#define _ISOC99_SOURCE

#include <stdio.h>
#include <math.h>

const char
	*xml_header = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n",
	*svg_dtd = "<!DOCTYPE svg PUBLIC \"-//W3C//DTD SVG 1.0//EN\" \"http://www.w3.org/TR/2001/REC-SVG-20010904/DTD/svg10.dtd\">\n";

#define DEPTH_INCR(x) if ((x) != NULL) (*(x))++;
#define DEPTH_DECR(x) if ((x) != NULL) (*(x))--;

// thanks to LordHavoc for inspiration here
double ticklen(double frac, int divs)
{
	int x, n, iter = 0;
	double len;

	len = log2(divs) + 1;
	
	x = rint(frac * divs);
	
	for (n = divs; n > 0; n >>= 1, iter++) {
		if ((x % n) == 0)
			return (len - iter) / len;
	}

	return 0.0;
}


void indent(int *depth)
{
	int x;

	if (depth) {
		for (x = 0; x < *depth; x++)
			printf("\t");
	}
}

void svg_start(int *depth)
{
	indent(depth);
	printf("<svg>\n");
	DEPTH_INCR(depth);
}

void svg_end(int *depth)
{
	DEPTH_DECR(depth);
	indent(depth);
	printf("</svg>\n");
}

void svg_group_start(int *depth, const char *attrib)
{
	indent(depth);
	printf("<g%s%s>\n", attrib ? " " : "", attrib ? attrib : "");
	DEPTH_INCR(depth);
}

void svg_group_end(int *depth)
{
	DEPTH_DECR(depth);
	indent(depth);
	printf("</g>\n");
}

void svg_line(int *depth, double x1, double y1, double x2, double y2, const char *xu, const char *yu)
{
	indent(depth);
	printf("<line x1=\"%.6f%s\" y1=\"%.6f%s\" x2=\"%.6f%s\" y2=\"%.6f%s\" />\n",
		x1, xu, y1, yu, x2, xu, y2, yu);
}

void svg_text(int *depth, double x, double y, const char *xu, const char *yu, const char *text)
{
	indent(depth);
	printf("<text x=\"%.6f%s\" y=\"%.6f%s\" style=\"text-anchor:middle;\">%s</text>\n",
		x, xu, y, yu, text);
}

void ruler_inches(int *depth, double x, double y, double len)
{
	int tick = 0;
	double inchticks[] = { 0.5, 0.25, 0.35, 0.25, 0.45, 0.25, 0.35, 0.25 };
	double cur;
	char buf[128];

	svg_group_start(depth, "stroke=\"black\" stroke-width=\"1\"");
	svg_line(depth, x, y + 0.65, x + len, y + 0.65, "in", "in");
	for (cur = 0.0; cur <= len; cur += 1.0/8.0) {
		if (!tick) {
			if ((int)cur == 0)
				snprintf(buf, sizeof(buf), "INCHES");
			else
				snprintf(buf, sizeof(buf), "%d", (int)cur);
			svg_text(depth, x + cur, y, "in", "in", buf);
		}

		svg_line(depth, x + cur, y + 0.65 - inchticks[tick], x + cur, y + 0.65, "in", "in");
		tick++;
		tick %= 8;
	}
	svg_group_end(depth);
}

#define HEIGHT		0.65
#define TICKOFS		0.15
#define TICKHEIGHT	0.50
#define PRECISION	0.0000001

// real unit (cm, in); divisions (8 for in, 2 sizes)
void ruler(int *depth, double x, double y, double bias, double unitlen, double rulerlen, double subdiv, const char *baseunit)
{
	double cur, baselen;
	char buf[128];

	baselen = rulerlen * unitlen;

	svg_group_start(depth, "stroke=\"black\" stroke-width=\"1\"");

	// draw the bottom line - x to x + bias + length (base units)
	svg_line(depth, x, y + HEIGHT, x + bias + baselen, y + HEIGHT, baseunit, baseunit);

	// draw first tick if bias != 0
	if (bias != 0.0)
		svg_line(depth, x, y + TICKOFS, x, y + HEIGHT, baseunit, "in");
	
	for (cur = 0.0; cur <= rulerlen * unitlen + PRECISION; cur += unitlen / subdiv) {
		if (fabs(rint(cur / unitlen) - (cur / unitlen)) < PRECISION) {
			snprintf(buf, sizeof(buf), "%.0f", rint(cur / unitlen));
			svg_text(depth, x + bias + cur, y, baseunit, baseunit, buf);
		}
		svg_line(depth, x + bias + cur, y + TICKOFS + (TICKHEIGHT - (TICKHEIGHT * ticklen(cur / unitlen, subdiv))), x + bias + cur, y + HEIGHT, baseunit, "in");
	}

	svg_group_end(depth);
}

#define CM 2.54
// subtract 11/12" for foot size vs. shoe size
#define SHOEBIAS -(11.0/12.0)

int main(int argc, char *argv[])
{
	int depth = 0;
	
	printf(xml_header);
	printf(svg_dtd);
	
	svg_start(&depth);
	
	// + 11/12" for shoe size from foot size
	
	// draw a normal ruler (inches)
	ruler(&depth, 1.0, 1.0, 0.0, 1.0, 14.0, 16.0, "in");
//	// USA, Men's - 7 1/3" + 1/3" per size
	// USA, Men's - 8 1/4" + 1/3" per size
//	ruler(&depth, 1.0, 2.0, 7.0 + (1.0/3.0), 1.0/3.0, 19.0, 2.0, "in");
	ruler(&depth, 1.0, 2.0, 8.0 + (1.0/4.0) + SHOEBIAS, 1.0/3.0, 19.0, 2.0, "in");
	// USA, Women's - 7 11/12" + 1/3" per size
	ruler(&depth, 1.0, 3.0, 7.0 + (11.0/12.0) + SHOEBIAS, 1.0/3.0, 19.0, 2.0, "in");

//	// USA, "Junior" - 3 1/4" + 1/3" per size
	// USA, "Junior" -
//	ruler(&depth, 1.0, 4.0, 3.0 + (1.0/4.0), 1.0/3.0, 20.0, 2.0, "in");
	// USA, Boy's - 3 11/12" + 1/3" per size
	ruler(&depth, 1.0, 4.0, 3.0 + (11.0/12.0) + SHOEBIAS, 1.0/3.0, 20.0, 2.0, "in");
	// USA, Girl's - 3 7/12" + 1/3" per size
	ruler(&depth, 1.0, 5.0, 3.0 + (7.0/12.0) + SHOEBIAS, 1.0/3.0, 20.0, 2.0, "in");

	// UK, Adult - 7 1/2" + 1/3" per size
	ruler(&depth, 1.0, 6.0, 7.0 + (1.0/2.0) + SHOEBIAS, 1.0/3.0, 18.0, 2.0, "in");
	// UK, "Junior" - 4 3/8" + 1/3" per size
	ruler(&depth, 1.0, 7.0, 4.0 + (3.0/8.0) + SHOEBIAS, 1.0/3.0, 18.0, 2.0, "in");

	// Europe, Adult - 2/3 cm per size
	ruler(&depth, 1.0, 8.0, 0.0 + SHOEBIAS, (2.0/3.0)/CM, 50.0, 2.0, "in");
	// Europe, Junior - -2/3cm + 2/3 cm per size
	ruler(&depth, 1.0, 9.0, -(2.0/3.0)/CM + SHOEBIAS, (2.0/3.0)/CM, 50.0, 2.0, "in");

	// Mondopoint, 1 mm/size
	

	svg_end(&depth);

	return 0;
}