/* -----------------------------------------------------------------------------
 *
 * (c) The GHC Team 1998-2000
 *
 * Main function for a standalone Haskell program.
 *
 * ---------------------------------------------------------------------------*/

#define COMPILING_RTS_MAIN

#include "PosixSource.h"
#include "Rts.h"
#include "RtsAPI.h"

#include "RtsUtils.h"
#include "RtsMain.h"
#include "Prelude.h"
#include "Task.h"
#if defined(mingw32_HOST_OS)
#include "win32/seh_excn.h"
#endif

#ifdef DEBUG
# include "Printer.h"   /* for printing        */
#endif

#if defined(PARALLEL_RTS)
#include "Schedule.h"
#endif

#ifdef HAVE_WINDOWS_H
# include <windows.h>
#endif

extern void __stginit_ZCMain(void);

/* Annoying global vars for passing parameters to real_main() below
 * This is to get around problem with Windows SEH, see hs_main(). */
static int progargc;
static char **progargv;
static void (*progmain_init)(void);   /* This will be __stginit_ZCMain */
static StgClosure *progmain_closure;  /* This will be ZCMain_main_closure */

/* Hack: we assume that we're building a batch-mode system unless 
 * INTERPRETER is set
 */
#ifndef INTERPRETER /* Hack */
static void real_main(void)
{
    int exit_status;
    SchedulerStatus status;
    /* all GranSim/GUM init is done in startupHaskell; sets IAmMainThread! */

    startupHaskell(progargc,progargv,progmain_init);

    /* kick off the computation by creating the main thread with a pointer
       to mainIO_closure representing the computation of the overall program;
       then enter the scheduler with this thread and off we go;
      
       the same for GranSim (we have only one instance of this code)

       in a parallel setup, where we have many instances of this code
       running on different PEs, we should do this only for the main PE
       (IAmMainThread is set in startupHaskell) 
    */

#if defined(PARALLEL_RTS)

# if defined(DEBUG)
    /* put main PE asleep to allow attachment of gdb to UNIX threads */
    IF_PAR_DEBUG(verbose,
		 debugBelch("waiting for %lu seconds ...\n", (nat)RtsFlags.ParFlags.wait));

    sleep(RtsFlags.ParFlags.wait);

    IF_PAR_DEBUG(verbose,
		 debugBelch("...passed wait loop.\n"));
# endif

    if (IAmMainThread == rtsTrue) {

    /* ToDo: want to start with a larger stack size */
      Capability *cap;
	IF_PAR_DEBUG(verbose,
		     debugBelch("==== [%x] Main Thread Started ...\n", thisPE));

	cap = rts_lock();
	// copied from below...
	cap = rts_evalLazyIO(cap,progmain_closure, NULL);
	status = rts_getSchedStatus(cap);
	taskTimeStamp(myTask());
	rts_unlock(cap);

	IF_PAR_DEBUG(verbose,
		     debugBelch("== [%x] Main PE stopping ...\n",
				thisPE));
    } else {
      Capability *cap = rts_lock();

      /* Just to show we're alive */
      IF_PAR_DEBUG(verbose,
		   debugBelch("== [%x] Non-Main PE enters scheduler via taskStart() without work ...\n",
			   thisPE));
      /* all non-main threads enter the scheduler without work */
      startEmptyScheduler(cap);

      rts_unlock(cap);
      IF_PAR_DEBUG(verbose,
		   debugBelch("== [%x] Non-Main PE stopping ...\n",
			   thisPE));
      status = Success;  // declare victory (see shutdownParallelSystem)
    }

#  else /* !PARALLEL_RTS */

    /* ToDo: want to start with a larger stack size */
    { 
	Capability *cap = rts_lock();
	cap = rts_evalLazyIO(cap,progmain_closure, NULL);
	status = rts_getSchedStatus(cap);
	taskTimeStamp(myTask());
	rts_unlock(cap);
    }

#endif /* PARALLEL_RTS */

    /* check the status of the entire Haskell computation */
    switch (status) {
    case Killed:
      errorBelch("main thread exited (uncaught exception)");
      exit_status = EXIT_KILLED;
      break;
    case Interrupted:
      errorBelch("interrupted");
      exit_status = EXIT_INTERRUPTED;
      break;
    case HeapExhausted:
      exit_status = EXIT_HEAPOVERFLOW;
      break;
    case Success:
      exit_status = EXIT_SUCCESS;
      break;
    default:
      barf("main thread completed with invalid status");
    }
    shutdownHaskellAndExit(exit_status);
}

/* The rts entry point from a compiled program using a Haskell main function.
 * This gets called from a tiny main function which gets linked into each
 * compiled Haskell program that uses a Haskell main function.
 *
 * We expect the caller to pass __stginit_ZCMain for main_init and
 * ZCMain_main_closure for main_closure. The reason we cannot refer to
 * these symbols directly is because we're inside the rts and we do not know
 * for sure that we'll be using a Haskell main function.
 */
int hs_main(int argc, char *argv[], void (*main_init)(void), StgClosure *main_closure)
{
    /* We do this dance with argc and argv as otherwise the SEH exception
       stuff (the BEGIN/END CATCH below) on Windows gets confused */
    progargc = argc;
    progargv = argv;
    progmain_init    = main_init;
    progmain_closure = main_closure;

#if defined(mingw32_HOST_OS)
    BEGIN_CATCH
#endif
    real_main();
#if defined(mingw32_HOST_OS)
    END_CATCH
#endif
    return 0; /* not reached, but keeps gcc -Wall happy */
}
# endif /* BATCH_MODE */