<?php
/**
 * Queue pressure guard (§20.7).
 *
 * @package Kayvandra\MarginBeacon
 */

declare(strict_types=1);

namespace Kayvandra\MarginBeacon\Application\OrderRisk;

use Kayvandra\MarginBeacon\Infrastructure\Scheduler\SchedulerInterface;
use Kayvandra\MarginBeacon\Support\Constants;

/**
 * Soft limits that pause preview fan-out under pressure.
 */
final class QueuePressureGuard {

	const SOFT_PENDING_COUNT = 40;
	const SOFT_OLDEST_AGE_S  = 900; // 15 minutes.

	/**
	 * @var SchedulerInterface|null
	 */
	private $scheduler;

	/**
	 * @param SchedulerInterface|null $scheduler Scheduler.
	 */
	public function __construct( $scheduler = null ) {
		$this->scheduler = $scheduler;
	}

	/**
	 * Whether new preview fan-out should wait.
	 *
	 * @return array{blocked:bool,reason?:string,pending:int,oldest_age_s:?int}
	 */
	public function assess() {
		if ( ! $this->scheduler ) {
			return array(
				'blocked'      => false,
				'pending'      => 0,
				'oldest_age_s' => null,
			);
		}

		$health  = $this->scheduler->inspect_health( Constants::SCHEDULER_GROUP );
		$pending = isset( $health['pending'] ) ? (int) $health['pending'] : 0;
		$oldest  = isset( $health['oldest_pending_ts'] ) ? $health['oldest_pending_ts'] : null;
		$age     = null;
		if ( null !== $oldest ) {
			$age = max( 0, time() - (int) $oldest );
		}

		if ( $pending >= self::SOFT_PENDING_COUNT ) {
			return array(
				'blocked'      => true,
				'reason'       => sprintf(
					/* translators: %d: pending count */
					__( 'Queue pressure: %d pending MarginBeacon jobs. Finish realtime evaluations before Recent Orders Preview.', 'marginbeacon' ),
					$pending
				),
				'pending'      => $pending,
				'oldest_age_s' => $age,
			);
		}

		if ( null !== $age && $age >= self::SOFT_OLDEST_AGE_S ) {
			return array(
				'blocked'      => true,
				'reason'       => __( 'Queue pressure: oldest pending job is older than 15 minutes. Preview is deferred so new orders stay first.', 'marginbeacon' ),
				'pending'      => $pending,
				'oldest_age_s' => $age,
			);
		}

		return array(
			'blocked'      => false,
			'pending'      => $pending,
			'oldest_age_s' => $age,
		);
	}
}