use bytes::Bytes;
use std::process::Stdio;
use tokio::{
    fs::File,
    io::{self, AsyncBufReadExt, BufReader},
    prelude::*,
    process::Command,
    sync::mpsc::{self, Receiver, Sender},
};
use futures::future::join_all;
use tokio::task::JoinHandle;

const CRLF: &[u8; 2] = &[b'\r', b'\n'];
const LF: &[u8; 1] = &[b'\n'];

pub type Error = Box<dyn std::error::Error + Send + Sync>;
pub type Result<T> = std::result::Result<T, Error>;

#[tokio::main]
// async fn main() -> Result<(), Box<dyn std::error::Error>> {
async fn main() -> Result<()> {
    let mut dbgout = File::create("cmdproxy.log").await?;
    
    let mut child = Command::new("dotnet")
        .current_dir("/Users/cameron/.autorest/@microsoft.azure_autorest.go@2.1.153/node_modules/@microsoft.azure/autorest.go")
        .arg("src/bin/netcoreapp2.0/autorest.go.dll")
        .arg("--server")
        .stdin(Stdio::piped())
        .stdout(Stdio::piped())
        .stderr(Stdio::null())
        .spawn()?;

    let stdin = io::stdin();
    let mut stdin_reader = BufReader::new(stdin).lines();
    let mut childin = child.stdin.take().expect("child did not have a handle to stdin");
    let childout = child.stdout.take().expect("child did not have a handle to stdout");
    let mut childout_reader = BufReader::new(childout).lines();
    let mut stdout = io::stdout();

    let (mut dbgout_tx, mut dbgout_rx): (Sender<Bytes>, Receiver<Bytes>) = mpsc::channel(128);
    let mut dbgout_tx2 = dbgout_tx.clone();
    let mut dbgout_tx3 = dbgout_tx.clone();
    
    let task_child: JoinHandle<Result<()>> = tokio::spawn(async move {
        let status = child.await?; //.expect("child process encountered an error");
        let msg = Bytes::from(format!("exit {}", status));
        dbgout_tx.send(msg).await?; //.expect("send dbgout");
        Ok(())
    });

    let _task_dbg: JoinHandle<Result<()>> = tokio::spawn( async move {
        while let Some(msg) = dbgout_rx.recv().await {
            dbgout.write_all(&msg).await?;
            dbgout.write_all(LF).await?;
        }
        Ok(())
    });

    // println!("stdin_reader");
    // write stdin to log & childin
    let task_in: JoinHandle<Result<()>> = tokio::spawn( async move {
        while let Some(line) = stdin_reader.next_line().await? {
            dbgout_tx2.send(Bytes::from(format!("in {}", &line))).await?;
            // let line = ;
            // dbgout_tx2.send(line.clone()).await?;
            childin.write_all(&line.into_bytes()).await?;
            childin.write_all(CRLF).await?;
        }
        Ok(())
    });

    // println!("childout_reader");
    // write childout to log & stdout
    let task_out: JoinHandle<Result<()>> = tokio::spawn( async move {
        while let Some(line) = childout_reader.next_line().await? {
            // let line = Bytes::from(line);
            // dbgout_tx3.send(line.clone()).await?;
            dbgout_tx3.send(Bytes::from(format!("out {}", &line))).await?;
            stdout.write_all(&line.into_bytes()).await?;
            stdout.write_all(CRLF).await?;
        }
        Ok(())
    });

    join_all(vec![task_child, task_in, task_out]).await;

    Ok(())
}