#define _POSIX_C_SOURCE 199309L

#include <err.h>
#include <signal.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

#include <libical/ical.h>
#include <raylib.h>

// Unfortunately, 0 = Sunday.
int
weekday(int year, int month, int day)
{
	struct tm tm = {
	    .tm_year = year - 1900,
	    .tm_mon = month - 1,
	    .tm_mday = day,
	};
	mktime(&tm);
	return tm.tm_wday;
}

const char *maaned[] = {
    "",	    "JANUAR", "FEBRUAR",   "MARS",    "APRIL",	  "MAI",      "JUNI",
    "JULI", "AUGUST", "SEPTEMBER", "OKTOBER", "NOVEMBER", "DESEMBER",
};
const char *ukedag[] = {
    "SØNDAG", "MANDAG", "TIRSDAG", "ONSDAG", "TORSDAG", "FREDAG", "LØRDAG",
};

enum {
	MAX_EVENTS = 64,
	SIZEOF_TITLE = 256,
};
struct event {
	int year;
	int month;
	int day;
	int wday;
	int hour;
	int minute;
	char title[SIZEOF_TITLE];
};
struct event the_events[MAX_EVENTS];
int num_events;
char *
read_stream(char *s, size_t size, void *d)
{
	return fgets(s, (int)size, (FILE *)d);
}
void
load_the_events(void)
{
	icalparser *p = icalparser_new();
	assert(p);

	FILE *f = fopen("events.ical", "r");
	assert(f);

	icalparser_set_gen_data(p, f);
	for (;;) {
		char *line = icalparser_get_line(p, read_stream);
		if (!line) {
			break;
		}

		icalcomponent *comp = icalparser_add_line(p, line);
		if (!comp) {
			continue;
		}

		for (icalcompiter i = icalcomponent_begin_component(
			 comp, ICAL_VEVENT_COMPONENT);
		     icalcompiter_deref(&i); icalcompiter_next(&i)) {
			if (MAX_EVENTS <= num_events) {
				warnx("MAX_EVENTS exceeded at %u", num_events);
				break;
			}
			icalcomponent *c = icalcompiter_deref(&i);

			struct icaltimetype dts = icalcomponent_get_dtstart(c);
			const char *sum = icalcomponent_get_summary(c);

			the_events[num_events].year = dts.year;
			the_events[num_events].month = dts.month;
			the_events[num_events].day = dts.day;
			the_events[num_events].hour = dts.hour;
			the_events[num_events].minute = dts.minute;
			strncpy(the_events[num_events].title, sum,
				SIZEOF_TITLE);
			the_events[num_events].wday =
			    weekday(dts.year, dts.month, dts.day);
			++num_events;
		}

		icalcomponent_free(comp);
	}

	icalparser_free(p);
}

const char *the_alphabet = "0123456789"
			   "ABCDEFGHIJKLMNOPQRSTUVWXYZÆØÅ"
			   "abcdefghijklmnopqrstuvwxyzæøå"
			   "!@#$%^&*()[];'\\:\"|,./<>?";

void
line(int x, int y, Font f, Color c, char *s)
{
	DrawTextEx(f, s, (Vector2){x, y}, (float)f.baseSize, 2, c);
}

int
main(void)
{
	load_the_events();

	const int sw = 1920;
	const int sh = 1080;

	InitWindow(sw, sh, "opplysning");

	SetTargetFPS(60);

	int ncp = 0;
	int *cp = LoadCodepoints(the_alphabet, &ncp);
	Font font_h = LoadFontEx("font/adventpro-bold.ttf", 60, cp, ncp);
	Font font_p = LoadFontEx("font/adventpro-semibold.ttf", 40, cp, ncp);
	UnloadCodepoints(cp);

	Color bg = RAYWHITE;
	Color fg = BLACK;
	Color hd = {0xf0, 0x4a, 0x00, 0xff};

	while (!WindowShouldClose()) {
		struct timespec now = {0};
		clock_gettime(CLOCK_REALTIME, &now);
		struct tm *ti = localtime(&now.tv_sec);
		char ts[64] = {0};
		snprintf(ts, sizeof(ts), "%02d:%02d", ti->tm_hour, ti->tm_min);

		BeginDrawing();
		ClearBackground(bg);
		line(sw / 2 - 60, 0, font_h, fg, ts);

		int y = 0;
		int year = 0, month = 0, day = 0;
		for (int i = 0; i < num_events; ++i) {
			struct event *e = the_events + i;
			if (year != e->year || month != e->month ||
			    day != e->day) {
				year = e->year;
				month = e->month;
				day = e->day;

				char s[64] = {0};
				snprintf(s, sizeof(s), "%s %u. %s",
					 ukedag[e->wday], e->day,
					 maaned[e->month]);
				line(20, y += 50, font_h, hd, s);
				y += 20;
			}
			{
				char s[64] = {0};
				snprintf(s, sizeof(s), "%02u:%02u %s", e->hour,
					 e->minute, e->title);
				line(25, y += 40, font_p, fg, s);
			}
		}
		EndDrawing();
	}

	CloseWindow();
}