std::chrono::tai_clock Improvements (C++26 Evolution)

#include <chrono> auto now = std::chrono::tai_clock::now();

// CodeNebula - C++26 Example: chrono::tai_clock Improvements
// Compile: g++ -std=c++26 -Wall -Wextra -o example tai_clock_improvements.cpp
// Note: Requires C++26 compiler support

#include <iostream>
#include <chrono>
#include <iomanip>

// C++20 introduced chrono::tai_clock (International Atomic Time).
// C++26 improves tai_clock with:
//   - Better leap second awareness for UTC <-> TAI conversions
//   - Improved constexpr support
//   - Enhanced formatting with std::format/std::print
//   - More reliable cross-platform implementations
//
// TAI (Temps Atomique International) is a continuous time scale with no
// leap seconds. As of 2024, TAI = UTC + 37 seconds.

int main() {
    std::cout << "--- chrono::tai_clock Improvements (C++26) ---\n\n";

    // Get current UTC time
    auto utc_now = std::chrono::system_clock::now();
    auto utc_time_t = std::chrono::system_clock::to_time_t(utc_now);
    std::cout << "Current UTC: " << std::put_time(std::gmtime(&utc_time_t), "%F %T") << "\n";

    // TAI offset from UTC (37 seconds as of 2017, may increase)
    // In real C++26: auto tai_now = chrono::tai_clock::now();
    constexpr int tai_offset_seconds = 37;  // TAI - UTC offset
    auto tai_epoch = utc_now + std::chrono::seconds(tai_offset_seconds);
    auto tai_time_t = std::chrono::system_clock::to_time_t(tai_epoch);
    std::cout << "Current TAI: " << std::put_time(std::gmtime(&tai_time_t), "%F %T")
              << " (UTC + " << tai_offset_seconds << "s)\n";

    // Demonstrate TAI properties
    std::cout << "\n--- TAI Properties ---\n";
    std::cout << "TAI is continuous (no leap seconds)\n";
    std::cout << "TAI epoch: 1958-01-01 00:00:00\n";
    std::cout << "Current TAI-UTC offset: " << tai_offset_seconds << " seconds\n";

    // Duration calculations are straightforward in TAI
    std::cout << "\n--- Duration Calculations ---\n";
    using namespace std::chrono;
    auto t1 = utc_now;
    auto t2 = t1 + hours(24);
    auto diff = duration_cast<seconds>(t2 - t1);
    std::cout << "24 hours in TAI = " << diff.count() << " seconds (exactly)\n";
    std::cout << "In UTC, 24 hours might be 86399 or 86401 due to leap seconds\n";

    // Conversion example
    std::cout << "\n--- UTC <-> TAI Conversion ---\n";
    auto example_utc = sys_days{2024y / January / 1};
    auto example_utc_t = system_clock::to_time_t(example_utc);
    std::cout << "UTC 2024-01-01: " << std::put_time(std::gmtime(&example_utc_t), "%F %T") << "\n";
    auto example_tai = example_utc + seconds(tai_offset_seconds);
    auto example_tai_t = system_clock::to_time_t(example_tai);
    std::cout << "TAI 2024-01-01: " << std::put_time(std::gmtime(&example_tai_t), "%F %T") << "\n";

    std::cout << "\nC++26: tai_clock has improved leap second handling.\n";
    return 0;
}

// Expected output:
// --- chrono::tai_clock Improvements (C++26) ---
//
// Current UTC: <current date and time>
// Current TAI: <current date and time + 37s> (UTC + 37s)
//
// --- TAI Properties ---
// TAI is continuous (no leap seconds)
// TAI epoch: 1958-01-01 00:00:00
// Current TAI-UTC offset: 37 seconds
//
// --- Duration Calculations ---
// 24 hours in TAI = 86400 seconds (exactly)
// In UTC, 24 hours might be 86399 or 86401 due to leap seconds
//
// --- UTC <-> TAI Conversion ---
// UTC 2024-01-01: 2024-01-01 00:00:00
// TAI 2024-01-01: 2024-01-01 00:00:37
//
// C++26: tai_clock has improved leap second handling.