darkbio-wire 0.5.0

// wire-rs: encrypted protocol between Ark and host
// Copyright 2026 Dark Bio AG. All rights reserved.

//! Shared message bodies, generated from both protobuf content oneofs.

use super::Error;
use super::generated::*;

/// Defines the shared body enum and conversions from the schema-derived payload list.
/// The build script invokes this once with the union of both envelope directions.
macro_rules! messages {
    ($($variant:ident($payload:ty),)*) => {
        /// A request or successful response body, shared by hosts and servers.
        /// Variants and typed conversions are generated from the protobuf schema.
        /// Request IDs, wire envelopes and direction selection remain internal to
        /// the session API. The session checks whether it can send this message
        /// in its direction.
        ///
        /// Use `From`/`.into()` to submit a protobuf message, match variants to
        /// dispatch incoming work, and `TryFrom` to extract an expected body type.
        /// Extraction checks the variant and returns [`Error::UnexpectedResponse`]
        /// on mismatch. There is no static request/response pairing table.
        #[derive(Clone, Debug, PartialEq)]
        pub enum Message {
            $(
                #[doc = concat!("A `", stringify!($payload), "` payload.")]
                $variant($payload),
            )*
        }

        impl Message {
            /// Returns the payload's Rust type name for response mismatch errors.
            fn type_name(&self) -> &'static str {
                match self {
                    $(Self::$variant(_) => stringify!($payload),)*
                }
            }
        }

        $(
            impl From<$payload> for Message {
                /// Wraps a concrete payload in its corresponding message variant.
                fn from(message: $payload) -> Self {
                    Self::$variant(message)
                }
            }

            impl TryFrom<Message> for $payload {
                /// Variant mismatch between the received and requested payload types.
                type Error = Error;

                /// Extracts this payload only when the message variant matches.
                fn try_from(message: Message) -> Result<Self, Self::Error> {
                    match message {
                        Message::$variant(message) => Ok(message),
                        other => Err(Error::UnexpectedResponse {
                            expected: stringify!($payload),
                            received: other.type_name(),
                        }),
                    }
                }
            }
        )*
    };
}

/// Generates direction conversion from each envelope's actual schema fields.
/// Shared bodies remain usable in either direction without a hand-maintained list.
macro_rules! contents {
    ($module:ident, $($field:ident => $variant:ident,)*) => {
        impl From<$module::Content> for Message {
            /// Converts this envelope's content into the shared `Message` enum.
            fn from(content: $module::Content) -> Self {
                match content {
                    $($module::Content::$field(body) => Self::$variant(body),)*
                }
            }
        }

        impl TryFrom<Message> for $module::Content {
            /// A body absent from this envelope cannot travel in this direction.
            type Error = Error;

            /// Selects the envelope field by body type, independently of request ID.
            fn try_from(message: Message) -> Result<Self, Self::Error> {
                match message {
                    $(Message::$variant(body) => Ok(Self::$field(body)),)*
                    other => Err(Error::WrongDirection(other.type_name())),
                }
            }
        }
    };
}

include!(concat!(env!("OUT_DIR"), "/message.rs"));

/// Checks variant-safe conversion between message bodies and concrete payloads.
#[cfg(test)]
#[cfg_attr(coverage_nightly, coverage(off))]
mod tests {
    use crate::protocol::{self, DeviceInfoRequest, DeviceInfoResponse, Error, Message};

    /// Rejects a different `Message` variant even when its protobuf fields could
    /// be decoded as the requested type.
    #[test]
    fn response_extraction_checks_the_variant() {
        use prost::Message as _;

        let other = protocol::OnboardingResponse {};
        assert!(DeviceInfoResponse::decode(other.encode_to_vec().as_slice()).is_ok());
        let message: Message = other.into();
        assert!(matches!(
            DeviceInfoResponse::try_from(message),
            Err(Error::UnexpectedResponse {
                expected: "DeviceInfoResponse",
                received: "OnboardingResponse",
            })
        ));

        // These bodies have the same field name and tag in opposite wire envelopes,
        // but must remain distinct variants in the common public message enum.
        let message: Message = DeviceInfoRequest {}.into();
        assert!(matches!(
            DeviceInfoResponse::try_from(message),
            Err(Error::UnexpectedResponse {
                expected: "DeviceInfoResponse",
                received: "DeviceInfoRequest",
            })
        ));

        let response = DeviceInfoResponse {
            version_id: 7,
            ..Default::default()
        };
        let message: Message = response.clone().into();
        assert_eq!(DeviceInfoResponse::try_from(message).unwrap(), response);

        let message: Message = vec![1, 2, 3].into();
        assert_eq!(Vec::<u8>::try_from(message).unwrap(), vec![1, 2, 3]);
    }
}