Whether to return all fields or only the ones that are still registered. Default false.
	 *
	 * @return array An array of fields.
	 */
	public function get_all_fields_from_customer( $customer, $all = false ) {
		$customer_id = $customer->get_id();
		$meta_data   = array(
			'billing'    => array(),
			'shipping'   => array(),
			'additional' => array(),
		);
		if ( ! $customer_id ) {
			if ( isset( wc()->session ) ) {
				$meta_data['billing']    = wc()->session->get( self::BILLING_FIELDS_KEY, array() );
				$meta_data['shipping']   = wc()->session->get( self::SHIPPING_FIELDS_KEY, array() );
				$meta_data['additional'] = wc()->session->get( self::ADDITIONAL_FIELDS_KEY, array() );
			}
		} else {
			$meta_data['billing']    = get_user_meta( $customer_id, self::BILLING_FIELDS_KEY, true );
			$meta_data['shipping']   = get_user_meta( $customer_id, self::SHIPPING_FIELDS_KEY, true );
			$meta_data['additional'] = get_user_meta( $customer_id, self::ADDITIONAL_FIELDS_KEY, true );
		}

		return $this->format_meta_data( $meta_data, $all );
	}

	/**
	 * Returns an array of all fields values for a given order.
	 *
	 * @param \WC_Order $order The order to get the fields for.
	 * @param bool      $all Whether to return all fields or only the ones that are still registered. Default false.
	 *
	 * @return array An array of fields.
	 */
	public function get_all_fields_from_order( $order, $all = false ) {
		$meta_data = array(
			'billing'    => array(),
			'shipping'   => array(),
			'additional' => array(),
		);
		if ( $order instanceof \WC_Order ) {
			$meta_data['billing']    = $order->get_meta( self::BILLING_FIELDS_KEY, true );
			$meta_data['shipping']   = $order->get_meta( self::SHIPPING_FIELDS_KEY, true );
			$meta_data['additional'] = $order->get_meta( self::ADDITIONAL_FIELDS_KEY, true );
		}
		return $this->format_meta_data( $meta_data, $all );
	}

	/**
	 * Returns an array of all fields values for a given meta object. It would add the billing or shipping prefix to the keys.
	 *
	 * @param array $meta The meta data to format.
	 * @param bool  $all Whether to return all fields or only the ones that are still registered. Default false.
	 *
	 * @return array An array of fields.
	 */
	private function format_meta_data( $meta, $all = false ) {
		$billing_fields    = $meta['billing'] ?? array();
		$shipping_fields   = $meta['shipping'] ?? array();
		$additional_fields = $meta['additional'] ?? array();

		$fields = array();

		if ( is_array( $billing_fields ) ) {
			foreach ( $billing_fields as $key => $value ) {
				if ( ! $all && ! $this->is_field( $key ) ) {
					continue;
				}
				$fields[ '/billing/' . $key ] = $value;
			}
		}

		if ( is_array( $shipping_fields ) ) {
			foreach ( $shipping_fields as $key => $value ) {
				if ( ! $all && ! $this->is_field( $key ) ) {
					continue;
				}
				$fields[ '/shipping/' . $key ] = $value;
			}
		}

		if ( is_array( $additional_fields ) ) {
			foreach ( $additional_fields as $key => $value ) {
				if ( ! $all && ! $this->is_field( $key ) ) {
					continue;
				}
				$fields[ $key ] = $value;
			}
		}

		return $fields;
	}

	/**
	 * From a set of fields, returns only the ones that should be saved to the customer.
	 * For now, this only supports fields in address location.
	 *
	 * @param array $fields The fields to filter.
	 *
	 * @return array The filtered fields.
	 */
	public function filter_fields_for_customer( $fields ) {
		$customer_fields_keys = $this->get_address_fields_keys();
		return array_filter(
			$fields,
			function( $key ) use ( $customer_fields_keys ) {
				return in_array( $key, $customer_fields_keys, true );
			},
			ARRAY_FILTER_USE_KEY
		);
	}

}