public static function download_product() {
		$product_id = absint( $_GET['download_file'] ); // phpcs:ignore WordPress.VIP.SuperGlobalInputUsage.AccessDetected, WordPress.VIP.ValidatedSanitizedInput.InputNotValidated, WordPress.Security.ValidatedSanitizedInput.InputNotValidated
		$product    = wc_get_product( $product_id );
		$data_store = WC_Data_Store::load( 'customer-download' );

		if ( ! $product || empty( $_GET['key'] ) || empty( $_GET['order'] ) ) { // WPCS: input var ok, CSRF ok.
			self::download_error( __( 'Invalid download link.', 'woocommerce' ) );
		}

		// Fallback, accept email address if it's passed.
		if ( empty( $_GET['email'] ) && empty( $_GET['uid'] ) ) { // WPCS: input var ok, CSRF ok.
			self::download_error( __( 'Invalid download link.', 'woocommerce' ) );
		}

		$order_id = wc_get_order_id_by_order_key( wc_clean( wp_unslash( $_GET['order'] ) ) ); // WPCS: input var ok, CSRF ok.
		$order    = wc_get_order( $order_id );

		if ( isset( $_GET['email'] ) ) { // WPCS: input var ok, CSRF ok.
			$email_address = wp_unslash( $_GET['email'] ); // WPCS: input var ok, CSRF ok, sanitization ok.
		} else {
			// Get email address from order to verify hash.
			$email_address = is_a( $order, 'WC_Order' ) ? $order->get_billing_email() : null;

			// Prepare email address hash.
			$email_hash = function_exists( 'hash' ) ? hash( 'sha256', $email_address ) : sha1( $email_address );

			if ( is_null( $email_address ) || ! hash_equals( wp_unslash( $_GET['uid'] ), $email_hash ) ) { // WPCS: input var ok, CSRF ok, sanitization ok.
				self::download_error( __( 'Invalid download link.', 'woocommerce' ) );
			}
		}

		$download_ids = $data_store->get_downloads(
			array(
				'user_email'  => sanitize_email( str_replace( ' ', '+', $email_address ) ),
				'order_key'   => wc_clean( wp_unslash( $_GET['order'] ) ), // WPCS: input var ok, CSRF ok.
				'product_id'  => $product_id,
				'download_id' => wc_clean( preg_replace( '/\s+/', ' ', wp_unslash( $_GET['key'] ) ) ), // WPCS: input var ok, CSRF ok, sanitization ok.
				'orderby'     => 'downloads_remaining',
				'order'       => 'DESC',
				'limit'       => 1,
				'return'      => 'ids',
			)
		);

		if ( empty( $download_ids ) ) {
			self::download_error( __( 'Invalid download link.', 'woocommerce' ) );
		}

		$download = new WC_Customer_Download( current( $download_ids ) );

		/**
		 * Filter download filepath.
		 *
		 * @since 4.0.0
		 * @param string $file_path File path.
		 * @param string $email_address Email address.
		 * @param WC_Order|bool $order Order object or false.
		 * @param WC_Product $product Product object.
		 * @param WC_Customer_Download $download Download data.
		 */
		$file_path = apply_filters(
			'woocommerce_download_product_filepath',
			$product->get_file_download_path( $download->get_download_id() ),
			$email_address,
			$order,
			$product,
			$download
		);

		$parsed_file_path = self::parse_file_path( $file_path );
		$download_range   = self::get_download_range( @filesize( $parsed_file_path['file_path'] ) );  // @codingStandardsIgnoreLine.

		self::check_order_is_valid( $download );
		if ( ! $download_range['is_range_request'] ) {
			// If the remaining download count goes to 0, allow range requests to be able to finish streaming from iOS devices.
			self::check_downloads_remaining( $download );
		}
		self::check_download_expiry( $download );
		self::check_download_login_required( $download );

		do_action(
			'woocommerce_download_product',
			$download->get_user_email(),
			$download->get_order_key(),
			$download->get_product_id(),
			$download->get_user_id(),
			$download->get_download_id(),
			$download->get_order_id()
		);
		$download->save();

		// Track the download in logs and change remaining/counts.
		$current_user_id = get_current_user_id();
		$ip_address      = WC_Geolocation::get_ip_address();
		if ( ! $download_range['is_range_request'] ) {
			$download->track_download( $current_user_id > 0 ? $current_user_id : null, ! empty( $ip_address ) ? $ip_address : null );
		}

		self::download( $file_path, $download->get_product_id() );
	}