<?php

namespace RoosterLMS\Notify;

use RoosterLMS\Core\Clock;
use RoosterLMS\Domain\Services;

defined( 'ABSPATH' ) || exit;

final class NotifyJobs {

	public const HOOK = 'rooster_lms/send_notifications';

	public const GROUP = 'rooster-lms';

	private static ?int $deferred = null;

	private static bool $registered = false;

	public function register(): void {
		if ( self::$registered ) {
			return;
		}
		self::$registered = true;
		add_action( self::HOOK, array( $this, 'run' ), 10, 0 );
	}

	public function run(): void {
		Services::notifier()->send_due( 50, 20 );
		self::install();
	}

	public static function install(): void {
		$next = Services::notifier()->next_due();
		if ( null !== $next ) {
			self::schedule( max( Clock::timestamp(), (int) strtotime( $next . ' UTC' ) ) );
		}
	}

	public static function schedule( int $timestamp ): void {
		if ( ! did_action( 'action_scheduler_init' ) ) {
			if ( null === self::$deferred ) {
				add_action( 'action_scheduler_init', array( self::class, 'schedule_deferred' ) );
			}
			self::$deferred = null === self::$deferred ? $timestamp : min( self::$deferred, $timestamp );
			return;
		}
		if ( ! function_exists( 'as_get_scheduled_actions' ) || ! function_exists( 'as_schedule_single_action' ) ) {
			return;
		}
		$next = self::next_pending();
		if ( null !== $next && $next <= $timestamp ) {
			return;
		}
		if ( null !== $next && function_exists( 'as_unschedule_all_actions' ) ) {
			as_unschedule_all_actions( self::HOOK, array(), self::GROUP );
		}
		as_schedule_single_action( $timestamp, self::HOOK, array(), self::GROUP, false );
	}

	private static function next_pending(): ?int {
		if ( ! class_exists( '\ActionScheduler_Store' ) ) {
			return null;
		}
		$actions = as_get_scheduled_actions(
			array(
				'hook'     => self::HOOK,
				'group'    => self::GROUP,
				'status'   => \ActionScheduler_Store::STATUS_PENDING,
				'orderby'  => 'date',
				'order'    => 'ASC',
				'per_page' => 1,
			)
		);
		foreach ( is_array( $actions ) ? $actions : array() as $action ) {
			$date = $action instanceof \ActionScheduler_Action ? $action->get_schedule()->get_date() : null;
			return $date instanceof \DateTimeInterface ? $date->getTimestamp() : 0;
		}
		return null;
	}

	public static function schedule_deferred(): void {
		$at             = self::$deferred;
		self::$deferred = null;
		if ( null !== $at ) {
			self::schedule( $at );
		}
	}
}