Change: Let AI developers edit non-editable AI/Game Script Parameters (#8895)

[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 "strings_func.h"
#include "rev.h"
#include "core/endian_func.hpp"
#include "date_func.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 <stack>

#include "table/strings.h"
#include "table/control_codes.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 */

static uint64 _global_string_params_data[20];     ///< Global array of string parameters. To access, use #SetDParam.
static WChar _global_string_params_type[20];      ///< Type of parameters stored in #_global_string_params
StringParameters _global_string_params(_global_string_params_data, 20, _global_string_params_type);

/** Reset the type array. */
void StringParameters::ClearTypeInformation()
{
        assert(this->type != nullptr);
        MemSetT(this->type, 0, this->num_param);
}


/**
 * Read an int64 from the argument array. The offset is increased
 * so the next time GetInt64 is called the next value is read.
 */
int64 StringParameters::GetInt64(WChar type)
{
        if (this->offset >= this->num_param) {
                Debug(misc, 0, "Trying to read invalid string parameter");
                return 0;
        }
        if (this->type != nullptr) {
                if (this->type[this->offset] != 0 && this->type[this->offset] != type) {
                        Debug(misc, 0, "Trying to read string parameter with wrong type");
                        return 0;
                }
                this->type[this->offset] = type;
        }
        return this->data[this->offset++];
}

/**
 * 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(uint n, uint64 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(uint n, uint count, FontSize size)
{
        uint front = 0;
        uint next = 0;
        GetBroadestDigit(&front, &next, size);
        uint64 val = count > 1 ? front : next;
        for (; count > 1; count--) {
                val = 10 * val + next;
        }
        SetDParam(n, val);
}

/**
 * Copy \a num string parameters from array \a src into the global string parameter array.
 * @param offs Index in the global array to copy the first string parameter to.
 * @param src  Source array of string parameters.
 * @param num  Number of string parameters to copy.
 */
void CopyInDParam(int offs, const uint64 *src, int num)
{
        MemCpyT(_global_string_params.GetPointerToOffset(offs), src, num);
}

/**
 * Copy \a num string parameters from the global string parameter array to the \a dst array.
 * @param dst  Destination array of string parameters.
 * @param offs Index in the global array to copy the first string parameter from.
 * @param num  Number of string parameters to copy.
 */
void CopyOutDParam(uint64 *dst, int offs, int num)
{
        MemCpyT(dst, _global_string_params.GetPointerToOffset(offs), num);
}

/**
 * Copy \a num string parameters from the global string parameter array to the \a dst array.
 * Furthermore clone raw string parameters into \a strings and amend the data in \a dst.
 * @param dst     Destination array of string parameters.
 * @param strings Destination array for clone of the raw strings. Must be of same length as dst. Deallocation left to the caller.
 * @param string  The string used to determine where raw strings are and where there are no raw strings.
 * @param num     Number of string parameters to copy.
 */
void CopyOutDParam(uint64 *dst, const char **strings, StringID string, int num)
{
        char buf[DRAW_STRING_BUFFER];
        GetString(buf, string, lastof(buf));

        MemCpyT(dst, _global_string_params.GetPointerToOffset(0), num);
        for (int i = 0; i < num; i++) {
                if (_global_string_params.HasTypeInformation() && _global_string_params.GetTypeAtOffset(i) == SCC_RAW_STRING_POINTER) {
                        strings[i] = stredup((const char *)(size_t)_global_string_params.GetParam(i));
                        dst[i] = (size_t)strings[i];
                } else {
                        strings[i] = nullptr;
                }
        }
}

static char *StationGetSpecialString(char *buff, int x, const char *last);
static char *GetSpecialTownNameString(char *buff, int ind, uint32 seed, const char *last);
static char *GetSpecialNameString(char *buff, int ind, StringParameters *args, const char *last);

static char *FormatString(char *buff, const char *str, StringParameters *args, const char *last, 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 buffr  Pointer to a string buffer where the formatted string should be written to.
 * @param string
 * @param args   Arguments for the string.
 * @param last   Pointer just past the end of \a buffr.
 * @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.
 * @return       Pointer to the final zero byte of the formatted string.
 */
char *GetStringWithArgs(char *buffr, StringID string, StringParameters *args, const char *last, uint case_index, bool game_script)
{
        if (string == 0) return GetStringWithArgs(buffr, STR_UNDEFINED, args, last);

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

        switch (tab) {
                case TEXT_TAB_TOWN:
                        if (index >= 0xC0 && !game_script) {
                                return GetSpecialTownNameString(buffr, index - 0xC0, args->GetInt32(), last);
                        }
                        break;

                case TEXT_TAB_SPECIAL:
                        if (index >= 0xE4 && !game_script) {
                                return GetSpecialNameString(buffr, index - 0xE4, args, last);
                        }
                        break;

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

                case TEXT_TAB_GAMESCRIPT_START:
                        return FormatString(buffr, GetGameStringPtr(index), args, last, case_index, true);

                case TEXT_TAB_OLD_NEWGRF:
                        NOT_REACHED();

                case TEXT_TAB_NEWGRF_START:
                        return FormatString(buffr, GetGRFStringPtr(index), args, last, case_index);

                default:
                        break;
        }

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

        return FormatString(buffr, GetStringPtr(string), args, last, case_index);
}

char *GetString(char *buffr, StringID string, const char *last)
{
        _global_string_params.ClearTypeInformation();
        _global_string_params.offset = 0;
        return GetStringWithArgs(buffr, string, &_global_string_params, last);
}

/**
 * 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)
{
        char buffer[DRAW_STRING_BUFFER];
        GetString(buffer, string, lastof(buffer));
        return buffer;
}

/**
 * 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(uint n, const char *str)
{
        SetDParam(n, (uint64)(size_t)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(uint n, const std::string &str)
{
        SetDParamStr(n, str.c_str());
}

/**
 * Format a number into a string.
 * @param buff      the buffer to write to
 * @param number    the number to write down
 * @param last      the last element in the buffer
 * @param separator the thousands-separator to use
 * @param zerofill  minimum number of digits to print for the integer part. The number will be filled with zeros at the front if necessary.
 * @param fractional_digits number of fractional digits to display after a decimal separator. The decimal separator is inserted
 *                          in front of the \a fractional_digits last digit of \a number.
 * @return till where we wrote
 */
static char *FormatNumber(char *buff, int64 number, const char *last, const char *separator, int zerofill = 1, int fractional_digits = 0)
{
        static const int max_digits = 20;
        uint64 divisor = 10000000000000000000ULL;
        zerofill += fractional_digits;
        int thousands_offset = (max_digits - fractional_digits - 1) % 3;

        if (number < 0) {
                buff += seprintf(buff, last, "-");
                number = -number;
        }

        uint64 num = number;
        uint64 tot = 0;
        for (int i = 0; i < max_digits; i++) {
                if (i == max_digits - fractional_digits) {
                        const char *decimal_separator = _settings_game.locale.digit_decimal_separator.c_str();
                        if (StrEmpty(decimal_separator)) decimal_separator = _langpack.langpack->digit_decimal_separator;
                        buff += seprintf(buff, last, "%s", decimal_separator);
                }

                uint64 quot = 0;
                if (num >= divisor) {
                        quot = num / divisor;
                        num = num % divisor;
                }
                if ((tot |= quot) || i >= max_digits - zerofill) {
                        buff += seprintf(buff, last, "%i", (int)quot);
                        if ((i % 3) == thousands_offset && i < max_digits - 1 - fractional_digits) buff = strecpy(buff, separator, last);
                }

                divisor /= 10;
        }

        *buff = '\0';

        return buff;
}

static char *FormatCommaNumber(char *buff, int64 number, const char *last, int fractional_digits = 0)
{
        const char *separator = _settings_game.locale.digit_group_separator.c_str();
        if (StrEmpty(separator)) separator = _langpack.langpack->digit_group_separator;
        return FormatNumber(buff, number, last, separator, 1, fractional_digits);
}

static char *FormatNoCommaNumber(char *buff, int64 number, const char *last)
{
        return FormatNumber(buff, number, last, "");
}

static char *FormatZerofillNumber(char *buff, int64 number, int64 count, const char *last)
{
        return FormatNumber(buff, number, last, "", count);
}

static char *FormatHexNumber(char *buff, uint64 number, const char *last)
{
        return buff + seprintf(buff, last, "0x" OTTD_PRINTFHEX64, number);
}

/**
 * Format a given number as a number of bytes with the SI prefix.
 * @param buff   the buffer to write to
 * @param number the number of bytes to write down
 * @param last   the last element in the buffer
 * @return till where we wrote
 */
static char *FormatBytes(char *buff, int64 number, const char *last)
{
        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++;
        }

        const char *decimal_separator = _settings_game.locale.digit_decimal_separator.c_str();
        if (StrEmpty(decimal_separator)) decimal_separator = _langpack.langpack->digit_decimal_separator;

        if (number < 1024) {
                id = 0;
                buff += seprintf(buff, last, "%i", (int)number);
        } else if (number < 1024 * 10) {
                buff += seprintf(buff, last, "%i%s%02i", (int)number / 1024, decimal_separator, (int)(number % 1024) * 100 / 1024);
        } else if (number < 1024 * 100) {
                buff += seprintf(buff, last, "%i%s%01i", (int)number / 1024, decimal_separator, (int)(number % 1024) * 10 / 1024);
        } else {
                assert(number < 1024 * 1024);
                buff += seprintf(buff, last, "%i", (int)number / 1024);
        }

        assert(id < lengthof(iec_prefixes));
        buff += seprintf(buff, last, NBSP "%sB", iec_prefixes[id]);

        return buff;
}

static char *FormatYmdString(char *buff, Date date, const char *last, uint case_index)
{
        YearMonthDay ymd;
        ConvertDateToYMD(date, &ymd);

        int64 args[] = {ymd.day + STR_DAY_NUMBER_1ST - 1, STR_MONTH_ABBREV_JAN + ymd.month, ymd.year};
        StringParameters tmp_params(args);
        return FormatString(buff, GetStringPtr(STR_FORMAT_DATE_LONG), &tmp_params, last, case_index);
}

static char *FormatMonthAndYear(char *buff, Date date, const char *last, uint case_index)
{
        YearMonthDay ymd;
        ConvertDateToYMD(date, &ymd);

        int64 args[] = {STR_MONTH_JAN + ymd.month, ymd.year};
        StringParameters tmp_params(args);
        return FormatString(buff, GetStringPtr(STR_FORMAT_DATE_SHORT), &tmp_params, last, case_index);
}

static char *FormatTinyOrISODate(char *buff, Date date, StringID str, const char *last)
{
        YearMonthDay ymd;
        ConvertDateToYMD(date, &ymd);

        char day[3];
        char month[3];
        /* We want to zero-pad the days and months */
        seprintf(day,   lastof(day),   "%02i", ymd.day);
        seprintf(month, lastof(month), "%02i", ymd.month + 1);

        int64 args[] = {(int64)(size_t)day, (int64)(size_t)month, ymd.year};
        StringParameters tmp_params(args);
        return FormatString(buff, GetStringPtr(str), &tmp_params, last);
}

static char *FormatGenericCurrency(char *buff, const CurrencySpec *spec, Money number, bool compact, const char *last)
{
        /* 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;
        const char *multiplier = "";

        number *= spec->rate;

        /* convert from negative */
        if (number < 0) {
                if (buff + Utf8CharLen(SCC_PUSH_COLOUR) > last) return buff;
                buff += Utf8Encode(buff, SCC_PUSH_COLOUR);
                if (buff + Utf8CharLen(SCC_RED) > last) return buff;
                buff += Utf8Encode(buff, SCC_RED);
                buff = strecpy(buff, "-", last);
                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) buff = strecpy(buff, spec->prefix.c_str(), last);

        /* for huge numbers, compact the number into k or M */
        if (compact) {
                /* Take care of the 'k' rounding. Having 1 000 000 k
                 * and 1 000 M is inconsistent, so always use 1 000 M. */
                if (number >= 1000000000 - 500) {
                        number = (number + 500000) / 1000000;
                        multiplier = NBSP "M";
                } else if (number >= 1000000) {
                        number = (number + 500) / 1000;
                        multiplier = NBSP "k";
                }
        }

        const char *separator = _settings_game.locale.digit_group_separator_currency.c_str();
        if (StrEmpty(separator)) separator = _currency->separator.c_str();
        if (StrEmpty(separator)) separator = _langpack.langpack->digit_group_separator_currency;
        buff = FormatNumber(buff, number, last, separator);
        buff = strecpy(buff, multiplier, last);

        /* 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) buff = strecpy(buff, spec->suffix.c_str(), last);

        if (negative) {
                if (buff + Utf8CharLen(SCC_POP_COLOUR) > last) return buff;
                buff += Utf8Encode(buff, SCC_POP_COLOUR);
                *buff = '\0';
        }

        return buff;
}

/**
 * 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 count, int plural_form)
{
        /* The absolute value determines plurality */
        uint64 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, char **dst, const char *last)
{
        /* <NUM> {Length of each string} {each string} */
        uint n = (byte)*b++;
        uint pos, i, mypos = 0;

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

        *dst += seprintf(*dst, last, "%s", b + mypos);
        return b + pos;
}

/** Helper for unit conversion. */
struct UnitConversion {
        int multiplier; ///< Amount to multiply upon conversion.
        int shift;      ///< Amount to shift 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 ToDisplay(int64 input, bool round = true) const
        {
                return ((input * this->multiplier) + (round && this->shift != 0 ? 1 << (this->shift - 1) : 0)) >> this->shift;
        }

        /**
         * 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 FromDisplay(int64 input, bool round = true, int64 divider = 1) const
        {
                return ((input << this->shift) + (round ? (this->multiplier * divider) - 1 : 0)) / (this->multiplier * 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
};

/** Unit conversions for velocity. */
static const Units _units_velocity[] = {
        { {    1,  0}, STR_UNITS_VELOCITY_IMPERIAL,     0 },
        { {  103,  6}, STR_UNITS_VELOCITY_METRIC,       0 },
        { { 1831, 12}, STR_UNITS_VELOCITY_SI,           0 },
        { {37888, 16}, STR_UNITS_VELOCITY_GAMEUNITS,    1 },
};

/** Unit conversions for velocity. */
static const Units _units_power[] = {
        { {   1,  0}, STR_UNITS_POWER_IMPERIAL, 0 },
        { {4153, 12}, STR_UNITS_POWER_METRIC,   0 },
        { {6109, 13}, STR_UNITS_POWER_SI,       0 },
};

/** Unit conversions for weight. */
static const UnitsLong _units_weight[] = {
        { {4515, 12}, STR_UNITS_WEIGHT_SHORT_IMPERIAL, STR_UNITS_WEIGHT_LONG_IMPERIAL },
        { {   1,  0}, STR_UNITS_WEIGHT_SHORT_METRIC,   STR_UNITS_WEIGHT_LONG_METRIC   },
        { {1000,  0}, STR_UNITS_WEIGHT_SHORT_SI,       STR_UNITS_WEIGHT_LONG_SI       },
};

/** Unit conversions for volume. */
static const UnitsLong _units_volume[] = {
        { {4227,  4}, STR_UNITS_VOLUME_SHORT_IMPERIAL, STR_UNITS_VOLUME_LONG_IMPERIAL },
        { {1000,  0}, STR_UNITS_VOLUME_SHORT_METRIC,   STR_UNITS_VOLUME_LONG_METRIC   },
        { {   1,  0}, STR_UNITS_VOLUME_SHORT_SI,       STR_UNITS_VOLUME_LONG_SI       },
};

/** Unit conversions for force. */
static const Units _units_force[] = {
        { {3597,  4}, STR_UNITS_FORCE_IMPERIAL, 0 },
        { {3263,  5}, STR_UNITS_FORCE_METRIC,   0 },
        { {   1,  0}, 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 },
};

/**
 * Convert the given (internal) speed to the display speed.
 * @param speed the speed to convert
 * @return the converted speed.
 */
uint ConvertSpeedToDisplaySpeed(uint speed)
{
        /* 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 _units_velocity[_settings_game.locale.units_velocity].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)
{
        return _units_velocity[_settings_game.locale.units_velocity].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)
{
        return _units_velocity[_settings_game.locale.units_velocity].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)
{
        return _units_velocity[_settings_game.locale.units_velocity].c.FromDisplay(speed * 16, true, 10);
}
/**
 * Parse most format codes within a string and write the result to a buffer.
 * @param buff    The buffer 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 last    Pointer to just past the end of the buff array.
 * @param dry_run True when the argt array is not yet initialized.
 */
static char *FormatString(char *buff, const char *str_arg, StringParameters *args, const char *last, uint case_index, bool game_script, bool dry_run)
{
        uint orig_offset = args->offset;

        /* When there is no array with types there is no need to do a dry run. */
        if (args->HasTypeInformation() && !dry_run) {
                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(buff, str_arg, args, last, case_index, game_script, true);
                        RestoreTextRefStackBackup(backup);
                } else {
                        FormatString(buff, str_arg, args, last, case_index, game_script, true);
                }
                /* We have to restore the original offset here to to read the correct values. */
                args->offset = orig_offset;
        }
        WChar b = '\0';
        uint next_substr_case_index = 0;
        char *buf_start = buff;
        std::stack<const char *, std::vector<const char *>> str_stack;
        str_stack.push(str_arg);

        for (;;) {
                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. */
                        //todo: should argve be passed here too?
                        b = RemapNewGRFStringControlCode(b, buf_start, &buff, &str, (int64 *)args->GetDataPointer(), args->GetDataLeft(), dry_run);
                        if (b == 0) continue;
                }

                switch (b) {
                        case SCC_ENCODED: {
                                uint64 sub_args_data[20];
                                WChar sub_args_type[20];
                                bool sub_args_need_free[20];
                                StringParameters sub_args(sub_args_data, 20, sub_args_type);

                                sub_args.ClearTypeInformation();
                                memset(sub_args_need_free, 0, sizeof(sub_args_need_free));

                                char *p;
                                uint32 stringid = strtoul(str, &p, 16);
                                if (*p != ':' && *p != '\0') {
                                        while (*p != '\0') p++;
                                        str = p;
                                        buff = strecat(buff, "(invalid SCC_ENCODED)", last);
                                        break;
                                }
                                if (stringid >= TAB_SIZE_GAMESCRIPT) {
                                        while (*p != '\0') p++;
                                        str = p;
                                        buff = strecat(buff, "(invalid StringID)", last);
                                        break;
                                }

                                int i = 0;
                                while (*p != '\0' && i < 20) {
                                        uint64 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 */
                                                WChar l;
                                                size_t len = Utf8Decode(&l, s);
                                                bool lookup = (l == SCC_ENCODED);
                                                if (lookup) s += len;

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

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

                                                sub_args.SetParam(i++, param);
                                        } else {
                                                char *g = stredup(s);
                                                g[p - s] = '\0';

                                                sub_args_need_free[i] = true;
                                                sub_args.SetParam(i++, (uint64)(size_t)g);
                                        }
                                }
                                /* If we didn't error out, we can actually print the string. */
                                if (*str != '\0') {
                                        str = p;
                                        buff = GetStringWithArgs(buff, MakeStringID(TEXT_TAB_GAMESCRIPT_START, stringid), &sub_args, last, true);
                                }

                                for (int i = 0; i < 20; i++) {
                                        if (sub_args_need_free[i]) free((void *)sub_args.GetParam(i));
                                }
                                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->GetInt32(SCC_NEWGRF_PRINT_WORD_STRING_ID);
                                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. */
                                uint offset = orig_offset + (byte)*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';

                                        /* Now do the string formatting. */
                                        char buf[256];
                                        bool old_sgd = _scan_for_gender_data;
                                        _scan_for_gender_data = true;
                                        StringParameters tmp_params(args->GetPointerToOffset(offset), args->num_param - offset, nullptr);
                                        p = FormatString(buf, input, &tmp_params, lastof(buf));
                                        _scan_for_gender_data = old_sgd;
                                        *p = '\0';

                                        /* And determine the string. */
                                        const char *s = buf;
                                        WChar c = Utf8Consume(&s);
                                        /* Does this string have a gender, if so, set it */
                                        if (c == SCC_GENDER_INDEX) gender = (byte)s[0];
                                }
                                str = ParseStringChoice(str, gender, &buff, last);
                                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) {
                                        buff += Utf8Encode(buff, SCC_GENDER_INDEX);
                                        *buff++ = *str++;
                                } else {
                                        str++;
                                }
                                break;

                        case SCC_PLURAL_LIST: { // {P}
                                int plural_form = *str++;          // contains the plural form for this string
                                uint offset = orig_offset + (byte)*str++;
                                int64 v = *args->GetPointerToOffset(offset); // contains the number that determines plural
                                str = ParseStringChoice(str, DeterminePluralForm(v, plural_form), &buff, last);
                                break;
                        }

                        case SCC_ARG_INDEX: { // Move argument pointer
                                args->offset = orig_offset + (byte)*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 = (byte)*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 = (byte)*str++;
                                while (num) {
                                        if ((byte)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}
                                buff = strecpy(buff, _openttd_revision, last);
                                break;

                        case SCC_RAW_STRING_POINTER: { // {RAW_STRING}
                                if (game_script) break;
                                const char *str = (const char *)(size_t)args->GetInt64(SCC_RAW_STRING_POINTER);
                                buff = FormatString(buff, str, args, last);
                                break;
                        }

                        case SCC_STRING: {// {STRING}
                                StringID str = args->GetInt32(SCC_STRING);
                                if (game_script && GetStringTab(str) != TEXT_TAB_GAMESCRIPT_START) break;
                                /* WARNING. It's prohibited for the included string to consume any arguments.
                                 * For included strings that consume argument, you should use STRING1, STRING2 etc.
                                 * To debug stuff you can set argv to nullptr and it will tell you */
                                StringParameters tmp_params(args->GetDataPointer(), args->GetDataLeft(), nullptr);
                                buff = GetStringWithArgs(buff, str, &tmp_params, last, 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 str = args->GetInt32(b);
                                if (game_script && GetStringTab(str) != TEXT_TAB_GAMESCRIPT_START) break;
                                uint size = b - SCC_STRING1 + 1;
                                if (game_script && size > args->GetDataLeft()) {
                                        buff = strecat(buff, "(too many parameters)", last);
                                } else {
                                        StringParameters sub_args(*args, size);
                                        buff = GetStringWithArgs(buff, str, &sub_args, last, next_substr_case_index, game_script);
                                }
                                next_substr_case_index = 0;
                                break;
                        }

                        case SCC_COMMA: // {COMMA}
                                buff = FormatCommaNumber(buff, args->GetInt64(SCC_COMMA), last);
                                break;

                        case SCC_DECIMAL: {// {DECIMAL}
                                int64 number = args->GetInt64(SCC_DECIMAL);
                                int digits = args->GetInt32(SCC_DECIMAL);
                                buff = FormatCommaNumber(buff, number, last, digits);
                                break;
                        }

                        case SCC_NUM: // {NUM}
                                buff = FormatNoCommaNumber(buff, args->GetInt64(SCC_NUM), last);
                                break;

                        case SCC_ZEROFILL_NUM: { // {ZEROFILL_NUM}
                                int64 num = args->GetInt64();
                                buff = FormatZerofillNumber(buff, num, args->GetInt64(), last);
                                break;
                        }

                        case SCC_HEX: // {HEX}
                                buff = FormatHexNumber(buff, (uint64)args->GetInt64(SCC_HEX), last);
                                break;

                        case SCC_BYTES: // {BYTES}
                                buff = FormatBytes(buff, args->GetInt64(), last);
                                break;

                        case SCC_CARGO_TINY: { // {CARGO_TINY}
                                /* Tiny description of cargotypes. Layout:
                                 * param 1: cargo type
                                 * param 2: cargo count */
                                CargoID cargo = args->GetInt32(SCC_CARGO_TINY);
                                if (cargo >= CargoSpec::GetArraySize()) break;

                                StringID cargo_str = CargoSpec::Get(cargo)->units_volume;
                                int64 amount = 0;
                                switch (cargo_str) {
                                        case STR_TONS:
                                                amount = _units_weight[_settings_game.locale.units_weight].c.ToDisplay(args->GetInt64());
                                                break;

                                        case STR_LITERS:
                                                amount = _units_volume[_settings_game.locale.units_volume].c.ToDisplay(args->GetInt64());
                                                break;

                                        default: {
                                                amount = args->GetInt64();
                                                break;
                                        }
                                }

                                buff = FormatCommaNumber(buff, amount, last);
                                break;
                        }

                        case SCC_CARGO_SHORT: { // {CARGO_SHORT}
                                /* Short description of cargotypes. Layout:
                                 * param 1: cargo type
                                 * param 2: cargo count */
                                CargoID cargo = args->GetInt32(SCC_CARGO_SHORT);
                                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));
                                                int64 args_array[] = {_units_weight[_settings_game.locale.units_weight].c.ToDisplay(args->GetInt64())};
                                                StringParameters tmp_params(args_array);
                                                buff = FormatString(buff, GetStringPtr(_units_weight[_settings_game.locale.units_weight].l), &tmp_params, last);
                                                break;
                                        }

                                        case STR_LITERS: {
                                                assert(_settings_game.locale.units_volume < lengthof(_units_volume));
                                                int64 args_array[] = {_units_volume[_settings_game.locale.units_volume].c.ToDisplay(args->GetInt64())};
                                                StringParameters tmp_params(args_array);
                                                buff = FormatString(buff, GetStringPtr(_units_volume[_settings_game.locale.units_volume].l), &tmp_params, last);
                                                break;
                                        }

                                        default: {
                                                StringParameters tmp_params(*args, 1);
                                                buff = GetStringWithArgs(buff, cargo_str, &tmp_params, last);
                                                break;
                                        }
                                }
                                break;
                        }

                        case SCC_CARGO_LONG: { // {CARGO_LONG}
                                /* First parameter is cargo type, second parameter is cargo count */
                                CargoID cargo = args->GetInt32(SCC_CARGO_LONG);
                                if (cargo != CT_INVALID && cargo >= CargoSpec::GetArraySize()) break;

                                StringID cargo_str = (cargo == CT_INVALID) ? STR_QUANTITY_N_A : CargoSpec::Get(cargo)->quantifier;
                                StringParameters tmp_args(*args, 1);
                                buff = GetStringWithArgs(buff, cargo_str, &tmp_args, last);
                                break;
                        }

                        case SCC_CARGO_LIST: { // {CARGO_LIST}
                                CargoTypes cmask = args->GetInt64(SCC_CARGO_LIST);
                                bool first = true;

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

                                        if (buff >= last - 2) break; // ',' and ' '

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

                                        buff = GetStringWithArgs(buff, cs->name, args, last, next_substr_case_index, game_script);
                                }

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

                                *buff = '\0';
                                next_substr_case_index = 0;

                                /* Make sure we detect any buffer overflow */
                                assert(buff < last);
                                break;
                        }

                        case SCC_CURRENCY_SHORT: // {CURRENCY_SHORT}
                                buff = FormatGenericCurrency(buff, _currency, args->GetInt64(), true, last);
                                break;

                        case SCC_CURRENCY_LONG: // {CURRENCY_LONG}
                                buff = FormatGenericCurrency(buff, _currency, args->GetInt64(SCC_CURRENCY_LONG), false, last);
                                break;

                        case SCC_DATE_TINY: // {DATE_TINY}
                                buff = FormatTinyOrISODate(buff, args->GetInt32(SCC_DATE_TINY), STR_FORMAT_DATE_TINY, last);
                                break;

                        case SCC_DATE_SHORT: // {DATE_SHORT}
                                buff = FormatMonthAndYear(buff, args->GetInt32(SCC_DATE_SHORT), last, next_substr_case_index);
                                next_substr_case_index = 0;
                                break;

                        case SCC_DATE_LONG: // {DATE_LONG}
                                buff = FormatYmdString(buff, args->GetInt32(SCC_DATE_LONG), last, next_substr_case_index);
                                next_substr_case_index = 0;
                                break;

                        case SCC_DATE_ISO: // {DATE_ISO}
                                buff = FormatTinyOrISODate(buff, args->GetInt32(), STR_FORMAT_DATE_ISO, last);
                                break;

                        case SCC_FORCE: { // {FORCE}
                                assert(_settings_game.locale.units_force < lengthof(_units_force));
                                int64 args_array[1] = {_units_force[_settings_game.locale.units_force].c.ToDisplay(args->GetInt64())};
                                StringParameters tmp_params(args_array);
                                buff = FormatString(buff, GetStringPtr(_units_force[_settings_game.locale.units_force].s), &tmp_params, last);
                                break;
                        }

                        case SCC_HEIGHT: { // {HEIGHT}
                                assert(_settings_game.locale.units_height < lengthof(_units_height));
                                int64 args_array[] = {_units_height[_settings_game.locale.units_height].c.ToDisplay(args->GetInt64())};
                                StringParameters tmp_params(args_array);
                                buff = FormatString(buff, GetStringPtr(_units_height[_settings_game.locale.units_height].s), &tmp_params, last);
                                break;
                        }

                        case SCC_POWER: { // {POWER}
                                assert(_settings_game.locale.units_power < lengthof(_units_power));
                                int64 args_array[1] = {_units_power[_settings_game.locale.units_power].c.ToDisplay(args->GetInt64())};
                                StringParameters tmp_params(args_array);
                                buff = FormatString(buff, GetStringPtr(_units_power[_settings_game.locale.units_power].s), &tmp_params, last);
                                break;
                        }

                        case SCC_VELOCITY: { // {VELOCITY}
                                assert(_settings_game.locale.units_velocity < lengthof(_units_velocity));
                                unsigned int decimal_places = _units_velocity[_settings_game.locale.units_velocity].decimal_places;
                                uint64 args_array[] = {ConvertKmhishSpeedToDisplaySpeed(args->GetInt64(SCC_VELOCITY)), decimal_places};
                                StringParameters tmp_params(args_array, decimal_places ? 2 : 1, nullptr);
                                buff = FormatString(buff, GetStringPtr(_units_velocity[_settings_game.locale.units_velocity].s), &tmp_params, last);
                                break;
                        }

                        case SCC_VOLUME_SHORT: { // {VOLUME_SHORT}
                                assert(_settings_game.locale.units_volume < lengthof(_units_volume));
                                int64 args_array[1] = {_units_volume[_settings_game.locale.units_volume].c.ToDisplay(args->GetInt64())};
                                StringParameters tmp_params(args_array);
                                buff = FormatString(buff, GetStringPtr(_units_volume[_settings_game.locale.units_volume].s), &tmp_params, last);
                                break;
                        }

                        case SCC_VOLUME_LONG: { // {VOLUME_LONG}
                                assert(_settings_game.locale.units_volume < lengthof(_units_volume));
                                int64 args_array[1] = {_units_volume[_settings_game.locale.units_volume].c.ToDisplay(args->GetInt64(SCC_VOLUME_LONG))};
                                StringParameters tmp_params(args_array);
                                buff = FormatString(buff, GetStringPtr(_units_volume[_settings_game.locale.units_volume].l), &tmp_params, last);
                                break;
                        }

                        case SCC_WEIGHT_SHORT: { // {WEIGHT_SHORT}
                                assert(_settings_game.locale.units_weight < lengthof(_units_weight));
                                int64 args_array[1] = {_units_weight[_settings_game.locale.units_weight].c.ToDisplay(args->GetInt64())};
                                StringParameters tmp_params(args_array);
                                buff = FormatString(buff, GetStringPtr(_units_weight[_settings_game.locale.units_weight].s), &tmp_params, last);
                                break;
                        }

                        case SCC_WEIGHT_LONG: { // {WEIGHT_LONG}
                                assert(_settings_game.locale.units_weight < lengthof(_units_weight));
                                int64 args_array[1] = {_units_weight[_settings_game.locale.units_weight].c.ToDisplay(args->GetInt64(SCC_WEIGHT_LONG))};
                                StringParameters tmp_params(args_array);
                                buff = FormatString(buff, GetStringPtr(_units_weight[_settings_game.locale.units_weight].l), &tmp_params, last);
                                break;
                        }

                        case SCC_COMPANY_NAME: { // {COMPANY}
                                const Company *c = Company::GetIfValid(args->GetInt32());
                                if (c == nullptr) break;

                                if (!c->name.empty()) {
                                        int64 args_array[] = {(int64)(size_t)c->name.c_str()};
                                        StringParameters tmp_params(args_array);
                                        buff = GetStringWithArgs(buff, STR_JUST_RAW_STRING, &tmp_params, last);
                                } else {
                                        int64 args_array[] = {c->name_2};
                                        StringParameters tmp_params(args_array);
                                        buff = GetStringWithArgs(buff, c->name_1, &tmp_params, last);
                                }
                                break;
                        }

                        case SCC_COMPANY_NUM: { // {COMPANY_NUM}
                                CompanyID company = (CompanyID)args->GetInt32();

                                /* Nothing is added for AI or inactive companies */
                                if (Company::IsValidHumanID(company)) {
                                        int64 args_array[] = {company + 1};
                                        StringParameters tmp_params(args_array);
                                        buff = GetStringWithArgs(buff, STR_FORMAT_COMPANY_NUM, &tmp_params, last);
                                }
                                break;
                        }

                        case SCC_DEPOT_NAME: { // {DEPOT}
                                VehicleType vt = (VehicleType)args->GetInt32(SCC_DEPOT_NAME);
                                if (vt == VEH_AIRCRAFT) {
                                        uint64 args_array[] = {(uint64)args->GetInt32()};
                                        WChar types_array[] = {SCC_STATION_NAME};
                                        StringParameters tmp_params(args_array, 1, types_array);
                                        buff = GetStringWithArgs(buff, STR_FORMAT_DEPOT_NAME_AIRCRAFT, &tmp_params, last);
                                        break;
                                }

                                const Depot *d = Depot::Get(args->GetInt32());
                                if (!d->name.empty()) {
                                        int64 args_array[] = {(int64)(size_t)d->name.c_str()};
                                        StringParameters tmp_params(args_array);
                                        buff = GetStringWithArgs(buff, STR_JUST_RAW_STRING, &tmp_params, last);
                                } else {
                                        int64 args_array[] = {d->town->index, d->town_cn + 1};
                                        StringParameters tmp_params(args_array);
                                        buff = GetStringWithArgs(buff, STR_FORMAT_DEPOT_NAME_TRAIN + 2 * vt + (d->town_cn == 0 ? 0 : 1), &tmp_params, last);
                                }
                                break;
                        }

                        case SCC_ENGINE_NAME: { // {ENGINE}
                                const Engine *e = Engine::GetIfValid(args->GetInt32(SCC_ENGINE_NAME));
                                if (e == nullptr) break;

                                if (!e->name.empty() && e->IsEnabled()) {
                                        int64 args_array[] = {(int64)(size_t)e->name.c_str()};
                                        StringParameters tmp_params(args_array);
                                        buff = GetStringWithArgs(buff, STR_JUST_RAW_STRING, &tmp_params, last);
                                } else {
                                        StringParameters tmp_params(nullptr, 0, nullptr);
                                        buff = GetStringWithArgs(buff, e->info.string_id, &tmp_params, last);
                                }
                                break;
                        }

                        case SCC_GROUP_NAME: { // {GROUP}
                                const Group *g = Group::GetIfValid(args->GetInt32());
                                if (g == nullptr) break;

                                if (!g->name.empty()) {
                                        int64 args_array[] = {(int64)(size_t)g->name.c_str()};
                                        StringParameters tmp_params(args_array);
                                        buff = GetStringWithArgs(buff, STR_JUST_RAW_STRING, &tmp_params, last);
                                } else {
                                        int64 args_array[] = {g->index};
                                        StringParameters tmp_params(args_array);

                                        buff = GetStringWithArgs(buff, STR_FORMAT_GROUP_NAME, &tmp_params, last);
                                }
                                break;
                        }

                        case SCC_INDUSTRY_NAME: { // {INDUSTRY}
                                const Industry *i = Industry::GetIfValid(args->GetInt32(SCC_INDUSTRY_NAME));
                                if (i == nullptr) break;

                                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 */
                                        StringParameters tmp_params(nullptr, 0, nullptr);
                                        buff = FormatString(buff, GetStringPtr(GetIndustrySpec(i->type)->name), &tmp_params, last, next_substr_case_index);
                                } else {
                                        /* First print the town name and the industry type name. */
                                        int64 args_array[2] = {i->town->index, GetIndustrySpec(i->type)->name};
                                        StringParameters tmp_params(args_array);

                                        buff = FormatString(buff, GetStringPtr(STR_FORMAT_INDUSTRY_NAME), &tmp_params, last, next_substr_case_index);
                                }
                                next_substr_case_index = 0;
                                break;
                        }

                        case SCC_PRESIDENT_NAME: { // {PRESIDENT_NAME}
                                const Company *c = Company::GetIfValid(args->GetInt32(SCC_PRESIDENT_NAME));
                                if (c == nullptr) break;

                                if (!c->president_name.empty()) {
                                        int64 args_array[] = {(int64)(size_t)c->president_name.c_str()};
                                        StringParameters tmp_params(args_array);
                                        buff = GetStringWithArgs(buff, STR_JUST_RAW_STRING, &tmp_params, last);
                                } else {
                                        int64 args_array[] = {c->president_name_2};
                                        StringParameters tmp_params(args_array);
                                        buff = GetStringWithArgs(buff, c->president_name_1, &tmp_params, last);
                                }
                                break;
                        }

                        case SCC_STATION_NAME: { // {STATION}
                                StationID sid = args->GetInt32(SCC_STATION_NAME);
                                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. */
                                        StringParameters tmp_params(nullptr, 0, nullptr);
                                        buff = GetStringWithArgs(buff, STR_UNKNOWN_STATION, &tmp_params, last);
                                        break;
                                }

                                if (!st->name.empty()) {
                                        int64 args_array[] = {(int64)(size_t)st->name.c_str()};
                                        StringParameters tmp_params(args_array);
                                        buff = GetStringWithArgs(buff, STR_JUST_RAW_STRING, &tmp_params, last);
                                } else {
                                        StringID str = 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) {
                                                        str = indsp->station_name;
                                                }
                                        }

                                        uint64 args_array[] = {STR_TOWN_NAME, st->town->index, st->index};
                                        WChar types_array[] = {0, SCC_TOWN_NAME, SCC_NUM};
                                        StringParameters tmp_params(args_array, 3, types_array);
                                        buff = GetStringWithArgs(buff, str, &tmp_params, last);
                                }
                                break;
                        }

                        case SCC_TOWN_NAME: { // {TOWN}
                                const Town *t = Town::GetIfValid(args->GetInt32(SCC_TOWN_NAME));
                                if (t == nullptr) break;

                                if (!t->name.empty()) {
                                        int64 args_array[] = {(int64)(size_t)t->name.c_str()};
                                        StringParameters tmp_params(args_array);
                                        buff = GetStringWithArgs(buff, STR_JUST_RAW_STRING, &tmp_params, last);
                                } else {
                                        buff = GetTownName(buff, t, last);
                                }
                                break;
                        }

                        case SCC_WAYPOINT_NAME: { // {WAYPOINT}
                                Waypoint *wp = Waypoint::GetIfValid(args->GetInt32(SCC_WAYPOINT_NAME));
                                if (wp == nullptr) break;

                                if (!wp->name.empty()) {
                                        int64 args_array[] = {(int64)(size_t)wp->name.c_str()};
                                        StringParameters tmp_params(args_array);
                                        buff = GetStringWithArgs(buff, STR_JUST_RAW_STRING, &tmp_params, last);
                                } else {
                                        int64 args_array[] = {wp->town->index, wp->town_cn + 1};
                                        StringParameters tmp_params(args_array);
                                        StringID str = ((wp->string_id == STR_SV_STNAME_BUOY) ? STR_FORMAT_BUOY_NAME : STR_FORMAT_WAYPOINT_NAME);
                                        if (wp->town_cn != 0) str++;
                                        buff = GetStringWithArgs(buff, str, &tmp_params, last);
                                }
                                break;
                        }

                        case SCC_VEHICLE_NAME: { // {VEHICLE}
                                const Vehicle *v = Vehicle::GetIfValid(args->GetInt32(SCC_VEHICLE_NAME));
                                if (v == nullptr) break;

                                if (!v->name.empty()) {
                                        int64 args_array[] = {(int64)(size_t)v->name.c_str()};
                                        StringParameters tmp_params(args_array);
                                        buff = GetStringWithArgs(buff, STR_JUST_RAW_STRING, &tmp_params, last);
                                } else if (v->group_id != DEFAULT_GROUP) {
                                        /* The vehicle has no name, but is member of a group, so print group name */
                                        int64 args_array[] = {v->group_id, v->unitnumber};
                                        StringParameters tmp_params(args_array);
                                        buff = GetStringWithArgs(buff, STR_FORMAT_GROUP_VEHICLE_NAME, &tmp_params, last);
                                } else {
                                        int64 args_array[] = {v->unitnumber};
                                        StringParameters tmp_params(args_array);

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

                                        buff = GetStringWithArgs(buff, str, &tmp_params, last);
                                }
                                break;
                        }

                        case SCC_SIGN_NAME: { // {SIGN}
                                const Sign *si = Sign::GetIfValid(args->GetInt32());
                                if (si == nullptr) break;

                                if (!si->name.empty()) {
                                        int64 args_array[] = {(int64)(size_t)si->name.c_str()};
                                        StringParameters tmp_params(args_array);
                                        buff = GetStringWithArgs(buff, STR_JUST_RAW_STRING, &tmp_params, last);
                                } else {
                                        StringParameters tmp_params(nullptr, 0, nullptr);
                                        buff = GetStringWithArgs(buff, STR_DEFAULT_SIGN_NAME, &tmp_params, last);
                                }
                                break;
                        }

                        case SCC_STATION_FEATURES: { // {STATIONFEATURES}
                                buff = StationGetSpecialString(buff, args->GetInt32(SCC_STATION_FEATURES), last);
                                break;
                        }

                        default:
                                if (buff + Utf8CharLen(b) < last) buff += Utf8Encode(buff, b);
                                break;
                }
        }
        *buff = '\0';
        return buff;
}


static char *StationGetSpecialString(char *buff, int x, const char *last)
{
        if ((x & FACIL_TRAIN)      && (buff + Utf8CharLen(SCC_TRAIN) < last)) buff += Utf8Encode(buff, SCC_TRAIN);
        if ((x & FACIL_TRUCK_STOP) && (buff + Utf8CharLen(SCC_LORRY) < last)) buff += Utf8Encode(buff, SCC_LORRY);
        if ((x & FACIL_BUS_STOP)   && (buff + Utf8CharLen(SCC_BUS)   < last)) buff += Utf8Encode(buff, SCC_BUS);
        if ((x & FACIL_DOCK)       && (buff + Utf8CharLen(SCC_SHIP)  < last)) buff += Utf8Encode(buff, SCC_SHIP);
        if ((x & FACIL_AIRPORT)    && (buff + Utf8CharLen(SCC_PLANE) < last)) buff += Utf8Encode(buff, SCC_PLANE);
        *buff = '\0';
        return buff;
}

static char *GetSpecialTownNameString(char *buff, int ind, uint32 seed, const char *last)
{
        return GenerateTownNameString(buff, last, 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 char *GenAndCoName(char *buff, uint32 arg, const char *last)
{
        const char * const *base;
        uint num;

        if (_settings_game.game_creation.landscape == LT_TOYLAND) {
                base = _silly_surname_list;
                num  = lengthof(_silly_surname_list);
        } else {
                base = _surname_list;
                num  = lengthof(_surname_list);
        }

        buff = strecpy(buff, base[num * GB(arg, 16, 8) >> 8], last);
        buff = strecpy(buff, " & Co.", last);

        return buff;
}

static char *GenPresidentName(char *buff, uint32 x, const char *last)
{
        char initial[] = "?. ";
        const char * const *base;
        uint num;
        uint i;

        initial[0] = _initial_name_letters[sizeof(_initial_name_letters) * GB(x, 0, 8) >> 8];
        buff = strecpy(buff, initial, last);

        i = (sizeof(_initial_name_letters) + 35) * GB(x, 8, 8) >> 8;
        if (i < sizeof(_initial_name_letters)) {
                initial[0] = _initial_name_letters[i];
                buff = strecpy(buff, initial, last);
        }

        if (_settings_game.game_creation.landscape == LT_TOYLAND) {
                base = _silly_surname_list;
                num  = lengthof(_silly_surname_list);
        } else {
                base = _surname_list;
                num  = lengthof(_surname_list);
        }

        buff = strecpy(buff, base[num * GB(x, 16, 8) >> 8], last);

        return buff;
}

static char *GetSpecialNameString(char *buff, int ind, StringParameters *args, const char *last)
{
        switch (ind) {
                case 1: // not used
                        return strecpy(buff, _silly_company_names[std::min<uint>(args->GetInt32() & 0xFFFF, lengthof(_silly_company_names) - 1)], last);

                case 2: // used for Foobar & Co company names
                        return GenAndCoName(buff, args->GetInt32(), last);

                case 3: // President name
                        return GenPresidentName(buff, args->GetInt32(), last);
        }

        /* town name? */
        if (IsInsideMM(ind - 6, 0, SPECSTR_TOWNNAME_LAST - SPECSTR_TOWNNAME_START + 1)) {
                buff = GetSpecialTownNameString(buff, ind - 6, args->GetInt32(), last);
                return strecpy(buff, " Transport", last);
        }

        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,                           lastof(this->name)) &&
               StrValid(this->own_name,                       lastof(this->own_name)) &&
               StrValid(this->isocode,                        lastof(this->isocode)) &&
               StrValid(this->digit_group_separator,          lastof(this->digit_group_separator)) &&
               StrValid(this->digit_group_separator_currency, lastof(this->digit_group_separator_currency)) &&
               StrValid(this->digit_decimal_separator,        lastof(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(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;
        }

#if TTD_ENDIAN == TTD_BIG_ENDIAN
        for (uint i = 0; i < TEXT_TAB_END; i++) {
                lang_pack->offsets[i] = ReadLE16Aligned(&lang_pack->offsets[i]);
        }
#endif /* TTD_ENDIAN == TTD_BIG_ENDIAN */

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

        uint count = 0;
        for (uint i = 0; i < TEXT_TAB_END; i++) {
                uint16 num = 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 = (byte)*s++;
        for (uint i = 0; i < count; i++) {
                if (s + len >= end) return false;

                if (len >= 0xC0) {
                        len = ((len & 0x3F) << 8) + (byte)*s++;
                        if (s + len >= end) return false;
                }
                offs[i] = s;
                s += len;
                len = (byte)*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;
        const char *c_file = strrchr(_current_language->file, PATHSEPCHAR) + 1;
        _config_language_file = c_file;
        SetCurrentGrfLangID(_current_language->newgrflangid);

#ifdef _WIN32
        extern void Win32SetCurrentLocaleName(const char *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 */

        /* 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__)) */

bool StringIDSorter(const StringID &a, const StringID &b)
{
        char stra[512];
        char strb[512];
        GetString(stra, a, lastof(stra));
        GetString(strb, b, lastof(strb));

        return strnatcmp(stra, strb) < 0;
}

/**
 * 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(byte 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 char *file, LanguagePackHeader *hdr)
{
        FILE *f = fopen(file, "rb");
        if (f == nullptr) return false;

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

/**
 * Gets a list of languages from the given directory.
 * @param path  the base directory to search in
 */
static void GetLanguageList(const char *path)
{
        DIR *dir = ttd_opendir(path);
        if (dir != nullptr) {
                struct dirent *dirent;
                while ((dirent = readdir(dir)) != nullptr) {
                        std::string d_name = FS2OTTD(dirent->d_name);
                        const char *extension = strrchr(d_name.c_str(), '.');

                        /* Not a language file */
                        if (extension == nullptr || strcmp(extension, ".lng") != 0) continue;

                        LanguageMetadata lmd;
                        seprintf(lmd.file, lastof(lmd.file), "%s%s", path, d_name.c_str());

                        /* Check whether the file is of the correct version */
                        if (!GetLanguageFileHeader(lmd.file, &lmd)) {
                                Debug(misc, 3, "{} is not a valid language file", lmd.file);
                        } else if (GetLanguage(lmd.newgrflangid) != nullptr) {
                                Debug(misc, 3, "{}'s language ID is already known", lmd.file);
                        } else {
                                _languages.push_back(lmd);
                        }
                }
                closedir(dir);
        }
}

/**
 * Make a list of the available language packs. Put the data in
 * #_languages list.
 */
void InitializeLanguagePacks()
{
        for (Searchpath sp : _valid_searchpaths) {
                std::string path = FioGetDirectory(sp, LANG_DIR);
                GetLanguageList(path.c_str());
        }
        if (_languages.size() == 0) 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. */
                const char *lang_file = strrchr(lng.file, PATHSEPCHAR) + 1;
                if (_config_language_file == lang_file) {
                        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 '%s'", 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());
        const Sprite *question_mark[FS_END];

        for (FontSize size = this->Monospace() ? FS_MONO : FS_BEGIN; size < (this->Monospace() ? FS_END : FS_MONO); size++) {
                question_mark[size] = GetGlyph(size, '?');
        }

        this->Reset();
        for (const char *text = this->NextString(); text != nullptr; text = this->NextString()) {
                FontSize size = this->DefaultSize();
                for (WChar c = Utf8Consume(&text); c != '\0'; c = Utf8Consume(&text)) {
                        if (c >= SCC_FIRST_FONT && c <= SCC_LAST_FONT) {
                                size = (FontSize)(c - SCC_FIRST_FONT);
                        } else if (!IsInsideMM(c, SCC_SPRITE_START, SCC_SPRITE_END) && IsPrintable(c) && !IsTextDirectionChar(c) && c != '?' && GetGlyph(size, c) == question_mark[size]) {
                                /* 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 0: size_name = "medium"; break;
                                        case 1: size_name = "small"; break;
                                        case 2: size_name = "large"; break;
                                        case 3: 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;
        }

        const char *NextString() override
        {
                if (this->i >= TEXT_TAB_END) return nullptr;

                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(FontCacheSettings *settings, const char *font_name, 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 char *err_str = stredup("XXXThe current font is missing some of the characters used in the texts for this language. Using system fallback font instead.");
                        Utf8Encode(err_str, 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 char *err_str = stredup("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, 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_LX) && !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 char *err_str = stredup("XXXThis version of OpenTTD does not support right-to-left languages. Recompile with icu enabled.");
                Utf8Encode(err_str, SCC_YELLOW);
                SetDParamStr(0, err_str);
                ShowErrorMessage(STR_JUST_RAW_STRING, INVALID_STRING_ID, WL_ERROR);
        }
#endif /* !WITH_ICU_LX */
}