#include <math.h>
#include <grass/gis.h>
#include <grass/raster.h>
#include "local_proto.h"

static int first;
static int prevx, prevy;

int get_circle (FILE *fd, struct Categories *labels)
{
    int ok;

    static struct point              /* used to build 1/4 arc of the circle */
    {
	int x,y;
    } *points = NULL;

    char east[128], north[128];

    int cx, cy, px, py;
    int radius;
    int i,count;
    double r2, atx, aty;

    fprintf (stdout,"Mark the center of the circle\n");
    instructions(0);
    instructions(1);

    cx = cy = -9999;
    if (!get_point (&cx, &cy, east, north))
	return 0;

    px = cx+10;
    py = cy+10;
    first = 1;
    do
    {
	fprintf (stdout,"Mark a point on the perimeter\n");
	if (first) instructions(0);
	instructions(1);
	first = 0;

	if (!get_point (&px, &py, east, north))
	    return 0;

	radius = (int) (hypot((double)(cx-px), (double)(cy-py)) + 0.5);
	if (radius <= 0)
	{
	    fprintf (stdout,"Circle too small\n");
	    instructions(1);
	}
    }
    while (radius <= 0);

    r2 = (double) radius * radius;

    points = (struct point *) G_realloc (points, sizeof(*points) * radius + 1);

    count = 0;
    for (atx=(double)radius, aty = 0.0; atx >= aty; /*empty*/)
    {
	points[count].x = (int) (atx+0.5);
	points[count].y = (int) (aty+0.5);
	count++;
	aty += 1.0;
	atx = sqrt (r2 - aty*aty);
    }

    first = 1;
    fprintf(fd, "AREA (circle)\n");

/* 0 to 45 degrees */
    for (i=0; i<count; i++)
	draw_and_record (fd, points[i].x, points[i].y, cx, cy);

/* 45 to 90 degrees */
    for (i=count-1; i>=0; i--)
	draw_and_record (fd, points[i].y, points[i].x, cx, cy);

/* 90 to 135 degrees */
    for (i=0; i<count; i++)
	draw_and_record (fd, -points[i].y, points[i].x, cx, cy);

/* 135 to 180 degrees */
    for (i=count-1; i>=0; i--)
	draw_and_record (fd, -points[i].x, points[i].y, cx, cy);

/* 180 to 225 degrees */
    for (i=0; i<count; i++)
	draw_and_record (fd, -points[i].x, -points[i].y, cx, cy);

/* 225 to 270 degrees */
    for (i=count-1; i>=0; i--)
	draw_and_record (fd, -points[i].y, -points[i].x, cx, cy);

/* 270 to 315 degrees */
    for (i=0; i<count; i++)
	draw_and_record (fd, points[i].y, -points[i].x, cx, cy);

/* 315 to 360 degrees */
    for (i=count-1; i>=0; i--)
	draw_and_record (fd, points[i].x, -points[i].y, cx, cy);

    R_flush();

    get_category (fd, "circle", labels);
    return 1;
}

int 
draw_and_record (FILE *fd, int x, int y, int cx, int cy)
{
    char east[128], north[128];

    x += cx;
    y += cy;
    get_east_north(x, y, east, north);
    fprintf (fd, " %s %s\n", east, north);
    if (!first)
	black_and_white_line (prevx, prevy, x, y);
    first = 0;
    prevx = x;
    prevy = y;
    return 0;
}