/*
 * 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()
{
	InitFreeType(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(freetype, 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(FreeTypeSettings *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. */
		FreeTypeSettings backup = _freetype;

		_freetype.mono.os_handle = nullptr;
		_freetype.medium.os_handle = nullptr;

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

		_freetype = backup;

		if (!bad_font) {
			/* Show that we loaded fallback font. 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. 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 */
			InitFreeType(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 */
}