#define _GNU_SOURCE
#include <fcntl.h>        // for AT_FDCWD
#include <sys/syscall.h>
#include <unistd.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <X11/Xlib.h>
#include <stdarg.h>
#include <sys/stat.h>

static volatile sig_atomic_t done;

void die(const char *fmt, ...) {
	va_list ap;
	va_start(ap, fmt);
	vfprintf(stderr, fmt, ap);
	va_end(ap);
	fputc('\n', stderr);
	exit(1);
}

struct arg {
	const char *(*func)(const char *);
	const char *fmt;
	const char *args;
};

static void terminate() {
	done = 1;
}

const char* bg_timer(const char *unused) {
	(void)unused;
	static char buf[6];
	time_t now = time(NULL), last = now;
	FILE *f = fopen("/tmp/last_wallpaper_time", "r");
	if (f) {
		if (fscanf(f, "%ld", &last) != 1) last = now;
		fclose(f);
	}

	int rem = 600 - (int)(now - last);
	if (rem < 0) rem = 0;
	if (snprintf(buf, sizeof(buf), "%02d:%02d", (rem / 60), (rem % 60)) < 0) return NULL;
	return buf;
}

const char* run_command(const char *cmd) {
	static char buf[8];
	FILE *fp = popen(cmd, "r");
	if (!fp) return NULL;
	char *p = fgets(buf, sizeof(buf) - 1, fp);
	pclose(fp);
	if (!p) return NULL;
	if ((p = strrchr(buf, '\n'))) *p = '\0';
	return *buf ? buf : NULL;
}

const char* age(const char *_) {
    static char buf[4];
    static time_t last;
    time_t now = time(NULL);
    if (now - last < 3600) return buf;

    time_t created = 0;
    struct statx stx;
    if (!syscall(SYS_statx, AT_FDCWD, "/", 0, STATX_BTIME, &stx) && (stx.stx_mask & STATX_BTIME)) created = stx.stx_btime.tv_sec;
    else created = now;

    snprintf(buf, sizeof(buf), "%d", (int)((now - created) / 86400));
    last = now;
    return buf;
}

int main(int argc, char *argv[]) {
	static Display *dpy;
	struct sigaction act;
	size_t i, len;
	int ret;
	char status[64];
	const char *res;
	static const struct arg args[] = {
		{ bg_timer, 	" %s till swap · ", 	NULL },	
		{ run_command, 	"VOL at %s · ", 	"wpctl get-volume @DEFAULT_AUDIO_SINK@ | awk '{printf \"%d%%\", $2 * 100}'" },
		{ age,		"%s / 731 installed ", 	NULL },
	};

	memset(&act, 0, sizeof(act));
	act.sa_handler = terminate;
	sigaction(SIGINT,  &act, NULL);
	sigaction(SIGTERM, &act, NULL);
	act.sa_flags |= SA_RESTART;

	if (!(dpy = XOpenDisplay(NULL))) die("XOpenDisplay: Failed to open display");
	do {
		status[0] = '\0';
		for (i = len = 0; i < (sizeof(args) / sizeof(args[0])); i++) {
			res = args[i].func(args[i].args);
			if (!res) res = "n/a";
			if ((ret = snprintf(status + len, sizeof(status) - len, args[i].fmt, res)) < 0) break;
			len += ret;
		}

		if (XStoreName(dpy, DefaultRootWindow(dpy), status) < 0) die("XStoreName: Allocation failed");
		XFlush(dpy);

		if (!done) {
			struct timespec ts = { .tv_sec = 0, .tv_nsec = 100 * 1000000 }; // 100ms
			nanosleep(&ts, NULL);
		}
	} while (!done);

	XStoreName(dpy, DefaultRootWindow(dpy), NULL);
	if (XCloseDisplay(dpy) < 0) die("XCloseDisplay: Failed to close display");
	return 0;
}