use runa_protocol::Value;
use std::io::{BufRead, BufReader};
use std::net::SocketAddr;
use std::process::{Child, Command as ProcessCommand, Stdio};

use runa_client::{LocalClient, WebSocketClient};
use runa_protocol::{Command, Reply};
use tokio_tungstenite::tungstenite::{self, Message, client::IntoClientRequest};

fn start_server() -> (ServerProcess, SocketAddr) {
    let child = ProcessCommand::new(env!("CARGO_BIN_EXE_runa-server"))
        .args(["--listen", "127.0.0.1:0"])
        .stdout(Stdio::null())
        .stderr(Stdio::piped())
        .spawn()
        .unwrap();
    let mut server = ServerProcess(child);
    let mut stderr = BufReader::new(server.0.stderr.take().unwrap());
    let mut startup = String::new();
    stderr.read_line(&mut startup).unwrap();
    let address = startup
        .strip_prefix("runa-server: listening on ")
        .expect("server should report its bound address")
        .trim()
        .parse()
        .unwrap();
    std::thread::spawn(move || {
        std::io::copy(&mut stderr, &mut std::io::sink()).unwrap();
    });
    (server, address)
}

fn watcher(address: SocketAddr) -> tungstenite::WebSocket<std::net::TcpStream> {
    let mut request = format!("ws://{address}/").into_client_request().unwrap();
    request
        .headers_mut()
        .insert("sec-websocket-protocol", "runa-debug".parse().unwrap());
    let stream = std::net::TcpStream::connect(address).unwrap();
    stream
        .set_read_timeout(Some(std::time::Duration::from_secs(2)))
        .unwrap();
    let (socket, response) = tungstenite::client(request, stream).unwrap();
    assert_eq!(response.headers()["sec-websocket-protocol"], "runa-debug");
    socket
}

fn revision(socket: &mut tungstenite::WebSocket<std::net::TcpStream>) -> u64 {
    let message = socket.read().unwrap();
    let event: runa_protocol::Notification =
        serde_json::from_str(message.to_text().unwrap()).unwrap();
    assert_eq!(event.version, runa_protocol::PROTOCOL_VERSION);
    let runa_protocol::ImageEvent::ImageChanged { revision } = event.event;
    revision
}

#[test]
fn websocket_broadcasts_non_destructive_invalidations_for_mailbox_state_and_lifecycle() {
    let (_server, address) = start_server();
    let mut first = watcher(address);
    let mut second = watcher(address);
    let mut client = WebSocketClient::connect(address).unwrap();
    let actor_ref = match client
        .request(Command::Spawn {
            behavior_name: "counter".to_owned(),
            state: Value::Integer(1),
            mailbox_capacity: 4,
        })
        .unwrap()
        .result
        .unwrap()
    {
        Reply::ActorSpawned { actor_ref } => actor_ref,
        other => panic!("unexpected spawn: {other:?}"),
    };
    let mut previous = 0;
    for command in [
        Command::ListActors,
        Command::Send {
            actor_ref: actor_ref.clone(),
            message: Value::Record(std::collections::BTreeMap::from([
                ("op".to_owned(), Value::String("add".to_owned())),
                ("value".to_owned(), Value::Integer(3)),
            ])),
        },
        Command::Tick {
            ticks: 100,
            instruction_budget: 10,
        },
        Command::PauseActor {
            actor_ref: actor_ref.clone(),
        },
        Command::ResumeActor {
            actor_ref: actor_ref.clone(),
        },
        Command::StopActor {
            actor_ref: actor_ref.clone(),
        },
        Command::RestartActor {
            actor_ref: actor_ref.clone(),
        },
    ] {
        if !matches!(command, Command::ListActors) {
            client.request(command).unwrap().result.unwrap();
        }
        let current = revision(&mut first);
        assert!(current > previous);
        assert_eq!(revision(&mut second), current);
        previous = current;
    }
    // Both subscribers have seen notifications, but neither consumed runtime events.
    let Reply::Events(events) = client.request(Command::GetEvents).unwrap().result.unwrap() else {
        panic!("expected runtime events")
    };
    assert!(
        events
            .iter()
            .any(|event| matches!(event, runa_protocol::EventDto::Spawned { .. }))
    );
    let Reply::Actor(snapshot) = client
        .request(Command::InspectActor { actor_ref })
        .unwrap()
        .result
        .unwrap()
    else {
        panic!("expected actor")
    };
    assert_eq!(snapshot.state, Value::Integer(4));

    // A read after a failed mutation is a fence: no invalidation should precede its reply.
    assert!(
        client
            .request(Command::Spawn {
                behavior_name: "missing".to_owned(),
                state: Value::Null,
                mailbox_capacity: 1,
            })
            .unwrap()
            .result
            .is_err()
    );
    first
        .send(Message::Text(
            serde_json::to_string(&runa_protocol::Request {
                version: 3,
                request_id: "read-fence".to_owned(),
                command: Command::ListActors,
            })
            .unwrap()
            .into(),
        ))
        .unwrap();
    let message = first.read().unwrap();
    let response: runa_protocol::Response =
        serde_json::from_str(message.to_text().unwrap()).unwrap();
    assert_eq!(response.request_id, "read-fence");
}

#[test]
fn websocket_requires_subprotocol_and_rejects_browser_origins_without_blocking_other_clients() {
    let (_server, address) = start_server();
    // An idle HTTP handshake cannot stall the image or another client's upgrade.
    let _idle = std::net::TcpStream::connect(address).unwrap();
    for (protocol, origin) in [
        (None, false),
        (Some("debug"), false),
        (Some("runa-debug"), true),
    ] {
        let mut request = format!("ws://{address}/").into_client_request().unwrap();
        if let Some(protocol) = protocol {
            request
                .headers_mut()
                .insert("sec-websocket-protocol", protocol.parse().unwrap());
        }
        if origin {
            request
                .headers_mut()
                .insert("origin", "https://example.test".parse().unwrap());
        }
        let stream = std::net::TcpStream::connect(address).unwrap();
        stream
            .set_read_timeout(Some(std::time::Duration::from_secs(2)))
            .unwrap();
        assert!(tungstenite::client(request, stream).is_err());
    }
    let mut client = WebSocketClient::connect(address).unwrap();
    assert_eq!(
        client.request(Command::ListActors).unwrap().result.unwrap(),
        Reply::Actors(Vec::new())
    );
}

#[test]
fn websocket_rejects_binary_malformed_and_oversized_requests() {
    let (_server, address) = start_server();
    for message in [
        Message::Binary(b"{}".to_vec().into()),
        Message::Text("{not-json}".into()),
        Message::Text(" ".repeat(runa_server::MAX_REQUEST_LINE_BYTES + 1).into()),
    ] {
        let mut socket = watcher(address);
        // An oversized frame may be rejected as soon as its header arrives,
        // before the sender finishes writing its payload.
        let _ = socket.send(message);
        assert!(socket.read().is_err());
    }
    let mut client = WebSocketClient::connect(address).unwrap();
    assert!(client.request(Command::ListActors).unwrap().result.is_ok());
}

struct ServerProcess(Child);

impl Drop for ServerProcess {
    fn drop(&mut self) {
        let _ = self.0.kill();
        let _ = self.0.wait();
    }
}

#[test]
fn local_client_launches_server_and_operates_the_same_live_image() {
    let mut client = LocalClient::spawn(env!("CARGO_BIN_EXE_runa-server"), &[] as &[&str]).unwrap();

    let published = client
        .request(Command::PublishBehavior {
            name: "counter".to_owned(),
            expected_revision: None,
            source: "pub fn handle(state, message) { (state + message.value, []) }".to_owned(),
        })
        .unwrap();
    assert_eq!(published.request_id, "runa-client-1");
    assert!(matches!(published.result, Ok(Reply::Behavior(_))));

    let spawned = client
        .request(Command::Spawn {
            behavior_name: "counter".to_owned(),
            state: Value::Integer(5),
            mailbox_capacity: 2,
        })
        .unwrap();
    assert_eq!(spawned.request_id, "runa-client-2");
    let actor_ref = match spawned.result {
        Ok(Reply::ActorSpawned { actor_ref }) => actor_ref,
        other => panic!("unexpected spawn response: {other:?}"),
    };
    assert_eq!(actor_ref.len(), 21);

    client
        .request(Command::Send {
            actor_ref: actor_ref.clone(),
            message: test_message(0, 7, None),
        })
        .unwrap();
    client
        .request(Command::Tick {
            ticks: 100,
            instruction_budget: 10,
        })
        .unwrap();
    let inspected = client.request(Command::InspectActor { actor_ref }).unwrap();
    assert!(matches!(
        inspected.result,
        Ok(Reply::Actor(actor)) if actor.state == Value::Integer(12)
    ));
    assert!(client.shutdown().unwrap().success());
}

#[test]
fn websocket_server_accepts_local_protocol_requests() {
    let child = ProcessCommand::new(env!("CARGO_BIN_EXE_runa-server"))
        .args(["--listen", "127.0.0.1:0"])
        .stdout(Stdio::null())
        .stderr(Stdio::piped())
        .spawn()
        .unwrap();
    let mut server = ServerProcess(child);
    let stderr = server.0.stderr.take().unwrap();
    let mut stderr = BufReader::new(stderr);
    let mut startup = String::new();
    stderr.read_line(&mut startup).unwrap();
    let address = startup
        .strip_prefix("runa-server: listening on ")
        .expect("server should report its bound address")
        .trim()
        .parse::<SocketAddr>()
        .unwrap();

    let mut client = WebSocketClient::connect(address).unwrap();
    let response = client.request(Command::ListActors).unwrap();
    assert_eq!(response.result, Ok(Reply::Actors(Vec::new())));

    let mut first = WebSocketClient::connect(address).unwrap();
    let mut second = WebSocketClient::connect(address).unwrap();
    let actor_ref = match first
        .request(Command::Spawn {
            behavior_name: "counter".to_owned(),
            state: Value::Integer(5),
            mailbox_capacity: 2,
        })
        .unwrap()
        .result
        .unwrap()
    {
        Reply::ActorSpawned { actor_ref } => actor_ref,
        other => panic!("unexpected spawn response: {other:?}"),
    };
    assert!(matches!(second.request(Command::InspectActor {
        actor_ref: actor_ref.clone(),
    }).unwrap().result, Ok(Reply::Actor(actor)) if actor.state == Value::Integer(5)));
    assert!(matches!(
        first
            .request(Command::RollbackBehavior {
                name: "counter".to_owned(),
                expected_revision: 1,
                target_revision: 1,
            })
            .unwrap()
            .result,
        Ok(Reply::Behavior(behavior)) if behavior.revision == 2
    ));
    drop(first);
    drop(second);

    let mut reconnected = WebSocketClient::connect(address).unwrap();
    assert!(matches!(
        reconnected
            .request(Command::GetBehavior {
                name: "counter".to_owned(),
            })
            .unwrap()
            .result,
        Ok(Reply::Behavior(behavior)) if behavior.revision == 2
    ));
    reconnected
        .request(Command::Send {
            actor_ref: actor_ref.clone(),
            message: Value::Record(std::collections::BTreeMap::from([
                ("op".to_owned(), Value::String("add".to_owned())),
                ("value".to_owned(), Value::Integer(7)),
            ])),
        })
        .unwrap()
        .result
        .unwrap();
    reconnected
        .request(Command::Tick {
            ticks: 100,
            instruction_budget: 10,
        })
        .unwrap()
        .result
        .unwrap();
    assert!(matches!(reconnected.request(Command::InspectActor {
        actor_ref: actor_ref.clone(),
    }).unwrap().result, Ok(Reply::Actor(actor)) if actor.state == Value::Integer(12)));

    reconnected
        .request(Command::PublishBehavior {
            name: "echo".to_owned(),
            expected_revision: None,
            source: "pub fn handle(state, message) { (message, []) }".to_owned(),
        })
        .unwrap()
        .result
        .unwrap();
    let nested = Value::Record(std::collections::BTreeMap::from([(
        "items".to_owned(),
        Value::List(vec![
            Value::Null,
            Value::Bool(true),
            Value::Integer(-42),
            Value::String("hello world".to_owned()),
            Value::ActorRef(runa_actor::ActorRef::parse(&actor_ref).unwrap()),
        ]),
    )]));
    let echo = match reconnected
        .request(Command::Spawn {
            behavior_name: "echo".to_owned(),
            state: nested.clone(),
            mailbox_capacity: 2,
        })
        .unwrap()
        .result
        .unwrap()
    {
        Reply::ActorSpawned { actor_ref } => actor_ref,
        other => panic!("unexpected spawn: {other:?}"),
    };
    assert!(matches!(reconnected.request(Command::InspectActor {
        actor_ref: echo.clone(),
    }).unwrap().result, Ok(Reply::Actor(actor)) if actor.state == nested));
    reconnected
        .request(Command::Send {
            actor_ref: echo.clone(),
            message: nested.clone(),
        })
        .unwrap()
        .result
        .unwrap();
    reconnected
        .request(Command::Tick {
            ticks: 100,
            instruction_budget: 10,
        })
        .unwrap()
        .result
        .unwrap();
    assert!(matches!(reconnected.request(Command::InspectActor {
        actor_ref: echo,
    }).unwrap().result, Ok(Reply::Actor(actor)) if actor.state == nested && actor.reserved.is_none()));
}

fn test_message(kind: i64, value: i64, target: Option<runa_actor::ActorRef>) -> Value {
    Value::Record(std::collections::BTreeMap::from([
        ("kind".to_owned(), Value::Integer(kind)),
        ("value".to_owned(), Value::Integer(value)),
        (
            "target".to_owned(),
            target.map_or(Value::Null, Value::ActorRef),
        ),
    ]))
}