uniq-ids.rs

use rustagen::*;
use std::io::StdoutLock;
use std::io::Write;

use anyhow::Context;
use serde::{Deserialize, Serialize};

#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(tag = "type")]
#[serde(rename_all = "snake_case")]
enum Payload {
    Generate,
    GenerateOk {
        #[serde(rename = "id")]
        guid: String,
    },
}

struct UniqNode {
    node: String,
    id: usize,
}

impl Node<(), Payload> for UniqNode {
    fn from_init(_state: (), init: Init) -> anyhow::Result<Self>
    where
        Self: Sized,
    {
        Ok(UniqNode {
            id: 1,
            node: init.node_id,
        })
    }

    fn step(&mut self, input: Message<Payload>, output: &mut StdoutLock) -> anyhow::Result<()> {
        let mut reply = input.into_reply(Some(&mut self.id));
        match reply.body.payload {
            Payload::Generate => {
                let guid = format!("{}-{}", self.node, self.id);
                reply.body.payload = Payload::GenerateOk { guid };

                serde_json::to_writer(&mut *output, &reply)
                    .context("serialize response to generate")?;
                output.write_all(b"\n").context("write trailing newline")?;
            }
            Payload::GenerateOk { .. } => {}
        }

        Ok(())
    }
}
fn main() -> anyhow::Result<()> {
    main_loop::<_, UniqNode, _>(())
}