#include <stdio.h>

#define N 5

struct gshape
{
  int type; // 0/1/2
  int ID;

  union
  {
    struct
    {
      float radius;
      float x,y;

    }circle;

    struct
    {
      float x1,y1,x2,y2,x3,y3;
    }triangle;

    struct
    {
      float x1,y1; //upper left
      float x4,y4; //right bottom
    }rectangle;

  }gshape;


  void (*read_gshape) (struct gshape *gs);

  void (*write_gshape) (struct gshape *gs);

};

void read_circle(struct gshape *gs)
{
  printf("radius? ");
  scanf("%f", &(gs->gshape.circle.radius));
  printf("X center? ");
  scanf("%f", &(gs->gshape.circle.x));
  printf("Y center? ");
  scanf("%f", &(gs->gshape.circle.y));
}

void write_circle(struct gshape *gs)
{
  printf("Printing circle ID=%d: \n", gs->ID);
}

void read_triangle(struct gshape *gs)
{
  printf("Reading triangle:\n");
}

void write_triangle(struct gshape *gs)
{
  printf("Triangle (%f,%f) (%f,%f), (%f,%f)\n",gs->gshape.triangle.x1,gs->gshape.triangle.y1,gs->gshape.triangle.x2,gs->gshape.triangle.y2,gs->gshape.triangle.x3,gs->gshape.triangle.y3);
}

void read_rectangle(struct gshape *gs)
{
  printf("Reading rectangle:\n");
}

void write_rectangle(struct gshape *gs)
{
  printf("Printing rectangle:\n");
}

int main()
{
  int i, type;
  struct gshape gs[N];

  printf("Initializing the geometric shapes colletcion:\n");

  for(i=0;i<N;i++)
    {
      do
	{
	  printf("Shape ID %d: ",i);
	  printf("What type of shape is it? (0=circle, 1=triangle, 2=rectangle) ");
	  scanf("%d", &type);
	  gs[i].type=type;
	  gs[i].ID= i;

	  switch(gs[i].type)
	    {
	    case 0:
	      gs[i].read_gshape = &read_circle;
	      gs[i].write_gshape = &write_circle;
	      break;

	    case 1:
	      gs[i].read_gshape =  &read_circle;
	      gs[i].write_gshape = &write_circle;
	      break;

	    case 2:
	      gs[i].read_gshape = &read_rectangle;
	      gs[i].write_gshape = &write_rectangle;
	      break;

	    default:
	      printf("Yikes!\n");
	    }
	}while((gs[i].type != 0) && (gs[i].type != 1) && (gs[i].type != 2));
    }

  printf("Printing all the circles from our collection:\n ");

  for(i=0;i<N;i++)
    if(gs[i].type==0)
      gs[i].write_gshape(&gs[i]);

  return 1;

}