to 19.
                 * Used in:
                 *   Romanian */
                case 14:
                        return n == 1 ? 0 : (n == 0 || (n % 100 > 0 && n % 100 < 20)) ? 1 : 2;
        }
}

static const char *ParseStringChoice(const char *b, uint form, StringBuilder &builder)
{
        /* <NUM> {Length of each string} {each string} */
        uint n = (uint8_t)*b++;
        uint pos, i, mypos = 0;

        for (i = pos = 0; i != n; i++) {
                uint len = (uint8_t)*b++;
                if (i == form) mypos = pos;
                pos += len;
        }

        builder += b + mypos;
        return b + pos;
}

/** Helper for unit conversion. */
struct UnitConversion {
        double factor; ///< Amount to multiply or divide upon conversion.

        /**
         * Convert value from OpenTTD's internal unit into the displayed value.
         * @param input The input to convert.
         * @param round Whether to round the value or not.
         * @return The converted value.
         */
        int64_t ToDisplay(int64_t input, bool round = true) const
        {
                return round
                        ? (int64_t)std::round(input * this->factor)
                        : (int64_t)(input * this->factor);
        }

        /**
         * Convert the displayed value back into a value of OpenTTD's internal unit.
         * @param input The input to convert.
         * @param round Whether to round the value up or not.
         * @param divider Divide the return value by this.
         * @return The converted value.
         */
        int64_t FromDisplay(int64_t input, bool round = true, int64_t divider = 1) const
        {
                return round
                        ? (int64_t)std::round(input / this->factor / divider)
                        : (int64_t)(input / this->factor / divider);
        }
};

/** Information about a specific unit system. */
struct Units {
        UnitConversion c; ///< Conversion
        StringID s;       ///< String for the unit
        unsigned int decimal_places; ///< Number of decimal places embedded in the value. For example, 1 if the value is in tenths, and 3 if the value is in thousandths.
};

/** Information about a specific unit system with a long variant. */
struct UnitsLong {
        UnitConversion c; ///< Conversion
        StringID s;       ///< String for the short variant of the unit
        StringID l;       ///< String for the long variant of the unit
        unsigned int decimal_places; ///< Number of decimal places embedded in the value. For example, 1 if the value is in tenths, and 3 if the value is in thousandths.
};

/** Unit conversions for velocity. */
static const Units _units_velocity_calendar[] = {
        { { 1.0      }, STR_UNITS_VELOCITY_IMPERIAL,      0 },
        { { 1.609344 }, STR_UNITS_VELOCITY_METRIC,        0 },
        { { 0.44704  }, STR_UNITS_VELOCITY_SI,            0 },
        { { 0.578125 }, STR_UNITS_VELOCITY_GAMEUNITS_DAY, 1 },
        { { 0.868976 }, STR_UNITS_VELOCITY_KNOTS,         0 },
};

/** Unit conversions for velocity. */
static const Units _units_velocity_realtime[] = {
        { { 1.0      }, STR_UNITS_VELOCITY_IMPERIAL,      0 },
        { { 1.609344 }, STR_UNITS_VELOCITY_METRIC,        0 },
        { { 0.44704  }, STR_UNITS_VELOCITY_SI,            0 },
        { { 0.289352 }, STR_UNITS_VELOCITY_GAMEUNITS_SEC, 1 },
        { { 0.868976 }, STR_UNITS_VELOCITY_KNOTS,         0 },
};

/** Unit conversions for power. */
static const Units _units_power[] = {
        { { 1.0      }, STR_UNITS_POWER_IMPERIAL, 0 },
        { { 1.01387  }, STR_UNITS_POWER_METRIC,   0 },
        { { 0.745699 }, STR_UNITS_POWER_SI,       0 },
};

/** Unit conversions for power to weight. */
static const Units _units_power_to_weight[] = {
        { { 0.907185 }, STR_UNITS_POWER_IMPERIAL_TO_WEIGHT_IMPERIAL, 1 },
        { { 1.0      }, STR_UNITS_POWER_IMPERIAL_TO_WEIGHT_METRIC,   1 },
        { { 1.0      }, STR_UNITS_POWER_IMPERIAL_TO_WEIGHT_SI,       1 },
        { { 0.919768 }, STR_UNITS_POWER_METRIC_TO_WEIGHT_IMPERIAL,   1 },
        { { 1.01387  }, STR_UNITS_POWER_METRIC_TO_WEIGHT_METRIC,     1 },
        { { 1.01387  }, STR_UNITS_POWER_METRIC_TO_WEIGHT_SI,         1 },
        { { 0.676487 }, STR_UNITS_POWER_SI_TO_WEIGHT_IMPERIAL,       1 },
        { { 0.745699 }, STR_UNITS_POWER_SI_TO_WEIGHT_METRIC,         1 },
        { { 0.745699 }, STR_UNITS_POWER_SI_TO_WEIGHT_SI,             1 },
};

/** Unit conversions for weight. */
static const UnitsLong _units_weight[] = {
        { {    1.102311 }, STR_UNITS_WEIGHT_SHORT_IMPERIAL, STR_UNITS_WEIGHT_LONG_IMPERIAL, 0 },
        { {    1.0      }, STR_UNITS_WEIGHT_SHORT_METRIC,   STR_UNITS_WEIGHT_LONG_METRIC,   0 },
        { { 1000.0      }, STR_UNITS_WEIGHT_SHORT_SI,       STR_UNITS_WEIGHT_LONG_SI,       0 },
};

/** Unit conversions for volume. */
static const UnitsLong _units_volume[] = {
        { {  264.172 }, STR_UNITS_VOLUME_SHORT_IMPERIAL, STR_UNITS_VOLUME_LONG_IMPERIAL, 0 },
        { { 1000.0   }, STR_UNITS_VOLUME_SHORT_METRIC,   STR_UNITS_VOLUME_LONG_METRIC,   0 },
        { {    1.0   }, STR_UNITS_VOLUME_SHORT_SI,       STR_UNITS_VOLUME_LONG_SI,       0 },
};

/** Unit conversions for force. */
static const Units _units_force[] = {
        { { 0.224809 }, STR_UNITS_FORCE_IMPERIAL, 0 },
        { { 0.101972 }, STR_UNITS_FORCE_METRIC,   0 },
        { { 0.001    }, STR_UNITS_FORCE_SI,       0 },
};

/** Unit conversions for height. */
static const Units _units_height[] = {
        { { 3.0 }, STR_UNITS_HEIGHT_IMPERIAL, 0 }, // "Wrong" conversion factor for more nicer GUI values
        { { 1.0 }, STR_UNITS_HEIGHT_METRIC,   0 },
        { { 1.0 }, STR_UNITS_HEIGHT_SI,       0 },
};

/** Unit conversions for time in calendar days or wallclock seconds */
static const Units _units_time_days_or_seconds[] = {
        { { 1 }, STR_UNITS_DAYS,    0 },
        { { 2 }, STR_UNITS_SECONDS, 0 },
};

/** Unit conversions for time in calendar months or wallclock minutes */
static const Units _units_time_months_or_minutes[] = {
        { { 1 }, STR_UNITS_MONTHS,  0 },
        { { 1 }, STR_UNITS_MINUTES, 0 },
};

/** Unit conversions for time in calendar years or economic periods */
static const Units _units_time_years_or_periods[] = {
        { { 1 }, STR_UNITS_YEARS,  0 },
        { { 1 }, STR_UNITS_PERIODS, 0 },
};

/** Unit conversions for time in calendar years or wallclock minutes */
static const Units _units_time_years_or_minutes[] = {
        { { 1  }, STR_UNITS_YEARS,  0 },
        { { 12 }, STR_UNITS_MINUTES, 0 },
};

/**
 * Get the correct velocity units depending on the vehicle type and whether we're using real-time units.
 * @param type VehicleType to convert velocity for.
 * @return The Units for the proper vehicle and time mode.
 */
static const Units GetVelocityUnits(VehicleType type)
{
        uint8_t setting = (type == VEH_SHIP || type == VEH_AIRCRAFT) ? _settings_game.locale.units_velocity_nautical : _settings_game.locale.units_velocity;

        assert(setting < lengthof(_units_velocity_calendar));
        assert(setting < lengthof(_units_velocity_realtime));

        if (TimerGameEconomy::UsingWallclockUnits()) return _units_velocity_realtime[setting];

        return _units_velocity_calendar[setting];
}

/**
 * Convert the given (internal) speed to the display speed.
 * @param speed the speed to convert
 * @return the converted speed.
 */
uint ConvertSpeedToDisplaySpeed(uint speed, VehicleType type)
{
        /* For historical reasons we don't want to mess with the
         * conversion for speed. So, don't round it and keep the
         * original conversion factors instead of the real ones. */
        return GetVelocityUnits(type).c.ToDisplay(speed, false);
}

/**
 * Convert the given display speed to the (internal) speed.
 * @param speed the speed to convert
 * @return the converted speed.
 */
uint ConvertDisplaySpeedToSpeed(uint speed, VehicleType type)
{
        return GetVelocityUnits(type).c.FromDisplay(speed);
}

/**
 * Convert the given km/h-ish speed to the display speed.
 * @param speed the speed to convert
 * @return the converted speed.
 */
uint ConvertKmhishSpeedToDisplaySpeed(uint speed, VehicleType type)
{
        return GetVelocityUnits(type).c.ToDisplay(speed * 10, false) / 16;
}

/**
 * Convert the given display speed to the km/h-ish speed.
 * @param speed the speed to convert
 * @return the converted speed.
 */
uint ConvertDisplaySpeedToKmhishSpeed(uint speed, VehicleType type)
{
        return GetVelocityUnits(type).c.FromDisplay(speed * 16, true, 10);
}

/**
 * Parse most format codes within a string and write the result to a buffer.
 * @param builder The string builder to write the final string to.
 * @param str_arg The original string with format codes.
 * @param args    Pointer to extra arguments used by various string codes.
 * @param dry_run True when the args' type data is not yet initialized.
 */
static void FormatString(StringBuilder &builder, const char *str_arg, StringParameters &args, uint case_index, bool game_script, bool dry_run)
{
        size_t orig_offset = args.GetOffset();

        if (!dry_run) {
                /*
                 * This function is normally called with `dry_run` false, then we call this function again
                 * with `dry_run` being true. The dry run is required for the gender formatting. For the
                 * gender determination we need to format a sub string to get the gender, but for that we
                 * need to know as what string control code type the specific parameter is encoded. Since
                 * gendered words can be before the "parameter" words, this needs to be determined before
                 * the actual formatting.
                 */
                std::string buffer;
                StringBuilder dry_run_builder(buffer);
                if (UsingNewGRFTextStack()) {
                        /* Values from the NewGRF text stack are only copied to the normal
                         * argv array at the time they are encountered. That means that if
                         * another string command references a value later in the string it
                         * would fail. We solve that by running FormatString twice. The first
                         * pass makes sure the argv array is correctly filled and the second
                         * pass can reference later values without problems. */
                        struct TextRefStack *backup = CreateTextRefStackBackup();
                        FormatString(dry_run_builder, str_arg, args, case_index, game_script, true);
                        RestoreTextRefStackBackup(backup);
                } else {
                        FormatString(dry_run_builder, str_arg, args, case_index, game_script, true);
                }
                /* We have to restore the original offset here to to read the correct values. */
                args.SetOffset(orig_offset);
        }
        char32_t b = '\0';
        uint next_substr_case_index = 0;
        std::stack<const char *, std::vector<const char *>> str_stack;
        str_stack.push(str_arg);

        for (;;) {
                try {
                        while (!str_stack.empty() && (b = Utf8Consume(&str_stack.top())) == '\0') {
                                str_stack.pop();
                        }
                        if (str_stack.empty()) break;
                        const char *&str = str_stack.top();

                        if (SCC_NEWGRF_FIRST <= b && b <= SCC_NEWGRF_LAST) {
                                /* We need to pass some stuff as it might be modified. */
                                StringParameters remaining = args.GetRemainingParameters();
                                b = RemapNewGRFStringControlCode(b, &str, remaining, dry_run);
                                if (b == 0) continue;
                        }

                        if (b < SCC_CONTROL_START || b > SCC_CONTROL_END) {
                                builder.Utf8Encode(b);
                                continue;
                        }

                        args.SetTypeOfNextParameter(b);
                        switch (b) {
                                case SCC_ENCODED: {
                                        ArrayStringParameters<20> sub_args;

                                        char *p;
                                        uint32_t stringid = std::strtoul(str, &p, 16);
                                        if (*p != ':' && *p != '\0') {
                                                while (*p != '\0') p++;
                                                str = p;
                                                builder += "(invalid SCC_ENCODED)";
                                                break;
                                        }
                                        if (stringid >= TAB_SIZE_GAMESCRIPT) {
                                                while (*p != '\0') p++;
                                                str = p;
                                                builder += "(invalid StringID)";
                                                break;
                                        }

                                        int i = 0;
                                        while (*p != '\0' && i < 20) {
                                                uint64_t param;
                                                const char *s = ++p;

                                                /* Find the next value */
                                                bool instring = false;
                                                bool escape = false;
                                                for (;; p++) {
                                                        if (*p == '\\') {
                                                                escape = true;
                                                                continue;
                                                        }
                                                        if (*p == '"' && escape) {
                                                                escape = false;
                                                                continue;
                                                        }
                                                        escape = false;

                                                        if (*p == '"') {
                                                                instring = !instring;
                                                                continue;
                                                        }
                                                        if (instring) {
                                                                continue;
                                                        }

                                                        if (*p == ':') break;
                                                        if (*p == '\0') break;
                                                }

                                                if (*s != '"') {
                                                        /* Check if we want to look up another string */
                                                        char32_t l;
                                                        size_t len = Utf8Decode(&l, s);
                                                        bool lookup = (l == SCC_ENCODED);
                                                        if (lookup) s += len;

                                                        param = std::strtoull(s, &p, 16);

                                                        if (lookup) {
                                                                if (param >= TAB_SIZE_GAMESCRIPT) {
                                                                        while (*p != '\0') p++;
                                                                        str = p;
                                                                        builder += "(invalid sub-StringID)";
                                                                        break;
                                                                }
                                                                param = MakeStringID(TEXT_TAB_GAMESCRIPT_START, param);
                                                        }

                                                        sub_args.SetParam(i++, param);
                                                } else {
                                                        s++; // skip the leading \"
                                                        sub_args.SetParam(i++, std::string(s, p - s - 1)); // also skip the trailing \".
                                                }
                                        }
                                        /* If we didn't error out, we can actually print the string. */
                                        if (*str != '\0') {
                                                str = p;
                                                GetStringWithArgs(builder, MakeStringID(TEXT_TAB_GAMESCRIPT_START, stringid), sub_args, true);
                                        }
                                        break;
                                }

                                case SCC_NEWGRF_STRINL: {
                                        StringID substr = Utf8Consume(&str);
                                        str_stack.push(GetStringPtr(substr));
                                        break;
                                }

                                case SCC_NEWGRF_PRINT_WORD_STRING_ID: {
                                        StringID substr = args.GetNextParameter<StringID>();
                                        str_stack.push(GetStringPtr(substr));
                                        case_index = next_substr_case_index;
                                        next_substr_case_index = 0;
                                        break;
                                }


                                case SCC_GENDER_LIST: { // {G 0 Der Die Das}
                                        /* First read the meta data from the language file. */
                                        size_t offset = orig_offset + (uint8_t)*str++;
                                        int gender = 0;
                                        if (!dry_run && args.GetTypeAtOffset(offset) != 0) {
                                                /* Now we need to figure out what text to resolve, i.e.
                                                 * what do we need to draw? So get the actual raw string
                                                 * first using the control code to get said string. */
                                                char input[4 + 1];
                                                char *p = input + Utf8Encode(input, args.GetTypeAtOffset(offset));
                                                *p = '\0';

                                                /* The gender is stored at the start of the formatted string. */
                                                bool old_sgd = _scan_for_gender_data;
                                                _scan_for_gender_data = true;
                                                std::string buffer;
                                                StringBuilder tmp_builder(buffer);
                                                StringParameters tmp_params = args.GetRemainingParameters(offset);
                                                FormatString(tmp_builder, input, tmp_params);
                                                _scan_for_gender_data = old_sgd;

                                                /* And determine the string. */
                                                const char *s = buffer.c_str();
                                                char32_t c = Utf8Consume(&s);
                                                /* Does this string have a gender, if so, set it */
                                                if (c == SCC_GENDER_INDEX) gender = (uint8_t)s[0];
                                        }
                                        str = ParseStringChoice(str, gender, builder);
                                        break;
                                }

                                /* This sets up the gender for the string.
                                 * We just ignore this one. It's used in {G 0 Der Die Das} to determine the case. */
                                case SCC_GENDER_INDEX: // {GENDER 0}
                                        if (_scan_for_gender_data) {
                                                builder.Utf8Encode(SCC_GENDER_INDEX);
                                                builder += *str++;
                                        } else {
                                                str++;
                                        }
                                        break;

                                case SCC_PLURAL_LIST: { // {P}
                                        int plural_form = *str++;          // contains the plural form for this string
                                        size_t offset = orig_offset + (uint8_t)*str++;
                                        const uint64_t *v = std::get_if<uint64_t>(&args.GetParam(offset)); // contains the number that determines plural
                                        if (v != nullptr) {
                                                str = ParseStringChoice(str, DeterminePluralForm(static_cast<int64_t>(*v), plural_form), builder);
                                        } else {
                                                builder += "(invalid PLURAL parameter)";
                                        }
                                        break;
                                }

                                case SCC_ARG_INDEX: { // Move argument pointer
                                        args.SetOffset(orig_offset + (uint8_t)*str++);
                                        break;
                                }

                                case SCC_SET_CASE: { // {SET_CASE}
                                        /* This is a pseudo command, it's outputted when someone does {STRING.ack}
                                         * The modifier is added to all subsequent GetStringWithArgs that accept the modifier. */
                                        next_substr_case_index = (uint8_t)*str++;
                                        break;
                                }

                                case SCC_SWITCH_CASE: { // {Used to implement case switching}
                                        /* <0x9E> <NUM CASES> <CASE1> <LEN1> <STRING1> <CASE2> <LEN2> <STRING2> <CASE3> <LEN3> <STRING3> <STRINGDEFAULT>
                                         * Each LEN is printed using 2 bytes in big endian order. */
                                        uint num = (uint8_t)*str++;
                                        while (num) {
                                                if ((uint8_t)str[0] == case_index) {
                                                        /* Found the case, adjust str pointer and continue */
                                                        str += 3;
                                                        break;
                                                }
                                                /* Otherwise skip to the next case */
                                                str += 3 + (str[1] << 8) + str[2];
                                                num--;
                                        }
                                        break;
                                }

                                case SCC_REVISION: // {REV}
                                        builder += _openttd_revision;
                                        break;

                                case SCC_RAW_STRING_POINTER: { // {RAW_STRING}
                                        const char *raw_string = args.GetNextParameterString();
                                        /* raw_string can be nullptr. */
                                        if (raw_string == nullptr) {
                                                builder += "(invalid RAW_STRING parameter)";
                                                break;
                                        }
                                        FormatString(builder, raw_string, args);
                                        break;
                                }

                                case SCC_STRING: {// {STRING}
                                        StringID string_id = args.GetNextParameter<StringID>();
                                        if (game_script && GetStringTab(string_id) != TEXT_TAB_GAMESCRIPT_START) break;
                                        /* It's prohibited for the included string to consume any arguments. */
                                        StringParameters tmp_params(args, game_script ? args.GetDataLeft() : 0);
                                        GetStringWithArgs(builder, string_id, tmp_params, next_substr_case_index, game_script);
                                        next_substr_case_index = 0;
                                        break;
                                }

                                case SCC_STRING1:
                                case SCC_STRING2:
                                case SCC_STRING3:
                                case SCC_STRING4:
                                case SCC_STRING5:
                                case SCC_STRING6:
                                case SCC_STRING7: { // {STRING1..7}
                                        /* Strings that consume arguments */
                                        StringID string_id = args.GetNextParameter<StringID>();
                                        if (game_script && GetStringTab(string_id) != TEXT_TAB_GAMESCRIPT_START) break;
                                        uint size = b - SCC_STRING1 + 1;
                                        if (game_script && size > args.GetDataLeft()) {
                                                builder += "(too many parameters)";
                                        } else {
                                                StringParameters sub_args(args, game_script ? args.GetDataLeft() : size);
                                                GetStringWithArgs(builder, string_id, sub_args, next_substr_case_index, game_script);
                                                args.AdvanceOffset(size);
                                        }
                                        next_substr_case_index = 0;
                                        break;
                                }

                                case SCC_COMMA: // {COMMA}
                                        FormatCommaNumber(builder, args.GetNextParameter<int64_t>());
                                        break;

                                case SCC_DECIMAL: { // {DECIMAL}
                                        int64_t number = args.GetNextParameter<int64_t>();
                                        int digits = args.GetNextParameter<int>();
                                        if (digits == 0) {
                                                FormatCommaNumber(builder, number);
                                                break;
                                        }

                                        int64_t divisor = PowerOfTen(digits);
                                        int64_t fractional = number % divisor;
                                        number /= divisor;
                                        FormatCommaNumber(builder, number);
                                        fmt::format_to(builder, "{}{:0{}d}", GetDecimalSeparator(), fractional, digits);
                                        break;
                                }

                                case SCC_NUM: // {NUM}
                                        FormatNoCommaNumber(builder, args.GetNextParameter<int64_t>());
                                        break;

                                case SCC_ZEROFILL_NUM: { // {ZEROFILL_NUM}
                                        int64_t num = args.GetNextParameter<int64_t>();
                                        FormatZerofillNumber(builder, num, args.GetNextParameter<int>());
                                        break;
                                }

                                case SCC_HEX: // {HEX}
                                        FormatHexNumber(builder, args.GetNextParameter<uint64_t>());
                                        break;

                                case SCC_BYTES: // {BYTES}
                                        FormatBytes(builder, args.GetNextParameter<int64_t>());
                                        break;

                                case SCC_CARGO_TINY: { // {CARGO_TINY}
                                        /* Tiny description of cargotypes. Layout:
                                         * param 1: cargo type
                                         * param 2: cargo count */
                                        CargoID cargo = args.GetNextParameter<CargoID>();
                                        if (cargo >= CargoSpec::GetArraySize()) break;

                                        StringID cargo_str = CargoSpec::Get(cargo)->units_volume;
                                        int64_t amount = 0;
                                        switch (cargo_str) {
                                                case STR_TONS:
                                                        amount = _units_weight[_settings_game.locale.units_weight].c.ToDisplay(args.GetNextParameter<int64_t>());
                                                        break;

                                                case STR_LITERS:
                                                        amount = _units_volume[_settings_game.locale.units_volume].c.ToDisplay(args.GetNextParameter<int64_t>());
                                                        break;

                                                default: {
                                                        amount = args.GetNextParameter<int64_t>();
                                                        break;
                                                }
                                        }

                                        FormatCommaNumber(builder, amount);
                                        break;
                                }

                                case SCC_CARGO_SHORT: { // {CARGO_SHORT}
                                        /* Short description of cargotypes. Layout:
                                         * param 1: cargo type
                                         * param 2: cargo count */
                                        CargoID cargo = args.GetNextParameter<CargoID>();
                                        if (cargo >= CargoSpec::GetArraySize()) break;

                                        StringID cargo_str = CargoSpec::Get(cargo)->units_volume;
                                        switch (cargo_str) {
                                                case STR_TONS: {
                                                        assert(_settings_game.locale.units_weight < lengthof(_units_weight));
                                                        const auto &x = _units_weight[_settings_game.locale.units_weight];
                                                        auto tmp_params = MakeParameters(x.c.ToDisplay(args.GetNextParameter<int64_t>()), x.decimal_places);
                                                        FormatString(builder, GetStringPtr(x.l), tmp_params);
                                                        break;
                                                }

                                                case STR_LITERS: {
                                                        assert(_settings_game.locale.units_volume < lengthof(_units_volume));
                                                        const auto &x = _units_volume[_settings_game.locale.units_volume];
                                                        auto tmp_params = MakeParameters(x.c.ToDisplay(args.GetNextParameter<int64_t>()), x.decimal_places);
                                                        FormatString(builder, GetStringPtr(x.l), tmp_params);
                                                        break;
                                                }

                                                default: {
                                                        auto tmp_params = MakeParameters(args.GetNextParameter<int64_t>());
                                                        GetStringWithArgs(builder, cargo_str, tmp_params);
                                                        break;
                                                }
                                        }
                                        break;
                                }

                                case SCC_CARGO_LONG: { // {CARGO_LONG}
                                        /* First parameter is cargo type, second parameter is cargo count */
                                        CargoID cargo = args.GetNextParameter<CargoID>();
                                        if (IsValidCargoID(cargo) && cargo >= CargoSpec::GetArraySize()) break;

                                        StringID cargo_str = !IsValidCargoID(cargo) ? STR_QUANTITY_N_A : CargoSpec::Get(cargo)->quantifier;
                                        auto tmp_args = MakeParameters(args.GetNextParameter<int64_t>());
                                        GetStringWithArgs(builder, cargo_str, tmp_args);
                                        break;
                                }

                                case SCC_CARGO_LIST: { // {CARGO_LIST}
                                        CargoTypes cmask = args.GetNextParameter<CargoTypes>();
                                        bool first = true;

                                        for (const auto &cs : _sorted_cargo_specs) {
                                                if (!HasBit(cmask, cs->Index())) continue;

                                                if (first) {
                                                        first = false;
                                                } else {
                                                        /* Add a comma if this is not the first item */
                                                        builder += ", ";
                                                }

                                                GetStringWithArgs(builder, cs->name, args, next_substr_case_index, game_script);
                                        }

                                        /* If first is still true then no cargo is accepted */
                                        if (first) GetStringWithArgs(builder, STR_JUST_NOTHING, args, next_substr_case_index, game_script);

                                        next_substr_case_index = 0;
                                        break;
                                }

                                case SCC_CURRENCY_SHORT: // {CURRENCY_SHORT}
                                        FormatGenericCurrency(builder, &GetCurrency(), args.GetNextParameter<int64_t>(), true);
                                        break;

                                case SCC_CURRENCY_LONG: // {CURRENCY_LONG}
                                        FormatGenericCurrency(builder, &GetCurrency(), args.GetNextParameter<int64_t>(), false);
                                        break;

                                case SCC_DATE_TINY: // {DATE_TINY}
                                        FormatTinyOrISODate(builder, args.GetNextParameter<TimerGameCalendar::Date>(), STR_FORMAT_DATE_TINY);
                                        break;

                                case SCC_DATE_SHORT: // {DATE_SHORT}
                                        FormatMonthAndYear(builder, args.GetNextParameter<TimerGameCalendar::Date>(), next_substr_case_index);
                                        next_substr_case_index = 0;
                                        break;

                                case SCC_DATE_LONG: // {DATE_LONG}
                                        FormatYmdString(builder, args.GetNextParameter<TimerGameCalendar::Date>(), next_substr_case_index);
                                        next_substr_case_index = 0;
                                        break;

                                case SCC_DATE_ISO: // {DATE_ISO}
                                        FormatTinyOrISODate(builder, args.GetNextParameter<TimerGameCalendar::Date>(), STR_FORMAT_DATE_ISO);
                                        break;

                                case SCC_FORCE: { // {FORCE}
                                        assert(_settings_game.locale.units_force < lengthof(_units_force));
                                        const auto &x = _units_force[_settings_game.locale.units_force];
                                        auto tmp_params = MakeParameters(x.c.ToDisplay(args.GetNextParameter<int64_t>()), x.decimal_places);
                                        FormatString(builder, GetStringPtr(x.s), tmp_params);
                                        break;
                                }

                                case SCC_HEIGHT: { // {HEIGHT}
                                        assert(_settings_game.locale.units_height < lengthof(_units_height));
                                        const auto &x = _units_height[_settings_game.locale.units_height];
                                        auto tmp_params = MakeParameters(x.c.ToDisplay(args.GetNextParameter<int64_t>()), x.decimal_places);
                                        FormatString(builder, GetStringPtr(x.s), tmp_params);
                                        break;
                                }

                                case SCC_POWER: { // {POWER}
                                        assert(_settings_game.locale.units_power < lengthof(_units_power));
                                        const auto &x = _units_power[_settings_game.locale.units_power];
                                        auto tmp_params = MakeParameters(x.c.ToDisplay(args.GetNextParameter<int64_t>()), x.decimal_places);
                                        FormatString(builder, GetStringPtr(x.s), tmp_params);
                                        break;
                                }

                                case SCC_POWER_TO_WEIGHT: { // {POWER_TO_WEIGHT}
                                        auto setting = _settings_game.locale.units_power * 3u + _settings_game.locale.units_weight;
                                        assert(setting < lengthof(_units_power_to_weight));
                                        const auto &x = _units_power_to_weight[setting];
                                        auto tmp_params = MakeParameters(x.c.ToDisplay(args.GetNextParameter<int64_t>()), x.decimal_places);
                                        FormatString(builder, GetStringPtr(x.s), tmp_params);
                                        break;
                                }

                                case SCC_VELOCITY: { // {VELOCITY}
                                        int64_t arg = args.GetNextParameter<int64_t>();
                                        // Unpack vehicle type from packed argument to get desired units.
                                        VehicleType vt = static_cast<VehicleType>(GB(arg, 56, 8));
                                        const auto &x = GetVelocityUnits(vt);
                                        auto tmp_params = MakeParameters(ConvertKmhishSpeedToDisplaySpeed(GB(arg, 0, 56), vt), x.decimal_places);
                                        FormatString(builder, GetStringPtr(x.s), tmp_params);
                                        break;
                                }

                                case SCC_VOLUME_SHORT: { // {VOLUME_SHORT}
                                        assert(_settings_game.locale.units_volume < lengthof(_units_volume));
                                        const auto &x = _units_volume[_settings_game.locale.units_volume];
                                        auto tmp_params = MakeParameters(x.c.ToDisplay(args.GetNextParameter<int64_t>()), x.decimal_places);
                                        FormatString(builder, GetStringPtr(x.s), tmp_params);
                                        break;
                                }

                                case SCC_VOLUME_LONG: { // {VOLUME_LONG}
                                        assert(_settings_game.locale.units_volume < lengthof(_units_volume));
                                        const auto &x = _units_volume[_settings_game.locale.units_volume];
                                        auto tmp_params = MakeParameters(x.c.ToDisplay(args.GetNextParameter<int64_t>()), x.decimal_places);
                                        FormatString(builder, GetStringPtr(x.l), tmp_params);
                                        break;
                                }

                                case SCC_WEIGHT_SHORT: { // {WEIGHT_SHORT}
                                        assert(_settings_game.locale.units_weight < lengthof(_units_weight));
                                        const auto &x = _units_weight[_settings_game.locale.units_weight];
                                        auto tmp_params = MakeParameters(x.c.ToDisplay(args.GetNextParameter<int64_t>()), x.decimal_places);
                                        FormatString(builder, GetStringPtr(x.s), tmp_params);
                                        break;
                                }

                                case SCC_WEIGHT_LONG: { // {WEIGHT_LONG}
                                        assert(_settings_game.locale.units_weight < lengthof(_units_weight));
                                        const auto &x = _units_weight[_settings_game.locale.units_weight];
                                        auto tmp_params = MakeParameters(x.c.ToDisplay(args.GetNextParameter<int64_t>()), x.decimal_places);
                                        FormatString(builder, GetStringPtr(x.l), tmp_params);
                                        break;
                                }

                                case SCC_UNITS_DAYS_OR_SECONDS: { // {UNITS_DAYS_OR_SECONDS}
                                        uint8_t realtime = TimerGameEconomy::UsingWallclockUnits(_game_mode == GM_MENU);
                                        const auto &x = _units_time_days_or_seconds[realtime];
                                        auto tmp_params = MakeParameters(x.c.ToDisplay(args.GetNextParameter<int64_t>()), x.decimal_places);
                                        FormatString(builder, GetStringPtr(x.s), tmp_params);
                                        break;
                                }

                                case SCC_UNITS_MONTHS_OR_MINUTES: { // {UNITS_MONTHS_OR_MINUTES}
                                        uint8_t realtime = TimerGameEconomy::UsingWallclockUnits(_game_mode == GM_MENU);
                                        const auto &x = _units_time_months_or_minutes[realtime];
                                        auto tmp_params = MakeParameters(x.c.ToDisplay(args.GetNextParameter<int64_t>()), x.decimal_places);
                                        FormatString(builder, GetStringPtr(x.s), tmp_params);
                                        break;
                                }

                                case SCC_UNITS_YEARS_OR_PERIODS: { // {UNITS_YEARS_OR_PERIODS}
                                        uint8_t realtime = TimerGameEconomy::UsingWallclockUnits(_game_mode == GM_MENU);
                                        const auto &x = _units_time_years_or_periods[realtime];
                                        auto tmp_params = MakeParameters(x.c.ToDisplay(args.GetNextParameter<int64_t>()), x.decimal_places);
                                        FormatString(builder, GetStringPtr(x.s), tmp_params);
                                        break;
                                }

                                case SCC_UNITS_YEARS_OR_MINUTES: { // {UNITS_YEARS_OR_MINUTES}
                                        uint8_t realtime = TimerGameEconomy::UsingWallclockUnits(_game_mode == GM_MENU);
                                        const auto &x = _units_time_years_or_minutes[realtime];
                                        auto tmp_params = MakeParameters(x.c.ToDisplay(args.GetNextParameter<int64_t>()), x.decimal_places);
                                        FormatString(builder, GetStringPtr(x.s), tmp_params);
                                        break;
                                }

                                case SCC_COMPANY_NAME: { // {COMPANY}
                                        const Company *c = Company::GetIfValid(args.GetNextParameter<CompanyID>());
                                        if (c == nullptr) break;

                                        if (!c->name.empty()) {
                                                auto tmp_params = MakeParameters(c->name);
                                                GetStringWithArgs(builder, STR_JUST_RAW_STRING, tmp_params);
                                        } else {
                                                auto tmp_params = MakeParameters(c->name_2);
                                                GetStringWithArgs(builder, c->name_1, tmp_params);
                                        }
                                        break;
                                }

                                case SCC_COMPANY_NUM: { // {COMPANY_NUM}
                                        CompanyID company = args.GetNextParameter<CompanyID>();

                                        /* Nothing is added for AI or inactive companies */
                                        if (Company::IsValidHumanID(company)) {
                                                auto tmp_params = MakeParameters(company + 1);
                                                GetStringWithArgs(builder, STR_FORMAT_COMPANY_NUM, tmp_params);
                                        }
                                        break;
                                }

                                case SCC_DEPOT_NAME: { // {DEPOT}
                                        VehicleType vt = args.GetNextParameter<VehicleType>();
                                        if (vt == VEH_AIRCRAFT) {
                                                auto tmp_params = MakeParameters(args.GetNextParameter<StationID>());
                                                GetStringWithArgs(builder, STR_FORMAT_DEPOT_NAME_AIRCRAFT, tmp_params);
                                                break;
                                        }

                                        const Depot *d = Depot::Get(args.GetNextParameter<DepotID>());
                                        if (!d->name.empty()) {
                                                auto tmp_params = MakeParameters(d->name);
                                                GetStringWithArgs(builder, STR_JUST_RAW_STRING, tmp_params);
                                        } else {
                                                auto tmp_params = MakeParameters(d->town->index, d->town_cn + 1);
                                                GetStringWithArgs(builder, STR_FORMAT_DEPOT_NAME_TRAIN + 2 * vt + (d->town_cn == 0 ? 0 : 1), tmp_params);
                                        }
                                        break;
                                }

                                case SCC_ENGINE_NAME: { // {ENGINE}
                                        int64_t arg = args.GetNextParameter<int64_t>();
                                        const Engine *e = Engine::GetIfValid(static_cast<EngineID>(arg));
                                        if (e == nullptr) break;

                                        if (!e->name.empty() && e->IsEnabled()) {
                                                auto tmp_params = MakeParameters(e->name);
                                                GetStringWithArgs(builder, STR_JUST_RAW_STRING, tmp_params);
                                                break;
                                        }

                                        if (HasBit(e->info.callback_mask, CBM_VEHICLE_NAME)) {
                                                uint16_t callback = GetVehicleCallback(CBID_VEHICLE_NAME, static_cast<uint32_t>(arg >> 32), 0, e->index, nullptr);
                                                /* Not calling ErrorUnknownCallbackResult due to being inside string processing. */
                                                if (callback != CALLBACK_FAILED && callback < 0x400) {
                                                        const GRFFile *grffile = e->GetGRF();
                                                        assert(grffile != nullptr);

                                                        StartTextRefStackUsage(grffile, 6);
                                                        ArrayStringParameters<6> tmp_params;
                                                        GetStringWithArgs(builder, GetGRFStringID(grffile->grfid, 0xD000 + callback), tmp_params);
                                                        StopTextRefStackUsage();

                                                        break;
                                                }
                                        }

                                        auto tmp_params = ArrayStringParameters<0>();
                                        GetStringWithArgs(builder, e->info.string_id, tmp_params);
                                        break;
                                }

                                case SCC_GROUP_NAME: { // {GROUP}
                                        const Group *g = Group::GetIfValid(args.GetNextParameter<GroupID>());
                                        if (g == nullptr) break;

                                        if (!g->name.empty()) {
                                                auto tmp_params = MakeParameters(g->name);
                                                GetStringWithArgs(builder, STR_JUST_RAW_STRING, tmp_params);
                                        } else {
                                                auto tmp_params = MakeParameters(g->number);
                                                GetStringWithArgs(builder, STR_FORMAT_GROUP_NAME, tmp_params);
                                        }
                                        break;
                                }

                                case SCC_INDUSTRY_NAME: { // {INDUSTRY}
                                        const Industry *i = Industry::GetIfValid(args.GetNextParameter<IndustryID>());
                                        if (i == nullptr) break;

                                        static bool use_cache = true;
                                        if (_scan_for_gender_data) {
                                                /* Gender is defined by the industry type.
                                                 * STR_FORMAT_INDUSTRY_NAME may have the town first, so it would result in the gender of the town name */
                                                auto tmp_params = ArrayStringParameters<0>();
                                                FormatString(builder, GetStringPtr(GetIndustrySpec(i->type)->name), tmp_params, next_substr_case_index);
                                        } else if (use_cache) { // Use cached version if first call
                                                AutoRestoreBackup cache_backup(use_cache, false);
                                                builder += i->GetCachedName();
                                        } else {
                                                /* First print the town name and the industry type name. */
                                                auto tmp_params = MakeParameters(i->town->index, GetIndustrySpec(i->type)->name);
                                                FormatString(builder, GetStringPtr(STR_FORMAT_INDUSTRY_NAME), tmp_params, next_substr_case_index);
                                        }
                                        next_substr_case_index = 0;
                                        break;
                                }

                                case SCC_PRESIDENT_NAME: { // {PRESIDENT_NAME}
                                        const Company *c = Company::GetIfValid(args.GetNextParameter<CompanyID>());
                                        if (c == nullptr) break;

                                        if (!c->president_name.empty()) {
                                                auto tmp_params = MakeParameters(c->president_name);
                                                GetStringWithArgs(builder, STR_JUST_RAW_STRING, tmp_params);
                                        } else {
                                                auto tmp_params = MakeParameters(c->president_name_2);
                                                GetStringWithArgs(builder, c->president_name_1, tmp_params);
                                        }
                                        break;
                                }

                                case SCC_STATION_NAME: { // {STATION}
                                        StationID sid = args.GetNextParameter<StationID>();
                                        const Station *st = Station::GetIfValid(sid);

                                        if (st == nullptr) {
                                                /* The station doesn't exist anymore. The only place where we might
                                                 * be "drawing" an invalid station is in the case of cargo that is
                                                 * in transit. */
                                                auto tmp_params = ArrayStringParameters<0>();
                                                GetStringWithArgs(builder, STR_UNKNOWN_STATION, tmp_params);
                                                break;
                                        }

                                        static bool use_cache = true;
                                        if (use_cache) { // Use cached version if first call
                                                AutoRestoreBackup cache_backup(use_cache, false);
                                                builder += st->GetCachedName();
                                        } else if (!st->name.empty()) {
                                                auto tmp_params = MakeParameters(st->name);
                                                GetStringWithArgs(builder, STR_JUST_RAW_STRING, tmp_params);
                                        } else {
                                                StringID string_id = st->string_id;
                                                if (st->indtype != IT_INVALID) {
                                                        /* Special case where the industry provides the name for the station */
                                                        const IndustrySpec *indsp = GetIndustrySpec(st->indtype);

                                                        /* Industry GRFs can change which might remove the station name and
                                                         * thus cause very strange things. Here we check for that before we
                                                         * actually set the station name. */
                                                        if (indsp->station_name != STR_NULL && indsp->station_name != STR_UNDEFINED) {
                                                                string_id = indsp->station_name;
                                                        }
                                                }

                                                auto tmp_params = MakeParameters(STR_TOWN_NAME, st->town->index, st->index);
                                                GetStringWithArgs(builder, string_id, tmp_params);
                                        }
                                        break;
                                }

                                case SCC_TOWN_NAME: { // {TOWN}
                                        const Town *t = Town::GetIfValid(args.GetNextParameter<TownID>());
                                        if (t == nullptr) break;

                                        static bool use_cache = true;
                                        if (use_cache) { // Use cached version if first call
                                                AutoRestoreBackup cache_backup(use_cache, false);
                                                builder += t->GetCachedName();
                                        } else if (!t->name.empty()) {
                                                auto tmp_params = MakeParameters(t->name);
                                                GetStringWithArgs(builder, STR_JUST_RAW_STRING, tmp_params);
                                        } else {
                                                GetTownName(builder, t);
                                        }
                                        break;
                                }

                                case SCC_WAYPOINT_NAME: { // {WAYPOINT}
                                        Waypoint *wp = Waypoint::GetIfValid(args.GetNextParameter<StationID>());
                                        if (wp == nullptr) break;

                                        if (!wp->name.empty()) {
                                                auto tmp_params = MakeParameters(wp->name);
                                                GetStringWithArgs(builder, STR_JUST_RAW_STRING, tmp_params);
                                        } else {
                                                auto tmp_params = MakeParameters(wp->town->index, wp->town_cn + 1);
                                                StringID string_id = ((wp->string_id == STR_SV_STNAME_BUOY) ? STR_FORMAT_BUOY_NAME : STR_FORMAT_WAYPOINT_NAME);
                                                if (wp->town_cn != 0) string_id++;
                                                GetStringWithArgs(builder, string_id, tmp_params);
                                        }
                                        break;
                                }

                                case SCC_VEHICLE_NAME: { // {VEHICLE}
                                        const Vehicle *v = Vehicle::GetIfValid(args.GetNextParameter<VehicleID>());
                                        if (v == nullptr) break;

                                        if (!v->name.empty()) {
                                                auto tmp_params = MakeParameters(v->name);
                                                GetStringWithArgs(builder, STR_JUST_RAW_STRING, tmp_params);
                                        } else if (v->group_id != DEFAULT_GROUP) {
                                                /* The vehicle has no name, but is member of a group, so print group name */
                                                auto tmp_params = MakeParameters(v->group_id, v->unitnumber);
                                                GetStringWithArgs(builder, STR_FORMAT_GROUP_VEHICLE_NAME, tmp_params);
                                        } else {
                                                auto tmp_params = MakeParameters(v->unitnumber);

                                                StringID string_id;
                                                switch (v->type) {
                                                        default:           string_id = STR_INVALID_VEHICLE; break;
                                                        case VEH_TRAIN:    string_id = STR_SV_TRAIN_NAME; break;
                                                        case VEH_ROAD:     string_id = STR_SV_ROAD_VEHICLE_NAME; break;
                                                        case VEH_SHIP:     string_id = STR_SV_SHIP_NAME; break;
                                                        case VEH_AIRCRAFT: string_id = STR_SV_AIRCRAFT_NAME; break;
                                                }

                                                GetStringWithArgs(builder, string_id, tmp_params);
                                        }
                                        break;
                                }

                                case SCC_SIGN_NAME: { // {SIGN}
                                        const Sign *si = Sign::GetIfValid(args.GetNextParameter<SignID>());
                                        if (si == nullptr) break;

                                        if (!si->name.empty()) {
                                                auto tmp_params = MakeParameters(si->name);
                                                GetStringWithArgs(builder, STR_JUST_RAW_STRING, tmp_params);
                                        } else {
                                                auto tmp_params = ArrayStringParameters<0>();
                                                GetStringWithArgs(builder, STR_DEFAULT_SIGN_NAME, tmp_params);
                                        }
                                        break;
                                }

                                case SCC_STATION_FEATURES: { // {STATIONFEATURES}
                                        StationGetSpecialString(builder, args.GetNextParameter<StationFacility>());
                                        break;
                                }

                                case SCC_COLOUR: { // {COLOUR}
                                        StringControlCode scc = (StringControlCode)(SCC_BLUE + args.GetNextParameter<Colours>());
                                        if (IsInsideMM(scc, SCC_BLUE, SCC_COLOUR)) builder.Utf8Encode(scc);
                                        break;
                                }

                                default:
                                        builder.Utf8Encode(b);
                                        break;
                        }
                } catch (std::out_of_range &e) {
                        Debug(misc, 0, "FormatString: {}", e.what());
                        builder += "(invalid parameter)";
                }
        }
}


static void StationGetSpecialString(StringBuilder &builder, StationFacility x)
{
        if ((x & FACIL_TRAIN) != 0) builder.Utf8Encode(SCC_TRAIN);
        if ((x & FACIL_TRUCK_STOP) != 0) builder.Utf8Encode(SCC_LORRY);
        if ((x & FACIL_BUS_STOP) != 0) builder.Utf8Encode(SCC_BUS);
        if ((x & FACIL_DOCK) != 0) builder.Utf8Encode(SCC_SHIP);
        if ((x & FACIL_AIRPORT) != 0) builder.Utf8Encode(SCC_PLANE);
}

static void GetSpecialTownNameString(StringBuilder &builder, int ind, uint32_t seed)
{
        GenerateTownNameString(builder, ind, seed);
}

static const char * const _silly_company_names[] = {
        "Bloggs Brothers",
        "Tiny Transport Ltd.",
        "Express Travel",
        "Comfy-Coach & Co.",
        "Crush & Bump Ltd.",
        "Broken & Late Ltd.",
        "Sam Speedy & Son",
        "Supersonic Travel",
        "Mike's Motors",
        "Lightning International",
        "Pannik & Loozit Ltd.",
        "Inter-City Transport",
        "Getout & Pushit Ltd."
};

static const char * const _surname_list[] = {
        "Adams",
        "Allan",
        "Baker",
        "Bigwig",
        "Black",
        "Bloggs",
        "Brown",
        "Campbell",
        "Gordon",
        "Hamilton",
        "Hawthorn",
        "Higgins",
        "Green",
        "Gribble",
        "Jones",
        "McAlpine",
        "MacDonald",
        "McIntosh",
        "Muir",
        "Murphy",
        "Nelson",
        "O'Donnell",
        "Parker",
        "Phillips",
        "Pilkington",
        "Quigley",
        "Sharkey",
        "Thomson",
        "Watkins"
};

static const char * const _silly_surname_list[] = {
        "Grumpy",
        "Dozy",
        "Speedy",
        "Nosey",
        "Dribble",
        "Mushroom",
        "Cabbage",
        "Sniffle",
        "Fishy",
        "Swindle",
        "Sneaky",
        "Nutkins"
};

static const char _initial_name_letters[] = {
        'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',
        'K', 'L', 'M', 'N', 'P', 'R', 'S', 'T', 'W',
};

static std::span<const char * const> GetSurnameOptions()
{
        if (_settings_game.game_creation.landscape == LT_TOYLAND) return _silly_surname_list;
        return _surname_list;
}

/**
 * Get the surname of the president with the given seed.
 * @param seed The seed the surname was generated from.
 * @return The surname.
 */
static const char *GetSurname(uint32_t seed)
{
        auto surname_options = GetSurnameOptions();
        return surname_options[surname_options.size() * GB(seed, 16, 8) >> 8];
}

static void GenAndCoName(StringBuilder &builder, uint32_t seed)
{
        builder += GetSurname(seed);
        builder += " & Co.";
}

static void GenPresidentName(StringBuilder &builder, uint32_t seed)
{
        builder += _initial_name_letters[std::size(_initial_name_letters) * GB(seed, 0, 8) >> 8];
        builder += ". ";

        /* The second initial is optional. */
        size_t index = (std::size(_initial_name_letters) + 35) * GB(seed, 8, 8) >> 8;
        if (index < std::size(_initial_name_letters)) {
                builder += _initial_name_letters[index];
                builder += ". ";
        }

        builder += GetSurname(seed);
}

static void GetSpecialNameString(StringBuilder &builder, int ind, StringParameters &args)
{
        switch (ind) {
                case 1: // not used
                        builder += _silly_company_names[std::min<size_t>(args.GetNextParameter<uint16_t>(), std::size(_silly_company_names) - 1)];
                        return;

                case 2: // used for Foobar & Co company names
                        GenAndCoName(builder, args.GetNextParameter<uint32_t>());
                        return;

                case 3: // President name
                        GenPresidentName(builder, args.GetNextParameter<uint32_t>());
                        return;
        }

        /* town name? */
        if (IsInsideMM(ind - 6, 0, SPECSTR_TOWNNAME_LAST - SPECSTR_TOWNNAME_START + 1)) {
                GetSpecialTownNameString(builder, ind - 6, args.GetNextParameter<uint32_t>());
                builder += " Transport";
                return;
        }

        NOT_REACHED();
}

/**
 * Check whether the header is a valid header for OpenTTD.
 * @return true iff the header is deemed valid.
 */
bool LanguagePackHeader::IsValid() const
{
        return this->ident        == TO_LE32(LanguagePackHeader::IDENT) &&
               this->version      == TO_LE32(LANGUAGE_PACK_VERSION) &&
               this->plural_form  <  LANGUAGE_MAX_PLURAL &&
               this->text_dir     <= 1 &&
               this->newgrflangid < MAX_LANG &&
               this->num_genders  < MAX_NUM_GENDERS &&
               this->num_cases    < MAX_NUM_CASES &&
               StrValid(this->name) &&
               StrValid(this->own_name) &&
               StrValid(this->isocode) &&
               StrValid(this->digit_group_separator) &&
               StrValid(this->digit_group_separator_currency) &&
               StrValid(this->digit_decimal_separator);
}

/**
 * Check whether a translation is sufficiently finished to offer it to the public.
 */
bool LanguagePackHeader::IsReasonablyFinished() const
{
        /* "Less than 25% missing" is "sufficiently finished". */
        return 4 * this->missing < LANGUAGE_TOTAL_STRINGS;
}

/**
 * Read a particular language.
 * @param lang The metadata about the language.
 * @return Whether the loading went okay or not.
 */
bool ReadLanguagePack(const LanguageMetadata *lang)
{
        /* Current language pack */
        size_t len = 0;
        std::unique_ptr<LanguagePack, LanguagePackDeleter> lang_pack(reinterpret_cast<LanguagePack *>(ReadFileToMem(FS2OTTD(lang->file), len, 1U << 20).release()));
        if (!lang_pack) return false;

        /* End of read data (+ terminating zero added in ReadFileToMem()) */
        const char *end = (char *)lang_pack.get() + len + 1;

        /* We need at least one byte of lang_pack->data */
        if (end <= lang_pack->data || !lang_pack->IsValid()) {
                return false;
        }

        std::array<uint, TEXT_TAB_END> tab_start, tab_num;

        uint count = 0;
        for (uint i = 0; i < TEXT_TAB_END; i++) {
                uint16_t num = FROM_LE16(lang_pack->offsets[i]);
                if (num > TAB_SIZE) return false;

                tab_start[i] = count;
                tab_num[i] = num;
                count += num;
        }

        /* Allocate offsets */
        std::vector<char *> offs(count);

        /* Fill offsets */
        char *s = lang_pack->data;
        len = (uint8_t)*s++;
        for (uint i = 0; i < count; i++) {
                if (s + len >= end) return false;

                if (len >= 0xC0) {
                        len = ((len & 0x3F) << 8) + (uint8_t)*s++;
                        if (s + len >= end) return false;
                }
                offs[i] = s;
                s += len;
                len = (uint8_t)*s;
                *s++ = '\0'; // zero terminate the string
        }

        _langpack.langpack = std::move(lang_pack);
        _langpack.offsets = std::move(offs);
        _langpack.langtab_num = tab_num;
        _langpack.langtab_start = tab_start;

        _current_language = lang;
        _current_text_dir = (TextDirection)_current_language->text_dir;
        _config_language_file = FS2OTTD(_current_language->file.filename());
        SetCurrentGrfLangID(_current_language->newgrflangid);

#ifdef _WIN32
        extern void Win32SetCurrentLocaleName(std::string iso_code);
        Win32SetCurrentLocaleName(_current_language->isocode);
#endif

#ifdef WITH_COCOA
        extern void MacOSSetCurrentLocaleName(const char *iso_code);
        MacOSSetCurrentLocaleName(_current_language->isocode);
#endif

#ifdef WITH_ICU_I18N
        /* Create a collator instance for our current locale. */
        UErrorCode status = U_ZERO_ERROR;
        _current_collator.reset(icu::Collator::createInstance(icu::Locale(_current_language->isocode), status));
        /* Sort number substrings by their numerical value. */
        if (_current_collator) _current_collator->setAttribute(UCOL_NUMERIC_COLLATION, UCOL_ON, status);
        /* Avoid using the collator if it is not correctly set. */
        if (U_FAILURE(status)) {
                _current_collator.reset();
        }
#endif /* WITH_ICU_I18N */

        Layouter::Initialize();

        /* Some lists need to be sorted again after a language change. */
        ReconsiderGameScriptLanguage();
        InitializeSortedCargoSpecs();
        SortIndustryTypes();
        BuildIndustriesLegend();
        BuildContentTypeStringList();
        InvalidateWindowClassesData(WC_BUILD_VEHICLE);      // Build vehicle window.
        InvalidateWindowClassesData(WC_TRAINS_LIST);        // Train group window.
        InvalidateWindowClassesData(WC_ROADVEH_LIST);       // Road vehicle group window.
        InvalidateWindowClassesData(WC_SHIPS_LIST);         // Ship group window.
        InvalidateWindowClassesData(WC_AIRCRAFT_LIST);      // Aircraft group window.
        InvalidateWindowClassesData(WC_INDUSTRY_DIRECTORY); // Industry directory window.
        InvalidateWindowClassesData(WC_STATION_LIST);       // Station list window.

        return true;
}

/* Win32 implementation in win32.cpp.
 * OS X implementation in os/macosx/macos.mm. */
#if !(defined(_WIN32) || defined(__APPLE__))
/**
 * Determine the current charset based on the environment
 * First check some default values, after this one we passed ourselves
 * and if none exist return the value for $LANG
 * @param param environment variable to check conditionally if default ones are not
 *        set. Pass nullptr if you don't want additional checks.
 * @return return string containing current charset, or nullptr if not-determinable
 */
const char *GetCurrentLocale(const char *param)
{
        const char *env;

        env = std::getenv("LANGUAGE");
        if (env != nullptr) return env;

        env = std::getenv("LC_ALL");
        if (env != nullptr) return env;

        if (param != nullptr) {
                env = std::getenv(param);
                if (env != nullptr) return env;
        }

        return std::getenv("LANG");
}
#else
const char *GetCurrentLocale(const char *param);
#endif /* !(defined(_WIN32) || defined(__APPLE__)) */

/**
 * Get the language with the given NewGRF language ID.
 * @param newgrflangid NewGRF languages ID to check.
 * @return The language's metadata, or nullptr if it is not known.
 */
const LanguageMetadata *GetLanguage(uint8_t newgrflangid)
{
        for (const LanguageMetadata &lang : _languages) {
                if (newgrflangid == lang.newgrflangid) return &lang;
        }

        return nullptr;
}

/**
 * Reads the language file header and checks compatibility.
 * @param file the file to read
 * @param hdr  the place to write the header information to
 * @return true if and only if the language file is of a compatible version
 */
static bool GetLanguageFileHeader(const std::string &file, LanguagePackHeader *hdr)
{
        auto f = FileHandle::Open(file, "rb");
        if (!f.has_value()) return false;

        size_t read = fread(hdr, sizeof(*hdr), 1, *f);

        bool ret = read == 1 && hdr->IsValid();

        /* Convert endianness for the windows language ID */
        if (ret) {
                hdr->missing = FROM_LE16(hdr->missing);
                hdr->winlangid = FROM_LE16(hdr->winlangid);
        }
        return ret;
}

/**
 * Search for the languages in the given directory and add them to the #_languages list.
 * @param path the base directory to search in
 */
static void FillLanguageList(const std::string &path)
{
        std::error_code error_code;
        for (const auto &dir_entry : std::filesystem::directory_iterator(OTTD2FS(path), error_code)) {
                if (!dir_entry.is_regular_file()) continue;
                if (dir_entry.path().extension() != ".lng") continue;

                LanguageMetadata lmd;
                lmd.file = dir_entry.path();

                /* Check whether the file is of the correct version */
                if (!GetLanguageFileHeader(FS2OTTD(lmd.file), &lmd)) {
                        Debug(misc, 3, "{} is not a valid language file", FS2OTTD(lmd.file));
                } else if (GetLanguage(lmd.newgrflangid) != nullptr) {
                        Debug(misc, 3, "{}'s language ID is already known", FS2OTTD(lmd.file));
                } else {
                        _languages.push_back(lmd);
                }
        }
        if (error_code) {
                Debug(misc, 9, "Unable to open directory {}: {}", path, error_code.message());
        }
}

/**
 * Make a list of the available language packs. Put the data in
 * #_languages list.
 */
void InitializeLanguagePacks()
{
        for (Searchpath sp : _valid_searchpaths) {
                FillLanguageList(FioGetDirectory(sp, LANG_DIR));
        }
        if (_languages.empty()) UserError("No available language packs (invalid versions?)");

        /* Acquire the locale of the current system */
        const char *lang = GetCurrentLocale("LC_MESSAGES");
        if (lang == nullptr) lang = "en_GB";

        const LanguageMetadata *chosen_language   = nullptr; ///< Matching the language in the configuration file or the current locale
        const LanguageMetadata *language_fallback = nullptr; ///< Using pt_PT for pt_BR locale when pt_BR is not available
        const LanguageMetadata *en_GB_fallback    = _languages.data(); ///< Fallback when no locale-matching language has been found

        /* Find a proper language. */
        for (const LanguageMetadata &lng : _languages) {
                /* We are trying to find a default language. The priority is by
                 * configuration file, local environment and last, if nothing found,
                 * English. */
                if (_config_language_file == FS2OTTD(lng.file.filename())) {
                        chosen_language = &lng;
                        break;
                }

                if (strcmp (lng.isocode, "en_GB") == 0) en_GB_fallback    = &lng;

                /* Only auto-pick finished translations */
                if (!lng.IsReasonablyFinished()) continue;

                if (strncmp(lng.isocode, lang, 5) == 0) chosen_language   = &lng;
                if (strncmp(lng.isocode, lang, 2) == 0) language_fallback = &lng;
        }

        /* We haven't found the language in the config nor the one in the locale.
         * Now we set it to one of the fallback languages */
        if (chosen_language == nullptr) {
                chosen_language = (language_fallback != nullptr) ? language_fallback : en_GB_fallback;
        }

        if (!ReadLanguagePack(chosen_language)) UserError("Can't read language pack '{}'", FS2OTTD(chosen_language->file));
}

/**
 * Get the ISO language code of the currently loaded language.
 * @return the ISO code.
 */
const char *GetCurrentLanguageIsoCode()
{
        return _langpack.langpack->isocode;
}

/**
 * Check whether there are glyphs missing in the current language.
 * @return If glyphs are missing, return \c true, else return \c false.
 */
bool MissingGlyphSearcher::FindMissingGlyphs()
{
        InitFontCache(this->Monospace());

        this->Reset();
        for (auto text = this->NextString(); text.has_value(); text = this->NextString()) {
                auto src = text->cbegin();

                FontSize size = this->DefaultSize();
                FontCache *fc = FontCache::Get(size);
                while (src != text->cend()) {
                        char32_t c = Utf8Consume(src);

                        if (c >= SCC_FIRST_FONT && c <= SCC_LAST_FONT) {
                                size = (FontSize)(c - SCC_FIRST_FONT);
                                fc = FontCache::Get(size);
                        } else if (!IsInsideMM(c, SCC_SPRITE_START, SCC_SPRITE_END) && IsPrintable(c) && !IsTextDirectionChar(c) && fc->MapCharToGlyph(c, false) == 0) {
                                /* The character is printable, but not in the normal font. This is the case we were testing for. */
                                std::string size_name;

                                switch (size) {
                                        case FS_NORMAL: size_name = "medium"; break;
                                        case FS_SMALL: size_name = "small"; break;
                                        case FS_LARGE: size_name = "large"; break;
                                        case FS_MONO: size_name = "mono"; break;
                                        default: NOT_REACHED();
                                }

                                Debug(fontcache, 0, "Font is missing glyphs to display char 0x{:X} in {} font size", (int)c, size_name);
                                return true;
                        }
                }
        }
        return false;
}

/** Helper for searching through the language pack. */
class LanguagePackGlyphSearcher : public MissingGlyphSearcher {
        uint i; ///< Iterator for the primary language tables.
        uint j; ///< Iterator for the secondary language tables.

        void Reset() override
        {
                this->i = 0;
                this->j = 0;
        }

        FontSize DefaultSize() override
        {
                return FS_NORMAL;
        }

        std::optional<std::string_view> NextString() override
        {
                if (this->i >= TEXT_TAB_END) return std::nullopt;

                const char *ret = _langpack.offsets[_langpack.langtab_start[this->i] + this->j];

                this->j++;
                while (this->i < TEXT_TAB_END && this->j >= _langpack.langtab_num[this->i]) {
                        this->i++;
                        this->j = 0;
                }

                return ret;
        }

        bool Monospace() override
        {
                return false;
        }

        void SetFontNames([[maybe_unused]] FontCacheSettings *settings, [[maybe_unused]] const char *font_name, [[maybe_unused]] const void *os_data) override
        {
#if defined(WITH_FREETYPE) || defined(_WIN32) || defined(WITH_COCOA)
                settings->small.font = font_name;
                settings->medium.font = font_name;
                settings->large.font = font_name;

                settings->small.os_handle = os_data;
                settings->medium.os_handle = os_data;
                settings->large.os_handle = os_data;
#endif
        }
};

/**
 * Check whether the currently loaded language pack
 * uses characters that the currently loaded font
 * does not support. If this is the case an error
 * message will be shown in English. The error
 * message will not be localized because that would
 * mean it might use characters that are not in the
 * font, which is the whole reason this check has
 * been added.
 * @param base_font Whether to look at the base font as well.
 * @param searcher  The methods to use to search for strings to check.
 *                  If nullptr the loaded language pack searcher is used.
 */
void CheckForMissingGlyphs(bool base_font, MissingGlyphSearcher *searcher)
{
        static LanguagePackGlyphSearcher pack_searcher;
        if (searcher == nullptr) searcher = &pack_searcher;
        bool bad_font = !base_font || searcher->FindMissingGlyphs();
#if defined(WITH_FREETYPE) || defined(_WIN32) || defined(WITH_COCOA)
        if (bad_font) {
                /* We found an unprintable character... lets try whether we can find
                 * a fallback font that can print the characters in the current language. */
                bool any_font_configured = !_fcsettings.medium.font.empty();
                FontCacheSettings backup = _fcsettings;

                _fcsettings.mono.os_handle = nullptr;
                _fcsettings.medium.os_handle = nullptr;

                bad_font = !SetFallbackFont(&_fcsettings, _langpack.langpack->isocode, _langpack.langpack->winlangid, searcher);

                _fcsettings = backup;

                if (!bad_font && any_font_configured) {
                        /* If the user configured a bad font, and we found a better one,
                         * show that we loaded the better font instead of the configured one.
                         * The colour 'character' might change in the
                         * future, so for safety we just Utf8 Encode it into the string,
                         * which takes exactly three characters, so it replaces the "XXX"
                         * with the colour marker. */
                        static std::string err_str("XXXThe current font is missing some of the characters used in the texts for this language. Using system fallback font instead.");
                        Utf8Encode(err_str.data(), SCC_YELLOW);
                        SetDParamStr(0, err_str);
                        ShowErrorMessage(STR_JUST_RAW_STRING, INVALID_STRING_ID, WL_WARNING);
                }

                if (bad_font && base_font) {
                        /* Our fallback font does miss characters too, so keep the
                         * user chosen font as that is more likely to be any good than
                         * the wild guess we made */
                        InitFontCache(searcher->Monospace());
                }
        }
#endif

        if (bad_font) {
                /* All attempts have failed. Display an error. As we do not want the string to be translated by
                 * the translators, we 'force' it into the binary and 'load' it via a BindCString. To do this
                 * properly we have to set the colour of the string, otherwise we end up with a lot of artifacts.
                 * The colour 'character' might change in the future, so for safety we just Utf8 Encode it into
                 * the string, which takes exactly three characters, so it replaces the "XXX" with the colour marker. */
                static std::string err_str("XXXThe current font is missing some of the characters used in the texts for this language. Read the readme to see how to solve this.");
                Utf8Encode(err_str.data(), SCC_YELLOW);
                SetDParamStr(0, err_str);
                ShowErrorMessage(STR_JUST_RAW_STRING, INVALID_STRING_ID, WL_WARNING);

                /* Reset the font width */
                LoadStringWidthTable(searcher->Monospace());
                return;
        }

        /* Update the font with cache */
        LoadStringWidthTable(searcher->Monospace());

#if !(defined(WITH_ICU_I18N) && defined(WITH_HARFBUZZ)) && !defined(WITH_UNISCRIBE) && !defined(WITH_COCOA)
        /*
         * For right-to-left languages we need the ICU library. If
         * we do not have support for that library we warn the user
         * about it with a message. As we do not want the string to
         * be translated by the translators, we 'force' it into the
         * binary and 'load' it via a BindCString. To do this
         * properly we have to set the colour of the string,
         * otherwise we end up with a lot of artifacts. The colour
         * 'character' might change in the future, so for safety
         * we just Utf8 Encode it into the string, which takes
         * exactly three characters, so it replaces the "XXX" with
         * the colour marker.
         */
        if (_current_text_dir != TD_LTR) {
                static std::string err_str("XXXThis version of OpenTTD does not support right-to-left languages. Recompile with ICU + Harfbuzz enabled.");
                Utf8Encode(err_str.data(), SCC_YELLOW);
                SetDParamStr(0, err_str);
                ShowErrorMessage(STR_JUST_RAW_STRING, INVALID_STRING_ID, WL_ERROR);
        }
#endif /* !(WITH_ICU_I18N && WITH_HARFBUZZ) && !WITH_UNISCRIBE && !WITH_COCOA */
}