/*
Copyright 2019 Mittendrein Markus

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"),
to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense,
and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

#pragma once
#include <string>
#include <string_view>
#include <optional>
#include <cstring>
#include <stdexcept>
#include <cstdint>

namespace format {

using FormatException = std::invalid_argument;

template<typename To, typename From, typename Enable = void>
struct FormatConvert {};

template<typename To, typename From>
struct ImplicitConversion
{
	static constexpr To convert(From from)
	{
		return from;
	}
};

template<typename From>
struct FormatConvert<std::intmax_t, From, std::enable_if_t<std::is_signed_v<From> && std::is_integral_v<From>>> : ImplicitConversion<std::intmax_t, From> {};

template<typename From>
struct FormatConvert<std::intmax_t, From, std::enable_if_t<std::is_unsigned_v<From> && std::is_integral_v<From> && (sizeof(From) < sizeof(std::intmax_t))>> : ImplicitConversion<std::intmax_t, From> {};

template<typename From>
struct FormatConvert<std::uintmax_t, From, std::enable_if_t<std::is_unsigned_v<From> && std::is_integral_v<From>>> : ImplicitConversion<std::uintmax_t, From> {};

template<typename String>
struct FormatConvert<std::string_view, String, std::enable_if_t<std::is_convertible_v<String, std::string_view>>> : ImplicitConversion<std::string_view, const String &> {};

template<typename From>
struct FormatConvert<double, From, std::enable_if_t<std::is_convertible_v<From, double> && !std::is_integral_v<From>>> : ImplicitConversion<double, const From &> {};

template<typename Pointer>
struct FormatConvert<const void *, Pointer, std::enable_if_t<std::is_pointer_v<Pointer> && !std::is_array_v<std::remove_pointer_t<Pointer>>>> : ImplicitConversion<const void *, const Pointer> {};

template<typename Pointer>
struct FormatConvert<const void *, Pointer, std::enable_if_t<std::is_pointer_v<Pointer> && std::is_array_v<std::remove_pointer_t<Pointer>>>> : ImplicitConversion<const void*, const Pointer> {};

template<typename From, typename Enable = void>
struct AutoConversion
{
	static bool conversion()
	{
		throw FormatException{""};
	}
};

template<char Conversion, typename From>
struct SimpleAutoConversion
{
	static constexpr char conversion()
	{
		return Conversion;
	}
};

template<typename From>
struct AutoConversion<From, std::enable_if_t<std::is_integral_v<From> && std::is_unsigned_v<From>>> : SimpleAutoConversion<'u', From> {};

template<typename From>
struct AutoConversion<From, std::enable_if_t<std::is_integral_v<From> && std::is_signed_v<From>>> : SimpleAutoConversion<'d', From> {};

template<typename From>
struct AutoConversion<From, std::enable_if_t<std::is_convertible_v<From, double> && !std::is_integral_v<From>>> : SimpleAutoConversion<'G', From> {};

template<typename From>
struct AutoConversion<From, std::enable_if_t<std::is_convertible_v<From, std::string_view>>> : SimpleAutoConversion<'s', From> {};

template<>
struct AutoConversion<char> : SimpleAutoConversion<'c', const char> {};

namespace detail
{
	template<typename T>
	struct remove_cvref { using type = std::remove_cv_t<std::remove_reference_t<T>>; };

	template<typename T>
	using remove_cvref_t = typename remove_cvref<T>::type;

	template<typename T, bool Ok = false>
	struct StointHelper
	{
		static T convert(const std::string &, std::size_t *, int)
		{
			static_assert(Ok, "stoint: Unsupported type");
			return T{};
		}
	};

	template<typename T, T(converter)(const std::string &, std::size_t *, int)>
	struct StointHelperConverter
	{
		static T convert(const std::string &str, std::size_t *pos, int base)
		{
			return converter(str, pos, base);
		}
	};

	template<>
	struct StointHelper<int> : StointHelperConverter<int, std::stoi> {};
	template<>
	struct StointHelper<long> : StointHelperConverter<long, std::stol> {};
	template<>
	struct StointHelper<long long> : StointHelperConverter<long long, std::stoll> {};
	template<>
	struct StointHelper<unsigned long> : StointHelperConverter<unsigned long, std::stoul> {};
	template<>
	struct StointHelper<unsigned long long> : StointHelperConverter<unsigned long long, std::stoull> {};

	template<typename T>
	T stoint(const std::string &str, std::size_t *pos = nullptr, int base = 10)
	{
		return StointHelper<T>::convert(str, pos, base);
	}

	template<typename... Args>
	std::string strprintf(const char *fmt, Args... args)
	{
		int size = std::snprintf(nullptr, 0, fmt, args...) + 1;
		std::string result;
		result.resize(size);
		std::snprintf(result.data(), size, fmt, args...);
		result.resize(size - 1);
		return result;
	}

	template<typename To, typename From, bool allowFallback, typename Enable = void>
	struct FormatConvertHelper
	{
		static constexpr To convert(const From &)
		{
			static_assert(allowFallback, "Impossible conversion needed");
			throw FormatException{""};
		}
	};

	template<typename T, bool allowFallback>
	struct FormatConvertHelper<T, T, allowFallback>
	{
		static constexpr const T &convert(const T &from)
		{
			return from;
		}
	};

	template<typename To, typename From, bool allowFallback>
	struct FormatConvertHelper<To, From, allowFallback, std::enable_if_t<!std::is_same_v<To, From> && std::is_same_v<remove_cvref_t<decltype(FormatConvert<To, remove_cvref_t<From>>::convert(std::declval<From>()))>, remove_cvref_t<To>>>>
	{
		static constexpr To convert(const From &from)
		{
			return FormatConvert<To, remove_cvref_t<From>>::convert(from);
		}
	};

	template<typename To, bool allowFallback = true, typename From>
	auto convert(const From &from, const char *toName, std::size_t index = 0)
	{
		try
		{
			return FormatConvertHelper<To, From, allowFallback>::convert(from);
		}
		catch (const FormatException &)
		{
			throw FormatException{"Argument#" + std::to_string(index) + " is not convertible to " + std::string{toName}};
		}
	}

	template<typename From, typename Enable = void>
	struct StringOrStringViewHelper
	{
		using type = std::string_view;
	};

	template<typename From>
	struct StringOrStringViewHelper<From, std::enable_if_t<std::is_same_v<std::string, std::decay_t<decltype(FormatConvert<std::string, From>::convert(std::declval<From>()))>>>>
	{
		using type = std::string;
	};

	template<typename From>
	using string_or_string_view = typename StringOrStringViewHelper<From>::type;

	template<bool allowPointer = false, bool allowFallback = true, typename From>
	constexpr char autoConversionSpecifier(std::size_t index = 0)
	{
		try
		{
			if constexpr (!allowFallback)
			{
				if constexpr(!std::is_same_v<char, decltype(AutoConversion<remove_cvref_t<From>>::conversion())>)
				{
					if constexpr (std::is_pointer_v<From>)
					{
						if constexpr (allowPointer)
						{
							return 'p';
						}
						else
						{
							if constexpr (!allowFallback) static_assert(allowPointer, "%v doesn't allow automatic conversions for pointers; use %V to alsow allow arbitrary pointers");
							else throw FormatException{"Argument#" + std::to_string(index) + " is not applicable for auto conversion with %v, use %V to also allow arbitrary pointers"};
						}
					}
				}
			}
			return AutoConversion<remove_cvref_t<From>>::conversion();
		}
		catch (const FormatException &)
		{
			if constexpr (std::is_pointer_v<From>)
			{
				if constexpr (allowPointer)
				{
					return 'p';
				}
				else
				{
					if constexpr (!allowFallback) static_assert(allowPointer, "%v doesn't allow automatic conversions for pointers; use %V to alsow allow arbitrary pointers");
					throw FormatException{"Argument#" + std::to_string(index) + " is not applicable for auto conversion with %v, use %V to also allow arbitrary pointers"};
				}
			}
			throw FormatException{"Argument#" + std::to_string(index) + " is not applicable for auto conversion (%v / %V)"};
		}
	}

	std::string format(std::string_view fmt, const std::size_t argumentIndex)
	{
		const auto fmtSize = fmt.size();
		for (std::size_t i = 0; i < fmtSize; ++i)
		{
			if (fmt[i] == '%')
			{
				if (i >= fmtSize - 1)
				{
					throw FormatException{"Incomplete directive"};
				}

				if (fmt[++i] == '%')
				{
					return std::string{fmt.substr(0, i)} + format(fmt.substr(i + 1), argumentIndex);
				}

				throw FormatException{"Not enough arguments passed"};
			}
		}
		return std::string{fmt};
	}

	template<typename Arg, typename... Args>
	std::string format(std::string_view fmt, const std::size_t argumentIndex, Arg &&arg, Args &&... args)
	{
		const auto fmtSize = fmt.size();
		for (std::size_t i = 0; i < fmtSize; ++i)
		{
			auto checkFmtLength = [i, fmtSize]
			{
				if (i >= fmtSize - 1)
				{
					throw FormatException{"Incomplete directive"};
				}
			};
			const auto current = fmt[i];
			if (current == '%')
			{
				const auto directiveStart = i;
				checkFmtLength();
				std::string specification{"%"};

				if (fmt[i + 1] == '%') // handle %% here
				{
					return std::string{fmt.substr(0, directiveStart + 1)} + format(fmt.substr(i + 1), argumentIndex, std::forward<Arg>(arg), std::forward<Args>(args)...);
				}
				while(i < fmtSize - 1)
				{
					switch (const auto flag = fmt[++i])
					{
						case '#': case '0': case '-': case ' ': case '+':
							specification.push_back(flag);
							checkFmtLength();
							break;
						default:
							--i;
							goto afterFlagLoop;
					}
				}
			afterFlagLoop:

				std::string tempNumber;
				// field width
				while (std::isdigit(fmt[++i]))
				{
					tempNumber.push_back(fmt[i]);
					checkFmtLength();
				}
				--i;
				const auto fieldWidth = tempNumber.empty() ? 0 : stoint<std::size_t>(tempNumber);
				tempNumber.clear();

				std::optional<std::size_t> precision;
				// precision
				if (fmt[++i] == '.')
				{
					checkFmtLength();
					while (std::isdigit(fmt[++i]))
					{
						tempNumber.push_back(fmt[i]);
						checkFmtLength();
					}
					precision = tempNumber.empty() ? 0 : stoint<std::size_t>(tempNumber);
				}
				--i;

				std::string conversion{fmt[++i]};
				if(conversion.front() == 'v')
				{
					conversion = autoConversionSpecifier<false, true, Arg>(argumentIndex);
				}
				else if(conversion.front() == 'V')
				{
					conversion = autoConversionSpecifier<true, true, Arg>(argumentIndex);
				}

				auto continueFormatting = [directiveStart, &args..., fmt, &specification, &fieldWidth, &precision, i, conversion, argumentIndex](auto length, auto converted)
				{
					if (fieldWidth) specification += std::to_string(fieldWidth);
					if (precision) specification += '.' + std::to_string(*precision);
					if (length) specification += length;
					specification += conversion;
					return std::string{fmt.substr(0, directiveStart)} + strprintf(specification.c_str(), converted) + format(fmt.substr(i + 1), argumentIndex + 1, std::forward<Args>(args)...);
				};

				switch (conversion.back())
				{
					case 'c':
						return continueFormatting(false, convert<char>(std::forward<Arg>(arg), "character", argumentIndex));

					case 'd': case 'i':
						return continueFormatting('j', convert<std::intmax_t>(std::forward<Arg>(arg), "signed integer", argumentIndex));

					case 'u': case 'o': case 'x': case 'X':
						return continueFormatting('j', convert<std::uintmax_t>(std::forward<Arg>(arg), "unsigned integer", argumentIndex));

					case 's':
					{
						const auto& string = convert<string_or_string_view<remove_cvref_t<Arg>>>(std::forward<Arg>(arg), "string", argumentIndex);
						precision = precision ? std::min(*precision, string.size()) : string.size();
						return continueFormatting(false, string.data());
					}

					case 'e': case 'E': case 'f': case 'F': case 'g': case 'G': case 'a': case 'A':
						return continueFormatting(false, convert<double>(std::forward<Arg>(arg), "double", argumentIndex));

					case 'p':
						return continueFormatting(false, convert<const void *>(std::forward<Arg>(arg), "pointer", argumentIndex));

					default:
						throw FormatException{std::string{"Unknown conversion specifier: \""} + conversion + "\""};
				}
			}
		}

		throw FormatException{std::to_string(argumentIndex - 1) + " placeholders found, but " + std::to_string(argumentIndex + sizeof...(args)) + " arguments passed"};
	}
}

template<bool NoThrow = false, typename String, typename... Args>
std::string format(const String &fmt, Args &&... args)
{
	const auto fmtStr = detail::convert<std::string_view, false>(fmt, "string");
	try
	{
		return detail::format(fmtStr, 1, std::forward<Args>(args)...);
	}
	catch (const FormatException &e)
	{
		const auto &message = std::string{"format(\""} + std::string{fmtStr} + "\", " + std::to_string(sizeof...(args)) + " more arguments...): " + e.what();

		if constexpr (NoThrow) return message;
		else throw FormatException(message);
	}
}

template<size_t i>
struct str_index { static constexpr size_t n = i; };

template<size_t N>
struct str
{
public:
	const char s[N + 1];
	static constexpr size_t size = N;

private:
	template<size_t... indices>
	constexpr str<N + 1> appendCharHelper(const char c, std::index_sequence<indices...>) const
	{
		return str<N + 1>{s[indices]..., c};
	}

	template<size_t... indices>
	static constexpr str<N + 1> prependCharHelper(const char c, const str<N> &s, std::index_sequence<indices...>)
	{
		return str<N + 1>{c, s.s[indices]...};
	}

	template<auto other, size_t... ownIndices, size_t... othersIndices>
	constexpr str<N + sizeof...(othersIndices)> appendStrHelper(std::index_sequence<ownIndices...>, std::index_sequence<othersIndices...>) const
	{
		return str<N + sizeof...(othersIndices)>{s[ownIndices]..., other.s[othersIndices]...};
	}

public:
	template<size_t... indices>
	constexpr str(const char (&s)[N + 1], std::index_sequence<indices...>) : s{s[indices]...}
	{

	}

	constexpr str(const char (&s)[N + 1]) : str{s, std::make_index_sequence<N + 1>()}
	{

	}

	template<typename... Chars>
	constexpr str(Chars... chars) : s{chars..., '\0'}
	{
		static_assert(N == sizeof...(chars), "O.o");
	}

	template<size_t index>
	constexpr char get() const
	{
		static_assert(index < N, "str::get: index out of range");
		return s[index];
	}

	template<size_t offset, size_t... indices>
	constexpr str<sizeof...(indices)> extract(std::index_sequence<indices...>) const
	{
		static_assert(((indices + offset < N) && ...), "str::extract: index out of range");
		return str<sizeof...(indices)>{s[indices + offset]...};
	}

	constexpr str<N + 1> operator+(const char c) const
	{
		return appendCharHelper(c, std::make_index_sequence<N>());
	}

	template<size_t otherN>
	constexpr str<N + otherN> operator+(const str<otherN> &other) const
	{
		return appendStrHelper<other>(std::make_index_sequence<N>(), std::make_index_sequence<otherN>());
	}

	template<size_t _N>
	friend constexpr str<_N + 1> operator+(const char c, const str<_N> &other);
};

template<size_t N>
constexpr str<N + 1> operator+(const char c, const str<N> &other)
{
	return str<N>::prependCharHelper(c, other, std::make_index_sequence<N>());
}

template<size_t N>
str(const char(&)[N]) -> str<N - 1>;

template<typename... Chars>
str(Chars... chars) -> str<sizeof...(Chars)>;

namespace detail
{
	template<size_t i, size_t N>
	constexpr char get(const str<N>& s)
	{
		return s.template get<i>();
	}

	template<size_t N, size_t offset, size_t... indices>
	constexpr str<sizeof...(indices)> extractStr(const str<N> &source, std::index_sequence<indices...>)
	{
		return str<sizeof...(indices)>{get<indices + offset>(source)...};
	}

	template<size_t start, size_t end = std::string::npos, bool endIsIndex = false, size_t N>
	constexpr str<end == std::string::npos ? N - start : (endIsIndex ? end + 1 - start : end)> substr(const str<N> &s)
	{
		static_assert(!endIsIndex || end < N, "substr: end index / substr-length is out of range");
		if constexpr (!endIsIndex && end == 0) return str<0>{};
		else if constexpr (end == std::string::npos) return substr<start, N - 1, true>(s);
		else if constexpr (!endIsIndex) return substr<start, start + end - 1, true>(s);
		else return s.template extract<start>(std::make_index_sequence<end - start + 1>());
	}

	template<typename T, auto s, size_t i = 0, bool allowSign = true, T parsedPart = 0>
	constexpr T strToInt()
	{
		if constexpr (i == s.size) return parsedPart;
		else
		{
			constexpr char c = get<i>(s);
			if constexpr (c == '-')
			{
				static_assert(allowSign, "strToInt: invalid character found");
				static_assert(std::is_signed_v<T>, "strToInt: negative sign found when converting to an unsigned type");
				return -strToInt<T, s, i + 1, false>();
			}
			else if constexpr (c == '+')
			{
				static_assert(allowSign, "strToInt: invalid character found");
				return strToInt<T, s, i + 1, false>();
			}
			else
			{
				static_assert(c >= '0' && c <= '9', "strToInt: invalid character found");
				return strToInt<T, s, i + 1, false, parsedPart * T{10} + T{c - '0'}>();
			}
		}
	}

	template<typename T, T N>
	constexpr size_t decimalLength()
	{
		if constexpr (N < 0) return 1 + decimalLength<T, -N>();
		else if constexpr (N < 10) return 1;
		else return 1 + decimalLength<T, N / 10>();
	}

	template<typename T, T N>
	constexpr str<decimalLength<T, N>()> toStr()
	{
		if constexpr (N < 0) return '-' + toStr<T, -N>();
		else if constexpr (N < 10)
		{
			return str<1>{'0' + N};
		}
		else return toStr<T, N / 10>() + char(N % 10 + '0');
	}

	template<auto fmt, size_t i, size_t argumentIndex>
	std::string format_s()
	{
		if constexpr (i == fmt.size) return "";
		else if constexpr (get<i>(fmt) == '%')
		{
			if constexpr (get<i + 1>(fmt) == '%') return substr<0, i, true>(fmt).s + format_s<substr<i + 2>(fmt), 0, argumentIndex>();
			else
			{
				static_assert(get<i + 1>(fmt) == '%', "Not enough arguments passed");
				throw FormatException{"Not enough arguments passed"};
			}
		}
		else return format_s<fmt, i + 1, argumentIndex>();
	}

	template<auto fmt, size_t i, size_t offset = 0>
	constexpr size_t getFlagEnd()
	{
		constexpr char next = get<i + offset>(fmt);
		if constexpr (next == '#' || next == '0' || next == '-' || next == ' ' || next == '+') return getFlagEnd<fmt, i, offset + 1>();
		else return i + offset;
	}

	template<auto fmt, size_t i>
	constexpr size_t getNumberEnd()
	{
		if constexpr (std::isdigit(get<i>(fmt))) return getNumberEnd<fmt, i + 1>();
		else return i;
	}

	template<char conversion, size_t argumentIndex, typename Arg>
	constexpr char checkReplaceAutoConversion()
	{
		if constexpr (conversion == 'v' || conversion == 'V') return autoConversionSpecifier<conversion == 'V', false, Arg>(argumentIndex);
		else return conversion;
	}

	template<bool havePrecision, auto fmt, size_t iAfterFieldWidth, size_t iAfterPrecision, typename String>
	size_t determineStringPrecision(const String& string)
	{
		if constexpr (havePrecision) return std::min(strToInt<size_t, substr<iAfterFieldWidth + 1, iAfterPrecision - 1, true>(fmt)>(), string.size());
		else return string.size();
	}

	template<auto fmt, char conversion, size_t i, size_t iAfterPrecision, char length>
	constexpr auto makeDirective()
	{
		if constexpr (length) return substr<i, iAfterPrecision - 1, true>(fmt) + length + conversion;
		else return substr<i, iAfterPrecision - 1, true>(fmt) + conversion;
	}

	template<auto fmt, size_t i, size_t argumentIndex, typename Arg, typename... Args>
	std::string format_s(Arg &&arg, Args &&...args)
	{
		static_assert(i < fmt.size, "Too many arguments passed");
		if constexpr (i == fmt.size)
		{
			throw FormatException{std::to_string(argumentIndex - 1) + " placeholders found, but " + std::to_string(argumentIndex + sizeof...(args)) + " arguments passed"};
		}
		else if constexpr (get<i>(fmt) == '%')
		{
			if constexpr (get<i + 1>(fmt) == '%') return substr<0, i, true>(fmt).s + format_s<substr<i + 2>(fmt), 0, argumentIndex>(std::forward<Arg>(arg), std::forward<Args>(args)...);

			constexpr char iAfterFlag = getFlagEnd<fmt, i + 1>();
			constexpr size_t iAfterFieldWidth = getNumberEnd<fmt, iAfterFlag>();

			constexpr auto havePrecision = get<iAfterFieldWidth>(fmt) == '.';
			constexpr size_t iAfterPrecision = [havePrecision, iAfterFieldWidth]() -> size_t { if constexpr (havePrecision) return getNumberEnd<fmt, iAfterFieldWidth + 1>(); else return iAfterFieldWidth; }();

			constexpr char conversion = checkReplaceAutoConversion<get<iAfterPrecision>(fmt), argumentIndex, Arg>();

			if constexpr (conversion == 'c') return substr<0, i>(fmt).s + strprintf(makeDirective<fmt, conversion, i, iAfterPrecision, 0>().s, convert<char, false>(std::forward<Arg>(arg), "character", argumentIndex)) + format_s<substr<iAfterPrecision + 1>(fmt), 0, argumentIndex + 1>(std::forward<Args>(args)...);
			else if constexpr (conversion == 'd' || conversion == 'i') return substr<0, i>(fmt).s + strprintf(makeDirective<fmt, conversion, i, iAfterPrecision, 'j'>().s, convert<std::intmax_t, false>(std::forward<Arg>(arg), "signed integer", argumentIndex)) + format_s<substr<iAfterPrecision + 1>(fmt), 0, argumentIndex + 1>(std::forward<Args>(args)...);
			else if constexpr (conversion == 'u' || conversion == 'o' || conversion == 'x' || conversion == 'X') return substr<0, i>(fmt).s + strprintf(makeDirective<fmt, conversion, i, iAfterPrecision, 'j'>().s, convert<std::uintmax_t, false>(std::forward<Arg>(arg), "unsigned integer", argumentIndex)) + format_s<substr<iAfterPrecision + 1>(fmt), 0, argumentIndex + 1>(std::forward<Args>(args)...);
			else if constexpr (conversion == 'e' || conversion == 'E' || conversion == 'f' || conversion == 'F' || conversion == 'g' || conversion == 'G' || conversion == 'a' || conversion == 'A') return substr<0, i>(fmt).s + strprintf(makeDirective<fmt, conversion, i, iAfterPrecision, 0>().s, convert<double, false>(std::forward<Arg>(arg), "double", argumentIndex)) + format_s<substr<iAfterPrecision + 1>(fmt), 0, argumentIndex + 1>(std::forward<Args>(args)...);
			else if constexpr (conversion == 'p') return substr<0, i>(fmt).s + strprintf(makeDirective<fmt, conversion, i, iAfterPrecision, 0>().s, convert<const void *, false>(std::forward<Arg>(arg), "pointer", argumentIndex)) + format_s<substr<iAfterPrecision + 1>(fmt), 0, argumentIndex + 1>(std::forward<Args>(args)...);
			else if constexpr (conversion == 's')
			{
				const auto& string = convert<string_or_string_view<remove_cvref_t<Arg>>, false>(std::forward<Arg>(arg), "string", argumentIndex);
				return substr<0, i>(fmt).s + strprintf("%.*s", determineStringPrecision<havePrecision, fmt, iAfterFieldWidth, iAfterPrecision>(string), string.data()) + format_s<substr<iAfterPrecision + 1>(fmt), 0, argumentIndex + 1>(std::forward<Args>(args)...);
			}
			else
			{
				static_assert(fmt.size == 0, "Unknown conversion specifier!");
				throw FormatException{std::string{"Unknown conversion specifier: \""} + conversion + "\""};
			}
		}
		else return format_s<fmt, i + 1, argumentIndex>(std::forward<Arg>(arg), std::forward<Args>(args)...);
	}
}

template<str fmt, typename... Args>
std::string format(Args &&...args)
{
	return detail::format_s<fmt, 0, 1>(std::forward<Args>(args)...);
}
}