#include "generator.h"


int main ( int argc , char* argv[] )
{
  int ievt ;
  event* evt ;
  FILE* outfile ;

  ScanArguments ( argc , argv ) ;

  if ( 0==strcmp(OutFile,"") )   outfile = stdout ;
  else if ( ! (outfile=fopen(OutFile,"w")) )
    {
      fprintf(stderr,"Error opening output file %s\n",OutFile) ;
      exit (-2) ;
    }

  for ( ievt=1 ; ievt<=Nevts ; ievt++ )
    {
      evt = evt_gen (Ecm) ;
      if (evt) 
	{
	  evt->number = ievt ;
	  write_event (outfile,evt) ;
	}
    }
  fclose (outfile) ;

  return 0 ;
}


/* --------------------------------------------------------------------------------------------- */


void ScanArguments ( int argc , char* argv[] )
{
  int i ;
  for ( i=1 ; i<argc ; i++ )
    {
      if ( *argv[i] != '-' ) 
	{
	  strncpy(OutFile,argv[i],30) ;
	}
      else if ( 0==strcmp(argv[i],"-n") )
	{
	  i++ ;
	  if ( ! sscanf(argv[i],"%d",&Nevts) )
	    {
	      printf("Bad number of events: %s\n",argv[i]) ;
	      ArgError() ;
	    }
	  
	}
      else if ( 0==strcmp(argv[i],"-o") )
	{
	  i++ ;
	  strncpy(OutFile,argv[i],30) ;
	}
      else if ( 0==strcmp(argv[i],"-E") )
	{
	  i++ ;
	  if ( ! sscanf(argv[i],"%f",&Ecm) )
	    {
	      printf("Bad energy: %s\n",argv[i]) ;
	      ArgError() ;
	    }
	}
      else  ArgError() ;
    }

  if ( 0==strcmp(OutFile,"") )  printf("Output on screen\n") ;
  else printf("Output file: %s\n",OutFile) ;

  printf("%4d events will be generated at Energy = %6.2f\n",Nevts,Ecm) ;

  /*
    if ( argc!=3 )  ArgError () ;
    if ( ! (sscanf(argv[1],"%d",&Nevts)) ) ArgError () ;
    strncpy(OutFile,argv[2],30) ;
  */
}



/* --------------------------------------------------------------------------------------------- */


void ArgError ()
{
  fprintf(stderr,"Error in calling sequence\n") ;
  fprintf(stderr,"Usage: generator [-n <number of events>] [[-o] <output file>] [-E <energy>]\n") ;
  exit(-1) ;
}


/* --------------------------------------------------------------------------------------------- */


event * evt_gen ( float Ecm ) 
{
  event* evt ;
  int igood , ibad , ngood , nbad , this_one ;
  track* trk ;

  evt = Create_event() ;

  if ( flat_random() < 0.1 )  ngood = 2 ; else  ngood = 2*(int)(flat_random()*20) ;
  nbad = (int)(flat_random()*15) ;

  evt->ntrack = ngood + nbad ;

  igood = ibad = 0 ;
  while ( 1 )
    {
      /* Please note that the way we generate track parameters does not follow
	 any physical law, so don't try to understand it! */

      if ( igood < ngood )
	{
	  if ( ibad < nbad )  this_one = (flat_random()<.5) ? 1 : 0 ;
	  else  this_one = 1 ;
	}
      else 
	{
	  if ( ibad < nbad )  this_one = 0 ;
	  else break ;
	}
      
      trk = Create_track () ;

      if ( this_one )
	{
	  igood++ ;
	  trk->charge = ( (igood%2) ? +1 : -1 ) ;
	  trk->Nhits  = binom_random( 150 , 0.8 ) ;
	  trk->origin = scale( spher_random() , exp_random(1) ) ;
	  trk->P = scale( spher_random() , exp_random(Ecm/evt->ntrack) ) ;
	  trk->chi2 = chi2_random(trk->Nhits) ;
	  trk->dEdx = gauss_random(10.,3.5) ;
	}
      else
	{
	  ibad++ ;
	  trk->charge = ( (flat_random()<0.5) ? +1 : -1 ) ;
	  trk->Nhits  = binom_random( 150 , 0.2 ) ;
	  trk->origin = scale( spher_random() , exp_random(5.) ) ;
	  trk->P = scale( spher_random() , exp_random(0.8) ) ;
	  trk->chi2 = (int) (flat_random()*10.) ;
	  trk->dEdx = gauss_random(10.,6.0) ;
	}

      append_track_to_event ( evt , trk ) ;
    }

  return evt ;
}