mod store;

use super::{
    auth::process_auth_header,
    db::{ChannelId, MessageId, UserId},
    AppState,
};
use anyhow::anyhow;
use async_std::task;
use async_tungstenite::{tungstenite::protocol::Role, WebSocketStream};
use collections::{HashMap, HashSet};
use futures::{future::BoxFuture, FutureExt, StreamExt};
use parking_lot::{RwLock, RwLockReadGuard, RwLockWriteGuard};
use postage::{mpsc, prelude::Sink as _};
use rpc::{
    proto::{self, AnyTypedEnvelope, EnvelopedMessage},
    Connection, ConnectionId, Peer, TypedEnvelope,
};
use sha1::{Digest as _, Sha1};
use std::{any::TypeId, future::Future, mem, path::PathBuf, sync::Arc, time::Instant};
use store::{Store, Worktree};
use surf::StatusCode;
use tide::log;
use tide::{
    http::headers::{HeaderName, CONNECTION, UPGRADE},
    Request, Response,
};
use time::OffsetDateTime;

type MessageHandler = Box<
    dyn Send
        + Sync
        + Fn(Arc<Server>, Box<dyn AnyTypedEnvelope>) -> BoxFuture<'static, tide::Result<()>>,
>;

pub struct Server {
    peer: Arc<Peer>,
    store: RwLock<Store>,
    app_state: Arc<AppState>,
    handlers: HashMap<TypeId, MessageHandler>,
    notifications: Option<mpsc::Sender<()>>,
}

const MESSAGE_COUNT_PER_PAGE: usize = 100;
const MAX_MESSAGE_LEN: usize = 1024;
const NO_SUCH_PROJECT: &'static str = "no such project";

impl Server {
    pub fn new(
        app_state: Arc<AppState>,
        peer: Arc<Peer>,
        notifications: Option<mpsc::Sender<()>>,
    ) -> Arc<Self> {
        let mut server = Self {
            peer,
            app_state,
            store: Default::default(),
            handlers: Default::default(),
            notifications,
        };

        server
            .add_handler(Server::ping)
            .add_handler(Server::register_project)
            .add_handler(Server::unregister_project)
            .add_handler(Server::share_project)
            .add_handler(Server::unshare_project)
            .add_handler(Server::join_project)
            .add_handler(Server::leave_project)
            .add_handler(Server::register_worktree)
            .add_handler(Server::unregister_worktree)
            .add_handler(Server::share_worktree)
            .add_handler(Server::update_worktree)
            .add_handler(Server::update_diagnostic_summary)
            .add_handler(Server::disk_based_diagnostics_updating)
            .add_handler(Server::disk_based_diagnostics_updated)
            .add_handler(Server::open_buffer)
            .add_handler(Server::close_buffer)
            .add_handler(Server::update_buffer)
            .add_handler(Server::buffer_saved)
            .add_handler(Server::save_buffer)
            .add_handler(Server::format_buffer)
            .add_handler(Server::get_channels)
            .add_handler(Server::get_users)
            .add_handler(Server::join_channel)
            .add_handler(Server::leave_channel)
            .add_handler(Server::send_channel_message)
            .add_handler(Server::get_channel_messages);

        Arc::new(server)
    }

    fn add_handler<F, Fut, M>(&mut self, handler: F) -> &mut Self
    where
        F: 'static + Send + Sync + Fn(Arc<Self>, TypedEnvelope<M>) -> Fut,
        Fut: 'static + Send + Future<Output = tide::Result<()>>,
        M: EnvelopedMessage,
    {
        let prev_handler = self.handlers.insert(
            TypeId::of::<M>(),
            Box::new(move |server, envelope| {
                let envelope = envelope.into_any().downcast::<TypedEnvelope<M>>().unwrap();
                (handler)(server, *envelope).boxed()
            }),
        );
        if prev_handler.is_some() {
            panic!("registered a handler for the same message twice");
        }
        self
    }

    pub fn handle_connection(
        self: &Arc<Self>,
        connection: Connection,
        addr: String,
        user_id: UserId,
        mut send_connection_id: Option<postage::mpsc::Sender<ConnectionId>>,
    ) -> impl Future<Output = ()> {
        let mut this = self.clone();
        async move {
            let (connection_id, handle_io, mut incoming_rx) =
                this.peer.add_connection(connection).await;

            if let Some(send_connection_id) = send_connection_id.as_mut() {
                let _ = send_connection_id.send(connection_id).await;
            }

            this.state_mut().add_connection(connection_id, user_id);
            if let Err(err) = this.update_contacts_for_users(&[user_id]).await {
                log::error!("error updating contacts for {:?}: {}", user_id, err);
            }

            let handle_io = handle_io.fuse();
            futures::pin_mut!(handle_io);
            loop {
                let next_message = incoming_rx.next().fuse();
                futures::pin_mut!(next_message);
                futures::select_biased! {
                    message = next_message => {
                        if let Some(message) = message {
                            let start_time = Instant::now();
                            log::info!("RPC message received: {}", message.payload_type_name());
                            if let Some(handler) = this.handlers.get(&message.payload_type_id()) {
                                if let Err(err) = (handler)(this.clone(), message).await {
                                    log::error!("error handling message: {:?}", err);
                                } else {
                                    log::info!("RPC message handled. duration:{:?}", start_time.elapsed());
                                }

                                if let Some(mut notifications) = this.notifications.clone() {
                                    let _ = notifications.send(()).await;
                                }
                            } else {
                                log::warn!("unhandled message: {}", message.payload_type_name());
                            }
                        } else {
                            log::info!("rpc connection closed {:?}", addr);
                            break;
                        }
                    }
                    handle_io = handle_io => {
                        if let Err(err) = handle_io {
                            log::error!("error handling rpc connection {:?} - {:?}", addr, err);
                        }
                        break;
                    }
                }
            }

            if let Err(err) = this.sign_out(connection_id).await {
                log::error!("error signing out connection {:?} - {:?}", addr, err);
            }
        }
    }

    async fn sign_out(self: &mut Arc<Self>, connection_id: ConnectionId) -> tide::Result<()> {
        self.peer.disconnect(connection_id);
        let removed_connection = self.state_mut().remove_connection(connection_id)?;

        for (project_id, project) in removed_connection.hosted_projects {
            if let Some(share) = project.share {
                broadcast(
                    connection_id,
                    share.guests.keys().copied().collect(),
                    |conn_id| {
                        self.peer
                            .send(conn_id, proto::UnshareProject { project_id })
                    },
                )
                .await?;
            }
        }

        for (project_id, peer_ids) in removed_connection.guest_project_ids {
            broadcast(connection_id, peer_ids, |conn_id| {
                self.peer.send(
                    conn_id,
                    proto::RemoveProjectCollaborator {
                        project_id,
                        peer_id: connection_id.0,
                    },
                )
            })
            .await?;
        }

        self.update_contacts_for_users(removed_connection.contact_ids.iter())
            .await?;

        Ok(())
    }

    async fn ping(self: Arc<Server>, request: TypedEnvelope<proto::Ping>) -> tide::Result<()> {
        self.peer.respond(request.receipt(), proto::Ack {}).await?;
        Ok(())
    }

    async fn register_project(
        mut self: Arc<Server>,
        request: TypedEnvelope<proto::RegisterProject>,
    ) -> tide::Result<()> {
        let project_id = {
            let mut state = self.state_mut();
            let user_id = state.user_id_for_connection(request.sender_id)?;
            state.register_project(request.sender_id, user_id)
        };
        self.peer
            .respond(
                request.receipt(),
                proto::RegisterProjectResponse { project_id },
            )
            .await?;
        Ok(())
    }

    async fn unregister_project(
        mut self: Arc<Server>,
        request: TypedEnvelope<proto::UnregisterProject>,
    ) -> tide::Result<()> {
        let project = self
            .state_mut()
            .unregister_project(request.payload.project_id, request.sender_id)
            .ok_or_else(|| anyhow!("no such project"))?;
        self.update_contacts_for_users(project.authorized_user_ids().iter())
            .await?;
        Ok(())
    }

    async fn share_project(
        mut self: Arc<Server>,
        request: TypedEnvelope<proto::ShareProject>,
    ) -> tide::Result<()> {
        self.state_mut()
            .share_project(request.payload.project_id, request.sender_id);
        self.peer.respond(request.receipt(), proto::Ack {}).await?;
        Ok(())
    }

    async fn unshare_project(
        mut self: Arc<Server>,
        request: TypedEnvelope<proto::UnshareProject>,
    ) -> tide::Result<()> {
        let project_id = request.payload.project_id;
        let project = self
            .state_mut()
            .unshare_project(project_id, request.sender_id)?;

        broadcast(request.sender_id, project.connection_ids, |conn_id| {
            self.peer
                .send(conn_id, proto::UnshareProject { project_id })
        })
        .await?;
        self.update_contacts_for_users(&project.authorized_user_ids)
            .await?;

        Ok(())
    }

    async fn join_project(
        mut self: Arc<Server>,
        request: TypedEnvelope<proto::JoinProject>,
    ) -> tide::Result<()> {
        let project_id = request.payload.project_id;

        let user_id = self.state().user_id_for_connection(request.sender_id)?;
        let response_data = self
            .state_mut()
            .join_project(request.sender_id, user_id, project_id)
            .and_then(|joined| {
                let share = joined.project.share()?;
                let peer_count = share.guests.len();
                let mut collaborators = Vec::with_capacity(peer_count);
                collaborators.push(proto::Collaborator {
                    peer_id: joined.project.host_connection_id.0,
                    replica_id: 0,
                    user_id: joined.project.host_user_id.to_proto(),
                });
                let worktrees = joined
                    .project
                    .worktrees
                    .iter()
                    .filter_map(|(id, worktree)| {
                        worktree.share.as_ref().map(|share| proto::Worktree {
                            id: *id,
                            root_name: worktree.root_name.clone(),
                            entries: share.entries.values().cloned().collect(),
                            diagnostic_summaries: share
                                .diagnostic_summaries
                                .values()
                                .cloned()
                                .collect(),
                        })
                    })
                    .collect();
                for (peer_conn_id, (peer_replica_id, peer_user_id)) in &share.guests {
                    if *peer_conn_id != request.sender_id {
                        collaborators.push(proto::Collaborator {
                            peer_id: peer_conn_id.0,
                            replica_id: *peer_replica_id as u32,
                            user_id: peer_user_id.to_proto(),
                        });
                    }
                }
                let response = proto::JoinProjectResponse {
                    worktrees,
                    replica_id: joined.replica_id as u32,
                    collaborators,
                };
                let connection_ids = joined.project.connection_ids();
                let contact_user_ids = joined.project.authorized_user_ids();
                Ok((response, connection_ids, contact_user_ids))
            });

        match response_data {
            Ok((response, connection_ids, contact_user_ids)) => {
                broadcast(request.sender_id, connection_ids, |conn_id| {
                    self.peer.send(
                        conn_id,
                        proto::AddProjectCollaborator {
                            project_id: project_id,
                            collaborator: Some(proto::Collaborator {
                                peer_id: request.sender_id.0,
                                replica_id: response.replica_id,
                                user_id: user_id.to_proto(),
                            }),
                        },
                    )
                })
                .await?;
                self.peer.respond(request.receipt(), response).await?;
                self.update_contacts_for_users(&contact_user_ids).await?;
            }
            Err(error) => {
                self.peer
                    .respond_with_error(
                        request.receipt(),
                        proto::Error {
                            message: error.to_string(),
                        },
                    )
                    .await?;
            }
        }

        Ok(())
    }

    async fn leave_project(
        mut self: Arc<Server>,
        request: TypedEnvelope<proto::LeaveProject>,
    ) -> tide::Result<()> {
        let sender_id = request.sender_id;
        let project_id = request.payload.project_id;
        let worktree = self.state_mut().leave_project(sender_id, project_id);
        if let Some(worktree) = worktree {
            broadcast(sender_id, worktree.connection_ids, |conn_id| {
                self.peer.send(
                    conn_id,
                    proto::RemoveProjectCollaborator {
                        project_id,
                        peer_id: sender_id.0,
                    },
                )
            })
            .await?;
            self.update_contacts_for_users(&worktree.authorized_user_ids)
                .await?;
        }
        Ok(())
    }

    async fn register_worktree(
        mut self: Arc<Server>,
        request: TypedEnvelope<proto::RegisterWorktree>,
    ) -> tide::Result<()> {
        let receipt = request.receipt();
        let host_user_id = self.state().user_id_for_connection(request.sender_id)?;

        let mut contact_user_ids = HashSet::default();
        contact_user_ids.insert(host_user_id);
        for github_login in request.payload.authorized_logins {
            match self.app_state.db.create_user(&github_login, false).await {
                Ok(contact_user_id) => {
                    contact_user_ids.insert(contact_user_id);
                }
                Err(err) => {
                    let message = err.to_string();
                    self.peer
                        .respond_with_error(receipt, proto::Error { message })
                        .await?;
                    return Ok(());
                }
            }
        }

        let contact_user_ids = contact_user_ids.into_iter().collect::<Vec<_>>();
        let ok = self.state_mut().register_worktree(
            request.payload.project_id,
            request.payload.worktree_id,
            Worktree {
                authorized_user_ids: contact_user_ids.clone(),
                root_name: request.payload.root_name,
                share: None,
            },
        );

        if ok {
            self.peer.respond(receipt, proto::Ack {}).await?;
            self.update_contacts_for_users(&contact_user_ids).await?;
        } else {
            self.peer
                .respond_with_error(
                    receipt,
                    proto::Error {
                        message: NO_SUCH_PROJECT.to_string(),
                    },
                )
                .await?;
        }

        Ok(())
    }

    async fn unregister_worktree(
        mut self: Arc<Server>,
        request: TypedEnvelope<proto::UnregisterWorktree>,
    ) -> tide::Result<()> {
        let project_id = request.payload.project_id;
        let worktree_id = request.payload.worktree_id;
        let (worktree, guest_connection_ids) =
            self.state_mut()
                .unregister_worktree(project_id, worktree_id, request.sender_id)?;

        broadcast(request.sender_id, guest_connection_ids, |conn_id| {
            self.peer.send(
                conn_id,
                proto::UnregisterWorktree {
                    project_id,
                    worktree_id,
                },
            )
        })
        .await?;
        self.update_contacts_for_users(&worktree.authorized_user_ids)
            .await?;
        Ok(())
    }

    async fn share_worktree(
        mut self: Arc<Server>,
        mut request: TypedEnvelope<proto::ShareWorktree>,
    ) -> tide::Result<()> {
        let worktree = request
            .payload
            .worktree
            .as_mut()
            .ok_or_else(|| anyhow!("missing worktree"))?;
        let entries = mem::take(&mut worktree.entries)
            .into_iter()
            .map(|entry| (entry.id, entry))
            .collect();

        let diagnostic_summaries = mem::take(&mut worktree.diagnostic_summaries)
            .into_iter()
            .map(|summary| (PathBuf::from(summary.path.clone()), summary))
            .collect();

        let contact_user_ids = self.state_mut().share_worktree(
            request.payload.project_id,
            worktree.id,
            request.sender_id,
            entries,
            diagnostic_summaries,
        );
        if let Some(contact_user_ids) = contact_user_ids {
            self.peer.respond(request.receipt(), proto::Ack {}).await?;
            self.update_contacts_for_users(&contact_user_ids).await?;
        } else {
            self.peer
                .respond_with_error(
                    request.receipt(),
                    proto::Error {
                        message: "no such worktree".to_string(),
                    },
                )
                .await?;
        }
        Ok(())
    }

    async fn update_worktree(
        mut self: Arc<Server>,
        request: TypedEnvelope<proto::UpdateWorktree>,
    ) -> tide::Result<()> {
        let connection_ids = self
            .state_mut()
            .update_worktree(
                request.sender_id,
                request.payload.project_id,
                request.payload.worktree_id,
                &request.payload.removed_entries,
                &request.payload.updated_entries,
            )
            .ok_or_else(|| anyhow!("no such worktree"))?;

        broadcast(request.sender_id, connection_ids, |connection_id| {
            self.peer
                .forward_send(request.sender_id, connection_id, request.payload.clone())
        })
        .await?;

        Ok(())
    }

    async fn update_diagnostic_summary(
        mut self: Arc<Server>,
        request: TypedEnvelope<proto::UpdateDiagnosticSummary>,
    ) -> tide::Result<()> {
        let receiver_ids = request
            .payload
            .summary
            .clone()
            .and_then(|summary| {
                self.state_mut().update_diagnostic_summary(
                    request.payload.project_id,
                    request.payload.worktree_id,
                    request.sender_id,
                    summary,
                )
            })
            .ok_or_else(|| anyhow!(NO_SUCH_PROJECT))?;

        broadcast(request.sender_id, receiver_ids, |connection_id| {
            self.peer
                .forward_send(request.sender_id, connection_id, request.payload.clone())
        })
        .await?;
        Ok(())
    }

    async fn disk_based_diagnostics_updating(
        self: Arc<Server>,
        request: TypedEnvelope<proto::DiskBasedDiagnosticsUpdating>,
    ) -> tide::Result<()> {
        let receiver_ids = self
            .state()
            .project_connection_ids(request.payload.project_id, request.sender_id)
            .ok_or_else(|| anyhow!(NO_SUCH_PROJECT))?;
        broadcast(request.sender_id, receiver_ids, |connection_id| {
            self.peer
                .forward_send(request.sender_id, connection_id, request.payload.clone())
        })
        .await?;
        Ok(())
    }

    async fn disk_based_diagnostics_updated(
        self: Arc<Server>,
        request: TypedEnvelope<proto::DiskBasedDiagnosticsUpdated>,
    ) -> tide::Result<()> {
        let receiver_ids = self
            .state()
            .project_connection_ids(request.payload.project_id, request.sender_id)
            .ok_or_else(|| anyhow!(NO_SUCH_PROJECT))?;
        broadcast(request.sender_id, receiver_ids, |connection_id| {
            self.peer
                .forward_send(request.sender_id, connection_id, request.payload.clone())
        })
        .await?;
        Ok(())
    }

    async fn open_buffer(
        self: Arc<Server>,
        request: TypedEnvelope<proto::OpenBuffer>,
    ) -> tide::Result<()> {
        let receipt = request.receipt();
        let host_connection_id = self
            .state()
            .read_project(request.payload.project_id, request.sender_id)
            .ok_or_else(|| anyhow!(NO_SUCH_PROJECT))?
            .host_connection_id;
        let response = self
            .peer
            .forward_request(request.sender_id, host_connection_id, request.payload)
            .await?;
        self.peer.respond(receipt, response).await?;
        Ok(())
    }

    async fn close_buffer(
        self: Arc<Server>,
        request: TypedEnvelope<proto::CloseBuffer>,
    ) -> tide::Result<()> {
        let host_connection_id = self
            .state()
            .read_project(request.payload.project_id, request.sender_id)
            .ok_or_else(|| anyhow!(NO_SUCH_PROJECT))?
            .host_connection_id;
        self.peer
            .forward_send(request.sender_id, host_connection_id, request.payload)
            .await?;
        Ok(())
    }

    async fn save_buffer(
        self: Arc<Server>,
        request: TypedEnvelope<proto::SaveBuffer>,
    ) -> tide::Result<()> {
        let host;
        let guests;
        {
            let state = self.state();
            let project = state
                .read_project(request.payload.project_id, request.sender_id)
                .ok_or_else(|| anyhow!(NO_SUCH_PROJECT))?;
            host = project.host_connection_id;
            guests = project.guest_connection_ids()
        }

        let sender = request.sender_id;
        let receipt = request.receipt();
        let response = self
            .peer
            .forward_request(sender, host, request.payload.clone())
            .await?;

        broadcast(host, guests, |conn_id| {
            let response = response.clone();
            let peer = &self.peer;
            async move {
                if conn_id == sender {
                    peer.respond(receipt, response).await
                } else {
                    peer.forward_send(host, conn_id, response).await
                }
            }
        })
        .await?;

        Ok(())
    }

    async fn format_buffer(
        self: Arc<Server>,
        request: TypedEnvelope<proto::FormatBuffer>,
    ) -> tide::Result<()> {
        let host;
        {
            let state = self.state();
            let project = state
                .read_project(request.payload.project_id, request.sender_id)
                .ok_or_else(|| anyhow!(NO_SUCH_PROJECT))?;
            host = project.host_connection_id;
        }

        let sender = request.sender_id;
        let receipt = request.receipt();
        let response = self
            .peer
            .forward_request(sender, host, request.payload.clone())
            .await?;
        self.peer.respond(receipt, response).await?;

        Ok(())
    }

    async fn update_buffer(
        self: Arc<Server>,
        request: TypedEnvelope<proto::UpdateBuffer>,
    ) -> tide::Result<()> {
        let receiver_ids = self
            .state()
            .project_connection_ids(request.payload.project_id, request.sender_id)
            .ok_or_else(|| anyhow!(NO_SUCH_PROJECT))?;
        broadcast(request.sender_id, receiver_ids, |connection_id| {
            self.peer
                .forward_send(request.sender_id, connection_id, request.payload.clone())
        })
        .await?;
        self.peer.respond(request.receipt(), proto::Ack {}).await?;
        Ok(())
    }

    async fn buffer_saved(
        self: Arc<Server>,
        request: TypedEnvelope<proto::BufferSaved>,
    ) -> tide::Result<()> {
        let receiver_ids = self
            .state()
            .project_connection_ids(request.payload.project_id, request.sender_id)
            .ok_or_else(|| anyhow!(NO_SUCH_PROJECT))?;
        broadcast(request.sender_id, receiver_ids, |connection_id| {
            self.peer
                .forward_send(request.sender_id, connection_id, request.payload.clone())
        })
        .await?;
        Ok(())
    }

    async fn get_channels(
        self: Arc<Server>,
        request: TypedEnvelope<proto::GetChannels>,
    ) -> tide::Result<()> {
        let user_id = self.state().user_id_for_connection(request.sender_id)?;
        let channels = self.app_state.db.get_accessible_channels(user_id).await?;
        self.peer
            .respond(
                request.receipt(),
                proto::GetChannelsResponse {
                    channels: channels
                        .into_iter()
                        .map(|chan| proto::Channel {
                            id: chan.id.to_proto(),
                            name: chan.name,
                        })
                        .collect(),
                },
            )
            .await?;
        Ok(())
    }

    async fn get_users(
        self: Arc<Server>,
        request: TypedEnvelope<proto::GetUsers>,
    ) -> tide::Result<()> {
        let receipt = request.receipt();
        let user_ids = request.payload.user_ids.into_iter().map(UserId::from_proto);
        let users = self
            .app_state
            .db
            .get_users_by_ids(user_ids)
            .await?
            .into_iter()
            .map(|user| proto::User {
                id: user.id.to_proto(),
                avatar_url: format!("https://github.com/{}.png?size=128", user.github_login),
                github_login: user.github_login,
            })
            .collect();
        self.peer
            .respond(receipt, proto::GetUsersResponse { users })
            .await?;
        Ok(())
    }

    async fn update_contacts_for_users<'a>(
        self: &Arc<Server>,
        user_ids: impl IntoIterator<Item = &'a UserId>,
    ) -> tide::Result<()> {
        let mut send_futures = Vec::new();

        {
            let state = self.state();
            for user_id in user_ids {
                let contacts = state.contacts_for_user(*user_id);
                for connection_id in state.connection_ids_for_user(*user_id) {
                    send_futures.push(self.peer.send(
                        connection_id,
                        proto::UpdateContacts {
                            contacts: contacts.clone(),
                        },
                    ));
                }
            }
        }
        futures::future::try_join_all(send_futures).await?;

        Ok(())
    }

    async fn join_channel(
        mut self: Arc<Self>,
        request: TypedEnvelope<proto::JoinChannel>,
    ) -> tide::Result<()> {
        let user_id = self.state().user_id_for_connection(request.sender_id)?;
        let channel_id = ChannelId::from_proto(request.payload.channel_id);
        if !self
            .app_state
            .db
            .can_user_access_channel(user_id, channel_id)
            .await?
        {
            Err(anyhow!("access denied"))?;
        }

        self.state_mut().join_channel(request.sender_id, channel_id);
        let messages = self
            .app_state
            .db
            .get_channel_messages(channel_id, MESSAGE_COUNT_PER_PAGE, None)
            .await?
            .into_iter()
            .map(|msg| proto::ChannelMessage {
                id: msg.id.to_proto(),
                body: msg.body,
                timestamp: msg.sent_at.unix_timestamp() as u64,
                sender_id: msg.sender_id.to_proto(),
                nonce: Some(msg.nonce.as_u128().into()),
            })
            .collect::<Vec<_>>();
        self.peer
            .respond(
                request.receipt(),
                proto::JoinChannelResponse {
                    done: messages.len() < MESSAGE_COUNT_PER_PAGE,
                    messages,
                },
            )
            .await?;
        Ok(())
    }

    async fn leave_channel(
        mut self: Arc<Self>,
        request: TypedEnvelope<proto::LeaveChannel>,
    ) -> tide::Result<()> {
        let user_id = self.state().user_id_for_connection(request.sender_id)?;
        let channel_id = ChannelId::from_proto(request.payload.channel_id);
        if !self
            .app_state
            .db
            .can_user_access_channel(user_id, channel_id)
            .await?
        {
            Err(anyhow!("access denied"))?;
        }

        self.state_mut()
            .leave_channel(request.sender_id, channel_id);

        Ok(())
    }

    async fn send_channel_message(
        self: Arc<Self>,
        request: TypedEnvelope<proto::SendChannelMessage>,
    ) -> tide::Result<()> {
        let receipt = request.receipt();
        let channel_id = ChannelId::from_proto(request.payload.channel_id);
        let user_id;
        let connection_ids;
        {
            let state = self.state();
            user_id = state.user_id_for_connection(request.sender_id)?;
            if let Some(ids) = state.channel_connection_ids(channel_id) {
                connection_ids = ids;
            } else {
                return Ok(());
            }
        }

        // Validate the message body.
        let body = request.payload.body.trim().to_string();
        if body.len() > MAX_MESSAGE_LEN {
            self.peer
                .respond_with_error(
                    receipt,
                    proto::Error {
                        message: "message is too long".to_string(),
                    },
                )
                .await?;
            return Ok(());
        }
        if body.is_empty() {
            self.peer
                .respond_with_error(
                    receipt,
                    proto::Error {
                        message: "message can't be blank".to_string(),
                    },
                )
                .await?;
            return Ok(());
        }

        let timestamp = OffsetDateTime::now_utc();
        let nonce = if let Some(nonce) = request.payload.nonce {
            nonce
        } else {
            self.peer
                .respond_with_error(
                    receipt,
                    proto::Error {
                        message: "nonce can't be blank".to_string(),
                    },
                )
                .await?;
            return Ok(());
        };

        let message_id = self
            .app_state
            .db
            .create_channel_message(channel_id, user_id, &body, timestamp, nonce.clone().into())
            .await?
            .to_proto();
        let message = proto::ChannelMessage {
            sender_id: user_id.to_proto(),
            id: message_id,
            body,
            timestamp: timestamp.unix_timestamp() as u64,
            nonce: Some(nonce),
        };
        broadcast(request.sender_id, connection_ids, |conn_id| {
            self.peer.send(
                conn_id,
                proto::ChannelMessageSent {
                    channel_id: channel_id.to_proto(),
                    message: Some(message.clone()),
                },
            )
        })
        .await?;
        self.peer
            .respond(
                receipt,
                proto::SendChannelMessageResponse {
                    message: Some(message),
                },
            )
            .await?;
        Ok(())
    }

    async fn get_channel_messages(
        self: Arc<Self>,
        request: TypedEnvelope<proto::GetChannelMessages>,
    ) -> tide::Result<()> {
        let user_id = self.state().user_id_for_connection(request.sender_id)?;
        let channel_id = ChannelId::from_proto(request.payload.channel_id);
        if !self
            .app_state
            .db
            .can_user_access_channel(user_id, channel_id)
            .await?
        {
            Err(anyhow!("access denied"))?;
        }

        let messages = self
            .app_state
            .db
            .get_channel_messages(
                channel_id,
                MESSAGE_COUNT_PER_PAGE,
                Some(MessageId::from_proto(request.payload.before_message_id)),
            )
            .await?
            .into_iter()
            .map(|msg| proto::ChannelMessage {
                id: msg.id.to_proto(),
                body: msg.body,
                timestamp: msg.sent_at.unix_timestamp() as u64,
                sender_id: msg.sender_id.to_proto(),
                nonce: Some(msg.nonce.as_u128().into()),
            })
            .collect::<Vec<_>>();
        self.peer
            .respond(
                request.receipt(),
                proto::GetChannelMessagesResponse {
                    done: messages.len() < MESSAGE_COUNT_PER_PAGE,
                    messages,
                },
            )
            .await?;
        Ok(())
    }

    fn state<'a>(self: &'a Arc<Self>) -> RwLockReadGuard<'a, Store> {
        self.store.read()
    }

    fn state_mut<'a>(self: &'a mut Arc<Self>) -> RwLockWriteGuard<'a, Store> {
        self.store.write()
    }
}

pub async fn broadcast<F, T>(
    sender_id: ConnectionId,
    receiver_ids: Vec<ConnectionId>,
    mut f: F,
) -> anyhow::Result<()>
where
    F: FnMut(ConnectionId) -> T,
    T: Future<Output = anyhow::Result<()>>,
{
    let futures = receiver_ids
        .into_iter()
        .filter(|id| *id != sender_id)
        .map(|id| f(id));
    futures::future::try_join_all(futures).await?;
    Ok(())
}

pub fn add_routes(app: &mut tide::Server<Arc<AppState>>, rpc: &Arc<Peer>) {
    let server = Server::new(app.state().clone(), rpc.clone(), None);
    app.at("/rpc").get(move |request: Request<Arc<AppState>>| {
        let server = server.clone();
        async move {
            const WEBSOCKET_GUID: &str = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";

            let connection_upgrade = header_contains_ignore_case(&request, CONNECTION, "upgrade");
            let upgrade_to_websocket = header_contains_ignore_case(&request, UPGRADE, "websocket");
            let upgrade_requested = connection_upgrade && upgrade_to_websocket;
            let client_protocol_version: Option<u32> = request
                .header("X-Zed-Protocol-Version")
                .and_then(|v| v.as_str().parse().ok());

            if !upgrade_requested || client_protocol_version != Some(rpc::PROTOCOL_VERSION) {
                return Ok(Response::new(StatusCode::UpgradeRequired));
            }

            let header = match request.header("Sec-Websocket-Key") {
                Some(h) => h.as_str(),
                None => return Err(anyhow!("expected sec-websocket-key"))?,
            };

            let user_id = process_auth_header(&request).await?;

            let mut response = Response::new(StatusCode::SwitchingProtocols);
            response.insert_header(UPGRADE, "websocket");
            response.insert_header(CONNECTION, "Upgrade");
            let hash = Sha1::new().chain(header).chain(WEBSOCKET_GUID).finalize();
            response.insert_header("Sec-Websocket-Accept", base64::encode(&hash[..]));
            response.insert_header("Sec-Websocket-Version", "13");

            let http_res: &mut tide::http::Response = response.as_mut();
            let upgrade_receiver = http_res.recv_upgrade().await;
            let addr = request.remote().unwrap_or("unknown").to_string();
            task::spawn(async move {
                if let Some(stream) = upgrade_receiver.await {
                    server
                        .handle_connection(
                            Connection::new(
                                WebSocketStream::from_raw_socket(stream, Role::Server, None).await,
                            ),
                            addr,
                            user_id,
                            None,
                        )
                        .await;
                }
            });

            Ok(response)
        }
    });
}

fn header_contains_ignore_case<T>(
    request: &tide::Request<T>,
    header_name: HeaderName,
    value: &str,
) -> bool {
    request
        .header(header_name)
        .map(|h| {
            h.as_str()
                .split(',')
                .any(|s| s.trim().eq_ignore_ascii_case(value.trim()))
        })
        .unwrap_or(false)
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::{
        auth,
        db::{tests::TestDb, UserId},
        github, AppState, Config,
    };
    use ::rpc::Peer;
    use async_std::task;
    use gpui::{executor, ModelHandle, TestAppContext};
    use parking_lot::Mutex;
    use postage::{mpsc, watch};
    use rpc::PeerId;
    use serde_json::json;
    use sqlx::types::time::OffsetDateTime;
    use std::{
        ops::Deref,
        path::Path,
        rc::Rc,
        sync::{
            atomic::{AtomicBool, Ordering::SeqCst},
            Arc,
        },
        time::Duration,
    };
    use zed::{
        client::{
            self, test::FakeHttpClient, Channel, ChannelDetails, ChannelList, Client, Credentials,
            EstablishConnectionError, UserStore,
        },
        editor::{Editor, EditorSettings, Input, MultiBuffer},
        fs::{FakeFs, Fs as _},
        language::{
            tree_sitter_rust, Diagnostic, DiagnosticEntry, Language, LanguageConfig,
            LanguageRegistry, LanguageServerConfig, Point,
        },
        lsp,
        project::{DiagnosticSummary, Project, ProjectPath},
    };

    #[gpui::test]
    async fn test_share_project(mut cx_a: TestAppContext, mut cx_b: TestAppContext) {
        let (window_b, _) = cx_b.add_window(|_| EmptyView);
        let lang_registry = Arc::new(LanguageRegistry::new());
        let fs = Arc::new(FakeFs::new());
        cx_a.foreground().forbid_parking();

        // Connect to a server as 2 clients.
        let mut server = TestServer::start(cx_a.foreground()).await;
        let client_a = server.create_client(&mut cx_a, "user_a").await;
        let client_b = server.create_client(&mut cx_b, "user_b").await;

        // Share a project as client A
        fs.insert_tree(
            "/a",
            json!({
                ".zed.toml": r#"collaborators = ["user_b"]"#,
                "a.txt": "a-contents",
                "b.txt": "b-contents",
            }),
        )
        .await;
        let project_a = cx_a.update(|cx| {
            Project::local(
                client_a.clone(),
                client_a.user_store.clone(),
                lang_registry.clone(),
                fs.clone(),
                cx,
            )
        });
        let worktree_a = project_a
            .update(&mut cx_a, |p, cx| p.add_local_worktree("/a", cx))
            .await
            .unwrap();
        worktree_a
            .read_with(&cx_a, |tree, _| tree.as_local().unwrap().scan_complete())
            .await;
        let project_id = project_a
            .update(&mut cx_a, |project, _| project.next_remote_id())
            .await;
        project_a
            .update(&mut cx_a, |project, cx| project.share(cx))
            .await
            .unwrap();

        // Join that project as client B
        let project_b = Project::remote(
            project_id,
            client_b.clone(),
            client_b.user_store.clone(),
            lang_registry.clone(),
            fs.clone(),
            &mut cx_b.to_async(),
        )
        .await
        .unwrap();
        let worktree_b = project_b.update(&mut cx_b, |p, _| p.worktrees()[0].clone());

        let replica_id_b = project_b.read_with(&cx_b, |project, _| {
            assert_eq!(
                project
                    .collaborators()
                    .get(&client_a.peer_id)
                    .unwrap()
                    .user
                    .github_login,
                "user_a"
            );
            project.replica_id()
        });
        project_a
            .condition(&cx_a, |tree, _| {
                tree.collaborators()
                    .get(&client_b.peer_id)
                    .map_or(false, |collaborator| {
                        collaborator.replica_id == replica_id_b
                            && collaborator.user.github_login == "user_b"
                    })
            })
            .await;

        // Open the same file as client B and client A.
        let buffer_b = worktree_b
            .update(&mut cx_b, |worktree, cx| worktree.open_buffer("b.txt", cx))
            .await
            .unwrap();
        let buffer_b = cx_b.add_model(|cx| MultiBuffer::singleton(buffer_b, cx));
        buffer_b.read_with(&cx_b, |buf, cx| {
            assert_eq!(buf.read(cx).text(), "b-contents")
        });
        worktree_a.read_with(&cx_a, |tree, cx| assert!(tree.has_open_buffer("b.txt", cx)));
        let buffer_a = worktree_a
            .update(&mut cx_a, |tree, cx| tree.open_buffer("b.txt", cx))
            .await
            .unwrap();

        let editor_b = cx_b.add_view(window_b, |cx| {
            Editor::for_buffer(buffer_b, Arc::new(|cx| EditorSettings::test(cx)), cx)
        });
        // TODO
        // // Create a selection set as client B and see that selection set as client A.
        // buffer_a
        //     .condition(&cx_a, |buffer, _| buffer.selection_sets().count() == 1)
        //     .await;

        // Edit the buffer as client B and see that edit as client A.
        editor_b.update(&mut cx_b, |editor, cx| {
            editor.handle_input(&Input("ok, ".into()), cx)
        });
        buffer_a
            .condition(&cx_a, |buffer, _| buffer.text() == "ok, b-contents")
            .await;

        // TODO
        // // Remove the selection set as client B, see those selections disappear as client A.
        cx_b.update(move |_| drop(editor_b));
        // buffer_a
        //     .condition(&cx_a, |buffer, _| buffer.selection_sets().count() == 0)
        //     .await;

        // Close the buffer as client A, see that the buffer is closed.
        cx_a.update(move |_| drop(buffer_a));
        worktree_a
            .condition(&cx_a, |tree, cx| !tree.has_open_buffer("b.txt", cx))
            .await;

        // Dropping the client B's project removes client B from client A's collaborators.
        cx_b.update(move |_| drop(project_b));
        project_a
            .condition(&cx_a, |project, _| project.collaborators().is_empty())
            .await;
    }

    #[gpui::test]
    async fn test_unshare_project(mut cx_a: TestAppContext, mut cx_b: TestAppContext) {
        let lang_registry = Arc::new(LanguageRegistry::new());
        let fs = Arc::new(FakeFs::new());
        cx_a.foreground().forbid_parking();

        // Connect to a server as 2 clients.
        let mut server = TestServer::start(cx_a.foreground()).await;
        let client_a = server.create_client(&mut cx_a, "user_a").await;
        let client_b = server.create_client(&mut cx_b, "user_b").await;

        // Share a project as client A
        fs.insert_tree(
            "/a",
            json!({
                ".zed.toml": r#"collaborators = ["user_b"]"#,
                "a.txt": "a-contents",
                "b.txt": "b-contents",
            }),
        )
        .await;
        let project_a = cx_a.update(|cx| {
            Project::local(
                client_a.clone(),
                client_a.user_store.clone(),
                lang_registry.clone(),
                fs.clone(),
                cx,
            )
        });
        let worktree_a = project_a
            .update(&mut cx_a, |p, cx| p.add_local_worktree("/a", cx))
            .await
            .unwrap();
        worktree_a
            .read_with(&cx_a, |tree, _| tree.as_local().unwrap().scan_complete())
            .await;
        let project_id = project_a
            .update(&mut cx_a, |project, _| project.next_remote_id())
            .await;
        project_a
            .update(&mut cx_a, |project, cx| project.share(cx))
            .await
            .unwrap();

        // Join that project as client B
        let project_b = Project::remote(
            project_id,
            client_b.clone(),
            client_b.user_store.clone(),
            lang_registry.clone(),
            fs.clone(),
            &mut cx_b.to_async(),
        )
        .await
        .unwrap();

        let worktree_b = project_b.read_with(&cx_b, |p, _| p.worktrees()[0].clone());
        worktree_b
            .update(&mut cx_b, |tree, cx| tree.open_buffer("a.txt", cx))
            .await
            .unwrap();

        project_a
            .update(&mut cx_a, |project, cx| project.unshare(cx))
            .await
            .unwrap();
        project_b
            .condition(&mut cx_b, |project, _| project.is_read_only())
            .await;
    }

    #[gpui::test]
    async fn test_propagate_saves_and_fs_changes(
        mut cx_a: TestAppContext,
        mut cx_b: TestAppContext,
        mut cx_c: TestAppContext,
    ) {
        let lang_registry = Arc::new(LanguageRegistry::new());
        let fs = Arc::new(FakeFs::new());
        cx_a.foreground().forbid_parking();

        // Connect to a server as 3 clients.
        let mut server = TestServer::start(cx_a.foreground()).await;
        let client_a = server.create_client(&mut cx_a, "user_a").await;
        let client_b = server.create_client(&mut cx_b, "user_b").await;
        let client_c = server.create_client(&mut cx_c, "user_c").await;

        // Share a worktree as client A.
        fs.insert_tree(
            "/a",
            json!({
                ".zed.toml": r#"collaborators = ["user_b", "user_c"]"#,
                "file1": "",
                "file2": ""
            }),
        )
        .await;
        let project_a = cx_a.update(|cx| {
            Project::local(
                client_a.clone(),
                client_a.user_store.clone(),
                lang_registry.clone(),
                fs.clone(),
                cx,
            )
        });
        let worktree_a = project_a
            .update(&mut cx_a, |p, cx| p.add_local_worktree("/a", cx))
            .await
            .unwrap();
        worktree_a
            .read_with(&cx_a, |tree, _| tree.as_local().unwrap().scan_complete())
            .await;
        let project_id = project_a
            .update(&mut cx_a, |project, _| project.next_remote_id())
            .await;
        project_a
            .update(&mut cx_a, |project, cx| project.share(cx))
            .await
            .unwrap();

        // Join that worktree as clients B and C.
        let project_b = Project::remote(
            project_id,
            client_b.clone(),
            client_b.user_store.clone(),
            lang_registry.clone(),
            fs.clone(),
            &mut cx_b.to_async(),
        )
        .await
        .unwrap();
        let project_c = Project::remote(
            project_id,
            client_c.clone(),
            client_c.user_store.clone(),
            lang_registry.clone(),
            fs.clone(),
            &mut cx_c.to_async(),
        )
        .await
        .unwrap();

        // Open and edit a buffer as both guests B and C.
        let worktree_b = project_b.read_with(&cx_b, |p, _| p.worktrees()[0].clone());
        let worktree_c = project_c.read_with(&cx_c, |p, _| p.worktrees()[0].clone());
        let buffer_b = worktree_b
            .update(&mut cx_b, |tree, cx| tree.open_buffer("file1", cx))
            .await
            .unwrap();
        let buffer_c = worktree_c
            .update(&mut cx_c, |tree, cx| tree.open_buffer("file1", cx))
            .await
            .unwrap();
        buffer_b.update(&mut cx_b, |buf, cx| buf.edit([0..0], "i-am-b, ", cx));
        buffer_c.update(&mut cx_c, |buf, cx| buf.edit([0..0], "i-am-c, ", cx));

        // Open and edit that buffer as the host.
        let buffer_a = worktree_a
            .update(&mut cx_a, |tree, cx| tree.open_buffer("file1", cx))
            .await
            .unwrap();

        buffer_a
            .condition(&mut cx_a, |buf, _| buf.text() == "i-am-c, i-am-b, ")
            .await;
        buffer_a.update(&mut cx_a, |buf, cx| {
            buf.edit([buf.len()..buf.len()], "i-am-a", cx)
        });

        // Wait for edits to propagate
        buffer_a
            .condition(&mut cx_a, |buf, _| buf.text() == "i-am-c, i-am-b, i-am-a")
            .await;
        buffer_b
            .condition(&mut cx_b, |buf, _| buf.text() == "i-am-c, i-am-b, i-am-a")
            .await;
        buffer_c
            .condition(&mut cx_c, |buf, _| buf.text() == "i-am-c, i-am-b, i-am-a")
            .await;

        // Edit the buffer as the host and concurrently save as guest B.
        let save_b = buffer_b.update(&mut cx_b, |buf, cx| buf.save(cx).unwrap());
        buffer_a.update(&mut cx_a, |buf, cx| buf.edit([0..0], "hi-a, ", cx));
        save_b.await.unwrap();
        assert_eq!(
            fs.load("/a/file1".as_ref()).await.unwrap(),
            "hi-a, i-am-c, i-am-b, i-am-a"
        );
        buffer_a.read_with(&cx_a, |buf, _| assert!(!buf.is_dirty()));
        buffer_b.read_with(&cx_b, |buf, _| assert!(!buf.is_dirty()));
        buffer_c.condition(&cx_c, |buf, _| !buf.is_dirty()).await;

        // Make changes on host's file system, see those changes on the guests.
        fs.rename("/a/file2".as_ref(), "/a/file3".as_ref())
            .await
            .unwrap();
        fs.insert_file(Path::new("/a/file4"), "4".into())
            .await
            .unwrap();

        worktree_b
            .condition(&cx_b, |tree, _| tree.file_count() == 4)
            .await;
        worktree_c
            .condition(&cx_c, |tree, _| tree.file_count() == 4)
            .await;
        worktree_b.read_with(&cx_b, |tree, _| {
            assert_eq!(
                tree.paths()
                    .map(|p| p.to_string_lossy())
                    .collect::<Vec<_>>(),
                &[".zed.toml", "file1", "file3", "file4"]
            )
        });
        worktree_c.read_with(&cx_c, |tree, _| {
            assert_eq!(
                tree.paths()
                    .map(|p| p.to_string_lossy())
                    .collect::<Vec<_>>(),
                &[".zed.toml", "file1", "file3", "file4"]
            )
        });
    }

    #[gpui::test]
    async fn test_buffer_conflict_after_save(mut cx_a: TestAppContext, mut cx_b: TestAppContext) {
        cx_a.foreground().forbid_parking();
        let lang_registry = Arc::new(LanguageRegistry::new());
        let fs = Arc::new(FakeFs::new());

        // Connect to a server as 2 clients.
        let mut server = TestServer::start(cx_a.foreground()).await;
        let client_a = server.create_client(&mut cx_a, "user_a").await;
        let client_b = server.create_client(&mut cx_b, "user_b").await;

        // Share a project as client A
        fs.insert_tree(
            "/dir",
            json!({
                ".zed.toml": r#"collaborators = ["user_b", "user_c"]"#,
                "a.txt": "a-contents",
            }),
        )
        .await;

        let project_a = cx_a.update(|cx| {
            Project::local(
                client_a.clone(),
                client_a.user_store.clone(),
                lang_registry.clone(),
                fs.clone(),
                cx,
            )
        });
        let worktree_a = project_a
            .update(&mut cx_a, |p, cx| p.add_local_worktree("/dir", cx))
            .await
            .unwrap();
        worktree_a
            .read_with(&cx_a, |tree, _| tree.as_local().unwrap().scan_complete())
            .await;
        let project_id = project_a
            .update(&mut cx_a, |project, _| project.next_remote_id())
            .await;
        project_a
            .update(&mut cx_a, |project, cx| project.share(cx))
            .await
            .unwrap();

        // Join that project as client B
        let project_b = Project::remote(
            project_id,
            client_b.clone(),
            client_b.user_store.clone(),
            lang_registry.clone(),
            fs.clone(),
            &mut cx_b.to_async(),
        )
        .await
        .unwrap();
        let worktree_b = project_b.update(&mut cx_b, |p, _| p.worktrees()[0].clone());

        // Open a buffer as client B
        let buffer_b = worktree_b
            .update(&mut cx_b, |worktree, cx| worktree.open_buffer("a.txt", cx))
            .await
            .unwrap();
        let mtime = buffer_b.read_with(&cx_b, |buf, _| buf.file().unwrap().mtime());

        buffer_b.update(&mut cx_b, |buf, cx| buf.edit([0..0], "world ", cx));
        buffer_b.read_with(&cx_b, |buf, _| {
            assert!(buf.is_dirty());
            assert!(!buf.has_conflict());
        });

        buffer_b
            .update(&mut cx_b, |buf, cx| buf.save(cx))
            .unwrap()
            .await
            .unwrap();
        worktree_b
            .condition(&cx_b, |_, cx| {
                buffer_b.read(cx).file().unwrap().mtime() != mtime
            })
            .await;
        buffer_b.read_with(&cx_b, |buf, _| {
            assert!(!buf.is_dirty());
            assert!(!buf.has_conflict());
        });

        buffer_b.update(&mut cx_b, |buf, cx| buf.edit([0..0], "hello ", cx));
        buffer_b.read_with(&cx_b, |buf, _| {
            assert!(buf.is_dirty());
            assert!(!buf.has_conflict());
        });
    }

    #[gpui::test]
    async fn test_editing_while_guest_opens_buffer(
        mut cx_a: TestAppContext,
        mut cx_b: TestAppContext,
    ) {
        cx_a.foreground().forbid_parking();
        let lang_registry = Arc::new(LanguageRegistry::new());
        let fs = Arc::new(FakeFs::new());

        // Connect to a server as 2 clients.
        let mut server = TestServer::start(cx_a.foreground()).await;
        let client_a = server.create_client(&mut cx_a, "user_a").await;
        let client_b = server.create_client(&mut cx_b, "user_b").await;

        // Share a project as client A
        fs.insert_tree(
            "/dir",
            json!({
                ".zed.toml": r#"collaborators = ["user_b"]"#,
                "a.txt": "a-contents",
            }),
        )
        .await;
        let project_a = cx_a.update(|cx| {
            Project::local(
                client_a.clone(),
                client_a.user_store.clone(),
                lang_registry.clone(),
                fs.clone(),
                cx,
            )
        });
        let worktree_a = project_a
            .update(&mut cx_a, |p, cx| p.add_local_worktree("/dir", cx))
            .await
            .unwrap();
        worktree_a
            .read_with(&cx_a, |tree, _| tree.as_local().unwrap().scan_complete())
            .await;
        let project_id = project_a
            .update(&mut cx_a, |project, _| project.next_remote_id())
            .await;
        project_a
            .update(&mut cx_a, |project, cx| project.share(cx))
            .await
            .unwrap();

        // Join that project as client B
        let project_b = Project::remote(
            project_id,
            client_b.clone(),
            client_b.user_store.clone(),
            lang_registry.clone(),
            fs.clone(),
            &mut cx_b.to_async(),
        )
        .await
        .unwrap();
        let worktree_b = project_b.update(&mut cx_b, |p, _| p.worktrees()[0].clone());

        // Open a buffer as client A
        let buffer_a = worktree_a
            .update(&mut cx_a, |tree, cx| tree.open_buffer("a.txt", cx))
            .await
            .unwrap();

        // Start opening the same buffer as client B
        let buffer_b = cx_b
            .background()
            .spawn(worktree_b.update(&mut cx_b, |worktree, cx| worktree.open_buffer("a.txt", cx)));
        task::yield_now().await;

        // Edit the buffer as client A while client B is still opening it.
        buffer_a.update(&mut cx_a, |buf, cx| buf.edit([0..0], "z", cx));

        let text = buffer_a.read_with(&cx_a, |buf, _| buf.text());
        let buffer_b = buffer_b.await.unwrap();
        buffer_b.condition(&cx_b, |buf, _| buf.text() == text).await;
    }

    #[gpui::test]
    async fn test_leaving_worktree_while_opening_buffer(
        mut cx_a: TestAppContext,
        mut cx_b: TestAppContext,
    ) {
        cx_a.foreground().forbid_parking();
        let lang_registry = Arc::new(LanguageRegistry::new());
        let fs = Arc::new(FakeFs::new());

        // Connect to a server as 2 clients.
        let mut server = TestServer::start(cx_a.foreground()).await;
        let client_a = server.create_client(&mut cx_a, "user_a").await;
        let client_b = server.create_client(&mut cx_b, "user_b").await;

        // Share a project as client A
        fs.insert_tree(
            "/dir",
            json!({
                ".zed.toml": r#"collaborators = ["user_b"]"#,
                "a.txt": "a-contents",
            }),
        )
        .await;
        let project_a = cx_a.update(|cx| {
            Project::local(
                client_a.clone(),
                client_a.user_store.clone(),
                lang_registry.clone(),
                fs.clone(),
                cx,
            )
        });
        let worktree_a = project_a
            .update(&mut cx_a, |p, cx| p.add_local_worktree("/dir", cx))
            .await
            .unwrap();
        worktree_a
            .read_with(&cx_a, |tree, _| tree.as_local().unwrap().scan_complete())
            .await;
        let project_id = project_a
            .update(&mut cx_a, |project, _| project.next_remote_id())
            .await;
        project_a
            .update(&mut cx_a, |project, cx| project.share(cx))
            .await
            .unwrap();

        // Join that project as client B
        let project_b = Project::remote(
            project_id,
            client_b.clone(),
            client_b.user_store.clone(),
            lang_registry.clone(),
            fs.clone(),
            &mut cx_b.to_async(),
        )
        .await
        .unwrap();
        let worktree_b = project_b.update(&mut cx_b, |p, _| p.worktrees()[0].clone());

        // See that a guest has joined as client A.
        project_a
            .condition(&cx_a, |p, _| p.collaborators().len() == 1)
            .await;

        // Begin opening a buffer as client B, but leave the project before the open completes.
        let buffer_b = cx_b
            .background()
            .spawn(worktree_b.update(&mut cx_b, |worktree, cx| worktree.open_buffer("a.txt", cx)));
        cx_b.update(|_| drop(project_b));
        drop(buffer_b);

        // See that the guest has left.
        project_a
            .condition(&cx_a, |p, _| p.collaborators().len() == 0)
            .await;
    }

    #[gpui::test]
    async fn test_peer_disconnection(mut cx_a: TestAppContext, mut cx_b: TestAppContext) {
        cx_a.foreground().forbid_parking();
        let lang_registry = Arc::new(LanguageRegistry::new());
        let fs = Arc::new(FakeFs::new());

        // Connect to a server as 2 clients.
        let mut server = TestServer::start(cx_a.foreground()).await;
        let client_a = server.create_client(&mut cx_a, "user_a").await;
        let client_b = server.create_client(&mut cx_b, "user_b").await;

        // Share a project as client A
        fs.insert_tree(
            "/a",
            json!({
                ".zed.toml": r#"collaborators = ["user_b"]"#,
                "a.txt": "a-contents",
                "b.txt": "b-contents",
            }),
        )
        .await;
        let project_a = cx_a.update(|cx| {
            Project::local(
                client_a.clone(),
                client_a.user_store.clone(),
                lang_registry.clone(),
                fs.clone(),
                cx,
            )
        });
        let worktree_a = project_a
            .update(&mut cx_a, |p, cx| p.add_local_worktree("/a", cx))
            .await
            .unwrap();
        worktree_a
            .read_with(&cx_a, |tree, _| tree.as_local().unwrap().scan_complete())
            .await;
        let project_id = project_a
            .update(&mut cx_a, |project, _| project.next_remote_id())
            .await;
        project_a
            .update(&mut cx_a, |project, cx| project.share(cx))
            .await
            .unwrap();

        // Join that project as client B
        let _project_b = Project::remote(
            project_id,
            client_b.clone(),
            client_b.user_store.clone(),
            lang_registry.clone(),
            fs.clone(),
            &mut cx_b.to_async(),
        )
        .await
        .unwrap();

        // See that a guest has joined as client A.
        project_a
            .condition(&cx_a, |p, _| p.collaborators().len() == 1)
            .await;

        // Drop client B's connection and ensure client A observes client B leaving the worktree.
        client_b.disconnect(&cx_b.to_async()).unwrap();
        project_a
            .condition(&cx_a, |p, _| p.collaborators().len() == 0)
            .await;
    }

    #[gpui::test]
    async fn test_collaborating_with_diagnostics(
        mut cx_a: TestAppContext,
        mut cx_b: TestAppContext,
    ) {
        cx_a.foreground().forbid_parking();
        let mut lang_registry = Arc::new(LanguageRegistry::new());
        let fs = Arc::new(FakeFs::new());

        // Set up a fake language server.
        let (language_server_config, mut fake_language_server) =
            LanguageServerConfig::fake(cx_a.background()).await;
        Arc::get_mut(&mut lang_registry)
            .unwrap()
            .add(Arc::new(Language::new(
                LanguageConfig {
                    name: "Rust".to_string(),
                    path_suffixes: vec!["rs".to_string()],
                    language_server: Some(language_server_config),
                    ..Default::default()
                },
                Some(tree_sitter_rust::language()),
            )));

        // Connect to a server as 2 clients.
        let mut server = TestServer::start(cx_a.foreground()).await;
        let client_a = server.create_client(&mut cx_a, "user_a").await;
        let client_b = server.create_client(&mut cx_b, "user_b").await;

        // Share a project as client A
        fs.insert_tree(
            "/a",
            json!({
                ".zed.toml": r#"collaborators = ["user_b"]"#,
                "a.rs": "let one = two",
                "other.rs": "",
            }),
        )
        .await;
        let project_a = cx_a.update(|cx| {
            Project::local(
                client_a.clone(),
                client_a.user_store.clone(),
                lang_registry.clone(),
                fs.clone(),
                cx,
            )
        });
        let worktree_a = project_a
            .update(&mut cx_a, |p, cx| p.add_local_worktree("/a", cx))
            .await
            .unwrap();
        worktree_a
            .read_with(&cx_a, |tree, _| tree.as_local().unwrap().scan_complete())
            .await;
        let project_id = project_a
            .update(&mut cx_a, |project, _| project.next_remote_id())
            .await;
        let worktree_id = worktree_a.read_with(&cx_a, |tree, _| tree.id());
        project_a
            .update(&mut cx_a, |project, cx| project.share(cx))
            .await
            .unwrap();

        // Cause the language server to start.
        let _ = cx_a
            .background()
            .spawn(worktree_a.update(&mut cx_a, |worktree, cx| {
                worktree.open_buffer("other.rs", cx)
            }))
            .await
            .unwrap();

        // Simulate a language server reporting errors for a file.
        fake_language_server
            .notify::<lsp::notification::PublishDiagnostics>(lsp::PublishDiagnosticsParams {
                uri: lsp::Url::from_file_path("/a/a.rs").unwrap(),
                version: None,
                diagnostics: vec![lsp::Diagnostic {
                    severity: Some(lsp::DiagnosticSeverity::ERROR),
                    range: lsp::Range::new(lsp::Position::new(0, 4), lsp::Position::new(0, 7)),
                    message: "message 1".to_string(),
                    ..Default::default()
                }],
            })
            .await;

        // Wait for server to see the diagnostics update.
        server
            .condition(|store| {
                let worktree = store
                    .project(project_id)
                    .unwrap()
                    .worktrees
                    .get(&worktree_id.to_proto())
                    .unwrap();

                !worktree
                    .share
                    .as_ref()
                    .unwrap()
                    .diagnostic_summaries
                    .is_empty()
            })
            .await;

        // Join the worktree as client B.
        let project_b = Project::remote(
            project_id,
            client_b.clone(),
            client_b.user_store.clone(),
            lang_registry.clone(),
            fs.clone(),
            &mut cx_b.to_async(),
        )
        .await
        .unwrap();

        project_b.read_with(&cx_b, |project, cx| {
            assert_eq!(
                project.diagnostic_summaries(cx).collect::<Vec<_>>(),
                &[(
                    ProjectPath {
                        worktree_id,
                        path: Arc::from(Path::new("a.rs")),
                    },
                    DiagnosticSummary {
                        error_count: 1,
                        warning_count: 0,
                        ..Default::default()
                    },
                )]
            )
        });

        // Simulate a language server reporting more errors for a file.
        fake_language_server
            .notify::<lsp::notification::PublishDiagnostics>(lsp::PublishDiagnosticsParams {
                uri: lsp::Url::from_file_path("/a/a.rs").unwrap(),
                version: None,
                diagnostics: vec![
                    lsp::Diagnostic {
                        severity: Some(lsp::DiagnosticSeverity::ERROR),
                        range: lsp::Range::new(lsp::Position::new(0, 4), lsp::Position::new(0, 7)),
                        message: "message 1".to_string(),
                        ..Default::default()
                    },
                    lsp::Diagnostic {
                        severity: Some(lsp::DiagnosticSeverity::WARNING),
                        range: lsp::Range::new(
                            lsp::Position::new(0, 10),
                            lsp::Position::new(0, 13),
                        ),
                        message: "message 2".to_string(),
                        ..Default::default()
                    },
                ],
            })
            .await;

        // Client b gets the updated summaries
        project_b
            .condition(&cx_b, |project, cx| {
                project.diagnostic_summaries(cx).collect::<Vec<_>>()
                    == &[(
                        ProjectPath {
                            worktree_id,
                            path: Arc::from(Path::new("a.rs")),
                        },
                        DiagnosticSummary {
                            error_count: 1,
                            warning_count: 1,
                            ..Default::default()
                        },
                    )]
            })
            .await;

        // Open the file with the errors on client B. They should be present.
        let worktree_b = project_b.update(&mut cx_b, |p, _| p.worktrees()[0].clone());
        let buffer_b = cx_b
            .background()
            .spawn(worktree_b.update(&mut cx_b, |worktree, cx| worktree.open_buffer("a.rs", cx)))
            .await
            .unwrap();

        buffer_b.read_with(&cx_b, |buffer, _| {
            assert_eq!(
                buffer
                    .snapshot()
                    .diagnostics_in_range::<_, Point>(0..buffer.len())
                    .map(|entry| entry)
                    .collect::<Vec<_>>(),
                &[
                    DiagnosticEntry {
                        range: Point::new(0, 4)..Point::new(0, 7),
                        diagnostic: Diagnostic {
                            group_id: 0,
                            message: "message 1".to_string(),
                            severity: lsp::DiagnosticSeverity::ERROR,
                            is_primary: true,
                            ..Default::default()
                        }
                    },
                    DiagnosticEntry {
                        range: Point::new(0, 10)..Point::new(0, 13),
                        diagnostic: Diagnostic {
                            group_id: 1,
                            severity: lsp::DiagnosticSeverity::WARNING,
                            message: "message 2".to_string(),
                            is_primary: true,
                            ..Default::default()
                        }
                    }
                ]
            );
        });
    }

    #[gpui::test]
    async fn test_formatting_buffer(mut cx_a: TestAppContext, mut cx_b: TestAppContext) {
        cx_a.foreground().forbid_parking();
        let mut lang_registry = Arc::new(LanguageRegistry::new());
        let fs = Arc::new(FakeFs::new());

        // Set up a fake language server.
        let (language_server_config, mut fake_language_server) =
            LanguageServerConfig::fake(cx_a.background()).await;
        Arc::get_mut(&mut lang_registry)
            .unwrap()
            .add(Arc::new(Language::new(
                LanguageConfig {
                    name: "Rust".to_string(),
                    path_suffixes: vec!["rs".to_string()],
                    language_server: Some(language_server_config),
                    ..Default::default()
                },
                Some(tree_sitter_rust::language()),
            )));

        // Connect to a server as 2 clients.
        let mut server = TestServer::start(cx_a.foreground()).await;
        let client_a = server.create_client(&mut cx_a, "user_a").await;
        let client_b = server.create_client(&mut cx_b, "user_b").await;

        // Share a project as client A
        fs.insert_tree(
            "/a",
            json!({
                ".zed.toml": r#"collaborators = ["user_b"]"#,
                "a.rs": "let one = two",
            }),
        )
        .await;
        let project_a = cx_a.update(|cx| {
            Project::local(
                client_a.clone(),
                client_a.user_store.clone(),
                lang_registry.clone(),
                fs.clone(),
                cx,
            )
        });
        let worktree_a = project_a
            .update(&mut cx_a, |p, cx| p.add_local_worktree("/a", cx))
            .await
            .unwrap();
        worktree_a
            .read_with(&cx_a, |tree, _| tree.as_local().unwrap().scan_complete())
            .await;
        let project_id = project_a
            .update(&mut cx_a, |project, _| project.next_remote_id())
            .await;
        project_a
            .update(&mut cx_a, |project, cx| project.share(cx))
            .await
            .unwrap();

        // Join the worktree as client B.
        let project_b = Project::remote(
            project_id,
            client_b.clone(),
            client_b.user_store.clone(),
            lang_registry.clone(),
            fs.clone(),
            &mut cx_b.to_async(),
        )
        .await
        .unwrap();

        // Open the file to be formatted on client B.
        let worktree_b = project_b.update(&mut cx_b, |p, _| p.worktrees()[0].clone());
        let buffer_b = cx_b
            .background()
            .spawn(worktree_b.update(&mut cx_b, |worktree, cx| worktree.open_buffer("a.rs", cx)))
            .await
            .unwrap();

        let format = buffer_b.update(&mut cx_b, |buffer, cx| buffer.format(cx));
        let (request_id, _) = fake_language_server
            .receive_request::<lsp::request::Formatting>()
            .await;
        fake_language_server
            .respond(
                request_id,
                Some(vec![
                    lsp::TextEdit {
                        range: lsp::Range::new(lsp::Position::new(0, 4), lsp::Position::new(0, 4)),
                        new_text: "h".to_string(),
                    },
                    lsp::TextEdit {
                        range: lsp::Range::new(lsp::Position::new(0, 7), lsp::Position::new(0, 7)),
                        new_text: "y".to_string(),
                    },
                ]),
            )
            .await;
        format.await.unwrap();
        assert_eq!(
            buffer_b.read_with(&cx_b, |buffer, _| buffer.text()),
            "let honey = two"
        );
    }

    #[gpui::test]
    async fn test_basic_chat(mut cx_a: TestAppContext, mut cx_b: TestAppContext) {
        cx_a.foreground().forbid_parking();

        // Connect to a server as 2 clients.
        let mut server = TestServer::start(cx_a.foreground()).await;
        let client_a = server.create_client(&mut cx_a, "user_a").await;
        let client_b = server.create_client(&mut cx_b, "user_b").await;

        // Create an org that includes these 2 users.
        let db = &server.app_state.db;
        let org_id = db.create_org("Test Org", "test-org").await.unwrap();
        db.add_org_member(org_id, client_a.current_user_id(&cx_a), false)
            .await
            .unwrap();
        db.add_org_member(org_id, client_b.current_user_id(&cx_b), false)
            .await
            .unwrap();

        // Create a channel that includes all the users.
        let channel_id = db.create_org_channel(org_id, "test-channel").await.unwrap();
        db.add_channel_member(channel_id, client_a.current_user_id(&cx_a), false)
            .await
            .unwrap();
        db.add_channel_member(channel_id, client_b.current_user_id(&cx_b), false)
            .await
            .unwrap();
        db.create_channel_message(
            channel_id,
            client_b.current_user_id(&cx_b),
            "hello A, it's B.",
            OffsetDateTime::now_utc(),
            1,
        )
        .await
        .unwrap();

        let channels_a = cx_a
            .add_model(|cx| ChannelList::new(client_a.user_store.clone(), client_a.clone(), cx));
        channels_a
            .condition(&mut cx_a, |list, _| list.available_channels().is_some())
            .await;
        channels_a.read_with(&cx_a, |list, _| {
            assert_eq!(
                list.available_channels().unwrap(),
                &[ChannelDetails {
                    id: channel_id.to_proto(),
                    name: "test-channel".to_string()
                }]
            )
        });
        let channel_a = channels_a.update(&mut cx_a, |this, cx| {
            this.get_channel(channel_id.to_proto(), cx).unwrap()
        });
        channel_a.read_with(&cx_a, |channel, _| assert!(channel.messages().is_empty()));
        channel_a
            .condition(&cx_a, |channel, _| {
                channel_messages(channel)
                    == [("user_b".to_string(), "hello A, it's B.".to_string(), false)]
            })
            .await;

        let channels_b = cx_b
            .add_model(|cx| ChannelList::new(client_b.user_store.clone(), client_b.clone(), cx));
        channels_b
            .condition(&mut cx_b, |list, _| list.available_channels().is_some())
            .await;
        channels_b.read_with(&cx_b, |list, _| {
            assert_eq!(
                list.available_channels().unwrap(),
                &[ChannelDetails {
                    id: channel_id.to_proto(),
                    name: "test-channel".to_string()
                }]
            )
        });

        let channel_b = channels_b.update(&mut cx_b, |this, cx| {
            this.get_channel(channel_id.to_proto(), cx).unwrap()
        });
        channel_b.read_with(&cx_b, |channel, _| assert!(channel.messages().is_empty()));
        channel_b
            .condition(&cx_b, |channel, _| {
                channel_messages(channel)
                    == [("user_b".to_string(), "hello A, it's B.".to_string(), false)]
            })
            .await;

        channel_a
            .update(&mut cx_a, |channel, cx| {
                channel
                    .send_message("oh, hi B.".to_string(), cx)
                    .unwrap()
                    .detach();
                let task = channel.send_message("sup".to_string(), cx).unwrap();
                assert_eq!(
                    channel_messages(channel),
                    &[
                        ("user_b".to_string(), "hello A, it's B.".to_string(), false),
                        ("user_a".to_string(), "oh, hi B.".to_string(), true),
                        ("user_a".to_string(), "sup".to_string(), true)
                    ]
                );
                task
            })
            .await
            .unwrap();

        channel_b
            .condition(&cx_b, |channel, _| {
                channel_messages(channel)
                    == [
                        ("user_b".to_string(), "hello A, it's B.".to_string(), false),
                        ("user_a".to_string(), "oh, hi B.".to_string(), false),
                        ("user_a".to_string(), "sup".to_string(), false),
                    ]
            })
            .await;

        assert_eq!(
            server
                .state()
                .await
                .channel(channel_id)
                .unwrap()
                .connection_ids
                .len(),
            2
        );
        cx_b.update(|_| drop(channel_b));
        server
            .condition(|state| state.channel(channel_id).unwrap().connection_ids.len() == 1)
            .await;

        cx_a.update(|_| drop(channel_a));
        server
            .condition(|state| state.channel(channel_id).is_none())
            .await;
    }

    #[gpui::test]
    async fn test_chat_message_validation(mut cx_a: TestAppContext) {
        cx_a.foreground().forbid_parking();

        let mut server = TestServer::start(cx_a.foreground()).await;
        let client_a = server.create_client(&mut cx_a, "user_a").await;

        let db = &server.app_state.db;
        let org_id = db.create_org("Test Org", "test-org").await.unwrap();
        let channel_id = db.create_org_channel(org_id, "test-channel").await.unwrap();
        db.add_org_member(org_id, client_a.current_user_id(&cx_a), false)
            .await
            .unwrap();
        db.add_channel_member(channel_id, client_a.current_user_id(&cx_a), false)
            .await
            .unwrap();

        let channels_a = cx_a
            .add_model(|cx| ChannelList::new(client_a.user_store.clone(), client_a.clone(), cx));
        channels_a
            .condition(&mut cx_a, |list, _| list.available_channels().is_some())
            .await;
        let channel_a = channels_a.update(&mut cx_a, |this, cx| {
            this.get_channel(channel_id.to_proto(), cx).unwrap()
        });

        // Messages aren't allowed to be too long.
        channel_a
            .update(&mut cx_a, |channel, cx| {
                let long_body = "this is long.\n".repeat(1024);
                channel.send_message(long_body, cx).unwrap()
            })
            .await
            .unwrap_err();

        // Messages aren't allowed to be blank.
        channel_a.update(&mut cx_a, |channel, cx| {
            channel.send_message(String::new(), cx).unwrap_err()
        });

        // Leading and trailing whitespace are trimmed.
        channel_a
            .update(&mut cx_a, |channel, cx| {
                channel
                    .send_message("\n surrounded by whitespace  \n".to_string(), cx)
                    .unwrap()
            })
            .await
            .unwrap();
        assert_eq!(
            db.get_channel_messages(channel_id, 10, None)
                .await
                .unwrap()
                .iter()
                .map(|m| &m.body)
                .collect::<Vec<_>>(),
            &["surrounded by whitespace"]
        );
    }

    #[gpui::test]
    async fn test_chat_reconnection(mut cx_a: TestAppContext, mut cx_b: TestAppContext) {
        cx_a.foreground().forbid_parking();

        // Connect to a server as 2 clients.
        let mut server = TestServer::start(cx_a.foreground()).await;
        let client_a = server.create_client(&mut cx_a, "user_a").await;
        let client_b = server.create_client(&mut cx_b, "user_b").await;
        let mut status_b = client_b.status();

        // Create an org that includes these 2 users.
        let db = &server.app_state.db;
        let org_id = db.create_org("Test Org", "test-org").await.unwrap();
        db.add_org_member(org_id, client_a.current_user_id(&cx_a), false)
            .await
            .unwrap();
        db.add_org_member(org_id, client_b.current_user_id(&cx_b), false)
            .await
            .unwrap();

        // Create a channel that includes all the users.
        let channel_id = db.create_org_channel(org_id, "test-channel").await.unwrap();
        db.add_channel_member(channel_id, client_a.current_user_id(&cx_a), false)
            .await
            .unwrap();
        db.add_channel_member(channel_id, client_b.current_user_id(&cx_b), false)
            .await
            .unwrap();
        db.create_channel_message(
            channel_id,
            client_b.current_user_id(&cx_b),
            "hello A, it's B.",
            OffsetDateTime::now_utc(),
            2,
        )
        .await
        .unwrap();

        let channels_a = cx_a
            .add_model(|cx| ChannelList::new(client_a.user_store.clone(), client_a.clone(), cx));
        channels_a
            .condition(&mut cx_a, |list, _| list.available_channels().is_some())
            .await;

        channels_a.read_with(&cx_a, |list, _| {
            assert_eq!(
                list.available_channels().unwrap(),
                &[ChannelDetails {
                    id: channel_id.to_proto(),
                    name: "test-channel".to_string()
                }]
            )
        });
        let channel_a = channels_a.update(&mut cx_a, |this, cx| {
            this.get_channel(channel_id.to_proto(), cx).unwrap()
        });
        channel_a.read_with(&cx_a, |channel, _| assert!(channel.messages().is_empty()));
        channel_a
            .condition(&cx_a, |channel, _| {
                channel_messages(channel)
                    == [("user_b".to_string(), "hello A, it's B.".to_string(), false)]
            })
            .await;

        let channels_b = cx_b
            .add_model(|cx| ChannelList::new(client_b.user_store.clone(), client_b.clone(), cx));
        channels_b
            .condition(&mut cx_b, |list, _| list.available_channels().is_some())
            .await;
        channels_b.read_with(&cx_b, |list, _| {
            assert_eq!(
                list.available_channels().unwrap(),
                &[ChannelDetails {
                    id: channel_id.to_proto(),
                    name: "test-channel".to_string()
                }]
            )
        });

        let channel_b = channels_b.update(&mut cx_b, |this, cx| {
            this.get_channel(channel_id.to_proto(), cx).unwrap()
        });
        channel_b.read_with(&cx_b, |channel, _| assert!(channel.messages().is_empty()));
        channel_b
            .condition(&cx_b, |channel, _| {
                channel_messages(channel)
                    == [("user_b".to_string(), "hello A, it's B.".to_string(), false)]
            })
            .await;

        // Disconnect client B, ensuring we can still access its cached channel data.
        server.forbid_connections();
        server.disconnect_client(client_b.current_user_id(&cx_b));
        while !matches!(
            status_b.next().await,
            Some(client::Status::ReconnectionError { .. })
        ) {}

        channels_b.read_with(&cx_b, |channels, _| {
            assert_eq!(
                channels.available_channels().unwrap(),
                [ChannelDetails {
                    id: channel_id.to_proto(),
                    name: "test-channel".to_string()
                }]
            )
        });
        channel_b.read_with(&cx_b, |channel, _| {
            assert_eq!(
                channel_messages(channel),
                [("user_b".to_string(), "hello A, it's B.".to_string(), false)]
            )
        });

        // Send a message from client B while it is disconnected.
        channel_b
            .update(&mut cx_b, |channel, cx| {
                let task = channel
                    .send_message("can you see this?".to_string(), cx)
                    .unwrap();
                assert_eq!(
                    channel_messages(channel),
                    &[
                        ("user_b".to_string(), "hello A, it's B.".to_string(), false),
                        ("user_b".to_string(), "can you see this?".to_string(), true)
                    ]
                );
                task
            })
            .await
            .unwrap_err();

        // Send a message from client A while B is disconnected.
        channel_a
            .update(&mut cx_a, |channel, cx| {
                channel
                    .send_message("oh, hi B.".to_string(), cx)
                    .unwrap()
                    .detach();
                let task = channel.send_message("sup".to_string(), cx).unwrap();
                assert_eq!(
                    channel_messages(channel),
                    &[
                        ("user_b".to_string(), "hello A, it's B.".to_string(), false),
                        ("user_a".to_string(), "oh, hi B.".to_string(), true),
                        ("user_a".to_string(), "sup".to_string(), true)
                    ]
                );
                task
            })
            .await
            .unwrap();

        // Give client B a chance to reconnect.
        server.allow_connections();
        cx_b.foreground().advance_clock(Duration::from_secs(10));

        // Verify that B sees the new messages upon reconnection, as well as the message client B
        // sent while offline.
        channel_b
            .condition(&cx_b, |channel, _| {
                channel_messages(channel)
                    == [
                        ("user_b".to_string(), "hello A, it's B.".to_string(), false),
                        ("user_a".to_string(), "oh, hi B.".to_string(), false),
                        ("user_a".to_string(), "sup".to_string(), false),
                        ("user_b".to_string(), "can you see this?".to_string(), false),
                    ]
            })
            .await;

        // Ensure client A and B can communicate normally after reconnection.
        channel_a
            .update(&mut cx_a, |channel, cx| {
                channel.send_message("you online?".to_string(), cx).unwrap()
            })
            .await
            .unwrap();
        channel_b
            .condition(&cx_b, |channel, _| {
                channel_messages(channel)
                    == [
                        ("user_b".to_string(), "hello A, it's B.".to_string(), false),
                        ("user_a".to_string(), "oh, hi B.".to_string(), false),
                        ("user_a".to_string(), "sup".to_string(), false),
                        ("user_b".to_string(), "can you see this?".to_string(), false),
                        ("user_a".to_string(), "you online?".to_string(), false),
                    ]
            })
            .await;

        channel_b
            .update(&mut cx_b, |channel, cx| {
                channel.send_message("yep".to_string(), cx).unwrap()
            })
            .await
            .unwrap();
        channel_a
            .condition(&cx_a, |channel, _| {
                channel_messages(channel)
                    == [
                        ("user_b".to_string(), "hello A, it's B.".to_string(), false),
                        ("user_a".to_string(), "oh, hi B.".to_string(), false),
                        ("user_a".to_string(), "sup".to_string(), false),
                        ("user_b".to_string(), "can you see this?".to_string(), false),
                        ("user_a".to_string(), "you online?".to_string(), false),
                        ("user_b".to_string(), "yep".to_string(), false),
                    ]
            })
            .await;
    }

    #[gpui::test]
    async fn test_contacts(
        mut cx_a: TestAppContext,
        mut cx_b: TestAppContext,
        mut cx_c: TestAppContext,
    ) {
        cx_a.foreground().forbid_parking();
        let lang_registry = Arc::new(LanguageRegistry::new());
        let fs = Arc::new(FakeFs::new());

        // Connect to a server as 3 clients.
        let mut server = TestServer::start(cx_a.foreground()).await;
        let client_a = server.create_client(&mut cx_a, "user_a").await;
        let client_b = server.create_client(&mut cx_b, "user_b").await;
        let client_c = server.create_client(&mut cx_c, "user_c").await;

        // Share a worktree as client A.
        fs.insert_tree(
            "/a",
            json!({
                ".zed.toml": r#"collaborators = ["user_b", "user_c"]"#,
            }),
        )
        .await;

        let project_a = cx_a.update(|cx| {
            Project::local(
                client_a.clone(),
                client_a.user_store.clone(),
                lang_registry.clone(),
                fs.clone(),
                cx,
            )
        });
        let worktree_a = project_a
            .update(&mut cx_a, |p, cx| p.add_local_worktree("/a", cx))
            .await
            .unwrap();
        worktree_a
            .read_with(&cx_a, |tree, _| tree.as_local().unwrap().scan_complete())
            .await;

        client_a
            .user_store
            .condition(&cx_a, |user_store, _| {
                contacts(user_store) == vec![("user_a", vec![("a", vec![])])]
            })
            .await;
        client_b
            .user_store
            .condition(&cx_b, |user_store, _| {
                contacts(user_store) == vec![("user_a", vec![("a", vec![])])]
            })
            .await;
        client_c
            .user_store
            .condition(&cx_c, |user_store, _| {
                contacts(user_store) == vec![("user_a", vec![("a", vec![])])]
            })
            .await;

        let project_id = project_a
            .update(&mut cx_a, |project, _| project.next_remote_id())
            .await;
        project_a
            .update(&mut cx_a, |project, cx| project.share(cx))
            .await
            .unwrap();

        let _project_b = Project::remote(
            project_id,
            client_b.clone(),
            client_b.user_store.clone(),
            lang_registry.clone(),
            fs.clone(),
            &mut cx_b.to_async(),
        )
        .await
        .unwrap();

        client_a
            .user_store
            .condition(&cx_a, |user_store, _| {
                contacts(user_store) == vec![("user_a", vec![("a", vec!["user_b"])])]
            })
            .await;
        client_b
            .user_store
            .condition(&cx_b, |user_store, _| {
                contacts(user_store) == vec![("user_a", vec![("a", vec!["user_b"])])]
            })
            .await;
        client_c
            .user_store
            .condition(&cx_c, |user_store, _| {
                contacts(user_store) == vec![("user_a", vec![("a", vec!["user_b"])])]
            })
            .await;

        project_a
            .condition(&cx_a, |project, _| {
                project.collaborators().contains_key(&client_b.peer_id)
            })
            .await;

        cx_a.update(move |_| drop(project_a));
        client_a
            .user_store
            .condition(&cx_a, |user_store, _| contacts(user_store) == vec![])
            .await;
        client_b
            .user_store
            .condition(&cx_b, |user_store, _| contacts(user_store) == vec![])
            .await;
        client_c
            .user_store
            .condition(&cx_c, |user_store, _| contacts(user_store) == vec![])
            .await;

        fn contacts(user_store: &UserStore) -> Vec<(&str, Vec<(&str, Vec<&str>)>)> {
            user_store
                .contacts()
                .iter()
                .map(|contact| {
                    let worktrees = contact
                        .projects
                        .iter()
                        .map(|p| {
                            (
                                p.worktree_root_names[0].as_str(),
                                p.guests.iter().map(|p| p.github_login.as_str()).collect(),
                            )
                        })
                        .collect();
                    (contact.user.github_login.as_str(), worktrees)
                })
                .collect()
        }
    }

    struct TestServer {
        peer: Arc<Peer>,
        app_state: Arc<AppState>,
        server: Arc<Server>,
        foreground: Rc<executor::Foreground>,
        notifications: mpsc::Receiver<()>,
        connection_killers: Arc<Mutex<HashMap<UserId, watch::Sender<Option<()>>>>>,
        forbid_connections: Arc<AtomicBool>,
        _test_db: TestDb,
    }

    impl TestServer {
        async fn start(foreground: Rc<executor::Foreground>) -> Self {
            let test_db = TestDb::new();
            let app_state = Self::build_app_state(&test_db).await;
            let peer = Peer::new();
            let notifications = mpsc::channel(128);
            let server = Server::new(app_state.clone(), peer.clone(), Some(notifications.0));
            Self {
                peer,
                app_state,
                server,
                foreground,
                notifications: notifications.1,
                connection_killers: Default::default(),
                forbid_connections: Default::default(),
                _test_db: test_db,
            }
        }

        async fn create_client(&mut self, cx: &mut TestAppContext, name: &str) -> TestClient {
            let http = FakeHttpClient::with_404_response();
            let user_id = self.app_state.db.create_user(name, false).await.unwrap();
            let client_name = name.to_string();
            let mut client = Client::new(http.clone());
            let server = self.server.clone();
            let connection_killers = self.connection_killers.clone();
            let forbid_connections = self.forbid_connections.clone();
            let (connection_id_tx, mut connection_id_rx) = postage::mpsc::channel(16);

            Arc::get_mut(&mut client)
                .unwrap()
                .override_authenticate(move |cx| {
                    cx.spawn(|_| async move {
                        let access_token = "the-token".to_string();
                        Ok(Credentials {
                            user_id: user_id.0 as u64,
                            access_token,
                        })
                    })
                })
                .override_establish_connection(move |credentials, cx| {
                    assert_eq!(credentials.user_id, user_id.0 as u64);
                    assert_eq!(credentials.access_token, "the-token");

                    let server = server.clone();
                    let connection_killers = connection_killers.clone();
                    let forbid_connections = forbid_connections.clone();
                    let client_name = client_name.clone();
                    let connection_id_tx = connection_id_tx.clone();
                    cx.spawn(move |cx| async move {
                        if forbid_connections.load(SeqCst) {
                            Err(EstablishConnectionError::other(anyhow!(
                                "server is forbidding connections"
                            )))
                        } else {
                            let (client_conn, server_conn, kill_conn) = Connection::in_memory();
                            connection_killers.lock().insert(user_id, kill_conn);
                            cx.background()
                                .spawn(server.handle_connection(
                                    server_conn,
                                    client_name,
                                    user_id,
                                    Some(connection_id_tx),
                                ))
                                .detach();
                            Ok(client_conn)
                        }
                    })
                });

            client
                .authenticate_and_connect(&cx.to_async())
                .await
                .unwrap();

            let peer_id = PeerId(connection_id_rx.next().await.unwrap().0);
            let user_store = cx.add_model(|cx| UserStore::new(client.clone(), http, cx));
            let mut authed_user =
                user_store.read_with(cx, |user_store, _| user_store.watch_current_user());
            while authed_user.next().await.unwrap().is_none() {}

            TestClient {
                client,
                peer_id,
                user_store,
            }
        }

        fn disconnect_client(&self, user_id: UserId) {
            if let Some(mut kill_conn) = self.connection_killers.lock().remove(&user_id) {
                let _ = kill_conn.try_send(Some(()));
            }
        }

        fn forbid_connections(&self) {
            self.forbid_connections.store(true, SeqCst);
        }

        fn allow_connections(&self) {
            self.forbid_connections.store(false, SeqCst);
        }

        async fn build_app_state(test_db: &TestDb) -> Arc<AppState> {
            let mut config = Config::default();
            config.session_secret = "a".repeat(32);
            config.database_url = test_db.url.clone();
            let github_client = github::AppClient::test();
            Arc::new(AppState {
                db: test_db.db().clone(),
                handlebars: Default::default(),
                auth_client: auth::build_client("", ""),
                repo_client: github::RepoClient::test(&github_client),
                github_client,
                config,
            })
        }

        async fn state<'a>(&'a self) -> RwLockReadGuard<'a, Store> {
            self.server.store.read()
        }

        async fn condition<F>(&mut self, mut predicate: F)
        where
            F: FnMut(&Store) -> bool,
        {
            async_std::future::timeout(Duration::from_millis(500), async {
                while !(predicate)(&*self.server.store.read()) {
                    self.foreground.start_waiting();
                    self.notifications.next().await;
                    self.foreground.finish_waiting();
                }
            })
            .await
            .expect("condition timed out");
        }
    }

    impl Drop for TestServer {
        fn drop(&mut self) {
            self.peer.reset();
        }
    }

    struct TestClient {
        client: Arc<Client>,
        pub peer_id: PeerId,
        pub user_store: ModelHandle<UserStore>,
    }

    impl Deref for TestClient {
        type Target = Arc<Client>;

        fn deref(&self) -> &Self::Target {
            &self.client
        }
    }

    impl TestClient {
        pub fn current_user_id(&self, cx: &TestAppContext) -> UserId {
            UserId::from_proto(
                self.user_store
                    .read_with(cx, |user_store, _| user_store.current_user().unwrap().id),
            )
        }
    }

    fn channel_messages(channel: &Channel) -> Vec<(String, String, bool)> {
        channel
            .messages()
            .cursor::<()>()
            .map(|m| {
                (
                    m.sender.github_login.clone(),
                    m.body.clone(),
                    m.is_pending(),
                )
            })
            .collect()
    }

    struct EmptyView;

    impl gpui::Entity for EmptyView {
        type Event = ();
    }

    impl gpui::View for EmptyView {
        fn ui_name() -> &'static str {
            "empty view"
        }

        fn render(&mut self, _: &mut gpui::RenderContext<Self>) -> gpui::ElementBox {
            gpui::Element::boxed(gpui::elements::Empty)
        }
    }
}
