datetime/DateTime.h

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/*
 * MIT License
 *
 * Copyright (c) 2025 nfx
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
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 * furnished to do so, subject to the following conditions:
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 *
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#pragma once
 
#include <chrono>
#include <compare>
#include <cstdint>
#include <format>
#include <optional>
#include <string>
#include <string_view>
 
#include "TimeSpan.h"
 
namespace nfx::time
{
    class DateTime final
    {
    public:
        //----------------------------------------------
        // Enumerations
        //----------------------------------------------

        enum class Format : std::uint8_t
        {
            Iso8601Basic,

            Iso8601Extended,

            Iso8601WithOffset,

            DateOnly,

            TimeOnly,

            UnixSeconds,

            UnixMilliseconds,
        };
 
        //----------------------------------------------
        // Construction
        //----------------------------------------------

        constexpr DateTime() noexcept;

        explicit constexpr inline DateTime( std::int64_t ticks ) noexcept;

        explicit inline DateTime( std::chrono::system_clock::time_point timePoint ) noexcept;

        DateTime( std::int32_t year, std::int32_t month, std::int32_t day ) noexcept;

        DateTime( std::int32_t year, std::int32_t month, std::int32_t day,
            std::int32_t hour, std::int32_t minute, std::int32_t second ) noexcept;

        DateTime( std::int32_t year, std::int32_t month, std::int32_t day,
            std::int32_t hour, std::int32_t minute, std::int32_t second,
            std::int32_t millisecond ) noexcept;

        explicit inline DateTime( std::string_view iso8601String );

        DateTime( const DateTime& ) = default;

        DateTime( DateTime&& ) noexcept = default;
 
        //----------------------------------------------
        // Destruction
        //----------------------------------------------

        ~DateTime() = default;
 
        //----------------------------------------------
        // Assignment
        //----------------------------------------------

        DateTime& operator=( const DateTime& ) = default;

        DateTime& operator=( DateTime&& ) noexcept = default;
 
        //----------------------------------------------
        // Comparison operators
        //----------------------------------------------

        inline constexpr std::strong_ordering operator<=>( const DateTime& other ) const noexcept;

        inline constexpr bool operator==( const DateTime& other ) const noexcept;
 
        //----------------------------------------------
        // Arithmetic operators
        //----------------------------------------------

        inline constexpr DateTime operator+( const TimeSpan& duration ) const noexcept;

        inline constexpr DateTime operator-( const TimeSpan& duration ) const noexcept;

        inline constexpr TimeSpan operator-( const DateTime& other ) const noexcept;

        inline constexpr DateTime& operator+=( const TimeSpan& duration ) noexcept;

        inline constexpr DateTime& operator-=( const TimeSpan& duration ) noexcept;
 
        //----------------------------------------------
        // Property accessors
        //----------------------------------------------

        [[nodiscard]] std::int32_t year() const noexcept;

        [[nodiscard]] std::int32_t month() const noexcept;

        [[nodiscard]] std::int32_t day() const noexcept;

        [[nodiscard]] std::int32_t hour() const noexcept;

        [[nodiscard]] std::int32_t minute() const noexcept;

        [[nodiscard]] std::int32_t second() const noexcept;

        [[nodiscard]] std::int32_t millisecond() const noexcept;

        [[nodiscard]] std::int32_t microsecond() const noexcept;

        [[nodiscard]] std::int32_t nanosecond() const noexcept;

        [[nodiscard]] constexpr std::int64_t ticks() const noexcept;

        [[nodiscard]] std::int32_t dayOfWeek() const noexcept;

        [[nodiscard]] std::int32_t dayOfYear() const noexcept;
 
        //----------------------------------------------
        // Conversion methods
        //----------------------------------------------

        [[nodiscard]] inline constexpr std::int64_t toEpochSeconds() const noexcept;

        [[nodiscard]] inline constexpr std::int64_t toEpochMilliseconds() const noexcept;

        [[nodiscard]] DateTime date() const noexcept;

        [[nodiscard]] TimeSpan timeOfDay() const noexcept;
 
        //----------------------------------------------
        // Validation methods
        //----------------------------------------------

        [[nodiscard]] bool isValid() const noexcept;

        [[nodiscard]] inline static constexpr bool isLeapYear( std::int32_t year ) noexcept;

        [[nodiscard]] inline static constexpr std::int32_t daysInMonth( std::int32_t year, std::int32_t month ) noexcept;
 
        //----------------------------------------------
        // Static factory methods
        //----------------------------------------------

        [[nodiscard]] static DateTime now() noexcept;

        [[nodiscard]] static DateTime utcNow() noexcept;

        [[nodiscard]] static DateTime today() noexcept;

        [[nodiscard]] inline static constexpr DateTime min() noexcept;

        [[nodiscard]] inline static constexpr DateTime max() noexcept;

        [[nodiscard]] inline static constexpr DateTime epoch() noexcept;

        [[nodiscard]] static bool fromString( std::string_view iso8601String, DateTime& result ) noexcept;

        [[nodiscard]] static std::optional<DateTime> fromString( std::string_view iso8601String ) noexcept;

        [[nodiscard]] inline static constexpr DateTime fromEpochSeconds( std::int64_t seconds ) noexcept;

        [[nodiscard]] inline static constexpr DateTime fromEpochMilliseconds( std::int64_t milliseconds ) noexcept;
 
        //----------------------------------------------
        // String formatting
        //----------------------------------------------

        [[nodiscard]] std::string toString() const;

        [[nodiscard]] std::string toString( Format format ) const;

        [[nodiscard]] std::string toIso8601Extended() const;
 
        //----------------------------------------------
        // std::chrono interoperability
        //----------------------------------------------

        [[nodiscard]] std::chrono::system_clock::time_point toChrono() const noexcept;

        [[nodiscard]] static DateTime fromChrono( const std::chrono::system_clock::time_point& timePoint ) noexcept;
 
    private:
        std::int64_t m_ticks;
    };
} // namespace nfx::time
 
#include "nfx/detail/datetime/DateTime.inl"