/*
 * Copyright (C) 2017 Andy Spencer <andy753421@gmail.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#define _POSIX_C_SOURCE 200112L

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#include "util.h"
#include "conf.h"
#include "date.h"
#include "cal.h"
#include "daemon.h"

/* Config data */
static int   reminder = 15*60;
static char *command  = NULL;

/* Local data */
static date_t old;
static date_t new;

/* Local functions */
static void date_str(char *str, size_t size, date_t *date)
{
	snprintf(str, size, "%04d-%02d-%02d %02d:%02d:%02d",
			date->year+1, date->month+1, date->day,
			date->hour,   date->min,     date->sec);
}

static void notify(event_t *event)
{
	static char start_str[32];
	static char end_str[32];

	date_t start = event->start;
	date_t end   = event->end;
	wday_t wday  = day_of_week(start.year, start.month, start.day);

	if (command) {
		date_str(start_str, sizeof(start_str), &event->start);
		date_str(end_str, sizeof(end_str), &event->end);

		setenv("EVENT_NAME",  event->name ?: "", 1);
		setenv("EVENT_DESC",  event->desc ?: "", 1);
		setenv("EVENT_LOC",   event->loc  ?: "", 1);
		setenv("EVENT_START", start_str, 1);
		setenv("EVENT_END",   end_str,   1);

		system(command);

		unsetenv("EVENT_NAME");
		unsetenv("EVENT_DESC");
		unsetenv("EVENT_LOC");
		unsetenv("EVENT_START");
		unsetenv("EVENT_END");
	} else {
		printf("%s, %s %d, %d, %02d:%02d-%02d:%02d\n",
			day_to_string(wday),
			month_to_string(start.month),
			start.day+1,
			start.year,
			start.hour, start.min,
			end.hour,   end.min);

		if (event->name)
			printf("    Name:     %s\n", event->name);
		if (event->loc)
			printf("    Location: %s\n", event->loc);
		if (event->desc)
			printf("    Details:  %s\n", event->desc);
	}
}

static int step(void)
{
	int delay = 24*60*60;

	debug("Polling: %02dh %02dm %02ds",
		NOW.hour, NOW.min, NOW.sec);

	/* Bump timestamps */
	old = new;
	new = NOW;

	/* Print notifications */
	for (event_t *cur = EVENTS; cur; cur = cur->next) {
		if (compare(&cur->start, &old) < 0)
			continue;

		int old_until = get_secs(&old, &cur->start);
		int new_until = get_secs(&new, &cur->start);

		if (old_until > reminder && new_until <= reminder) {
			debug("Notify: %s", cur->name);
			notify(cur);
		}
		if (new_until > reminder) {
			delay = new_until - reminder;
			break;
		}
	}

	/* Return delay */
	return delay;
}

/* Initialize */
void daemon_init(void)
{
	old = NOW;
	new = NOW;
}

void daemon_main(void)
{
	int delay = 0;
	while (1) {
		date_sync();
		delay = step();
		fflush(stdout);
		sleep(delay);
	}
}

void daemon_exit(void)
{
}

/* Config parser */
void daemon_config(const char *group, const char *name, const char *key, const char *value)
{
	if (match(group, "daemon")) {
		if (match(key, "reminder")) {
			reminder = get_number(value);
		} else if (match(key, "notify")) {
			command = get_string(value);
		}
	}
}

/* Test */
void daemon_test(void)
{
	static event_t event0 = {
		.name   = "test event",
		.desc   = "this event is random and does not exist",
	};
	static event_t event1 = {
		.name   = "test event",
		.desc   = "this event is random and does not exist",
	};
	static todo_t todo = {
		.name   = "test todo",
		.desc   = "this todo is random and does not exist",
		.status = 50,
	};

	EVENTS = &event0;
	EVENTS->next = &event1;
	TODOS = &todo;

	date_sync();

	NOW.hour    = 0;
	NOW.min     = 0;
	NOW.sec     = 0;

	event0.start = ((date_t){NOW.year, NOW.month, NOW.day, 12, 0});
	event0.end   = ((date_t){NOW.year, NOW.month, NOW.day, 13, 0});
	event1.start = ((date_t){NOW.year, NOW.month, NOW.day, 14, 0});
	event1.end   = ((date_t){NOW.year, NOW.month, NOW.day, 15, 0});
	todo.due     = ((date_t){NOW.year, NOW.month, NOW.day, 16, 0});

	util_init();

	daemon_config("daemon", NULL, "reminder", "15");
	daemon_config("daemon", NULL, "notify", "lackey-notify");

	daemon_init();
	while (NOW.day == EVENTS->start.day) {
		int delay = step();
		delay = MIN(delay, rand() % (60*60));
		NOW = get_date(get_stamp(NOW)+delay);
	}
	daemon_exit();
}