#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <sys/inotify.h>
#include <poll.h>
#include <unistd.h>
#include <pthread.h>
#include <libudev.h>

static const char MONTHS[12][4] = {"Jan\0", "Feb\0", "Mar\0",
	"Apr\0", "May\0", "Jun\0",
	"Jul\0", "Aug\0", "Sep\0",
	"Oct\0", "Nov\0", "Dec\0"
};
static const char DAYS[7][4] = {"Sun\0", "Mon\0", "Tue\0", "Wed\0", "Thu\0", "Fri\0", "Sat\0"};
static const char PM[2][3] = {"AM\0", "PM\0"};

static const char TLPS[3][4] = {"\0", "\0","\0"};

struct sb26 {
	char *date;
	unsigned char tlp_status;
	unsigned short mem_used;
};

void *watchers(void *arg)
{
	struct sb26 *sb = (struct sb26*)arg;
	FILE *tlpf = fopen("/run/tlp/last_pwr", "r");
	int inf = inotify_init();
	int tlpw = inotify_add_watch(inf, "/run/tlp/last_pwr", IN_MODIFY);
	ssize_t ev_s = sizeof(struct inotify_event) + NAME_MAX + 1;
	struct pollfd pfd = {inf, POLLIN, 0};
	struct inotify_event ev;

	for (;;) {
		fscanf(tlpf, "%hhu", &sb->tlp_status);
		fseek(tlpf, 0, SEEK_SET);

		poll(&pfd, 1, INT_MAX);
		read(inf, (void *)&ev, ev_s);
		if (ev.wd == tlpw) {
			// TODO Handle other inotify watches
		}
	}
	return NULL;
}

void tmfmt(char *tmf)
{
	struct tm tm_s;
	time_t tm = time(NULL);
	tzset();
	localtime_r(&tm, &tm_s);
	unsigned char hr = tm_s.tm_hour % 12;
	if (hr == 0) hr = 12;
	snprintf(tmf, 21, "%s %s %02d %02d:%02d %s", DAYS[tm_s.tm_wday], MONTHS[tm_s.tm_mon], tm_s.tm_mday, hr, tm_s.tm_min, PM[tm_s.tm_hour/12]);
}

void *watch_mem(void *arg)
{
	struct sb26 *sb = (struct sb26*)arg;
	long total, avail;
	char buf[25];
	FILE *memf = fopen("/proc/meminfo", "r");

	for (;;) {
		fgets(buf, 25, memf);
		/* strtol can handle arbitrary leading whitespace */
		total = strtol((buf + 15), NULL, 10);
		fseek(memf, 32, SEEK_CUR);

		fgets(buf, 25, memf);
		avail = strtol((buf + 15), NULL, 10);
		unsigned int used = total - avail;
		sb->mem_used = used >> 10;
		fseek(memf, 0, SEEK_SET);
	}

	fclose(memf);
}

int main()
{
	char tmf[21];

	struct sb26 sb = { NULL, 0 };
	pthread_t watcher;
	pthread_create(&watcher, NULL, &watchers, (void *) &sb);
	pthread_t mem;
	pthread_create(&mem, NULL, &watch_mem , (void *) &sb);

	while (1) {
		tmfmt(tmf);
		printf("%d mB %s %s\n", sb.mem_used, tmf, TLPS[sb.tlp_status]);
		sleep(1);
	}

	pthread_join(watcher, NULL);
	return 0;
}