le the woocommerce_attribute_updated hook.
	 *
	 * @param int   $id The attribute ID.
	 * @param array $data The attribute data.
	 *
	 * @return void
	 *
	 * @since 10.5.0
	 *
	 * @internal
	 */
	public function handle_woocommerce_attribute_updated( $id, $data ): void {
		if ( ! is_array( $data ) || ! isset( $data['attribute_name'] ) ) {
			return;
		}

		$taxonomy = wc_attribute_taxonomy_name( $data['attribute_name'] );
		$this->invalidate_products_with_attribute( $taxonomy );
	}

	/**
	 * Handle the woocommerce_attribute_deleted hook.
	 *
	 * @param int    $id The attribute ID.
	 * @param string $name The attribute name.
	 * @param string $taxonomy The attribute taxonomy.
	 *
	 * @return void
	 *
	 * @since 10.5.0
	 *
	 * @internal
	 */
	public function handle_woocommerce_attribute_deleted( $id, $name, $taxonomy ): void {
		if ( ! is_string( $taxonomy ) || '' === $taxonomy ) {
			return;
		}

		$this->invalidate_products_with_attribute( $taxonomy );
	}

	/**
	 * Handle the woocommerce_updated_product_attribute_summary hook.
	 *
	 * @param int $variation_id The variation ID.
	 *
	 * @return void
	 *
	 * @since 10.5.0
	 *
	 * @internal
	 */
	public function handle_woocommerce_updated_product_attribute_summary( $variation_id ): void {
		$this->invalidate_variation_and_parent( (int) $variation_id );
	}

	/**
	 * Handle the edited_term hook.
	 *
	 * @param int    $term_id The term ID.
	 * @param int    $tt_id The term taxonomy ID.
	 * @param string $taxonomy The taxonomy slug.
	 *
	 * @return void
	 *
	 * @since 10.5.0
	 *
	 * @internal
	 */
	public function handle_edited_term( $term_id, $tt_id, $taxonomy ): void {
		if ( ! is_string( $taxonomy ) ) {
			return;
		}

		// Only handle product attribute taxonomies.
		if ( 0 !== strpos( $taxonomy, 'pa_' ) ) {
			return;
		}

		$this->invalidate_products_with_term( (int) $tt_id );
	}

	/**
	 * Get the parent product ID for a variation.
	 *
	 * The result is cached in the object cache to avoid repeated lookups.
	 *
	 * @param int $variation_id The variation ID.
	 *
	 * @return int|null The parent product ID, or null if not found.
	 */
	private function get_variation_parent_id( int $variation_id ): ?int {
		$cache_key = "wc_variation_parent_{$variation_id}";
		$cached    = wp_cache_get( $cache_key, 'woocommerce' );

		if ( false !== $cached ) {
			// Cast to int: persistent object cache backends (e.g. Redis) can return scalars as strings,
			// which would violate this method's ?int return type.
			return $cached ? (int) $cached : null;
		}

		if ( $this->is_using_cpt_data_store() ) {
			$parent_id = wp_get_post_parent_id( $variation_id );
			$parent_id = $parent_id ? (int) $parent_id : null;
		} else {
			$variation = wc_get_product( $variation_id );
			$parent_id = $variation ? (int) $variation->get_parent_id() : null;
			$parent_id = $parent_id ? $parent_id : null;
		}

		// Cache the result (store 0 for null to distinguish from cache miss).
		wp_cache_set( $cache_key, $parent_id ?? 0, 'woocommerce', HOUR_IN_SECONDS );

		return $parent_id;
	}

	/**
	 * Invalidate the cached parent ID for a variation.
	 *
	 * @param int $variation_id The variation ID.
	 *
	 * @return void
	 */
	private function invalidate_variation_parent_cache( int $variation_id ): void {
		wp_cache_delete( "wc_variation_parent_{$variation_id}", 'woocommerce' );
	}

	/**
	 * Invalidate a variation and its parent product.
	 *
	 * @param int      $variation_id The variation ID.
	 * @param int|null $parent_id Optional parent product ID. If not provided, will be looked up.
	 *
	 * @return void
	 */
	private function invalidate_variation_and_parent( int $variation_id, ?int $parent_id = null ): void {
		$this->invalidate( $variation_id );

		if ( is_null( $parent_id ) ) {
			$parent_id = $this->get_variation_parent_id( $variation_id );
		}

		if ( ! $parent_id ) {
			return;
		}

		$this->invalidate( $parent_id );
	}

	/**
	 * Invalidate all products and variations that have a specific term assigned.
	 *
	 * Uses the indexed wp_term_relationships table for efficient lookups.
	 * The list of entities associated with the term is cached for performance;
	 * the TTL can be customized via the 'woocommerce_version_string_invalidator_taxonomy_lookup_ttl' filter.
	 *
	 * @param int $tt_id The term taxonomy ID.
	 *
	 * @return void
	 */
	private function invalidate_products_with_term( int $tt_id ): void {
		global $wpdb;

		$cache_key  = 'wc_cache_inv_term_' . $tt_id;
		$entity_ids = wp_cache_get( $cache_key, 'woocommerce' );

		if ( false === $entity_ids ) {
			$entity_ids = $wpdb->get_col(
				$wpdb->prepare(
					"SELECT tr.object_id
					FROM {$wpdb->term_relationships} tr
					INNER JOIN {$wpdb->posts} p ON tr.object_id = p.ID
					WHERE tr.term_taxonomy_id = %d
					AND p.post_type IN ('product', 'product_variation')",
					$tt_id
				)
			);

			/**
			 * Filters the cache TTL for queries that find entities associated with a term or taxonomy.
			 *
			 * These queries are used during cache invalidation to determine which entities
			 * (e.g., products, variations) need their cache cleared when a term or attribute changes.
			 *
			 * @since 10.5.0
			 *
			 * @param int    $ttl         Cache TTL in seconds. Default 300 (5 minutes).
			 * @param string $entity_type The type of entity being invalidated ('product').
			 */
			$ttl = apply_filters( 'woocommerce_version_string_invalidator_taxonomy_lookup_ttl', self::DEFAULT_TAXONOMY_LOOKUP_CACHE_TTL, 'product' );
			wp_cache_set( $cache_key, $entity_ids, 'woocommerce', $ttl );
		}

		foreach ( $entity_ids as $entity_id ) {
			$post_type = get_post_type( (int) $entity_id );
			if ( 'product_variation' === $post_type ) {
				$this->invalidate_variation_and_parent( (int) $entity_id );
			} else {
				$this->invalidate( (int) $entity_id );
			}
		}
	}

	/**
	 * Invalidate all products using a specific attribute taxonomy.
	 *
	 * The list of entities associated with the taxonomy is cached for performance;
	 * the TTL can be customized via the 'woocommerce_version_string_invalidator_taxonomy_lookup_ttl' filter.
	 *
	 * @param string $taxonomy The attribute taxonomy slug.
	 *
	 * @return void
	 */
	private function invalidate_products_with_attribute( string $taxonomy ): void {
		global $wpdb;

		$cache_key = 'wc_cache_inv_attr_' . $taxonomy;
		$cached    = wp_cache_get( $cache_key, 'woocommerce' );

		if ( false === $cached ) {
			$product_ids = $wpdb->get_col(
				$wpdb->prepare(
					"SELECT DISTINCT post_id FROM {$wpdb->postmeta}
					WHERE meta_key = '_product_attributes'
					AND meta_value LIKE %s",
					'%' . $wpdb->esc_like( 's:' . strlen( $taxonomy ) . ':"' . $taxonomy . '"' ) . '%'
				)
			);

			$variation_ids = $wpdb->get_col(
				$wpdb->prepare(
					"SELECT DISTINCT post_id FROM {$wpdb->postmeta}
					WHERE meta_key = %s",
					'attribute_' . $taxonomy
				)
			);

			$cached = array(
				'product_ids'   => $product_ids,
				'variation_ids' => $variation_ids,
			);

			// phpcs:ignore WooCommerce.Commenting.CommentHooks.MissingHookComment -- Documented above.
			$ttl = apply_filters( 'woocommerce_version_string_invalidator_taxonomy_lookup_ttl', self::DEFAULT_TAXONOMY_LOOKUP_CACHE_TTL, 'product' );
			wp_cache_set( $cache_key, $cached, 'woocommerce', $ttl );
		}

		foreach ( $cached['product_ids'] as $product_id ) {
			$this->invalidate( (int) $product_id );
		}

		foreach ( $cached['variation_ids'] as $variation_id ) {
			$this->invalidate_variation_and_parent( (int) $variation_id );
		}
	}

	/**
	 * Invalidate a product version string.
	 *
	 * @param int $product_id The product ID.
	 *
	 * @return void
	 *
	 * @since 10.5.0
	 */
	public function invalidate( int $product_id ): void {
		wc_get_container()->get( VersionStringGenerator::class )->delete_version( "product_{$product_id}" );
	}

	/**
	 * Invalidate the product list version string.
	 *
	 * This should be called when products are created, deleted, or change status,
	 * as these operations affect collection/list endpoints.
	 *
	 * @return void
	 */
	private function invalidate_products_list(): void {
		wc_get_container()->get( VersionStringGenerator::class )->delete_version( 'list_products' );
	}

	/**
	 * Invalidate the variations list version string for a specific product.
	 *
	 * This should be called when variations are created, deleted, or change status,
	 * as these operations affect the variations collection/list endpoint for the parent product.
	 *
	 * @param int|null $product_id The parent product ID, or null/0 to skip invalidation.
	 *
	 * @return void
	 */
	private function invalidate_variations_list( ?int $product_id ): void {
		if ( $product_id ) {
			wc_get_container()->get( VersionStringGenerator::class )->delete_version( "list_product_variations_{$product_id}" );
		}
	}
}