<?php
/**
 * Feed scheduler.
 *
 * Integrates with Action Scheduler for background feed generation.
 * Falls back to WP-Cron if Action Scheduler is not available.
 *
 * @package AICommerce\Feed
 */

declare(strict_types=1);

namespace AICommerce\Feed;

/**
 * Manages scheduled feed generation tasks.
 */
class FeedScheduler {

	/**
	 * Action hook for full feed generation.
	 *
	 * @var string
	 */
	public const GENERATE_ACTION = 'aicommerce_generate_feed';

	/**
	 * Action hook for single product re-export.
	 *
	 * @var string
	 */
	public const PRODUCT_SYNC_ACTION = 'aicommerce_sync_product_feed';

	/**
	 * Default generation interval in seconds (6 hours).
	 *
	 * @var int
	 */
	private const DEFAULT_INTERVAL = 6 * HOUR_IN_SECONDS;

	/**
	 * Feed generator instance.
	 *
	 * @var FeedGenerator
	 */
	private FeedGenerator $generator;

	/**
	 * Constructor.
	 *
	 * @param FeedGenerator $generator Feed generator.
	 */
	public function __construct( FeedGenerator $generator ) {
		$this->generator = $generator;
	}

	/**
	 * Register Action Scheduler hooks.
	 *
	 * @return void
	 */
	public function register(): void {
		add_action( self::GENERATE_ACTION, array( $this, 'handle_generate' ) );
		add_action( self::PRODUCT_SYNC_ACTION, array( $this, 'handle_product_sync' ), 10, 1 );
	}

	/**
	 * Schedule recurring feed generation.
	 *
	 * @param int $interval_seconds Interval between generations. Default: 6 hours.
	 *
	 * @return void
	 */
	public function schedule_recurring( int $interval_seconds = 0 ): void {
		if ( 0 === $interval_seconds ) {
			$interval_seconds = self::DEFAULT_INTERVAL;
		}

		if ( $this->has_action_scheduler() ) {
			if ( ! as_has_scheduled_action( self::GENERATE_ACTION ) ) {
				as_schedule_recurring_action(
					time() + $interval_seconds,
					$interval_seconds,
					self::GENERATE_ACTION,
					array(),
					'aicommerce'
				);
			}
		} elseif ( ! wp_next_scheduled( self::GENERATE_ACTION ) ) {
				wp_schedule_event( time() + $interval_seconds, 'aicommerce_feed_interval', self::GENERATE_ACTION );
		}
	}

	/**
	 * Schedule an immediate one-time feed generation.
	 *
	 * @return void
	 */
	public function schedule_immediate(): void {
		if ( $this->has_action_scheduler() ) {
			as_enqueue_async_action( self::GENERATE_ACTION, array(), 'aicommerce' );
		} else {
			wp_schedule_single_event( time(), self::GENERATE_ACTION );
		}
	}

	/**
	 * Schedule a single product re-sync.
	 *
	 * @param int $product_id Product ID to re-sync.
	 *
	 * @return void
	 */
	public function schedule_product_sync( int $product_id ): void {
		if ( $this->has_action_scheduler() ) {
			// Prevent duplicate sync actions for the same product.
			if ( ! as_has_scheduled_action( self::PRODUCT_SYNC_ACTION, array( $product_id ) ) ) {
				as_enqueue_async_action(
					self::PRODUCT_SYNC_ACTION,
					array( $product_id ),
					'aicommerce'
				);
			}
		} elseif ( ! wp_next_scheduled( self::PRODUCT_SYNC_ACTION, array( $product_id ) ) ) {
				wp_schedule_single_event( time(), self::PRODUCT_SYNC_ACTION, array( $product_id ) );
		}
	}

	/**
	 * Unschedule all feed generation actions.
	 *
	 * @return void
	 */
	public function unschedule_all(): void {
		if ( $this->has_action_scheduler() ) {
			as_unschedule_all_actions( self::GENERATE_ACTION, array(), 'aicommerce' );
			as_unschedule_all_actions( self::PRODUCT_SYNC_ACTION, array(), 'aicommerce' );
		} else {
			$timestamp = wp_next_scheduled( self::GENERATE_ACTION );
			if ( $timestamp ) {
				wp_unschedule_event( $timestamp, self::GENERATE_ACTION );
			}
		}
	}

	/**
	 * Handle the scheduled full feed generation.
	 *
	 * @return void
	 */
	public function handle_generate(): void {
		$this->generator->generate_all();
	}

	/**
	 * Handle a single product feed sync.
	 *
	 * @param int $product_id The product ID to re-sync.
	 *
	 * @return void
	 */
	public function handle_product_sync( int $product_id ): void {
		$product = wc_get_product( $product_id );
		if ( ! $product instanceof \WC_Product ) {
			return;
		}

		$this->generator->sync_product( $product );
	}

	/**
	 * Check if Action Scheduler is available.
	 *
	 * @return bool
	 */
	public function has_action_scheduler(): bool {
		return function_exists( 'as_enqueue_async_action' );
	}

	/**
	 * Register custom cron interval as fallback.
	 *
	 * @param array $schedules Existing cron schedules.
	 *
	 * @return array Modified schedules.
	 */
	public static function add_cron_interval( array $schedules ): array {
		$schedules['aicommerce_feed_interval'] = array(
			'interval' => self::DEFAULT_INTERVAL,
			'display'  => __( 'Tyralix AI Discoverability Feed Generation Interval', 'ai-discoverability-kit' ),
		);

		return $schedules;
	}
}