public static function save( $order_id ) {
		self::init_address_fields();

		// Ensure gateways are loaded in case they need to insert data into the emails.
		WC()->payment_gateways();
		WC()->shipping();

		// Get order object.
		$order = wc_get_order( $order_id );
		$props = array();

		// Create order key.
		if ( ! $order->get_order_key() ) {
			$props['order_key'] = wc_generate_order_key();
		}

		// Update customer.
		$customer_id = isset( $_POST['customer_user'] ) ? absint( $_POST['customer_user'] ) : 0;
		if ( $customer_id !== $order->get_customer_id() ) {
			$props['customer_id'] = $customer_id;
		}

		// Update billing fields.
		if ( ! empty( self::$billing_fields ) ) {
			foreach ( self::$billing_fields as $key => $field ) {
				if ( ! isset( $field['id'] ) ) {
					$field['id'] = '_billing_' . $key;
				}

				if ( ! isset( $_POST[ $field['id'] ] ) ) {
					continue;
				}

				if ( is_callable( array( $order, 'set_billing_' . $key ) ) ) {
					$props[ 'billing_' . $key ] = wc_clean( wp_unslash( $_POST[ $field['id'] ] ) );
				} else {
					$order->update_meta_data( $field['id'], wc_clean( wp_unslash( $_POST[ $field['id'] ] ) ) );
				}
			}
		}

		// Update shipping fields.
		if ( ! empty( self::$shipping_fields ) ) {
			foreach ( self::$shipping_fields as $key => $field ) {
				if ( ! isset( $field['id'] ) ) {
					$field['id'] = '_shipping_' . $key;
				}

				if ( ! isset( $_POST[ $field['id'] ] ) ) {
					continue;
				}

				if ( is_callable( array( $order, 'set_shipping_' . $key ) ) ) {
					$props[ 'shipping_' . $key ] = wc_clean( wp_unslash( $_POST[ $field['id'] ] ) );
				} else {
					$order->update_meta_data( $field['id'], wc_clean( wp_unslash( $_POST[ $field['id'] ] ) ) );
				}
			}
		}

		if ( isset( $_POST['_transaction_id'] ) ) {
			$props['transaction_id'] = wc_clean( wp_unslash( $_POST['_transaction_id'] ) );
		}

		// Payment method handling.
		if ( $order->get_payment_method() !== wp_unslash( $_POST['_payment_method'] ) ) {
			$methods              = WC()->payment_gateways->payment_gateways();
			$payment_method       = wc_clean( wp_unslash( $_POST['_payment_method'] ) );
			$payment_method_title = $payment_method;

			if ( isset( $methods ) && isset( $methods[ $payment_method ] ) ) {
				$payment_method_title = $methods[ $payment_method ]->get_title();
			}

			$props['payment_method']       = $payment_method;
			$props['payment_method_title'] = $payment_method_title;
		}

		// Update date.
		if ( empty( $_POST['order_date'] ) ) {
			$date = time();
		} else {
			$date = gmdate( 'Y-m-d H:i:s', strtotime( $_POST['order_date'] . ' ' . (int) $_POST['order_date_hour'] . ':' . (int) $_POST['order_date_minute'] . ':' . (int) $_POST['order_date_second'] ) );
		}

		$props['date_created'] = $date;

		// Set created via prop if new post.
		if ( isset( $_POST['original_post_status'] ) && $_POST['original_post_status'] === 'auto-draft' ) {
			$props['created_via'] = 'admin';
		}

		// Save order data.
		$order->set_props( $props );
		$order->set_status( wc_clean( wp_unslash( $_POST['order_status'] ) ), '', true );
		$order->save();
	}