#![feature(impl_trait_in_assoc_type)]

use btrun::*;

use btlib::{
    crypto::{ConcreteCreds, CredStore, CredsPriv},
    log::BuilderExt,
    Result,
};
use btlib_tests::TEST_STORE;
use btproto::protocol;
use btserde::to_vec;
use bttp::{BlockAddr, Transmitter};
use ctor::ctor;
use lazy_static::lazy_static;
use serde::{Deserialize, Serialize};
use std::{
    future::{ready, Future, Ready},
    net::{IpAddr, Ipv4Addr},
    sync::{
        atomic::{AtomicU8, Ordering},
        Arc,
    },
    time::{Duration, Instant},
};
use tokio::{runtime::Builder, sync::mpsc};
use uuid::Uuid;

const RUNTIME_ADDR: IpAddr = IpAddr::V4(Ipv4Addr::new(127, 0, 0, 1));
lazy_static! {
    static ref RUNTIME_CREDS: Arc<ConcreteCreds> = TEST_STORE.node_creds().unwrap();
}
declare_runtime!(RUNTIME, RUNTIME_ADDR, RUNTIME_CREDS.clone());

lazy_static! {
    /// A tokio async runtime.
    ///
    /// When the `#[tokio::test]` attribute is used on a test, a new current thread runtime
    /// is created for each test
    /// (source: https://docs.rs/tokio/latest/tokio/attr.test.html#current-thread-runtime).
    /// This creates a problem, because the first test thread to access the `RUNTIME` static
    /// will initialize its `Receiver` in its runtime, which will stop running at the end of
    /// the test. Hence subsequent tests will not be able to send remote messages to this
    /// `Runtime`.
    ///
    /// By creating a single async runtime which is used by all of the tests, we can avoid this
    /// problem.
    static ref ASYNC_RT: tokio::runtime::Runtime = Builder::new_current_thread()
        .enable_all()
        .build()
        .unwrap();
}

/// The log level to use when running tests.
const LOG_LEVEL: &str = "warn";

#[ctor]
fn ctor() {
    std::env::set_var("RUST_LOG", format!("{},quinn=WARN", LOG_LEVEL));
    env_logger::Builder::from_default_env().btformat().init();
}

#[derive(Serialize, Deserialize)]
struct EchoMsg(String);

impl CallMsg for EchoMsg {
    type Reply = EchoMsg;
}

async fn echo(
    _rt: &'static Runtime,
    mut mailbox: mpsc::Receiver<Envelope<EchoMsg>>,
    _act_id: Uuid,
) {
    while let Some(envelope) = mailbox.recv().await {
        let (msg, replier, ..) = envelope.split();
        if let Some(replier) = replier {
            if let Err(_) = replier.send(msg) {
                panic!("failed to send reply");
            }
        }
    }
}

#[test]
fn local_call() {
    ASYNC_RT.block_on(async {
        const EXPECTED: &str = "hello";
        let name = RUNTIME.activate(echo).await;
        let from = ActorName::new(name.path().clone(), Uuid::default());

        let reply = RUNTIME
            .call(name.clone(), from, EchoMsg(EXPECTED.into()))
            .await
            .unwrap();

        assert_eq!(EXPECTED, reply.0);

        RUNTIME.take(&name).await.unwrap();
    })
}

#[test]
fn remote_call() {
    ASYNC_RT.block_on(async {
        const EXPECTED: &str = "hello";
        let actor_name = RUNTIME.activate(echo).await;
        let bind_path = Arc::new(RUNTIME_CREDS.bind_path().unwrap());
        let block_addr = Arc::new(BlockAddr::new(RUNTIME_ADDR, bind_path));
        let transmitter = Transmitter::new(block_addr, RUNTIME_CREDS.clone())
            .await
            .unwrap();
        let buf = to_vec(&EchoMsg(EXPECTED.to_string())).unwrap();
        let wire_msg = WireMsg::new(
            actor_name.clone(),
            RUNTIME.actor_name(Uuid::default()),
            &buf,
        );

        let reply = transmitter
            .call(wire_msg, ReplyCallback::<EchoMsg>::new())
            .await
            .unwrap()
            .unwrap();

        assert_eq!(EXPECTED, reply.0);

        RUNTIME.take(&actor_name).await.unwrap();
    });
}

/// Tests the `num_running` method.
///
/// This test uses its own runtime and so can use the `#[tokio::test]` attribute.
#[tokio::test]
async fn num_running() {
    declare_runtime!(
        LOCAL_RT,
        // This needs to be different from the address where `RUNTIME` is listening.
        IpAddr::from([127, 0, 0, 2]),
        TEST_STORE.node_creds().unwrap()
    );
    assert_eq!(0, LOCAL_RT.num_running().await);
    let name = LOCAL_RT.activate(echo).await;
    assert_eq!(1, LOCAL_RT.num_running().await);
    LOCAL_RT.take(&name).await.unwrap();
    assert_eq!(0, LOCAL_RT.num_running().await);
}

mod ping_pong {
    use super::*;

    // The following code is a proof-of-concept for what types should be generated for a
    // simple ping-pong protocol:
    protocol! {
        named PingPongProtocol;
        let server = [Server];
        let client = [Client, Waiting];
        Client -> Waiting, >service(Server)!Ping;
        Server?Ping -> End, >Waiting!Ping::Reply;
        Waiting?Ping::Reply -> End;
    }
    //
    // In words, the protocol is described as follows.
    // 1. The ClientInit state receives the Activate message. It returns the SentPing state and a
    //    Ping message to be sent to the Listening state.
    // 2. The ServerInit state receives the Activate message. It returns the Listening state.
    // 3. When the Listening state receives the Ping message it returns the End state and a
    //    Ping::Reply message to be sent to the SentPing state.
    // 4. When the SentPing state receives the Ping::Reply message it returns the End state.
    //
    // The End state represents an end to the session described by the protocol. When an actor
    // transitions to the End state its function returns.
    // The generated actor implementation is the sender of the Activate message.
    // When a state is expecting a Reply message, an error occurs if the message is not received
    // in a timely manner.

    #[derive(Serialize, Deserialize)]
    pub struct Ping;
    impl CallMsg for Ping {
        type Reply = PingReply;
    }

    // I was tempted to name this "Pong", but the proc macro wouldn't think to do that.
    #[derive(Serialize, Deserialize)]
    pub struct PingReply;

    trait ClientInit2 {
        type AfterActivate: SentPing2;
        type HandleActivateFut: Future<Output = Result<(Self::AfterActivate, Ping)>>;
        fn handle_activate(self, msg: Activate) -> Self::HandleActivateFut;
    }

    trait ServerInit2 {
        type AfterActivate: Listening2;
        type HandleActivateFut: Future<Output = Result<Self::AfterActivate>>;
        fn handle_activate(self, msg: Activate) -> Self::HandleActivateFut;
    }

    trait Listening2 {
        type HandlePingFut: Future<Output = Result<(End, PingReply)>>;
        fn handle_ping(self, msg: Ping) -> Self::HandlePingFut;
    }

    trait SentPing2 {
        type HandleReplyFut: Future<Output = Result<End>>;
        fn handle_reply(self, msg: PingReply) -> Self::HandleReplyFut;
    }

    #[derive(Serialize, Deserialize)]
    enum PingProtocolMsg {
        Ping(Ping),
        PingReply(PingReply),
    }
    impl CallMsg for PingProtocolMsg {
        type Reply = PingProtocolMsg;
    }
    impl SendMsg for PingProtocolMsg {}

    struct ClientInitState;

    impl ClientInit2 for ClientInitState {
        type AfterActivate = ClientState;
        type HandleActivateFut = impl Future<Output = Result<(Self::AfterActivate, Ping)>>;
        fn handle_activate(self, _msg: Activate) -> Self::HandleActivateFut {
            ready(Ok((ClientState, Ping)))
        }
    }

    struct ClientState;

    impl SentPing2 for ClientState {
        type HandleReplyFut = Ready<Result<End>>;
        fn handle_reply(self, _msg: PingReply) -> Self::HandleReplyFut {
            ready(Ok(End))
        }
    }

    #[allow(dead_code)]
    enum PingClientState {
        Init(ClientInitState),
        SentPing(ClientState),
        End(End),
    }

    struct ServerInitState;

    struct ServerState;

    impl ServerInit2 for ServerInitState {
        type AfterActivate = ServerState;
        type HandleActivateFut = Ready<Result<Self::AfterActivate>>;
        fn handle_activate(self, _msg: Activate) -> Self::HandleActivateFut {
            ready(Ok(ServerState))
        }
    }

    impl Listening2 for ServerState {
        type HandlePingFut = impl Future<Output = Result<(End, PingReply)>>;
        fn handle_ping(self, _msg: Ping) -> Self::HandlePingFut {
            ready(Ok((End, PingReply)))
        }
    }

    #[allow(dead_code)]
    enum PingServerState {
        ServerInit(ServerInitState),
        Listening(ServerState),
        End(End),
    }

    async fn ping_server(
        counter: Arc<AtomicU8>,
        rt: &'static Runtime,
        mut mailbox: mpsc::Receiver<Envelope<PingProtocolMsg>>,
        act_id: Uuid,
    ) {
        let mut state = {
            let init = ServerInitState;
            let state = init
                .handle_activate(Activate::new(rt, act_id))
                .await
                .unwrap();
            PingServerState::Listening(state)
        };
        while let Some(envelope) = mailbox.recv().await {
            let (msg, replier, _from) = envelope.split();
            match (state, msg) {
                (PingServerState::Listening(listening_state), PingProtocolMsg::Ping(msg)) => {
                    let (new_state, reply) = listening_state.handle_ping(msg).await.unwrap();
                    state = PingServerState::End(new_state);
                    if let Err(_) = replier.unwrap().send(PingProtocolMsg::PingReply(reply)) {
                        panic!("Failed to send Ping reply.");
                    }
                }
                (_prev_state, _) => {
                    panic!("Ping protocol violation.");
                    // A real implementation should assign the previous state and log the error.
                    // state = prev_state;
                }
            }
            if let PingServerState::End(_) = state {
                break;
            }
        }
        counter.fetch_sub(1, Ordering::SeqCst);
    }

    async fn ping_client(
        counter: Arc<AtomicU8>,
        server_name: ActorName,
        rt: &'static Runtime,
        _mailbox: mpsc::Receiver<Envelope<PingProtocolMsg>>,
        act_id: Uuid,
    ) {
        let init = ClientInitState;
        let (state, msg) = init
            .handle_activate(Activate::new(rt, act_id))
            .await
            .unwrap();
        let from = rt.actor_name(act_id);
        let reply = rt
            .call(server_name, from, PingProtocolMsg::Ping(msg))
            .await
            .unwrap();
        if let PingProtocolMsg::PingReply(msg) = reply {
            state.handle_reply(msg).await.unwrap();
        } else {
            panic!("Incorrect message type sent in reply to Ping.");
        }
        counter.fetch_sub(1, Ordering::SeqCst);
    }

    #[test]
    fn ping_pong_test() {
        ASYNC_RT.block_on(async {
            let counter = Arc::new(AtomicU8::new(2));
            let server_name = {
                let counter = counter.clone();
                RUNTIME
                    .activate(move |rt, mailbox, act_id| ping_server(counter, rt, mailbox, act_id))
                    .await
            };
            let client_name = {
                let server_name = server_name.clone();
                let counter = counter.clone();
                RUNTIME
                    .activate(move |rt, mailbox, act_id| {
                        ping_client(counter, server_name, rt, mailbox, act_id)
                    })
                    .await
            };

            let deadline = Instant::now() + Duration::from_millis(500);
            while counter.load(Ordering::SeqCst) > 0 && Instant::now() < deadline {
                tokio::time::sleep(Duration::from_millis(20)).await;
            }
            // Check that both tasks finished successfully and we didn't just timeout.
            assert_eq!(0, counter.load(Ordering::SeqCst));

            // TODO: Should actor which return be removed from the runtime automatically?
            RUNTIME.take(&server_name).await.unwrap();
            RUNTIME.take(&client_name).await.unwrap();
        });
    }
}

mod travel_agency {
    use super::*;

    // Here's another protocol example. This is the Customer and Travel Agency protocol used as an
    // example in the survey paper "Behavioral Types in Programming Languages."
    // Note that the Choosing state can send messages at any time, not just in response to another
    // message because there is a transition from Choosing that doesn't use the receive operator
    // (`?`).
    protocol! {
        named TravelAgency;
        let agency = [Listening];
        let customer = [Choosing];
        Choosing -> Choosing, >service(Listening)!Query;
        Choosing -> Choosing, >service(Listening)!Accept;
        Choosing -> Choosing, >service(Listening)!Reject;
        Listening?Query -> Listening, >Choosing!Query::Reply;
        Choosing?Query::Reply -> Choosing;
        Listening?Accept -> End, >Choosing!Accept::Reply;
        Choosing?Accept::Reply -> End;
        Listening?Reject -> End, >Choosing!Reject::Reply;
        Choosing?Reject::Reply -> End;
    }

    #[derive(Serialize, Deserialize)]
    pub struct Query;

    impl CallMsg for Query {
        type Reply = ();
    }

    #[derive(Serialize, Deserialize)]
    pub struct Reject;

    impl CallMsg for Reject {
        type Reply = ();
    }

    #[derive(Serialize, Deserialize)]
    pub struct Accept;

    impl CallMsg for Accept {
        type Reply = ();
    }
}