#define _GNU_SOURCE

#include <errno.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <X11/Xlib.h>


int stop = 0;

#ifdef BATTERY
char *readfile(char *buf, size_t len, const char *fn) {
	FILE *f;
	size_t n;

	f = fopen(fn, "r");
	if (!f) {
		return NULL;
	}
	n = fread(buf, 1, len-1, f);
	if (ferror(f)) {
		return NULL;
	}
	fclose(f);
	if (n >= len-1 || n < 1) {
		return NULL;
	}
	buf[n] = '\0';

	return buf;
}

int getnum(const char *fn) {
	char buf[1024];

	if (readfile(buf, sizeof(buf), fn)) {
		return atoi(buf);
	}
	return -1;
}

#ifdef CHARGING
int charging(void) {
	char buf[1024];

	if (readfile(buf, sizeof(buf), STATUS)) {
		return !strcmp(buf, CHARGING);
	}
	return 0;
}
#endif /* CHARGING */
#endif /* BATTERY */

void handler(int sig)
{
	stop = sig;
}

int main(void)
{
	struct tm *tm;
	time_t now;
#ifdef BATTERY
	long long curr, max, a=-1, b=-1, i;
	char name[8 + 9]; /* (p)pp.pp% hh:mm:ss\0 */
	char *perc = name;
	char *clock = name + 8;
	char sign = '%';
#else
	char name[9]; /* hh:mm:ss\0 */
	char *clock = name;
#endif /* BATTERY */
	struct sigaction act;
	Display *disp;
	int screen;
	Window root;

	act.sa_handler = handler;
	act.sa_flags = 0;
	sigemptyset(&act.sa_mask);
	sigaction(SIGHUP, &act, NULL);
	sigaction(SIGINT, &act, NULL);
	sigaction(SIGQUIT, &act, NULL);
	sigaction(SIGTERM, &act, NULL);


	disp = XOpenDisplay(NULL);
#ifdef BATTERY
	for (i=0; !stop; ++i) {
#else
	while (!stop) {
#endif /* BATTERY */
		if (!disp) {
			puts("Cannot open display!");
			return 1;
		}
		screen = DefaultScreen(disp);
		root = RootWindow(disp, screen);
#ifdef BATTERY
		if (i % (BAT_REFRESH_SECONDS) == 0) {
			curr = getnum(ENERGY_NOW) * MUL;
			max = getnum(ENERGY_FULL);
#ifdef CHARGING
			sign = charging() ? '+' : '%';
#endif /* CHARGING */
			if (curr < 0 || max < 1) {
				a = b = -1;
			} else {
				a = curr * 10000 / max;
				b = a % 100;
				a /= 100;
			}
		}

		if (a < 0 || b < 0) {
			snprintf(perc, 8, "NO BAT ");
		} else if (a < 0 || a > 999999 || b < 0 || b > 99) {
			snprintf(perc, 8, "INVALID");
		} else if (a > 999) {
			snprintf(perc, 8, "%6lld%c", a, sign);
		} else {
			snprintf(perc, 8, "%3lld.%02lld%c", a, b, sign);
		}
		perc[7] = ' ';
#endif /* BATTERY */

		now = time(NULL);
		tm = localtime(&now);
		strftime(clock, 9, "%H:%M:%S", tm);

		XStoreName(disp, root, name);
		XFlush(disp);
		sleep(1);
	}
	XCloseDisplay(disp);


	return 0;
}