#pragma once

#include "Partial.h"

/// note: for this header you need fmt library (not included as library dependency)

#include <fmt/format.h>

/// note: for this header you need strong19 (not included as library dependency)

#include <strong19/Strong.h>

template<class... Ts, class Char> struct fmt::formatter<partial19::PartialWhich<Ts...>, Char> {

constexpr auto parse(fmt::basic_format_parse_context<Char>& ctx) { return ctx.begin(); }

template<size_t I, class T> static auto format_type_index(bool hit, auto& first, auto& out) -> bool {

if (hit) {

if constexpr (strong19::is_strong<T>) {

if (first) {

out = fmt::format_to(out, "{}", strong19::strong_name<T>);

first = false;

}

else {

out = fmt::format_to(out, ", {}", strong19::strong_name<T>);

}

}

else {

if (first) {

out = fmt::format_to(out, "{}", I);

first = false;

}

else {

out = fmt::format_to(out, ", {}", I);

}

}

}

return true;

}

template<typename FormatContext> auto format(partial19::PartialWhich<Ts...> const& v, FormatContext& ctx) const {

if constexpr (sizeof...(Ts) == 0) {

return fmt::format_to(ctx.out(), "Which()");

}

else {

return [&]<size_t... Is>(std::index_sequence<Is...> const&) {

auto out = fmt::format_to(ctx.out(), "Which<");

bool first = true;

((format_type_index<Is, Ts>(v[Is], first, out)), ...);

return fmt::format_to(out, ">");

}(std::make_index_sequence<sizeof...(Ts)>{});

}

}

};