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// Copyright 2023 The Matrix.org Foundation C.I.C.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//! Widget API implementation.
use std::fmt;
use async_channel::{Receiver, Sender};
use serde::de::{self, Deserialize, Deserializer, Visitor};
use tokio::sync::mpsc::{unbounded_channel, UnboundedSender};
use tokio_util::sync::{CancellationToken, DropGuard};
use self::{
machine::{
Action, IncomingMessage, MatrixDriverRequestData, MatrixDriverResponse, SendEventRequest,
WidgetMachine,
},
matrix::MatrixDriver,
};
use crate::{room::Room, Result};
mod capabilities;
mod filter;
mod machine;
mod matrix;
mod settings;
pub use self::{
capabilities::{Capabilities, CapabilitiesProvider},
filter::{EventFilter, MessageLikeEventFilter, StateEventFilter},
settings::{
ClientProperties, EncryptionSystem, VirtualElementCallWidgetOptions, WidgetSettings,
},
};
/// An object that handles all interactions of a widget living inside a webview
/// or iframe with the Matrix world.
#[derive(Debug)]
pub struct WidgetDriver {
settings: WidgetSettings,
/// Raw incoming messages from the widget (normally formatted as JSON).
///
/// These can be both requests and responses.
from_widget_rx: Receiver<String>,
/// Raw outgoing messages from the client (SDK) to the widget (normally
/// formatted as JSON).
///
/// These can be both requests and responses.
to_widget_tx: Sender<String>,
}
/// A handle that encapsulates the communication between a widget driver and the
/// corresponding widget (inside a webview or iframe).
#[derive(Clone, Debug)]
pub struct WidgetDriverHandle {
/// Raw incoming messages from the widget driver to the widget (normally
/// formatted as JSON).
///
/// These can be both requests and responses. Users of this API should not
/// care what's what though because they are only supposed to forward
/// messages between the webview / iframe, and the SDK's widget driver.
to_widget_rx: Receiver<String>,
/// Raw outgoing messages from the widget to the widget driver (normally
/// formatted as JSON).
///
/// These can be both requests and responses. Users of this API should not
/// care what's what though because they are only supposed to forward
/// messages between the webview / iframe, and the SDK's widget driver.
from_widget_tx: Sender<String>,
}
impl WidgetDriverHandle {
/// Receive a message from the widget driver.
///
/// The message must be passed on to the widget.
///
/// Returns `None` if the widget driver is no longer running.
pub async fn recv(&self) -> Option<String> {
self.to_widget_rx.recv().await.ok()
}
/// Send a message from the widget to the widget driver.
///
/// Returns `false` if the widget driver is no longer running.
pub async fn send(&self, message: String) -> bool {
self.from_widget_tx.send(message).await.is_ok()
}
}
impl WidgetDriver {
/// Creates a new `WidgetDriver` and a corresponding set of channels to let
/// the widget (inside a webview or iframe) communicate with it.
pub fn new(settings: WidgetSettings) -> (Self, WidgetDriverHandle) {
let (from_widget_tx, from_widget_rx) = async_channel::unbounded();
let (to_widget_tx, to_widget_rx) = async_channel::unbounded();
let driver = Self { settings, from_widget_rx, to_widget_tx };
let channels = WidgetDriverHandle { from_widget_tx, to_widget_rx };
(driver, channels)
}
/// Starts a client widget API state machine for a given `widget` in a given
/// joined `room`. The function returns once the widget is disconnected or
/// any terminal error occurs.
///
/// Not implemented yet! Currently, it does not contain any useful
/// functionality, it only blindly forwards the messages and returns errors
/// once a non-implemented part is triggered.
pub async fn run(
self,
room: Room,
capabilities_provider: impl CapabilitiesProvider,
) -> Result<(), ()> {
// Create a channel so that we can conveniently send all events to it.
let (events_tx, mut events_rx) = unbounded_channel();
// Forward all of the incoming messages from the widget to the `events_tx`.
let tx = events_tx.clone();
tokio::spawn(async move {
while let Ok(msg) = self.from_widget_rx.recv().await {
let _ = tx.send(IncomingMessage::WidgetMessage(msg));
}
});
// Create widget API machine.
let (client_api, initial_actions) = WidgetMachine::new(
self.settings.widget_id().to_owned(),
room.room_id().to_owned(),
self.settings.init_on_content_load(),
None,
);
// The environment for the processing of actions from the widget machine.
let mut ctx = ProcessingContext {
widget_machine: client_api,
matrix_driver: MatrixDriver::new(room.clone()),
event_forwarding_guard: None,
to_widget_tx: self.to_widget_tx,
events_tx,
capabilities_provider,
};
// Process initial actions that "initialise" the widget api machine.
for action in initial_actions {
ctx.process_action(action).await?;
}
// Process incoming events.
while let Some(event) = events_rx.recv().await {
ctx.process_event(event).await?;
}
Ok(())
}
}
/// A small wrapper of all the data that we need to process an incoming event.
struct ProcessingContext<T> {
widget_machine: WidgetMachine,
matrix_driver: MatrixDriver,
event_forwarding_guard: Option<DropGuard>,
to_widget_tx: Sender<String>,
events_tx: UnboundedSender<IncomingMessage>,
capabilities_provider: T,
}
impl<T: CapabilitiesProvider> ProcessingContext<T> {
async fn process_event(&mut self, event: IncomingMessage) -> Result<(), ()> {
for action in self.widget_machine.process(event) {
self.process_action(action).await?;
}
Ok(())
}
async fn process_action(&mut self, action: Action) -> Result<(), ()> {
match action {
Action::SendToWidget(msg) => {
self.to_widget_tx.send(msg).await.map_err(|_| ())?;
}
Action::MatrixDriverRequest { request_id, data } => {
let response = match data {
MatrixDriverRequestData::AcquireCapabilities(cmd) => {
let obtained = self
.capabilities_provider
.acquire_capabilities(cmd.desired_capabilities)
.await;
Ok(MatrixDriverResponse::CapabilitiesAcquired(obtained))
}
MatrixDriverRequestData::GetOpenId => self
.matrix_driver
.get_open_id()
.await
.map(MatrixDriverResponse::OpenIdReceived)
.map_err(|e| e.to_string()),
MatrixDriverRequestData::ReadMessageLikeEvent(cmd) => self
.matrix_driver
.read_message_like_events(cmd.event_type.clone(), cmd.limit)
.await
.map(MatrixDriverResponse::MatrixEventRead)
.map_err(|e| e.to_string()),
MatrixDriverRequestData::ReadStateEvent(cmd) => self
.matrix_driver
.read_state_events(cmd.event_type.clone(), &cmd.state_key)
.await
.map(MatrixDriverResponse::MatrixEventRead)
.map_err(|e| e.to_string()),
MatrixDriverRequestData::SendMatrixEvent(req) => {
let SendEventRequest { event_type, state_key, content } = req;
self.matrix_driver
.send(event_type, state_key, content)
.await
.map(MatrixDriverResponse::MatrixEventSent)
.map_err(|e| e.to_string())
}
};
self.events_tx
.send(IncomingMessage::MatrixDriverResponse { request_id, response })
.map_err(|_| ())?;
}
Action::Subscribe => {
// Only subscribe if we are not already subscribed.
if self.event_forwarding_guard.is_none() {
let (stop_forwarding, guard) = {
let token = CancellationToken::new();
(token.child_token(), token.drop_guard())
};
self.event_forwarding_guard = Some(guard);
let (mut matrix, events_tx) =
(self.matrix_driver.events(), self.events_tx.clone());
tokio::spawn(async move {
loop {
tokio::select! {
_ = stop_forwarding.cancelled() => { return }
Some(event) = matrix.recv() => {
let _ = events_tx.send(IncomingMessage::MatrixEventReceived(event));
}
}
}
});
}
}
Action::Unsubscribe => {
self.event_forwarding_guard = None;
}
}
Ok(())
}
}
// TODO: Decide which module this type should live in
#[derive(Clone, Debug)]
pub(crate) enum StateKeySelector {
Key(String),
Any,
}
impl<'de> Deserialize<'de> for StateKeySelector {
fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
where
D: Deserializer<'de>,
{
struct StateKeySelectorVisitor;
impl<'de> Visitor<'de> for StateKeySelectorVisitor {
type Value = StateKeySelector;
fn expecting(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "a string or `true`")
}
fn visit_bool<E>(self, v: bool) -> Result<Self::Value, E>
where
E: de::Error,
{
if v {
Ok(StateKeySelector::Any)
} else {
Err(E::invalid_value(de::Unexpected::Bool(v), &self))
}
}
fn visit_str<E>(self, v: &str) -> Result<Self::Value, E>
where
E: de::Error,
{
self.visit_string(v.to_owned())
}
fn visit_string<E>(self, v: String) -> Result<Self::Value, E>
where
E: de::Error,
{
Ok(StateKeySelector::Key(v))
}
}
deserializer.deserialize_any(StateKeySelectorVisitor)
}
}
#[cfg(test)]
mod tests {
use assert_matches::assert_matches;
use serde_json::json;
use super::StateKeySelector;
#[test]
fn state_key_selector_from_true() {
let state_key = serde_json::from_value(json!(true)).unwrap();
assert_matches!(state_key, StateKeySelector::Any);
}
#[test]
fn state_key_selector_from_string() {
let state_key = serde_json::from_value(json!("test")).unwrap();
assert_matches!(state_key, StateKeySelector::Key(k) if k == "test");
}
#[test]
fn state_key_selector_from_false() {
let result = serde_json::from_value::<StateKeySelector>(json!(false));
assert_matches!(result, Err(e) if e.is_data());
}
#[test]
fn state_key_selector_from_number() {
let result = serde_json::from_value::<StateKeySelector>(json!(5));
assert_matches!(result, Err(e) if e.is_data());
}
}