<?php
/**
 * Delivery queue backed by Action Scheduler.
 *
 * @package AdPix\Analytics
 */

declare( strict_types = 1 );

namespace AdPix\Analytics\Queue;

use AdPix\Analytics\Contracts\QueueInterface;
use AdPix\Analytics\Model\Job;

defined( 'ABSPATH' ) || exit;

/**
 * Hands each delivery to Action Scheduler.
 *
 * Preferred whenever it is available, which on a WooCommerce site it always is: it stores each job
 * as its own row, runs them in a background request rather than on a customer's checkout, retries
 * without the plugin holding any state, and gives the site owner a log of every attempt under
 * WooCommerce to Status to Scheduled Actions.
 *
 * Nothing here loads or bundles Action Scheduler. It is used only when the host site already has it,
 * which is what keeps this plugin free of vendored third-party code.
 */
final class ActionSchedulerQueue implements QueueInterface {

	/**
	 * Hook fired for each queued delivery.
	 */
	public const ACTION = 'adpix_analytics_deliver';

	/**
	 * Group name, so the plugin's actions are filterable in the admin screen and can be cancelled as
	 * a set without touching anyone else's.
	 */
	public const GROUP = 'adpix-analytics';

	/**
	 * Whether this queue can be used on this site.
	 *
	 * @return bool
	 */
	public static function is_available(): bool {
		return function_exists( 'as_schedule_single_action' )
			&& function_exists( 'as_unschedule_all_actions' )
			&& function_exists( 'as_get_scheduled_actions' );
	}

	/**
	 * Schedule a delivery to run as soon as the scheduler gets to it.
	 *
	 * @param Job $job Job to deliver.
	 * @return bool
	 */
	public function push( Job $job ): bool {
		return $this->schedule( $job, 0 );
	}

	/**
	 * Schedule a retry.
	 *
	 * @param Job $job     Job carrying its incremented attempt count.
	 * @param int $delay_s Seconds to wait.
	 * @return bool
	 */
	public function retry( Job $job, int $delay_s ): bool {
		return $this->schedule( $job, max( 0, $delay_s ) );
	}

	/**
	 * How many deliveries are waiting.
	 *
	 * @return int
	 */
	public function size(): int {
		if ( ! self::is_available() ) {
			return 0;
		}

		$pending = as_get_scheduled_actions(
			array(
				'hook'     => self::ACTION,
				'group'    => self::GROUP,
				'status'   => 'pending',
				'per_page' => -1,
			),
			'ids'
		);

		return is_array( $pending ) ? count( $pending ) : 0;
	}

	/**
	 * Cancel every pending delivery.
	 *
	 * @return int
	 */
	public function purge(): int {
		if ( ! self::is_available() ) {
			return 0;
		}

		$size = $this->size();
		as_unschedule_all_actions( self::ACTION, array(), self::GROUP );

		return $size;
	}

	/**
	 * Name shown on the settings screen.
	 *
	 * @return string
	 */
	public function label(): string {
		return __( 'Action Scheduler', 'adpix-analytics' );
	}

	/**
	 * Schedule one job.
	 *
	 * @param Job $job     Job.
	 * @param int $delay_s Seconds to wait.
	 * @return bool
	 */
	private function schedule( Job $job, int $delay_s ): bool {
		if ( ! self::is_available() ) {
			return false;
		}

		// Unique is deliberately off. Two jobs for the same event carry the same event_id, and the
		// collector already collapses those; suppressing the second one here instead would also
		// suppress a genuine second status change that happened to look similar.
		$action = as_schedule_single_action(
			time() + $delay_s,
			self::ACTION,
			array( 'job' => $job->to_array() ),
			self::GROUP
		);

		return is_numeric( $action ) && (int) $action > 0;
	}
}