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// SPDX-FileCopyrightText: Copyright 2020 yuzu Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later
#include <chrono>
#include <exception>
#include <iomanip>
#include <map>
#include <sstream>
#include <stdexcept>
#include <fmt/chrono.h>
#include <fmt/core.h>
#include "common/logging/log.h"
#include "common/time_zone.h"
namespace Common::TimeZone {
// Time zone strings
constexpr std::array timezones{
"GMT", "GMT", "CET", "CST6CDT", "Cuba", "EET", "Egypt", "Eire",
"EST", "EST5EDT", "GB", "GB-Eire", "GMT", "GMT+0", "GMT-0", "GMT0",
"Greenwich", "Hongkong", "HST", "Iceland", "Iran", "Israel", "Jamaica", "Japan",
"Kwajalein", "Libya", "MET", "MST", "MST7MDT", "Navajo", "NZ", "NZ-CHAT",
"Poland", "Portugal", "PRC", "PST8PDT", "ROC", "ROK", "Singapore", "Turkey",
"UCT", "Universal", "UTC", "W-SU", "WET", "Zulu",
};
const std::array<const char*, 46>& GetTimeZoneStrings() {
return timezones;
}
std::string GetDefaultTimeZone() {
return "GMT";
}
// Results are not comparable to seconds since Epoch
static std::time_t TmSpecToSeconds(const struct std::tm& spec) {
const int year = spec.tm_year - 1; // Years up to now
const int leap_years = year / 4 - year / 100;
std::time_t cumulative = spec.tm_year;
cumulative = cumulative * 365 + leap_years + spec.tm_yday; // Years to days
cumulative = cumulative * 24 + spec.tm_hour; // Days to hours
cumulative = cumulative * 60 + spec.tm_min; // Hours to minutes
cumulative = cumulative * 60 + spec.tm_sec; // Minutes to seconds
return cumulative;
}
std::chrono::seconds GetCurrentOffsetSeconds() {
const std::time_t t{std::time(nullptr)};
const std::tm local{*std::localtime(&t)};
const std::tm gmt{*std::gmtime(&t)};
// gmt_seconds is a different offset than time(nullptr)
const auto gmt_seconds = TmSpecToSeconds(gmt);
const auto local_seconds = TmSpecToSeconds(local);
const auto seconds_offset = local_seconds - gmt_seconds;
return std::chrono::seconds{seconds_offset};
}
// Key is [Hours * 100 + Minutes], multiplied by 100 if DST
const static std::map<s64, const char*> off_timezones = {
{530, "Asia/Calcutta"}, {930, "Australia/Darwin"}, {845, "Australia/Eucla"},
{103000, "Australia/Adelaide"}, {1030, "Australia/Lord_Howe"}, {630, "Indian/Cocos"},
{1245, "Pacific/Chatham"}, {134500, "Pacific/Chatham"}, {-330, "Canada/Newfoundland"},
{-23000, "Canada/Newfoundland"}, {430, "Asia/Kabul"}, {330, "Asia/Tehran"},
{43000, "Asia/Tehran"}, {545, "Asia/Kathmandu"}, {-930, "Asia/Marquesas"},
};
std::string FindSystemTimeZone() {
const s64 seconds = static_cast<s64>(GetCurrentOffsetSeconds().count());
const s64 minutes = seconds / 60;
const s64 hours = minutes / 60;
const s64 minutes_off = minutes - hours * 60;
if (minutes_off != 0) {
const auto the_time = std::time(nullptr);
const struct std::tm& local = *std::localtime(&the_time);
const bool is_dst = local.tm_isdst != 0;
const s64 tz_index = (hours * 100 + minutes_off) * (is_dst ? 100 : 1);
try {
return off_timezones.at(tz_index);
} catch (std::out_of_range&) {
LOG_ERROR(Common, "Time zone {} not handled, defaulting to hour offset.", tz_index);
}
}
// For some reason the Etc/GMT times are reversed. GMT+6 contains -21600 as its offset,
// -6 hours instead of +6 hours, so these signs are purposefully reversed to fix it.
std::string postfix{""};
if (hours > 0) {
postfix = fmt::format("-{:d}", std::abs(hours));
} else if (hours < 0) {
postfix = fmt::format("+{:d}", std::abs(hours));
}
return fmt::format("Etc/GMT{:s}", postfix);
}
} // namespace Common::TimeZone
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