#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <termios.h>
#include <sys/ioctl.h>

struct scale {
	float read;
	float result;
};

const struct scale *current_scale = NULL;
const struct scale *voltage_scale = NULL;
float current_r = 0;

const struct scale current_scale_1 = {3851, 0.5367};
const float current_r_1 = 0.2;
const struct scale current_scale_2 = {3651, 0.9761};
const float current_r_2 = 0.1;
// const float current_r_3 = 0.05;
const struct scale voltage_scale_1 = {4041.5, 5.996};
const struct scale voltage_scale_2 = {4063.5, 13.547};
const struct scale voltage_scale_3 = {4038, 23.672};

volatile int quit;
const char *prog;

static void
set_quit(int s)
{
	quit = 1;
}

static void
usage()
{
	errx(1, "usage: %s -c [1|2] -v [1|2|3] <device>", prog);
}
int
main(int argc, char * const argv[])
{
	int d;
	int bytes;
	int nfds;
	char buf[256];
	int i;
	fd_set rfds;
	char gpio[2], current[4], tension[4];
	char *endp;
	int currenti, tensioni;
	float current_a, tension_v;
	int val;
        extern char *optarg;
	extern int optind;
	int ch;
	enum {
		INIT,
		GPIO,
		CURRENT,
		TENSION,
		MARK
	} state;

	struct termios t, ot;

	prog = argv[0];
	state = INIT;
	currenti = tensioni = 0;

	while ((ch = getopt(argc, argv, "c:v:")) != -1) {
		switch (ch) {
		case 'c':
			val = atoi(optarg);
			if (val == 1) {	
				current_scale = &current_scale_1;
				current_r = current_r_1;
			} else if (val == 2) {
				current_scale = &current_scale_2;
				current_r = current_r_2;
			}
			break;
		case 'v':
			val = atoi(optarg);
			if (val == 1) {	
				voltage_scale = &voltage_scale_1;
			} else if (val == 2) {
				voltage_scale = &voltage_scale_2;
			} else if (val == 3) {
				voltage_scale = &voltage_scale_3;
			}
			break;
		default: 
			usage();
		}
	}
	argc -= optind;
	argv += optind;

	if (argc != 1 || current_scale == NULL || voltage_scale == NULL) 
		usage();

	d = open(argv[0], O_RDWR | O_NOCTTY | O_NONBLOCK, 0);
	if (d < 0) {
		err(1, "open %s", argv[0]);
	}
	fprintf(stderr, "o\n");

	if (tcgetattr(d, &ot) < 0) {
		err(1, "tcgetattr");
	}
	fprintf(stderr, "tg\n");

	quit = 0;

	if (signal(SIGINT, set_quit) == SIG_ERR) {
		err(1, "signal(SIGINT)");
	}
	if (signal(SIGQUIT, set_quit) == SIG_ERR) {
		err(1, "signal(SIGQUIT)");
	}
	if (signal(SIGPIPE, set_quit) == SIG_ERR) {
		err(1, "signal(SIGPIPE)");
	}
	if (signal(SIGTERM, set_quit) == SIG_ERR) {
		err(1, "signal(SIGTERM)");
	}

	t = ot;
	cfmakeraw(&t);
	t.c_cflag |= CLOCAL;
	t.c_cflag &= ~CRTSCTS;
	cfsetspeed(&t, B921600);

	if (tcsetattr(d, TCSANOW | TCSAFLUSH, &t) < 0) {
		err(1, "tcsetattr");
	}
	fprintf(stderr, "tty ready\n");
	FD_ZERO(&rfds);
	while (quit == 0) {
		FD_SET(d, &rfds);
		nfds = select(d+1, &rfds, NULL, NULL, NULL);
		if (nfds > 0 && FD_ISSET(d, &rfds)) {
			bytes = read(d, buf, sizeof(buf));
			if (bytes < 0 && errno != EAGAIN) {
				warn("read");
			}
			for (i = 0; i < bytes; i++) {
				switch(state) {
				case INIT:
					/* look for an X mark */
					if (buf[i] == 'X')
						state = GPIO;
					break;
				case GPIO:
					gpio[0] = buf[i];
					gpio[1] = '\0';
					val = strtol(gpio, &endp, 16);
					if (*endp != '\0') {
						fprintf(stderr,
						    "gpio error: %c\n",
						    *endp);
						state = INIT;
					} else {
						state = TENSION;
						tensioni = 0;
						printf("%2d ", val);
					}
					break;
				case CURRENT:
					current[currenti] = buf[i];
					currenti++;
					if (currenti < 3)
						break;
					current[currenti] = '\0';
					val = strtol(current, &endp, 16);
					if (*endp != '\0') {
						fprintf(stderr,
						    "current error: %c\n",
						    *endp);
						state = INIT;
					} else {
						if (val == 4095) {
							fprintf(stderr,
							  "current saturation\n"
							  );
						}
						state = MARK;
						current_a = val / current_scale->read * current_scale->result;
						printf("%8f ", current_a);
						/* correct for in our resistor */
						tension_v -= current_a * current_r;
						printf("%8f ", tension_v);
						printf("%8f\n", current_a * tension_v);
					}
					break;
				case TENSION:
					tension[tensioni] = buf[i];
					tensioni++;
					if (tensioni < 3)
						break;
					tension[tensioni] = '\0';
					val = strtol(tension, &endp, 16);
					if (*endp != '\0') {
						fprintf(stderr,
						    "tension error: %c\n",
						    *endp);
						state = INIT;
					} else {
						if (val == 4095) {
							fprintf(stderr,
							  "tension saturation\n"
							  );
						}
						state = CURRENT;
						currenti = 0;
						tension_v = val / voltage_scale->read * voltage_scale->result;
					}
					break;
				case MARK:
					if (buf[i] != 'X') {
						fprintf(stderr,
						    "mark error: %c\n",
						    buf[i]);
						state = INIT;
					} else {
						state = GPIO;
					}
					break;
				}
			}
		} else if (nfds < 0) {
			warn("select");
		}
	}
	if (tcsetattr(d, TCSANOW, &ot) < 0) {
		err(1, "restore tcsetattr");
	}
	exit(0);
}