/*
 * rover.c
 *
 * This is the rover program from assignment 4.
 */
#include <stdio.h>
#include <math.h>

#define	OM_DIAMETER	550
#define OM_RADIUS 	(OM_DIAMETER/2)
#define LANDING_X	0
#define TARGET_X	(100+100+OM_DIAMETER)
#define OM_CENTER_X	(100+OM_DIAMETER)

int main (int argc, char *argv[]) {
	FILE	*f, *g;
	float	fuel, 		/* amount of fuel left */
		distance, 	/* distance travelled */
		xpos, 		/* x coordinate */
		ypos, 		/* y coordinate */
		h, 		/* length of hypotenuse; amount to go forward */
		angle, 		/* current heading */
		dx, 		/* difference in x coordinate */
		dy, 		/* difference in y coordinate */
		a, 		/* adjacent side length */
		o, 		/* opposite side length */
		dist;		/* distance from target */
	char	command;	/* current command */
	int	nread;		/* number of things read by fscanf */

	if (argc != 2) {
		fprintf (stderr, "not enough arguments\n");
		exit (1);
	}
	f = fopen (argv[1], "r");
	if (!f) {
		fprintf (stderr, "can't open file.\n");
		exit (1);
	}

	/* initially at (0,0) */

	xpos = LANDING_X;
	ypos = 0.0;

	/* heading east */

	angle = PI/2;

	/* 15 L of fuel */

	fuel = 15.0;

	/* get an initial command and parameter */

	nread = fscanf (f, "%c %f\n", &command, &h);

	/* while fscanf works... */

	while (nread == 2) {
		printf ("command: ");
		switch (command) {

			/* rotate; just change the heading */

			case 'r':
				printf ("rotate %6.2f\n", h);
				angle += h * (PI/180.0);
				break;

			/* go forward */

			case 'f': 
				printf ("forward %6.2f\n", h);
				/* the system forms a right triangle
				 * where 'p' is the hypotenuse,
				 * 'a' is the adjacent side, and 
			         * 'o' is the opposite side.
				 */
				a = h * cos (angle);
				o = h * sin (angle);
				xpos += o;
				ypos += a;
				fuel -= h / 70.0;
				break;
			default: printf ("not recognized!\n");
		}
		printf ("position: (%6.2f, %6.2f)\t", xpos, ypos);
		printf ("orientation: %6.2f\t", (float) (angle * (180.0/PI)));
		printf ("fuel: %6.2f\n", fuel);

		/* figure out how far we are from center of volcano */
		dx = xpos - OM_CENTER_X;
		dy = ypos - 0.0;
		dist = sqrt (dx*dx + dy*dy);

		/* give warning if too close to the volcano */

		if (dist < OM_RADIUS)
			fprintf (stderr, "we are on the volcano!\n");
		nread = fscanf (f, "%c %f\n", &command, &h);
	}
	fclose (f);

	/* how close are we to the target */

	dx = xpos - TARGET_X;
	dy = ypos - 0.0;
	dist = sqrt (dx*dx + dy*dy);
	if (fuel < 0.0) {
		fprintf (stderr, "out of fuel!\n");
	}
	if (dist < 5.0) {
		fprintf (stderr, "within 5 kilometers; ok to take sample.\n");
	} else {
		fprintf (stderr, "not within 5 kilometers; failed.\n");
	}
}