//! Real FTP commands over a native test socket, with an async local server.
//! This verifies guest recovery; WASM host integration is exercised separately.

use super::Ftp;
use memona_plugin_sdk::{ErrorCode, Guest, Locator, Setting};
use std::time::Duration;
use tokio::io::{AsyncBufReadExt, AsyncWriteExt, BufReader};
use tokio::net::{TcpListener, TcpStream};
use tokio::sync::oneshot;

type TestResult<T = ()> = Result<T, Box<dyn std::error::Error + Send + Sync>>;
type Channel = BufReader<TcpStream>;

fn guest<T>(value: Result<T, ErrorCode>) -> TestResult<T> {
  value.map_err(|error| format!("guest operation failed: {error:?}").into())
}

fn config(port: u16) -> Vec<(String, Setting)> {
  vec![
    ("host".into(), Setting::Text("127.0.0.1".into())),
    ("port".into(), Setting::Text(port.to_string())),
    ("username".into(), Setting::Text("fixture".into())),
    (
      "password".into(),
      Setting::Secret(" fixture secret ".into()),
    ),
  ]
}

async fn reply(channel: &mut Channel, text: &str) -> TestResult {
  channel.get_mut().write_all(text.as_bytes()).await?;
  Ok(())
}

async fn expect(channel: &mut Channel, expected: &str) -> TestResult {
  loop {
    let mut line = String::new();
    channel.read_line(&mut line).await?;
    if line == "NOOP\r\n" {
      reply(channel, "200 Still connected\r\n").await?;
      continue;
    }
    assert_eq!(line, format!("{expected}\r\n"));
    return Ok(());
  }
}

async fn login(listener: &TcpListener) -> TestResult<Channel> {
  let (stream, _) = listener.accept().await?;
  let mut channel = BufReader::new(stream);
  reply(&mut channel, "220 Fixture\r\n").await?;
  expect(&mut channel, "USER fixture").await?;
  reply(&mut channel, "331 Password required\r\n").await?;
  expect(&mut channel, "PASS  fixture secret ").await?;
  reply(&mut channel, "230 Signed in\r\n").await?;
  expect(&mut channel, "TYPE I").await?;
  reply(&mut channel, "200 Binary\r\n").await?;
  Ok(channel)
}

async fn listing(channel: &mut Channel) -> TestResult {
  expect(channel, "EPSV").await?;
  let listener = TcpListener::bind("127.0.0.1:0").await?;
  reply(
    channel,
    &format!("229 Passive (|||{}|)\r\n", listener.local_addr()?.port()),
  )
  .await?;
  expect(channel, "MLSD /").await?;
  reply(channel, "150 Listing\r\n").await?;
  let (mut data, _) = listener.accept().await?;
  data.write_all(b"type=file;size=3;  report.md \r\n").await?;
  data.shutdown().await?;
  drop(data);
  reply(channel, "226 Complete\r\n").await
}

#[tokio::test]
async fn a_listing_reconnects_after_the_server_expires_the_control_session()
-> TestResult {
  let listener = TcpListener::bind("127.0.0.1:0").await?;
  let port = listener.local_addr()?.port();
  let (expired, wait_expired) = oneshot::channel();
  let server = tokio::spawn(async move {
    tokio::time::timeout(Duration::from_secs(5), async {
      let mut channel = login(&listener).await?;
      listing(&mut channel).await?;
      reply(&mut channel, "421 Control connection timed out\r\n").await?;
      channel.get_mut().shutdown().await?;
      drop(channel);
      expired.send(()).map_err(|_| "guest disappeared")?;
      let mut channel = login(&listener).await?;
      listing(&mut channel).await?;
      expect(&mut channel, "QUIT").await?;
      reply(&mut channel, "221 Bye\r\n").await
    })
    .await?
  });
  let client = tokio::task::spawn_blocking(move || -> TestResult {
    guest(Ftp::open("ftp".into(), config(port)))?;
    let first = guest(Ftp::list(Locator::Path("/".into()), None, 10))?;
    assert_eq!(first.entries[0].name, " report.md ");
    wait_expired.blocking_recv()?;
    let next = guest(Ftp::list(Locator::Path("/".into()), None, 10))?;
    assert_eq!(next.entries[0].name, " report.md ");
    Ftp::close();
    Ok(())
  })
  .await?;
  if client.is_err() {
    server.abort();
  }
  client?;
  server.await??;
  Ok(())
}

#[tokio::test]
async fn recovery_before_a_mutation_never_replays_a_lost_mutation_reply()
-> TestResult {
  let listener = TcpListener::bind("127.0.0.1:0").await?;
  let port = listener.local_addr()?.port();
  let (expired, wait_expired) = oneshot::channel();
  let server = tokio::spawn(async move {
    tokio::time::timeout(Duration::from_secs(5), async {
      let mut channel = login(&listener).await?;
      channel.get_mut().shutdown().await?;
      drop(channel);
      expired.send(()).map_err(|_| "guest disappeared")?;
      let mut channel = login(&listener).await?;
      expect(&mut channel, "MKD /new").await?;
      // The mutation may have succeeded; lose its reply deliberately.
      channel.get_mut().shutdown().await?;
      drop(channel);
      Ok::<_, Box<dyn std::error::Error + Send + Sync>>(listener)
    })
    .await?
  });
  let client = tokio::task::spawn_blocking(move || -> TestResult {
    guest(Ftp::open("ftp".into(), config(port)))?;
    wait_expired.blocking_recv()?;
    assert!(matches!(
      Ftp::mkdir(Locator::Path("/new".into())),
      Err(ErrorCode::Unavailable)
    ));
    Ftp::close();
    Ok(())
  })
  .await?;
  if client.is_err() {
    server.abort();
  }
  client?;
  let listener = server.await??;
  assert!(
    tokio::time::timeout(Duration::from_millis(50), listener.accept())
      .await
      .is_err(),
    "a mutation must not be replayed on a third control connection"
  );
  Ok(())
}