matrix-ui-serializable 0.4.0

use anyhow::anyhow;
use std::{
    collections::HashMap,
    path::PathBuf,
    sync::{Arc, Condvar, LazyLock, Mutex, OnceLock},
    time::Duration,
};

use matrix_sdk::{
    Client, RoomMemberships,
    ruma::{OwnedRoomId, OwnedUserId},
};
use matrix_sdk_ui::sync_service::SyncService;
use tokio::{
    sync::{
        broadcast,
        mpsc::{Receiver, UnboundedSender},
    },
    time::{Instant, interval},
};

use crate::{
    events::timeline::TimelineKind,
    init::session::ClientSession,
    models::{
        async_requests::MatrixRequest, event_bridge::EventBridge,
        events::MatrixVerificationResponse,
    },
    submit_async_request,
};

/// The sender used by [`submit_async_request`] to send requests to the async worker thread.
/// Currently there is only one, but it can be cloned if we need more concurrent senders.
pub static REQUEST_SENDER: OnceLock<UnboundedSender<MatrixRequest>> = OnceLock::new();

/// The singleton sync service.
pub static SYNC_SERVICE: OnceLock<SyncService> = OnceLock::new();

/// Flag set by `handle_rooms_loading_state` when all rooms are loaded.
/// if rooms have been synced or not.
pub static ALL_ROOMS_LOADED: OnceLock<bool> = OnceLock::new();

pub(crate) struct TempClientSlot {
    pub(crate) lock: Mutex<Option<Client>>,
    pub(crate) cvar: Condvar,
}

/// The temporary Client used during login. It can be mutated
/// because the user can change its homeserver.
pub static TEMP_CLIENT: LazyLock<TempClientSlot> = LazyLock::new(|| TempClientSlot {
    lock: Mutex::new(None),
    cvar: Condvar::new(),
});

/// The temporary Client Session used during login
pub static TEMP_CLIENT_SESSION: LazyLock<Mutex<Option<ClientSession>>> =
    LazyLock::new(|| Mutex::new(None));

/// The logged-in Matrix client, which can be freely and cheaply cloned.
pub static CLIENT: OnceLock<Client> = OnceLock::new();

/// The current User's ID
pub static CURRENT_USER_ID: OnceLock<OwnedUserId> = OnceLock::new();

/// Flag to be set once the frontend Login Store is up and ready
pub static LOGIN_STORE_READY: OnceLock<bool> = OnceLock::new();

pub static HAS_SESSION_STORED: OnceLock<bool> = OnceLock::new();

#[derive(Debug, Clone)]
pub enum UIUpdateMessage {
    RefreshUI,
}

// Global broadcaster instance
static GLOBAL_BROADCASTER: OnceLock<GlobalBroadcaster> = OnceLock::new();

pub struct GlobalBroadcaster {
    sender: broadcast::Sender<UIUpdateMessage>,
}

pub static APP_DATA_DIR: OnceLock<PathBuf> = OnceLock::new();

impl GlobalBroadcaster {
    fn new(capacity: usize) -> Self {
        let (sender, _) = broadcast::channel(capacity);
        Self { sender }
    }

    fn broadcast(
        &self,
        message: UIUpdateMessage,
    ) -> Result<usize, broadcast::error::SendError<UIUpdateMessage>> {
        self.sender.send(message)
    }

    fn subscribe(&self) -> broadcast::Receiver<UIUpdateMessage> {
        self.sender.subscribe()
    }
}

// Initialize the global broadcaster (call this once at startup)
pub fn init_broadcaster(capacity: usize) -> Result<(), &'static str> {
    GLOBAL_BROADCASTER
        .set(GlobalBroadcaster::new(capacity))
        .map_err(|_| "Broadcaster already initialized")
}

// Globally available function to broadcast messages
pub fn broadcast_event(message: UIUpdateMessage) {
    let broadcaster = GLOBAL_BROADCASTER
        .get()
        .expect("Broadcaster not initialized. Call init_broadcaster() first.");

    let _ = broadcaster.broadcast(message);
}

// Globally available function to create receivers
pub fn subscribe_to_events() -> Result<broadcast::Receiver<UIUpdateMessage>, &'static str> {
    let broadcaster = GLOBAL_BROADCASTER
        .get()
        .ok_or("Broadcaster not initialized. Call init_broadcaster() first.")?;

    Ok(broadcaster.subscribe())
}

// Lib -> adapter communication

pub static EVENT_BRIDGE: OnceLock<EventBridge> = OnceLock::new();

pub fn get_event_bridge<'a>() -> anyhow::Result<&'a EventBridge> {
    let bridge = EVENT_BRIDGE
        .get()
        .ok_or(anyhow!("The event bridge is not yet set"))?;
    Ok(bridge)
}

// Adapter -> lib communication

pub static VERIFICATION_RESPONSE_RECEIVER: OnceLock<
    tokio::sync::Mutex<Receiver<MatrixVerificationResponse>>,
> = OnceLock::new();

pub async fn get_verification_response_receiver_lock<'a>()
-> anyhow::Result<tokio::sync::MutexGuard<'a, Receiver<MatrixVerificationResponse>>> {
    let recv = VERIFICATION_RESPONSE_RECEIVER
        .get()
        .ok_or(anyhow!("The verification response receiver is not yet set"))?;
    Ok(recv.lock().await)
}

// Membership changes expiry Map.
// Each time we receive a membership change from the Matrix sync
// we add a RoomId in this map. After a debounced period of time,
// this will send a request to update the members list.
pub(crate) struct ExpiryMap {
    // Stores the ID and the time it should expire
    items: Arc<Mutex<HashMap<OwnedRoomId, Instant>>>,
}

impl ExpiryMap {
    fn new() -> Self {
        let items: Arc<Mutex<HashMap<OwnedRoomId, Instant>>> = Arc::new(Mutex::new(HashMap::new()));
        let items_clone = Arc::clone(&items);

        tokio::spawn(async move {
            let mut ticker = interval(Duration::from_millis(500));

            loop {
                ticker.tick().await;

                let mut expired_ids = Vec::new();
                let now = Instant::now();

                {
                    let mut map = items_clone.lock().unwrap();

                    // .retain() is the most efficient way to remove items.
                    // If the closure returns 'false', the item is removed.
                    map.retain(|id, &mut expiry| {
                        if now >= expiry {
                            expired_ids.push(id.to_owned());
                            false
                        } else {
                            true
                        }
                    });
                }

                for id in expired_ids {
                    submit_async_request(MatrixRequest::GetRoomMembers {
                        timeline_kind: TimelineKind::MainRoom { room_id: id },
                        memberships: RoomMemberships::JOIN,
                        // Important so we don't try to fetch too many
                        // members from too large rooms.
                        local_only: true,
                    });
                }
            }
        });

        ExpiryMap { items }
    }

    pub(crate) fn insert(&self, id: OwnedRoomId, duration: Duration) {
        let expiry = Instant::now() + duration;
        self.items.lock().unwrap().insert(id, expiry);
    }
}

pub(crate) static MEMBERSHIP_UPDATES_EXPIRY_MAP: LazyLock<ExpiryMap> =
    LazyLock::new(ExpiryMap::new);