<?php
/**
 * Watches WooCommerce for changes to products that have adverts on a marketplace and schedules the checks:
 * a takedown check always, and an update check when automatic updates are switched on (Pro).
 * Changes happen outside wp-admin too (imports, REST, cron), so this runs on every request.
 *
 * @package Tidelist
 */

namespace Tidelist\Sync;

use Tidelist\Data\ListingStatus;
use Tidelist\Jobs\Takedown;
use Tidelist\Jobs\UpdateListing;
use Tidelist\Plugin;

/**
 * Product watcher.
 */
final class ProductWatcher {

	const DEBOUNCE = 120; // Seconds to wait for further edits before checking.

	/**
	 * Plugin.
	 *
	 * @var Plugin
	 */
	private $plugin;

	/**
	 * Adverts on the marketplace: listing ID => [product ID, variation ID] (loaded once per request).
	 *
	 * @var array<int, array{0:int, 1:int}>|null
	 */
	private $watched = null;

	/**
	 * Constructor.
	 *
	 * @param Plugin $plugin Plugin.
	 */
	public function __construct( Plugin $plugin ) {
		$this->plugin = $plugin;
	}

	/**
	 * Registers the hooks.
	 */
	public function register(): void {
		// Stock and stock status, however they are changed (product screen, import, REST, code).
		add_action( 'woocommerce_variation_set_stock', array( $this, 'on_item_object' ) );
		add_action( 'woocommerce_product_set_stock', array( $this, 'on_item_object' ) );
		add_action( 'woocommerce_variation_set_stock_status', array( $this, 'on_item' ) );
		add_action( 'woocommerce_product_set_stock_status', array( $this, 'on_item' ) );
		// Price, text, photos, attributes.
		add_action( 'woocommerce_update_product_variation', array( $this, 'on_item' ) );
		add_action( 'woocommerce_save_product_variation', array( $this, 'on_item' ) );
		add_action( 'woocommerce_update_product', array( $this, 'on_item' ) );
		// Trash, unpublish, delete.
		add_action( 'transition_post_status', array( $this, 'on_transition' ), 10, 3 );
		add_action( 'before_delete_post', array( $this, 'on_item' ) );
	}

	/**
	 * A stock change that passes the product object.
	 *
	 * @param mixed $product Product.
	 */
	public function on_item_object( $product ): void {
		if ( is_object( $product ) && method_exists( $product, 'get_id' ) ) {
			$this->on_item( (int) $product->get_id() );
		}
	}

	/**
	 * A product or variation changed.
	 *
	 * @param mixed $post_id Product or variation ID.
	 */
	public function on_item( $post_id ): void {
		$post_id = (int) $post_id;
		$touched = array();
		foreach ( $this->watched() as $listing_id => $ids ) {
			if ( $ids[0] === $post_id || $ids[1] === $post_id ) {
				$touched[] = $listing_id;
			}
		}
		if ( ! $touched ) {
			return;
		}
		$auto_update = (bool) apply_filters( 'tidelist_auto_update', false );
		foreach ( $touched as $listing_id ) {
			Takedown::schedule( $listing_id, self::DEBOUNCE );
			if ( $auto_update ) {
				UpdateListing::schedule( $listing_id, self::DEBOUNCE );
			}
		}
		do_action( 'tidelist_after_product_change', $touched, $post_id );
	}

	/**
	 * A product or variation changed its status (trash, draft, publish …).
	 *
	 * @param string   $new_status New status.
	 * @param string   $old_status Old status.
	 * @param \WP_Post $post       Post.
	 */
	public function on_transition( $new_status, $old_status, $post ): void {
		if ( $new_status !== $old_status && $post instanceof \WP_Post && in_array( $post->post_type, array( 'product', 'product_variation' ), true ) ) {
			$this->on_item( $post->ID );
		}
	}

	/**
	 * Adverts that are on the marketplace (live, being checked or waiting for payment).
	 *
	 * @return array<int, array{0:int, 1:int}>
	 */
	private function watched(): array {
		if ( null === $this->watched ) {
			$this->watched = array();
			foreach ( $this->plugin->listings()->all( array( 'status' => ListingStatus::on_marketplace() ) ) as $row ) {
				if ( '' !== (string) $row['remote_id'] ) {
					$this->watched[ (int) $row['id'] ] = array( (int) $row['product_id'], (int) $row['variation_id'] );
				}
			}
		}
		return $this->watched;
	}
}