chrono.hpp

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/*
    Copyright (C) 2024 - 2025
    Part of the Battle for Wesnoth Project https://www.wesnoth.org/
 
    This program 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; either version 2 of the License, or
    (at your option) any later version.
    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY.
 
    See the COPYING file for more details.
*/
 
#pragma once
 
#include "config_attribute_value.hpp"
#include "utils/general.hpp"
 
#include <algorithm>
#include <chrono>
#include <iomanip>
#include <sstream>
#include <string_view>
 
#if __cpp_lib_chrono >= 201907L
#define CPP20_CHRONO_SUPPORT
#endif
 
namespace chrono
{
#ifdef CPP20_CHRONO_SUPPORT
 
using std::chrono::days;
using std::chrono::weeks;
using std::chrono::months;
using std::chrono::years;
 
#else
 
using days   = std::chrono::duration<int, std::ratio<86400>>;
using weeks  = std::chrono::duration<int, std::ratio<604800>>;
using months = std::chrono::duration<int, std::ratio<2629746>>;
using years  = std::chrono::duration<int, std::ratio<31556952>>;
 
#endif
 
inline auto parse_timestamp(long long val)
{
    return std::chrono::system_clock::from_time_t(val);
}
 
inline auto parse_timestamp(const config_attribute_value& val)
{
    return std::chrono::system_clock::from_time_t(val.to_long_long());
}
 
inline auto serialize_timestamp(const std::chrono::system_clock::time_point& time)
{
    return std::chrono::system_clock::to_time_t(time);
}
 
inline auto get_local_timestamp(const std::chrono::system_clock::time_point& time)
{
    auto as_time_t = std::chrono::system_clock::to_time_t(time);
    std::tm local_tm{};
    return mktime(utils::localtime_r(&as_time_t, &local_tm));
}
 
// CAUTION: This does NOT return a language-localized string.  To achieve that,
//          use translation::translate_timestamp with chrono::get_local_timestamp.
inline auto format_local_timestamp(const std::chrono::system_clock::time_point& time, std::string_view format = "%F %T")
{
    std::ostringstream ss;
    auto as_time_t = std::chrono::system_clock::to_time_t(time);
    std::tm local_tm{};
    ss << std::put_time(utils::localtime_r(&as_time_t, &local_tm), format.data());
    return ss.str();
}
 
template<typename Duration>
inline auto parse_duration(const config_attribute_value& val, const Duration& def = Duration{0})
{
    return Duration{val.to_long_long(def.count())};
}
 
template<typename RepE, typename PeriodE, typename RepD, typename PeriodD>
constexpr double normalize_progress(
    const std::chrono::duration<RepE, PeriodE>& elapsed,
    const std::chrono::duration<RepD, PeriodD>& duration)
{
    return std::clamp(std::chrono::duration<double, PeriodE>{elapsed} / duration, 0.0, 1.0);
}
 
template<typename... Ts, typename Rep, typename Period>
constexpr auto deconstruct_duration(const std::chrono::duration<Rep, Period>& span)
{
    auto time_remaining = std::chrono::duration_cast<std::common_type_t<Ts...>>(span);
    return std::tuple{[&time_remaining]() {
        auto duration = std::chrono::duration_cast<Ts>(time_remaining);
        time_remaining -= duration;
        return duration;
    }()...};
}
 
} // namespace chrono