/***
    Copyright (C) 2021 J Reece Wilson (a/k/a "Reece"). All rights reserved.

    File: Sleep.cpp
    Date: 2021-6-12
    Author: Reece
***/
#include <Source/RuntimeInternal.hpp>
#include "Sleep.hpp"
#include "WaitFor.hpp"

#if defined(AURORA_IS_POSIX_DERIVED)
    #include <unistd.h>
#endif

#if defined(AURORA_IS_MODERNNT_DERIVED)
    #include <Time/Time.hpp>
#endif

namespace Aurora::Threading
{

#if defined(AURORA_IS_MODERNNT_DERIVED)
    using NtDelayExecution_f = DWORD(NTAPI *)(BOOLEAN Alertable, PLARGE_INTEGER       DelayInterval);
    static NtDelayExecution_f NtDelayExecution;
#endif

    AUKN_SYM void Sleep(AuUInt64 timeout)
    {
    #if defined(AURORA_IS_LINUX_DERIVED) 

        SleepNs(AuMSToNS<AuUInt64>(timeout));

    #elif defined(AURORA_IS_MODERNNT_DERIVED)
        
        ::Sleep(timeout);
    
    #else
        std::atomic<bool> value = false;
        BooleanWaitable waitable(value);
        WaitFor(&waitable, timeout);
    #endif 
    }

    AUKN_SYM void SleepNs(AuUInt64 timeout)
    {
    #if defined(AURORA_IS_LINUX_DERIVED) || defined(AURORA_IS_BSD_DERIVED)

        auto endTime = AuTime::CurrentClockNS() + timeout;

        if ((usleep(timeout / 1000) == -1) && 
            (errno == EINTR))
        {
            AuUInt64 now;
            while ((now = AuTime::CurrentClockNS()) < endTime)
            {
                usleep((endTime - now) / 1000);
            }
        }

    #else
    
    #if defined(AURORA_IS_MODERNNT_DERIVED)

        if (NtDelayExecution)
        {
            auto endTime = AuTime::CurrentClockNS() + timeout;
            auto targetTime = AuTime::ConvertTimestampNs(endTime);

            while (AuTime::CurrentClockNS() < endTime)
            {
                LARGE_INTEGER word;
                word.QuadPart = targetTime;
                NtDelayExecution(FALSE, &word);
            }

            return;
        }

    #endif

        auto status = YieldPollNs(true, timeout + Time::CurrentInternalClockNS(), [=]()
        {
            return false;
        });
    #endif
    }

    void InitSleep()
    {
    #if defined(AURORA_IS_MODERNNT_DERIVED)
        NtDelayExecution = AuReinterpretCast<NtDelayExecution_f>(GetProcAddress(LoadLibraryA("ntdll.dll"), "NtDelayExecution"));
    #endif
    }
}