#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>

#define BUTTON_DEV "/dev/ppb"

#define USLEEP_TIME 50000	/* sleep 0.05 s*/

#define NO_OF_BUTTONS 4

#define PRESSED 0
#define RELEASED 1

static int daemon_mode = 0;

static char * actions[2 * NO_OF_BUTTONS] = {
	NULL, NULL,
	"halt", NULL,
	NULL, NULL,
	NULL, NULL,
};

void usage ()
{
	fprintf(stderr, "Usage: button_exec [-d] <config file>\n");
}

void action (int act, int button)
{
	char * command;

	command = actions[act + 2*button];
	if (command != NULL) {
		if (system(command) < 0) {
			perror("action");
		}
	}
}

void check (unsigned char old_data, unsigned char new_data)
{
	int i, button;
	unsigned char changed;

	changed = old_data ^ new_data;
	for (i = 0; i < NO_OF_BUTTONS; i++) {
		button = 1 << i;
		if (changed & button) {
			if (new_data & button) {
				action(PRESSED, i);
			} else {
				action(RELEASED, i);
			}
		}
	}
}

int parse_commandline (int argc, char ** argv)
{
	int i;

	for (i = 1; i < argc; i++) {
		if (strcmp(argv[i], "-d") == 0) {
			daemon_mode = 1;
		} else {
			return 2;
		}
	}
	return 0;
}

int main (int argc, char ** argv)
{
	int fd, r, daemon_mode = 0;
	unsigned char old_data, data;

	if (parse_commandline(argc, argv) != 0) {
		usage();
		return 2;
	}

	fd = open(BUTTON_DEV, O_RDONLY);
	if (fd < 0) {
		perror("Error opening key device");
		return 1;
	}

	if (daemon_mode) {
		if (daemon(0, 1) == -1) {
			perror("Error detaching");
			return 1;
		}
	}

	while (1) {
		r = read(fd, &old_data, 1);
		if (r < 0) {
			perror("Read error");
			return 1;
		}
		do {
			usleep(USLEEP_TIME);
			r = read(fd, &data, 1);
			if (r < 0) {
				perror("Read error");
				return 1;
			}
		} while (data == old_data);
		check(old_data, data);
	}

}