<?php
/**
 * Cron events for scheduled email reports.
 *
 * @package TurtleReport
 */

namespace TurtleReport\Email;

use TurtleReport\Policy\Schedule;
use TurtleReport\Profiles\Profile;

defined( 'ABSPATH' ) || exit;

/**
 * Each client with an active schedule gets one single cron event at its next
 * send time; this class books, moves and clears those events and the next-send
 * time stored in the email log.
 */
final class SendSchedule {

	/** Single event per client: fires at that client's next send time. */
	const HOOK = 'turtlereport_send_report';

	/**
	 * Status log (next send time, last result) per client.
	 *
	 * @var EmailLog
	 */
	private $log;

	/**
	 * Constructor.
	 *
	 * @param EmailLog $log Status log.
	 */
	public function __construct( EmailLog $log ) {
		$this->log = $log;
	}

	/**
	 * Works out the next send time after the schedule changes, and books the cron event.
	 *
	 * @param Profile  $site Site.
	 * @param int|null $now  Unix timestamp.
	 * @return void
	 */
	public function reschedule( Profile $site, $now = null ) {
		$now = null === $now ? time() : (int) $now;
		if ( ! Schedule::is_active( $site->email ) ) {
			$this->forget( $site->id );
			return;
		}
		$status = $this->log->get( $site->id );
		if ( $status['next'] && $status['next'] <= $now ) {
			// Already due and not sent yet (cron was late): keep it, so saving the site doesn't skip a period.
			$this->schedule_event( $site->id, $now );
			return;
		}
		$next = Schedule::next_run( $site->email, $now, (int) $status['last_sent'] );
		$this->log->update( $site->id, array( 'next' => $next ) );
		$this->schedule_event( $site->id, $next );
	}

	/**
	 * Stops a site's emails: clears its cron event and next time.
	 *
	 * @param string $site_id Site ID.
	 * @return void
	 */
	public function forget( $site_id ) {
		wp_clear_scheduled_hook( self::HOOK, array( (string) $site_id ) );
		$this->log->update( (string) $site_id, array( 'next' => 0 ) );
	}

	/**
	 * Replaces a site's cron event with one at the given time.
	 *
	 * @param string $site_id Site ID.
	 * @param int    $when    Unix timestamp.
	 * @return void
	 */
	public function schedule_event( $site_id, $when ) {
		wp_clear_scheduled_hook( self::HOOK, array( (string) $site_id ) );
		wp_schedule_single_event( (int) $when, self::HOOK, array( (string) $site_id ) );
	}

	/**
	 * Books the cron event if it went missing or drifted.
	 *
	 * @param string $site_id Site ID.
	 * @param int    $when    Unix timestamp.
	 * @return void
	 */
	public function ensure_event( $site_id, $when ) {
		if ( (int) wp_next_scheduled( self::HOOK, array( (string) $site_id ) ) !== (int) $when ) {
			$this->schedule_event( $site_id, $when );
		}
	}
}