use slog::Logger;

use async_std::net::TcpStream;
use futures::io::AsyncWriteExt;

use crate::error::Result;

pub mod gen {
    include!(concat!(env!("OUT_DIR"), "/schema/connection_capnp.rs"));
}


pub async fn handle_connection(log: Logger, mut stream: TcpStream) -> Result<()> {
    let host = "localhost";
    let program = "Difluoroborane-0.1.0";
    let version = (0u32,1u32);


    {
        let receive_options = capnp::message::ReaderOptions::default();
        let message = capnp_futures::serialize::read_message(&mut stream, receive_options).await.unwrap().unwrap();
        let m = message.get_root::<gen::message::Reader>().unwrap();

        if m.has_greet() {
            match m.which() {
                Ok(gen::message::Which::Greet(Ok(r))) => {
                    println!("Host {} with program {} is saying hello. They speak API version {}.{}.",
                        r.get_host().unwrap(),
                        r.get_program().unwrap(),
                        r.get_major(),
                        r.get_minor())
                },
                _ => {
                    // We *JUST* checked that it's a greeting. This can not happen
                    unreachable!()
                }
            }
        }
    }

    {
        let mut message = capnp::message::Builder::new_default();
        let greet_outer = message.init_root::<gen::message::Builder>();
        let mut greeting = greet_outer.init_greet();
        greeting.set_host(host);
        greeting.set_program(program);
        greeting.set_major(version.0);
        greeting.set_minor(version.1);

        capnp_futures::serialize::write_message(&mut stream, message).await?;
    }

    stream.flush().await?;

    Ok(())
}