/* aircraft.c */

/* aircraft initialization module for hypothetical gaming system */

#include "ray.h"
#define AC_COOKIE 12345932
#define AC_MASK   7

typedef struct aircraft_type
{
   int    cookie;
   int    attrmask;
   char   name[NAME_LEN];
   vec_t  position;
   vec_t  direction;
   double speed;
}  aircraft_t;

static inline int getndx(
char *attrs[],       /* Table of attribute names  */
int  count,          /* Number of attribute names */
char *target)        /* name from input           */
{
   int code = -1;
   int i;

   for (i = 0; i < count; i++)
   {
      if (strcmp(target, attrs[i]) == 0)
         return(i);
   }
   return(code);
}

static char *ac_attrs[] =
{
   "position",       /* Current location of aircraft */
   "direction",      /* Direction of travel          */
   "speed",          /* Speed in NM/hr               */
};

#define NUM_ATTRS (sizeof(ac_attrs)/ sizeof(char *))

static inline void aircraft_load_position(
FILE       *in,
aircraft_t *ac)
{
   int count;
   assert(ac->cookie == AC_COOKIE);

   count = fscanf(in, "%lf %lf %lf",
                  &ac->position.x, &ac->position.y,
                  &ac->position.z);

   assert(count == 3);
}

static inline void aircraft_load_direction(
FILE       *in,
aircraft_t *ac)
{
   int count;
   assert(ac->cookie == AC_COOKIE);

   count = fscanf(in, "%lf %lf %lf",
                  &ac->direction.x, &ac->direction.y,
                  &ac->direction.z);

   assert(count == 3);
}

static inline void aircraft_load_speed(
FILE       *in,
aircraft_t *ac)
{
   int count;
   assert(ac->cookie == AC_COOKIE);

   count = fscanf(in, "%lf",  &ac->speed);

   assert(count == 1);
}

static inline void aircraft_attr_load(
FILE  *in,
aircraft_t *aircraft,
char *attr)
{
   char buf[18];
   int  ndx;

   assert(aircraft->cookie == AC_COOKIE);
   ndx = getndx(ac_attrs, NUM_ATTRS, attr);
   assert(ndx >= 0);

   aircraft->attrmask |= 1 << ndx;
   if (ndx == 0)
      aircraft_load_position(in, aircraft);
   else if (ndx == 1)
      aircraft_load_direction(in, aircraft);
   else
      aircraft_load_speed(in, aircraft);

}

/**/
/* Initialize aircraft data */

aircraft_t *aircraft_init(
FILE *in)
{
   char  buf[256];
   int   count;

/* Create new aircraft structure */

   aircraft_t *aircraft  = malloc(sizeof(aircraft_t));
   assert(aircraft != NULL);
   memset(aircraft, 0, sizeof(aircraft_t));
   aircraft->cookie = AC_COOKIE;

/* Verify the entity name */

   fscanf(in, "%s", buf);
   assert(strcmp(buf, "aircraft") == 0);

/* Acquire the name of the aircraft */

   fscanf(in, "%s", aircraft->name);

/* consume the "{" and verify we found it */

   fscanf(in, "%s", buf);
   assert(buf[0] == '{');

/* load required attributes */

   count = fscanf(in, "%s", buf);
   while ((count == 1) && (buf[0] != '}'))
   {
      aircraft_attr_load(in, aircraft, buf);
      *buf = 0;
      count = fscanf(in, "%s", buf);
   }

/* verify the closing '}'  */

   assert(buf[0] == '}');

/* Verify all required attributes loaded */

   assert(aircraft->attrmask == AC_MASK);
   return(aircraft);
}

main()
{
   aircraft_init(stdin);
}