crunch/crates/crunch-envelope/src/lib.rs

#[allow(dead_code)]
#[cfg(feature = "capnp")]
mod envelope_capnp;

#[cfg(feature = "json")]
mod json_envelope;

mod generated;
#[cfg(feature = "proto")]
mod proto_envelope;

#[cfg(feature = "json")]
pub mod json {
    pub use crate::json_envelope::*;
}

#[cfg(feature = "proto")]
pub mod proto {
    pub use crate::proto_envelope::*;
}

#[cfg(feature = "capnp")]
pub mod capnp {
    use capnp::message::{Builder, ReaderOptions};
    use capnp::serialize;

    use crate::{envelope_capnp, EnvelopeError, Metadata};

    pub fn wrap<'a>(domain: &'a str, entity: &'a str, content: &'a [u8]) -> Vec<u8> {
        let mut builder = Builder::new_default();
        let mut envelope = builder.init_root::<envelope_capnp::envelope::Builder>();
        envelope.set_content(content);

        let mut metadata = envelope.init_metadata();
        metadata.set_domain(domain);
        metadata.set_entity(entity);

        serialize::write_message_to_words(&builder)
    }

    pub fn unwrap(message: &[u8]) -> Result<(Vec<u8>, Metadata), EnvelopeError> {
        let mut message = message;
        let message_builder =
            serialize::read_message_from_flat_slice(&mut message, ReaderOptions::new())
                .map_err(EnvelopeError::CapnpError)?;

        let envelope = message_builder
            .get_root::<envelope_capnp::envelope::Reader>()
            .map_err(EnvelopeError::CapnpError)?;
        let content = envelope.get_content().map_err(EnvelopeError::CapnpError)?;
        let metadata = envelope.get_metadata().map_err(EnvelopeError::CapnpError)?;

        Ok((
            content.to_vec(),
            Metadata {
                domain: metadata
                    .get_domain()
                    .map_err(EnvelopeError::CapnpError)?
                    .to_string(),
                entity: metadata
                    .get_entity()
                    .map_err(EnvelopeError::CapnpError)?
                    .to_string(),
            },
        ))
    }

    #[cfg(test)]
    mod test {
        use super::*;

        #[test]
        fn test_can_serialize() {
            let domain = "some-domain";
            let entity = "some-entity";
            let message = b"some-content";
            let out = wrap(domain, entity, message);

            let original = unwrap(&out).expect("to be able to unwrap capnp message");

            assert_eq!(domain, original.1.domain);
            assert_eq!(entity, original.1.entity);
            assert_eq!(message, original.0.as_slice());
        }
    }
}

use thiserror::Error;

#[derive(Error, Debug)]
pub enum EnvelopeError {
    #[error("capnp failed to serialize or deserialize code")]
    #[cfg(feature = "capnp")]
    CapnpError(#[source] ::capnp::Error),
    #[cfg(feature = "json")]
    #[error("serde_json failed to serialize or deserialize code")]
    JsonError(#[source] serde_json::Error),
    #[cfg(feature = "json")]
    #[error("base64 failed to serialize or deserialize code")]
    Base64Error(#[source] base64::DecodeError),
    #[cfg(feature = "proto")]
    #[error("prost failed to serialize or deserialize code")]
    ProtoError(#[source] prost::DecodeError),
    #[error("metadata is missing from field")]
    MetadataError(),
}

#[allow(dead_code)]
#[derive(Debug, Clone)]
pub struct Metadata {
    domain: String,
    entity: String,
}