serde_utils.rs

// This file is Copyright its original authors, visible in version control
// history.
//
// This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
// or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
// You may not use this file except in accordance with one or both of these
// licenses.

//! Custom serde serializers for proto types.
//!
//! These are used via `#[serde(serialize_with = "...")]` attributes on generated
//! proto fields to produce human-readable output (hex strings for bytes, enum
//! names for integer enum fields).

use std::fmt::Write;

use serde::Serializer;

/// Generates a serde serializer that converts an `i32` proto enum field to its
/// lowercased string name via `from_i32()` and `as_str_name()`.
macro_rules! stringify_enum_serializer {
	($fn_name:ident, $enum_type:ty) => {
		pub fn $fn_name<S>(value: &i32, serializer: S) -> Result<S::Ok, S::Error>
		where
			S: serde::Serializer,
		{
			let name = match <$enum_type>::from_i32(*value) {
				Some(v) => v.as_str_name(),
				None => "unknown",
			};
			serializer.serialize_str(&name.to_ascii_lowercase())
		}
	};
}

stringify_enum_serializer!(serialize_payment_direction, crate::types::PaymentDirection);
stringify_enum_serializer!(serialize_payment_status, crate::types::PaymentStatus);
stringify_enum_serializer!(serialize_balance_source, crate::types::BalanceSource);

/// Serializes `Option<prost::bytes::Bytes>` as a hex string (or null).
pub fn serialize_opt_bytes_hex<S>(
	value: &Option<bytes::Bytes>, serializer: S,
) -> Result<S::Ok, S::Error>
where
	S: Serializer,
{
	match value {
		Some(bytes) => {
			let hex = bytes.iter().fold(String::with_capacity(bytes.len() * 2), |mut acc, b| {
				let _ = write!(acc, "{b:02x}");
				acc
			});
			serializer.serialize_some(&hex)
		},
		None => serializer.serialize_none(),
	}
}