#define _GNU_SOURCE

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


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)
{
#ifdef EXACT_SLEEP
	struct timespec ts;
#endif /* EXACT_SLEEP */
	struct tm *tm;
	time_t now;
#ifdef BATTERY
	long long ccur, cmax, ca=-1, cb=-1, i;
#ifdef POWER
	long long pcur, pa=-1, pb=-1;
	char name[8 + 6 + 9]; /* bbb.bb% pp.pW hh:mm:ss\0 */
	char *bat = name;
	char *power = name + 8;
	char *clock = name + 8 + 6;
#else /* POWER */
	char name[8 + 9]; /* bbb.bb% hh:mm:ss\0 */
	char *bat = name;
	char *clock = name + 8;
#endif /* POWER */
	char sign = '%';
#else /* BATTERY */
	char name[9]; /* hh:mm:ss\0 */
	char *clock = name;
#endif /* BATTERY */
	struct sigaction act;
#ifndef PRINT
	Display *disp;
	int screen;
	Window root;
	char *origname = NULL;
#endif /* !PRINT */

	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);

#ifndef PRINT
	if (!(disp = XOpenDisplay(NULL))) {
		return EXIT_FAILURE;
	}
	screen = DefaultScreen(disp);
	if (!(root = RootWindow(disp, screen))) {
		return EXIT_FAILURE;
	}
	XFetchName(disp, root, &origname);

	fclose(stdout);
	fclose(stderr);
#endif /* !PRINT */
	fclose(stdin);

#ifdef BATTERY
	for (i=0; !stop; ++i) {
#else /* BATTERY */
	while (!stop) {
#endif /* BATTERY */
#ifdef BATTERY
		if (i % (BAT_REFRESH_SECONDS) == 0) {
			ccur = getnum(ENERGY_NOW) * MUL;
			cmax = getnum(ENERGY_FULL);
#ifdef CHARGING
			sign = charging() ? '+' : '%';
#endif /* CHARGING */
			if (ccur < 0 || cmax < 1) {
				ca = cb = -1;
			} else {
				ca = ccur * 10000 / cmax;
				cb = ca % 100;
				ca /= 100;
			}

#ifdef POWER
#ifdef POWER_NOW
			pcur = getnum(POWER_NOW);
#elif defined(CURRENT_NOW) && defined(VOLTAGE_NOW) /* POWER_NOW */
			pcur = (long long)getnum(CURRENT_NOW) * (long long)getnum(VOLTAGE_NOW) / 1000000;
#else /* POWER_NOW */
#error "Either POWER_NOW or CURRENT_NOW and VOLTAGE_NOW must be defined"
#endif /* POWER_NOW*/
			if (pcur < 0) {
				pa = pb = -1;
			} else {
				pa = pcur / 100000;
				pb = pa % 10;
				pa /= 10;
			}
#endif /* POWER */
		}

		if (ca < 0 || cb < 0) {
			snprintf(bat, 8, "NO BAT ");
		} else if (ca < 0 || ca > 999999 || cb < 0 || cb > 99) {
			snprintf(bat, 8, "INVALID");
		} else if (ca > 999) {
			snprintf(bat, 8, "%6lld%c", ca, sign);
		} else {
			snprintf(bat, 8, "%3lld.%02lld%c", ca, cb, sign);
		}
		bat[7] = ' ';

#ifdef POWER
		if (pa < 0 || pb < 0) {
			snprintf(power, 6, "NOPOW");
		} else if (pa < 0 || pa > 9999 || pb < 0 || pb > 9) {
			snprintf(power, 6, "????W");
		} else if (pa > 99) {
			snprintf(power, 6, "%4lldW", pa);
		} else {
			snprintf(power, 6, "%2lld.%01lldW", pa, (unsigned long long)pb);
		}
		power[5] = ' ';
#endif /* POWER */
#endif /* BATTERY */

#ifdef EXACT_SLEEP
		clock_gettime(CLOCK_REALTIME, &ts);
		now = ts.tv_sec;
#else /* EXACT_SLEEP */
		now = time(NULL);
#endif /* EXACT_SLEEP */
		tm = localtime(&now);
		strftime(clock, 9, "%H:%M:%S", tm);

#ifdef PRINT
		printf("%s\n", name);
		fflush(stdout);
#else /* PRINT */
		XStoreName(disp, root, name);
		XFlush(disp);
#endif /* PRINT */

#ifdef EXACT_SLEEP
		ts.tv_sec = 0;
		ts.tv_nsec = 1000000000 - ts.tv_nsec;
		nanosleep(&ts, NULL);
#else /* EXACT_SLEEP */
		sleep(1);
#endif /* EXACT_SLEEP */
	}

#ifndef PRINT
	if (origname) {
		XStoreName(disp, root, origname);
	}
	XCloseDisplay(disp);
#endif /* !PRINT */

	return EXIT_SUCCESS;
}