#pragma once

#include "dtcore/inc/dtdefinitions.h"
#include "dtcore/inc/dtstream.h"
#include "dtcore/inc/dtstring.h"

struct _FILETIME;

namespace dt
{
    enum class DateTimeFormat
    {
        Iso8601Extended, // YYYY-MM-DDThh:mm:ss.sss+00:00
        Iso8601Basic,    // YYYYMMDDThhmmSS.sssZ
        Iso8601DateOnly  // YYYY-MM-DD
    };

    // This class works with UTC time. Provided values will be converted to UTC time, based on the 
    // given UTC offset. If no offset is provided, local offset is considered.
    class DateTime : public Serializable
    {
    public:
        DT_CORE_DLL_ENTRY DateTime() = default;
        DT_CORE_DLL_ENTRY explicit DateTime(MilliSeconds unixTimeMs);
        DT_CORE_DLL_ENTRY explicit DateTime(const String& value);
#if defined(DT_PLATFORM_X64) || defined(DT_PLATFORM_DURANGO) || defined(DT_PLATFORM_DURANGO_GDK) || defined(DT_PLATFORM_SCARLETT)
        DT_CORE_DLL_ENTRY explicit DateTime(_FILETIME* fileTime);
#endif

        DT_CORE_DLL_ENTRY void Add(MilliSeconds value);
        DT_CORE_DLL_ENTRY DateTime GetAdded(MilliSeconds value) const;

        DT_CORE_DLL_ENTRY DateTime GetDayStart() const;

        DT_CORE_DLL_ENTRY String ToString(DateTimeFormat format = DateTimeFormat::Iso8601Extended) const;
        DT_CORE_DLL_ENTRY String& ToString(String& inplaceStr, DateTimeFormat format = DateTimeFormat::Iso8601Extended) const;

        // Milliseconds since Epoch
        DT_CORE_DLL_ENTRY MilliSeconds GetUnixTimeMs() const { return m_UnixTimeMs; }

        // milliseconds after the second [0,999]
        DT_CORE_DLL_ENTRY int GetMsec() const;
        // seconds after the minute [0, 59]
        DT_CORE_DLL_ENTRY int GetSec() const;
        // minutes after the hour [0, 59]
        DT_CORE_DLL_ENTRY int GetMin() const;
        // hours since midnight [0, 23]
        DT_CORE_DLL_ENTRY int GetHour() const;
        // day of the month [1, 31]
        DT_CORE_DLL_ENTRY int GetMday() const;
        // month since January [1, 12]
        DT_CORE_DLL_ENTRY int GetMon() const;
        // years in AD [1, ...]
        DT_CORE_DLL_ENTRY int GetYear() const;
        // days since Sunday [0, 6]
        DT_CORE_DLL_ENTRY int GetWday() const;

        DT_CORE_DLL_ENTRY bool IsValid() const { return m_UnixTimeMs != MilliSeconds(INVALID_VALUE); }

        DT_CORE_DLL_ENTRY bool operator>(const DateTime& moment) const { return m_UnixTimeMs > moment.m_UnixTimeMs; }
        DT_CORE_DLL_ENTRY bool operator>=(const DateTime& moment) const { return m_UnixTimeMs >= moment.m_UnixTimeMs; }
        DT_CORE_DLL_ENTRY bool operator<(const DateTime& moment) const { return m_UnixTimeMs < moment.m_UnixTimeMs; }
        DT_CORE_DLL_ENTRY bool operator<=(const DateTime& moment) const { return m_UnixTimeMs <= moment.m_UnixTimeMs; }
        DT_CORE_DLL_ENTRY bool operator==(const DateTime& moment) const { return m_UnixTimeMs == moment.m_UnixTimeMs; }
        DT_CORE_DLL_ENTRY bool operator!=(const DateTime& moment) const { return m_UnixTimeMs != moment.m_UnixTimeMs; }

        DT_CORE_DLL_ENTRY static DateTime Now();

        DT_CORE_DLL_ENTRY virtual U8 GetSerializeVersion() const override { return 2; }
        DT_CORE_DLL_ENTRY virtual void Serialize(U8 version, Stream& stream) override;

        void Clear() { m_UnixTimeMs = MilliSeconds(INVALID_VALUE); }

    private:
        MilliSeconds m_UnixTimeMs = MilliSeconds(INVALID_VALUE);
    };

    DT_CORE_DLL_ENTRY String& operator<<(String& out, const DateTime& dateTime);

}