/*----------------------------------------------------------------------------*/
/*                                                                            */
/* Copyright (c) 1995, 2004 IBM Corporation. All rights reserved.             */
/* Copyright (c) 2005-2020 Rexx Language Association. All rights reserved.    */
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/* the terms of the Common Public License v1.0 which accompanies this         */
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/* derived from this software without specific prior written permission.      */
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/*----------------------------------------------------------------------------*/

#include "RexxCore.h"
#include "IntegerClass.hpp"
#include "RexxDateTime.hpp"
#include "Interpreter.hpp"
#include "SystemInterpreter.hpp"
#include <time.h>

#define DELTA_EPOCH_IN_MICROSECS  11644473600000000ULL

struct timezone
{
    int  tz_minuteswest; // minutes West of Greenwich
    int  tz_dsttime;     // the daylight savings time correction
};


/**
 * gets the time and date from the system clock
 *
 * @param Date   The date/time object that is used to return the time information.
 */
void SystemInterpreter::getCurrentTime(RexxDateTime *Date )
{
    FILETIME systemFileTime;
    FILETIME localFileTime;
    uint64_t sysTimeStamp = 0;
    uint64_t localTimeStamp = 0;
    // this retrieves the time as UTC, in a form we can do arithmetic with
    GetSystemTimeAsFileTime(&systemFileTime);
    // this converts the time to the local time zone
    FileTimeToLocalFileTime(&systemFileTime, &localFileTime);

    // now get these as long values so we can do math with them
    sysTimeStamp |= systemFileTime.dwHighDateTime;
    sysTimeStamp <<= 32;
    sysTimeStamp |= systemFileTime.dwLowDateTime;
    // the resolution of this is in tenths of micro seconds.  Convert to microseconds
    // which is a more realistic value
    sysTimeStamp = sysTimeStamp / 10UL;

    localTimeStamp |= localFileTime.dwHighDateTime;
    localTimeStamp <<= 32;
    localTimeStamp |= localFileTime.dwLowDateTime;
    localTimeStamp = localTimeStamp / 10UL;

    // ok, we can use this to calculate the timestamp directly
    Date->timeZoneOffset = localTimeStamp - sysTimeStamp;
    // The Citrix environment gives a strange result here that is off by
    // a few micro seconds.  This gives the DateTime class fits, so do an
    // extra rounding operation here to the nearest second.  If the offset is
    // negative, then do the rounding using the absolute value
    if ( Date->timeZoneOffset < 0)
    {
        Date->timeZoneOffset = -Date->timeZoneOffset;
        Date->timeZoneOffset = (Date->timeZoneOffset + 500000UL) / 1000000UL;
        Date->timeZoneOffset *= 1000000UL;
        Date->timeZoneOffset = -Date->timeZoneOffset;
    }
    else
    {
        Date->timeZoneOffset = (Date->timeZoneOffset + 500000UL) / 1000000UL;
        Date->timeZoneOffset *= 1000000UL;
    }

    SYSTEMTIME localTime;

    // get a localized version of the time
    FileTimeToSystemTime(&localFileTime, &localTime);

    Date->hours = localTime.wHour;
    Date->minutes = localTime.wMinute;
    Date->seconds = localTime.wSecond;
    Date->microseconds = localTime.wMilliseconds * 1000;
    Date->day = localTime.wDay;
    Date->month = localTime.wMonth;
    Date->year = localTime.wYear;
}


/**
 * Wait for a window timer message or for an event to be signaled.
 *
 * @param hev  Handle to an event object.  If this event is signaled, the
 *             function returns.
 */
static void waitTimerOrEvent(HANDLE hev)
{
    MSG msg = {0};

    /** Wait for a window timer message or for the event to be signaled. Note
     *  that MsgWaitForMultipleObjects() will return if a *new* message is
     *  placed in the message queue.  Once PeekMesage() is called, all messages
     *  in the queue need to be processed before MsgWaitForMultipleObjects() is
     *  called.
     */
    do
    {
        while ( PeekMessage(&msg, NULL, 0, 0, PM_REMOVE) )
        {
            // Check for the timer message.
            if ( msg.message == WM_TIMER )
            {
                return;
            }
            TranslateMessage(&msg);
            DispatchMessage(&msg);

            // Check if signaled.
            if ( WaitForSingleObject(hev, 0) == WAIT_OBJECT_0 )
            {
                return;
            }
        }
    } while ( MsgWaitForMultipleObjects(1, &hev, FALSE, INFINITE, QS_ALLINPUT) == WAIT_OBJECT_0 + 1 );
}


/**
 * starts a timer and waits for it to expire.
 * An event semaphore is created that can be
 * used to cancel the timer.
 *
 * numdays - number of whole days until timer should expire.
 * alarmtime - fractional portion (less than a
 *             day) until timer should expire, expressed in
 *             milliseconds.
 */
RexxMethod2(int, alarm_startTimer, wholenumber_t, numdays, wholenumber_t, alarmtime)
{
    bool fState = false;                 /* Initial state of semaphore        */
    unsigned int msecInADay = 86400000;  /* number of milliseconds in a day   */
    HANDLE SemHandle = 0;                /* Event-semaphore handle            */
    UINT_PTR TimerHandle = 0;            /* Timer handle                      */

    /* Create an event semaphore that can be used to cancel the alarm. */
    SemHandle = CreateEvent(NULL, TRUE, fState, NULL);
    if ( !SemHandle )
    {
        context->RaiseException0(Rexx_Error_System_service);
        return 0;
    }

    /* set the state variables           */
    context->SetObjectVariable("EVENTSEMHANDLE", context->NewPointer(SemHandle));
    context->SetObjectVariable("TIMERSTARTED", context->True());

    if ( numdays > 0 )
    {
        /** Alarm is for some day in the future, start a timer that wakes up
         *  once a day.
         */
        TimerHandle = SetTimer(NULL, 0, msecInADay, NULL);
        if ( TimerHandle == 0 )
        {
            /* Couldn't create a timer, raise an exception. */
            CloseHandle(SemHandle);
            context->RaiseException0(Rexx_Error_System_service);
            return 0;
        }

        while ( numdays > 0 )
        {
            /* Wait for the WM_TIMER message or for the alarm to be canceled. */
            waitTimerOrEvent(SemHandle);

            /* Check if the alarm is canceled. */
            RexxObjectPtr cancelObj = context->GetObjectVariable("CANCELED");

            if (cancelObj == context->True())
            {
                /* Alarm is canceled, delete timer, close semaphore, return. */
                KillTimer(NULL, TimerHandle);
                CloseHandle(SemHandle);
                return 0;
            }
            numdays--;
        }
        /* Done with the daily timer, delete it. */
        KillTimer(NULL, TimerHandle);
    }

    if ( alarmtime > 0 )
    {
        /* Start a timer for the fractional portion of the alarm. */
        TimerHandle = SetTimer(NULL, 0, (UINT)alarmtime, NULL);
        if ( !TimerHandle )
        {
            /* Couldn't create a timer, raise an exception. */
            CloseHandle(SemHandle);
            context->RaiseException0(Rexx_Error_System_service);
            return 0;
        }

        /* Wait for the WM_TIMER message or for the alarm to be canceled. */
        waitTimerOrEvent(SemHandle);

        /** Total alarm time has expired, or the alarm was canceled.  We don't
         *  care which, just clean up and return.
         */
        KillTimer(NULL, TimerHandle);
    }

    CloseHandle(SemHandle);
    return 0;
}


/**
 * stops an asynchronous timer.
 *
 * eventSemHandle - handle to event semaphore
 *                  used to signal the timer should be canceled.
 */
RexxMethod1(int, alarm_stopTimer, POINTER, eventSemHandle)
{
    /* Post the event semaphore to signal the alarm should be canceled. */
    if ( ! SetEvent((HANDLE)eventSemHandle) )
    {
        /* Raise an error if the semaphore could not be posted. */
        context->RaiseException0(Rexx_Error_System_service);
    }
    return 0;
}


/**
 * starts a timer and waits for it to expire.
 * An event semaphore is created that can be
 * used to cancel the timer.
 *
 * numdays - number of whole days until timer should expire.
 * alarmtime - fractional portion (less than a
 *             day) until timer should expire, expressed in
 *             milliseconds.
 */
RexxMethod3(int, ticker_waitTimer, POINTER, eventSemHandle, wholenumber_t, numdays, wholenumber_t, alarmtime)
{
    unsigned int msecInADay = 86400000;  /* number of milliseconds in a day   */
    UINT_PTR TimerHandle = 0;            /* Timer handle                      */
    HANDLE SemHandle = (HANDLE)eventSemHandle;

    if ( numdays > 0 )
    {
        /** Alarm is for some day in the future, start a timer that wakes up
         *  once a day.
         */
        TimerHandle = SetTimer(NULL, 0, msecInADay, NULL);
        if ( TimerHandle == 0 )
        {
            /* Couldn't create a timer, raise an exception. */
            CloseHandle(SemHandle);
            context->RaiseException0(Rexx_Error_System_service);
            return 0;
        }

        while ( numdays > 0 )
        {
            // Wait for the WM_TIMER message or for the Ticker to be canceled.
            waitTimerOrEvent(SemHandle);

            // Check if the Ticker was canceled.
            RexxObjectPtr cancelObj = context->GetObjectVariable("CANCELED");

            if (cancelObj == context->True())
            {
                // Ticker was canceled, delete timer, close semaphore, return
                KillTimer(NULL, TimerHandle);
                CloseHandle(SemHandle);
                return 0;
            }
            numdays--;
        }
        /* Done with the daily timer, delete it. */
        KillTimer(NULL, TimerHandle);
    }

    if ( alarmtime > 0 )
    {
        /* Start a timer for the fractional portion of the alarm. */
        TimerHandle = SetTimer(NULL, 0, (UINT)alarmtime, NULL);
        if ( !TimerHandle )
        {
            /* Couldn't create a timer, raise an exception. */
            CloseHandle(SemHandle);
            context->RaiseException0(Rexx_Error_System_service);
            return 0;
        }

        // wait for the timer to pop or the timer to be canceled.
        waitTimerOrEvent(SemHandle);
        KillTimer(NULL, TimerHandle);

        // Check if the Ticker was canceled.
        if (context->GetObjectVariable("CANCELED") == context->True())
        {
            // Ticker was canceled, close semaphore
            CloseHandle(SemHandle);
        }
    }

    return 0;
}


/**
 * set up for running a timer.
 */
RexxMethod0(int, ticker_createTimer)
{
    // create an event semaphore that we use to wait and also for canceling the alarm
    HANDLE SemHandle = CreateEvent(NULL, TRUE, false, NULL);
    if ( !SemHandle )
    {
        context->RaiseException0(Rexx_Error_System_service);
        return 0;
    }

    // store this in state variables
    context->SetObjectVariable("EVENTSEMHANDLE", context->NewPointer(SemHandle));
    context->SetObjectVariable("TIMERSTARTED", context->True());

    return 0;
}


/**
 * stops an asynchronous timer.
 *
 * eventSemHandle - handle to event semaphore
 *                  used to signal the timer should be canceled.
 */
RexxMethod1(int, ticker_stopTimer, POINTER, eventSemHandle)
{
    /* Post the event semaphore to signal the alarm should be canceled. */
    if ( ! SetEvent((HANDLE)eventSemHandle) )
    {
        /* Raise an error if the semaphore could not be posted. */
        context->RaiseException0(Rexx_Error_System_service);
    }
    return 0;
}