#include <charconv>

	strecpy(_lang.number_format, "00,000,000,000,000,000,000", lastof(_lang.number_format));

	strecpy(_lang.number_abbreviations, "3=00,000,000,000,000,000{NBSP}k|6=00,000,000,000,000{NBSP}m|9=00,000,000,000{NBSP}bn|12=00,000,000{NBSP}tn|15=00,000{NBSP}Qa|18=00{NBSP}Qi", lastof(_lang.number_abbreviations));

static const std::string_view NBSP_TOKEN = "{NBSP}";

static std::string ReplaceNBSP(std::string string)

{

	for (;;) {

		auto iter = string.find(NBSP_TOKEN);

		if (iter == std::string::npos) break;

		string.replace(iter, NBSP_TOKEN.size(), NBSP);

	}

	return string;

}

/**

 * Parse the \c NumberFormatSeparators out of the given format string, with the expected number of digits.

 *

 * Different cultures have different ways to separate their numbers when they get really big. In the Western world

 * these are often called thousands separators which come every three digits counted from the back. The actual

 * separator differs per language/country. In Chinese, Japanese and Korean they add a character every four digits

 * counted from the back, and this character differs for each spot as it denotes "ten thousand", "hundred million",

 * etc. In the Indic numbering system (Indian subcontinent), the first separator is after three digits counted

 * from the back, but the next separators are given every two digits.

 *

 * So, there's no simple single parameter that you can add to the digit grouping character that is already

 * configured. The simplest solution is just defining what character to place between each of the digits, i.e what

 * characters separate each of the digits. These are the \c NumberFormatSeparators.

 *

 * To define these, you simply write a string of \c length zeros and then add any characters in between at the right

 * locations so the digit grouping is correct. When formatting numbers, it will start at the appropriate digit and

 * continue from there with separators.

 *

 * Examples of formats are "00,000,000,000,000,000,000" and "0000{NBSP}0000{NBSP}0000{NBSP}0000{NBSP}0000".

 *

 * @param separators The separators to fill; it will be cleared first.

 * @param format The format that is going to be read.

 * @param length The number of digits that are expected in this format.

 * @return An \c std::optional with the error message, or \c std::nullopt when the parsing went without problems.

 */

std::optional<std::string> ParseNumberFormatSeparators(NumberFormatSeparators &separators, std::string_view format, size_t length)

{

	separators.fill({});

	size_t seen_zeros = 0;

	auto it_separator = separators.rbegin();

	auto iter = format.find_last_of('0');

	while (iter != std::string_view::npos && it_separator != separators.rend())  {

		seen_zeros++;

		*it_separator = ReplaceNBSP(std::string(format.substr(iter + 1)));

		++it_separator;

		format = format.substr(0, iter);

		iter = format.find_last_of('0');

	}

	if (seen_zeros != length) return fmt::format("Unexpected number of digits ({} vs {}) in format string: [{}]", seen_zeros, length, format);

	return std::nullopt;

}

/**

 * Parse the \c NumberAbbreviations out of the given input string.

 *

 * In some places in the UI numbers are getting really big yet their exact value is not that important. For example

 * in the graphs of company values. For this you want more compact number, e.g. 123 m for 123.456.789. However, due

 * to the grouping of digits differing in different cultures, see \c ParseNumberFormatSeparators, there are many

 * different ways of grouping digits.

 *

 * This function builds up a lookup table of these abbreviations by power of ten. The input will be a list of

 * definitions per power separator by a pipe character (|). Each definition is the power of ten and and the

 * associated number format with DIGITS_IN_UINT64_T - power digits, separated by the equals sign (=).

 *

 * For example, for English it defines every third power of ten with subsequently smaller number formats:

 * 3=00,000,000,000,000,000{NBSP}k|6=00,000,000,000,000{NBSP}m|9=00,000,000,000{NBSP}bn|12=00,000,000{NBSP}tn|15=00,000{NBSP}Qa|18=00{NBSP}Qi

 *

 * @param abbreviations The table to write the abbreviations in; is will be cleared before filling.

 * @param input The input format to parse.

 * @return An \c std::optional with the error message, or \c std::nullopt when the parsing went without problems.

 */

std::optional<std::string> ParseNumberAbbreviations(NumberAbbreviations &abbreviations, std::string_view input)

{

	abbreviations.clear();

	std::map<int, std::string_view> abbreviation_map;

	do {

		std::string_view part = input.substr(0, input.find_first_of('|'));

		input.remove_prefix(std::min(part.size() + 1, input.size()));

		auto equals = part.find_first_of('=');

		if (equals == std::string_view::npos) return fmt::format("Part [{}] does not have an '='", part);

		std::string_view power_sv = part.substr(0, equals);

		int power = 0;

		if (std::from_chars(power_sv.data(), power_sv.data() + power_sv.size(), power).ec != std::errc{}) return fmt::format("Power [{}] is not a number", power_sv);

		if (power >= DIGITS_IN_UINT64_T || power <= 0) return fmt::format("Power {} is not allowed", power_sv);

		abbreviation_map[power] = part.substr(equals + 1);

	} while (!input.empty());

	for (auto iter = abbreviation_map.rbegin(); iter != abbreviation_map.rend(); ++iter) {

		NumberFormatSeparators separators;

		auto result = ParseNumberFormatSeparators(separators, iter->second, DIGITS_IN_UINT64_T - iter->first);

		if (result.has_value()) return result;

		abbreviations.emplace_back(PowerOfTen(iter->first), separators);

	}

	return std::nullopt;

}