use std::io::{self, Write};

use common::{msg::*, run_with, Handler, MsgWriter};
use serde::{Deserialize, Serialize};

fn main() {
    run_with::<EchoHandler>(io::stdin(), io::stdout());
}

#[derive(Debug, Serialize, Deserialize)]
#[serde(tag = "type")]
pub enum EchoBody {
    #[serde(rename = "echo")]
    Echo { msg_id: usize, echo: String },

    #[serde(rename = "echo_ok")]
    EchoOk {
        msg_id: usize,
        in_reply_to: usize,
        echo: String,
    },
}

pub struct EchoHandler {
    next_msg_id: usize,
}

impl Handler for EchoHandler {
    type Body = EchoBody;

    fn init(_node_id: String, _node_ids: Vec<String>, _msg_id: usize) -> Self {
        EchoHandler { next_msg_id: 1 }
    }

    fn handle(
        &mut self,
        header: MessageHeader,
        body: Self::Body,
        writer: &mut MsgWriter<impl Write>,
    ) {
        match body {
            EchoBody::Echo { msg_id, echo } => {
                writer.write(
                    header.src,
                    &EchoBody::EchoOk {
                        msg_id: self.next_msg_id,
                        in_reply_to: msg_id,
                        echo,
                    },
                );

                self.next_msg_id += 1;
            }
            EchoBody::EchoOk { .. } => (),
        };
    }
}