// Copyright 2018 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#![deny(warnings)]
#![feature(async_await, await_macro)]

use {
    failure::{format_err, Error, ResultExt},
    fidl_fidl_test_compatibility::{
        EchoEvent,
        EchoMarker,
        EchoProxy,
        EchoRequest,
        EchoRequestStream,
    },
    fidl_fuchsia_sys::LauncherProxy,
    fuchsia_async as fasync,
    fuchsia_component::{
        client::{App, launcher, launch},
        server::ServiceFs,
    },
    futures::{StreamExt, TryStreamExt},
};

fn launch_and_connect_to_echo(launcher: &LauncherProxy, url: String) -> Result<(EchoProxy, App), Error> {
    let app = launch(&launcher, url, None)?;
    let echo = app.connect_to_service::<EchoMarker>()?;
    Ok((echo, app))
}

async fn echo_server(stream: EchoRequestStream, launcher: &LauncherProxy) -> Result<(), Error> {
    let handler = move |request| Box::pin(async move {
        match request {
            EchoRequest::EchoStruct { mut value, forward_to_server, responder } => {
                if !forward_to_server.is_empty() {
                    let (echo, app) = launch_and_connect_to_echo(launcher, forward_to_server)
                        .context("Error connecting to proxy")?;
                    value = await!(echo.echo_struct(&mut value, ""))
                        .context("Error calling echo_struct on proxy")?;
                    drop(app);
                }
                responder.send(&mut value)
                    .context("Error responding")?;
            }
            EchoRequest::EchoStructNoRetVal { mut value, forward_to_server, control_handle } => {
                if !forward_to_server.is_empty() {
                    let (echo, app) = launch_and_connect_to_echo(launcher, forward_to_server)
                        .context("Error connecting to proxy")?;
                    echo.echo_struct_no_ret_val(&mut value, "")
                        .context("Error sending echo_struct_no_ret_val to proxy")?;
                    let mut event_stream = echo.take_event_stream();
                    let EchoEvent::EchoEvent { value: response_val } =
                        await!(event_stream.try_next())
                            .context("Error getting event response from proxy")?
                            .ok_or_else(|| format_err!("Proxy sent no events"))?;
                    value = response_val;
                    drop(app);
                }
                control_handle.send_echo_event(&mut value)
                    .context("Error responding with event")?;
            }
        }
        Ok(())
    });

    let handle_requests_fut = stream
        .err_into() // change error type from fidl::Error to failure::Error
        .try_for_each_concurrent(None /* max concurrent requests per connection */, handler);

    await!(handle_requests_fut)
}

fn main() -> Result<(), Error> {
    let mut executor = fasync::Executor::new().context("Error creating executor")?;
    let launcher = launcher().context("Error connecting to application launcher")?;

    let mut fs = ServiceFs::new_local();
    fs.dir("public")
        .add_fidl_service(|stream| stream);
    fs.take_and_serve_directory_handle().context("Error serving directory handle")?;

    let serve_fut = fs.for_each_concurrent(None /* max concurrent connections */, |stream| async {
        if let Err(e) = await!(echo_server(stream, &launcher)) {
            eprintln!("Closing echo server {:?}", e);
        }
    });

    executor.run_singlethreaded(serve_fut);
    Ok(())
}