dora/apis/c++/node/src/lib.rs

use dora_node_api::{self, Event, EventStream};
use eyre::bail;

#[cxx::bridge]
#[allow(clippy::needless_lifetimes)]
mod ffi {
    struct DoraNode {
        events: Box<Events>,
        send_output: Box<OutputSender>,
    }

    pub enum DoraEventType {
        Stop,
        Input,
        InputClosed,
        Error,
        Unknown,
        AllInputsClosed,
    }

    struct DoraInput {
        id: String,
        data: Vec<u8>,
    }

    struct DoraResult {
        error: String,
    }

    extern "Rust" {
        type Events;
        type OutputSender;
        type DoraEvent<'a>;

        fn init_dora_node() -> Result<DoraNode>;

        fn next_event(inputs: &mut Box<Events>) -> Box<DoraEvent<'_>>;
        fn event_type(event: &Box<DoraEvent>) -> DoraEventType;
        fn event_as_input(event: Box<DoraEvent>) -> Result<DoraInput>;
        fn send_output(
            output_sender: &mut Box<OutputSender>,
            id: String,
            data: &[u8],
        ) -> DoraResult;
    }
}

fn init_dora_node() -> eyre::Result<ffi::DoraNode> {
    let (node, events) = dora_node_api::DoraNode::init_from_env()?;
    let inputs = Events(events);
    let send_output = OutputSender(node);

    Ok(ffi::DoraNode {
        events: Box::new(inputs),
        send_output: Box::new(send_output),
    })
}

pub struct Events(EventStream);

fn next_event(events: &mut Box<Events>) -> Box<DoraEvent> {
    Box::new(DoraEvent(events.0.recv()))
}

pub struct DoraEvent<'a>(Option<Event<'a>>);

fn event_type(event: &Box<DoraEvent>) -> ffi::DoraEventType {
    match &event.0 {
        Some(event) => match event {
            Event::Stop => ffi::DoraEventType::Stop,
            Event::Input { .. } => ffi::DoraEventType::Input,
            Event::InputClosed { .. } => ffi::DoraEventType::InputClosed,
            Event::Error(_) => ffi::DoraEventType::Error,
            _ => ffi::DoraEventType::Unknown,
        },
        None => ffi::DoraEventType::AllInputsClosed,
    }
}

fn event_as_input(event: Box<DoraEvent>) -> eyre::Result<ffi::DoraInput> {
    let Some(Event::Input { id, metadata: _, data }) = event.0 else {
        bail!("not an input event");
    };
    Ok(ffi::DoraInput {
        id: id.into(),
        data: data.map(|d| d.to_owned()).unwrap_or_default(),
    })
}

pub struct OutputSender(dora_node_api::DoraNode);

fn send_output(sender: &mut Box<OutputSender>, id: String, data: &[u8]) -> ffi::DoraResult {
    let result = sender
        .0
        .send_output(id.into(), Default::default(), data.len(), |out| {
            out.copy_from_slice(data)
        });
    let error = match result {
        Ok(()) => String::new(),
        Err(err) => format!("{err:?}"),
    };
    ffi::DoraResult { error }
}