/*
 * SPDX-License-Identifier: AGPL-3.0-only
 * Copyright (c) Camden Dixie O'Brien
 */

#include "alarms.h"

#include "alarm_store.h"
#include "console.h"
#include "sound.h"
#include "time_manager.h"

#include "esp_log.h"
#include "freertos/FreeRTOS.h"
#include "freertos/semphr.h"
#include <stdbool.h>
#include <stdio.h>
#include <string.h>

#define TAG "Alarms"

typedef struct {
	const Alarm *alarm;
	Time end;
} ActiveAlarm;

static ActiveAlarm active[CONFIG_MAX_ALARMS];
static unsigned active_count;
static ActiveAlarm snoozed[CONFIG_MAX_ALARMS];
static unsigned snoozed_count;
static Time last_check;
static SemaphoreHandle_t state_mutex;

static Time in_minutes(unsigned minutes)
{
	Time time = get_time();
	time.minute += minutes;
	if (time.minute >= 60) {
		time.minute %= 60;
		++time.hour;
	}
	return time;
}

static bool add_alarm(Time time, bool days[WEEK_DAY_COUNT])
{
	for (unsigned i = 0; i < CONFIG_MAX_ALARMS; ++i) {
		if (!alarms[i].set) {
			alarms[i].set = true;
			alarms[i].time = time;
			memcpy(alarms[i].days, days, WEEK_DAY_COUNT * sizeof(bool));
			alarm_store_save();
			return true;
		}
	}
	return false;
}

static void remove_alarm(unsigned index)
{
	alarms[index].set = false;
	alarm_store_save();
}

static void activate(const Alarm *alarm)
{
	if (alarm < &alarms[0] || alarm >= &alarms[CONFIG_MAX_ALARMS]
	    || !alarm->set) {
		ESP_LOGE(TAG, "Invalid alarm passed to %s()", __func__);
		return;
	}

	if (active_count == 0)
		sound_alert_on();

	active[active_count].alarm = alarm;
	active[active_count].end = in_minutes(CONFIG_ALERT_MINUTES);
	++active_count;
}

static void dismiss(unsigned index)
{
	if (index >= active_count) {
		ESP_LOGE(
		    TAG, "Invalid active index %u passed to %s()", index, __func__);
		return;
	}

	if (active_count == 1)
		sound_alert_off();

	for (unsigned i = index + 1; i < active_count; ++i)
		active[i - 1] = active[i];
	--active_count;
}

static void snooze(unsigned index)
{
	if (index >= active_count) {
		ESP_LOGE(
		    TAG, "Invalid active index %u passed to %s()", index, __func__);
		return;
	}

	const Alarm *alarm = active[index].alarm;
	dismiss(index);

	snoozed[snoozed_count].alarm = alarm;
	snoozed[snoozed_count].end = in_minutes(CONFIG_SNOOZE_MINUTES);
	++snoozed_count;

	ESP_LOGI(TAG, "Alarm %u snoozed", alarm - &alarms[0]);
}

static void unsnooze(unsigned index)
{
	if (index >= snoozed_count) {
		ESP_LOGE(
		    TAG, "Invalid snooze index %u passed to %s()", index, __func__);
		return;
	}

	activate(snoozed[index].alarm);

	for (unsigned i = index + 1; i < snoozed_count; ++i)
		snoozed[i - 1] = snoozed[i];
	--snoozed_count;
}

static bool passed_since_last_check(Time time, Time now)
{
	return last_check.hour <= time.hour && time.hour <= now.hour
	    && last_check.minute <= time.minute && time.minute <= now.minute
	    && last_check.second <= time.second && time.second <= now.second;
}

static void check_alarms(Time now)
{
	// Skip if time hasn't changed since last check
	if (last_check.hour == now.hour && last_check.minute == now.minute
	    && last_check.second == now.second)
		return;

	if (xSemaphoreTake(state_mutex, (TickType_t)10) == pdFALSE)
		return;

	for (unsigned i = 0; i < CONFIG_MAX_ALARMS; ++i) {
		if (!alarms[i].set)
			continue;
		if (passed_since_last_check(alarms[i].time, now)
		    && alarms[i].days[get_week_day()])
			activate(&alarms[i]);
	}

	for (unsigned i = 0; i < active_count; ++i) {
		if (passed_since_last_check(active[i].end, now))
			dismiss(i);
	}

	for (unsigned i = 0; i < snoozed_count; ++i) {
		if (passed_since_last_check(snoozed[i].end, now))
			unsnooze(i);
	}

	last_check = now;
	xSemaphoreGive(state_mutex);
}

static bool read_dayspec(const char *dayspec, bool days_out[WEEK_DAY_COUNT])
{
	if (strlen(dayspec) != WEEK_DAY_COUNT)
		return false;
	for (unsigned i = 0; i < WEEK_DAY_COUNT; ++i) {
		if (dayspec[i] == 'x')
			days_out[i] = true;
		else if (dayspec[i] == '-')
			days_out[i] = false;
		else
			return false;
	}
	return true;
}

static void format_dayspec(
    bool days[WEEK_DAY_COUNT], char dayspec_out[WEEK_DAY_COUNT + 1])
{
	for (unsigned i = 0; i < WEEK_DAY_COUNT; ++i)
		dayspec_out[i] = days[i] ? 'x' : '-';
	dayspec_out[WEEK_DAY_COUNT] = '\0';
}

static int command_func(int argc, char **argv)
{
	if (argc == 1) {
		char dayspec[WEEK_DAY_COUNT + 1];
		for (unsigned i = 0; i < CONFIG_MAX_ALARMS; ++i) {
			if (!alarms[i].set)
				continue;
			format_dayspec(alarms[i].days, dayspec);
			printf(
			    "[%2u] %02u:%02u %s\n", i, alarms[i].time.hour,
			    alarms[i].time.minute, dayspec);
		}
		return 0;
	} else if (argc == 2 && strcmp(argv[1], "clear") == 0) {
		memset(alarms, 0, sizeof(alarms));
		alarm_store_save();
		return 0;
	} else if (argc >= 3) {
		if (strcmp(argv[1], "add") == 0) {
			Time time = { .second = 0 };
			int n = sscanf(argv[2], "%02u:%02u", &time.hour, &time.minute);
			if (n != 2) {
				printf("Invalid time\n");
				return 1;
			}
			bool days[WEEK_DAY_COUNT];
			if (argc == 4) {
				if (!read_dayspec(argv[3], days)) {
					printf("Invalid dayspec\n");
					return 1;
				}
			} else {
				for (unsigned i = 0; i < WEEK_DAY_COUNT; ++i)
					days[i] = true;
			}
			if (!add_alarm(time, days)) {
				printf("Max number of alarms already set.\n");
				return 1;
			}
			return 0;
		} else if (strcmp(argv[1], "remove") == 0) {
			unsigned index;
			int n = sscanf(argv[2], "%u", &index);
			if (n != 1 || !alarms[index].set) {
				printf("Invalid index\n");
				return 1;
			}
			remove_alarm(index);
			return 0;
		} else {
			printf("Unrecognised subcommand\n");
			return 1;
		}
	} else {
		printf("Invalid number of arguments\n");
		return 1;
	}
}

void alarms_init(void)
{
	memset(active, 0, sizeof(active));
	active_count = 0;
	memset(snoozed, 0, sizeof(snoozed));
	snoozed_count = 0;
	last_check = get_time();

	alarm_store_init();

	add_time_callback(check_alarms);

	console_register(
	    "alarms",
	    "List, add and remove alarms\n\nIf a dayspec is specified, it "
	    "should be a sequence of 'x's and '-'s (for enabled or disabled "
	    "respectively). For example: \"*-*-*--\" means Mondays, Wednesdays "
	    "and Fridays only.",
	    "alarms OR alarms add <hh:mm> [dayspec] OR alarms remove <index> OR "
	    "alarms <clear>",
	    command_func);

	state_mutex = xSemaphoreCreateMutex();
}

void alarm_snooze(void)
{
	if (xSemaphoreTake(state_mutex, (TickType_t)10) == pdFALSE) {
		ESP_LOGE(TAG, "Unable to aquire state semaphore");
		return;
	}

	if (active_count > 0)
		snooze(0);

	xSemaphoreGive(state_mutex);
}

void alarm_dismiss(void)
{
	if (xSemaphoreTake(state_mutex, (TickType_t)10) == pdFALSE) {
		ESP_LOGE(TAG, "Unable to aquire state semaphore");
		return;
	}

	if (active_count > 0)
		dismiss(0);

	xSemaphoreGive(state_mutex);
}