#include <stdlib.h>
#include <stdarg.h>

#include "plot.h"
#include "istack.h"
#include "dirimpl.h"
#include "dir-line.h"

typedef struct priv PRIV;

struct priv {
  int n;
  int err;
  double x1;
  double y1;
  double x2;
  double y2;
  } ;

DIRRV dir_line(void **privp, DIROP op, ...)
{
 va_list ap;
 PRIV *p;
 char *s;
 char c;
 double v;

 va_start(ap,op);
 switch (op)
  { default:
       abort();
       break;
    case DIROP_INIT:
       p = malloc(sizeof(PRIV));
       p->n = 0;
       p->err = 0;
       *privp = p;
       return(DIRRV_MORE);
       break;
    case DIROP_ARG:
       p = *privp;
       s = va_arg(ap,char *);
       if (s == 0)
	{ switch (p->n++)
	   { default:
		abort();
		break;
	     case 0: istack_err("missing X1 value"); break;
	     case 1: istack_err("missing Y1 value"); break;
	     case 2: istack_err("missing X2 value"); break;
	     case 3: istack_err("missing Y2 value"); break;
	   }
	  free(p);
	  return(DIRRV_NOMORE);
	}
       if (!p->err && (sscanf(s,"%lg%c",&v,&c) != 1))
	{ p->err = 1;
	  switch (p->n)
	   { case 0: istack_err("invalid X1 value"); break;
	     case 1: istack_err("invalid Y1 value"); break;
	     case 2: istack_err("invalid X2 value"); break;
	     case 3: istack_err("invalid Y2 value"); break;
	     default: abort(); break;
	   }
	}
       if (p->err)
	{ p->n ++;
	  if (p->n < 4) return(DIRRV_MORE);
	  free(p);
	  return(DIRRV_NOMORE);
	}
       switch (p->n++)
	{ case 0: p->x1 = v; break;
	  case 1: p->y1 = v; break;
	  case 2: p->x2 = v; break;
	  case 3: p->y2 = v; break;
	}
       if (p->n > 3)
	{ plot_line(p->x1,p->y1,p->x2,p->y2);
	  free(p);
	  return(DIRRV_NOMORE);
	}
       return(DIRRV_MORE);
       break;
  }
 va_end(ap);
 abort();
}