/*

  silcwin32schedule.c

  Author: Pekka Riikonen <priikone@silcnet.org>

  Copyright (C) 2001 - 2005 Pekka Riikonen

  The contents of this file are subject to one of the Licenses specified 
  in the COPYING file;  You may not use this file except in compliance 
  with the License.
  
  The software distributed under the License is distributed on an "AS IS"
  basis, in the hope that it will be useful, but WITHOUT WARRANTY OF ANY
  KIND, either expressed or implied.  See the COPYING file for more
  information.

*/
/* $Id: silcwin32schedule.c,v 1.26.2.4 2005/04/30 15:31:27 priikone Exp $ */

#include "silcincludes.h"
#include "silcschedule_i.h"

/* Our "select()" for WIN32. This mimics the behaviour of select() system
   call. It does not call the Winsock's select() though. Its functions
   are derived from GLib's g_poll() and from some old Xemacs's sys_select().

   This makes following assumptions, which I don't know whether they
   are correct or not:

   o SILC_TASK_WRITE is ignored, if set this will return immediately.
   o If all arguments except timeout are NULL then this will register
     a timeout with SetTimer and will wait just for Windows messages
     with WaitMessage.
   o MsgWaitForMultipleObjects is used to wait all kind of events, this
     includes SOCKETs and Windows messages.
   o All Windows messages are dispatched from this function.
   o The Operating System has Winsock 2.

   References:

   o http://msdn.microsoft.com/library/default.asp?
     url=/library/en-us/winui/hh/winui/messques_77zk.asp 
   o http://msdn.microsoft.com/library/default.asp?
     url=/library/en-us/winsock/hh/winsock/apistart_9g1e.asp
   o http://msdn.microsoft.com/library/default.asp?
     url=/library/en-us/dnmgmt/html/msdn_getpeek.asp
   o http://developer.novell.com/support/winsock/doc/toc.htm

*/

int silc_select(SilcScheduleFd fds, SilcUInt32 fds_count, struct timeval *timeout)
{
  HANDLE handles[MAXIMUM_WAIT_OBJECTS];
  DWORD ready, curtime;
  LONG timeo;
  int nhandles = 0, i;
  MSG msg;

  if (fds_count > MAXIMUM_WAIT_OBJECTS)
    fds_count = MAXIMUM_WAIT_OBJECTS;

  for (i = 0; i < fds_count; i++) {
    if (!fds[i].events)
      continue;

    if (fds[i].events & SILC_TASK_READ)
      handles[nhandles++] = (HANDLE)fds[i].fd;

    /* If writing then just set the bit and return */
    if (fds[i].events & SILC_TASK_WRITE) {
      fds[i].revents = SILC_TASK_WRITE;
      return 1;
    }

    fds[i].revents = 0;
  }

  timeo = (timeout ? (timeout->tv_sec * 1000) + (timeout->tv_usec / 1000) :
	   INFINITE);

  /* If we have nothing to wait and timeout is set then register a timeout
     and wait just for windows messages. */
  if (nhandles == 0 && timeout) {
    UINT timer = SetTimer(NULL, 0, timeo, NULL);
    curtime = GetTickCount();
    while (timer) {
      WaitMessage();

      while (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE)) {
	if (msg.message == WM_TIMER) {
	  KillTimer(NULL, timer);
	  return 0;
	}
	TranslateMessage(&msg); 
	DispatchMessage(&msg); 
      }

      KillTimer(NULL, timer);
      if (timeo != INFINITE) {
	timeo -= GetTickCount() - curtime;
	curtime = GetTickCount();
	if (timeo < 0)
	  timeo = 0;
      }
      timer = SetTimer(NULL, 0, timeo, NULL);
    }
  }

 retry:
  curtime = GetTickCount();
  ready = MsgWaitForMultipleObjects(nhandles, handles, FALSE, timeo, 
				    QS_ALLINPUT);

  if (ready == WAIT_FAILED) {
    /* Wait failed with error */
    SILC_LOG_WARNING(("WaitForMultipleObjects() failed"));
    return -1;
  } else if (ready >= WAIT_ABANDONED_0 &&
	     ready < WAIT_ABANDONED_0 + nhandles) {
    /* Signal abandoned */
    SILC_LOG_WARNING(("WaitForMultipleObjects() failed (ABANDONED)"));
    return -1;
  } else if (ready == WAIT_TIMEOUT) {
    /* Timeout */
    return 0;
  } else if (ready == WAIT_OBJECT_0 + nhandles) {
    /* Windows messages. The MSDN online says that if the application
       creates a window then its main loop (and we're assuming that
       it is our SILC Scheduler) must handle the Windows messages, so do
       it here as the MSDN suggests. */
    while (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE)) {
      TranslateMessage(&msg); 
      DispatchMessage(&msg); 
    }

    /* If timeout is set then we must update the timeout since we won't
       return and we will give the wait another try. */
    if (timeo != INFINITE) {
      timeo -= GetTickCount() - curtime;
      curtime = GetTickCount();
      if (timeo < 0)
	timeo = 0;
    }

    /* Give the wait another try */
   goto retry;
  } else if (ready >= WAIT_OBJECT_0 && ready < WAIT_OBJECT_0 + nhandles) {
    /* Some other event, like SOCKET or something. */

    /* Go through all fds even though only one was set. This is to avoid
       starvation of high numbered fds. */
    ready -= WAIT_OBJECT_0;
    do {
      for (i = 0; i < fds_count; i++) {
	if (!fds[i].events)
	  continue;
	
	if (fds[i].fd == (int)handles[ready]) {
	  fds[i].revents |= SILC_TASK_READ;
	  break;
	}
      }

      /* Check the status of the next handle and set its fd to the fd
	 set if data is available. */
      while (++ready < fds_count)
	if (WaitForSingleObject(handles[ready], 0) == WAIT_OBJECT_0)
	  break;
    } while (ready < fds_count);

    return i + 1;
  }

  return -1;
}

#ifdef SILC_THREADS

/* Internal wakeup context. */
typedef struct {
  HANDLE wakeup_sema;
  SilcTask wakeup_task;
} *SilcWin32Wakeup;

SILC_TASK_CALLBACK(silc_schedule_wakeup_cb)
{
  /* Nothing */
}

#endif /* SILC_THREADS */

/* Initializes the platform specific scheduler.  This for example initializes
   the wakeup mechanism of the scheduler.  In multi-threaded environment
   the scheduler needs to be wakenup when tasks are added or removed from
   the task queues.  Returns context to the platform specific scheduler. */

void *silc_schedule_internal_init(SilcSchedule schedule, void *app_context)
{
#ifdef SILC_THREADS
  SilcWin32Wakeup wakeup;

  wakeup = silc_calloc(1, sizeof(*wakeup));

  wakeup->wakeup_sema = CreateSemaphore(NULL, 0, 100, NULL);
  if (!wakeup->wakeup_sema) {
    silc_free(wakeup);
    return NULL;
  }

  wakeup->wakeup_task = 
    silc_schedule_task_add(schedule, (int)wakeup->wakeup_sema,
			   silc_schedule_wakeup_cb, wakeup,
			   0, 0, SILC_TASK_FD, 
			   SILC_TASK_PRI_NORMAL);
  if (!wakeup->wakeup_task) {
    CloseHandle(wakeup->wakeup_sema);
    silc_free(wakeup);
    return NULL;
  }

  return (void *)wakeup;
#else
  return NULL;
#endif
}

/* Uninitializes the platform specific scheduler context. */

void silc_schedule_internal_uninit(void *context)
{
#ifdef SILC_THREADS
  SilcWin32Wakeup wakeup = (SilcWin32Wakeup)context;

  if (!wakeup)
    return;

  CloseHandle(wakeup->wakeup_sema);
  silc_free(wakeup);
#endif
}

/* Wakes up the scheduler */

void silc_schedule_internal_wakeup(void *context)
{
#ifdef SILC_THREADS
  SilcWin32Wakeup wakeup = (SilcWin32Wakeup)context;

  if (!wakeup)
    return;

  ReleaseSemaphore(wakeup->wakeup_sema, 1, NULL);
#endif
}

/* Register signal */

void silc_schedule_internal_signal_register(void *context,
                                            SilcUInt32 signal,
                                            SilcTaskCallback callback,
                                            void *callback_context)
{

}

/* Unregister signal */

void silc_schedule_internal_signal_unregister(void *context,
                                              SilcUInt32 signal,
                                              SilcTaskCallback callback,
                                              void *callback_context)
{

}

/* Mark signal to be called later. */

void silc_schedule_internal_signal_call(void *context, SilcUInt32 signal)
{

}

/* Call all signals */

void silc_schedule_internal_signals_call(void *context,
                                         SilcSchedule schedule)
{

}

/* Block registered signals in scheduler. */

void silc_schedule_internal_signals_block(void *context)
{

}

/* Unblock registered signals in schedule. */

void silc_schedule_internal_signals_unblock(void *context)
{

}