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use crate::{
async_trait, error::BasuError, event::Event, Arc, EventBus, Handler, HandlerId, HashMap, Mutex,
};
/// Implement for event handler
#[async_trait]
pub trait Handle<T>: Send + Sync {
/// Handle event which is published from `EventBus`
async fn handle(&self, event: &Event<T>) -> Result<(), BasuError>;
}
impl<T> EventBus<T> {
/// Subscribe to an event type.
/// It takes the event type as a string and a handler implementing the `Handle<T>` trait.
/// The method returns a `HandlerId` that uniquely identifies the handler within the event bus.
///
/// ## Example
/// ```no_run
/// struct MyEventData {
/// // Define your event data structure here
/// }
///
/// struct MyEventHandler;
///
/// #[async_trait]
/// impl Handle<MyEventData> for MyEventHandler {
/// async fn handle(&self, event: &Event<MyEventData>) -> Result<(), BasuError> {
/// // Handle the event here
/// // ...
/// Ok(())
/// }
/// }
///
/// let event_bus = EventBus::<MyEventData>::new();
/// let handler = MyEventHandler;
///
/// let handler_id = event_bus.subscribe("my_event", Box::new(handler)).await;
/// ```
pub async fn subscribe(&self, event_type: &str, handler: Handler<T>) -> HandlerId {
let mut event_handler_map = self.event_handler_map.lock().await;
match event_handler_map.get(event_type) {
Some(handler_map) => {
let mut handler_map = handler_map.lock().await;
let handler_id = HandlerId::new();
handler_map.insert(handler_id.clone(), handler);
handler_id
}
None => {
let mut handler_map = HashMap::new();
let handler_id = HandlerId::new();
handler_map.insert(handler_id.clone(), handler);
event_handler_map.insert(event_type.to_owned(), Arc::new(Mutex::new(handler_map)));
handler_id
}
}
}
/// Unsubscribe handler from an event type.
/// It takes the event type and the `HandlerId` of the handler to be removed.
///
/// ```no_run
/// struct MyEventData {
/// // Define your event data structure here
/// }
///
/// struct MyEventHandler;
///
/// #[async_trait]
/// impl Handle<MyEventData> for MyEventHandler {
/// async fn handle(&self, event: &Event<MyEventData>) -> Result<(), BasuError> {
/// // Handle the event here
/// // ...
/// Ok(())
/// }
/// }
///
/// let event_bus = EventBus::<MyEventData>::new();
/// let handler = MyEventHandler;
/// let handler_id = event_bus.subscribe("my_event", Box::new(handler)).await;
///
/// event_bus.unsubscribe("my_event", &handler_id).await?;
/// ```
pub async fn unsubscribe(
&self,
event_type: &str,
handler_id: &HandlerId,
) -> Result<(), BasuError> {
let event_handler_map = self.event_handler_map.lock().await;
match event_handler_map.get(event_type) {
Some(handler_map) => {
let mut handler_map = handler_map.lock().await;
handler_map.remove(handler_id);
Ok(())
}
None => Err(BasuError::EventTypeNotFOUND),
}
}
/// Publish an event to subscribed handlers,
/// It takes the event type and an `Event<T>` instance containing the event data.
///
/// ```no_run
/// struct MyEventData {
/// // Define your event data structure here
/// }
///
/// struct MyEventHandler;
///
/// #[async_trait]
/// impl Handle<MyEventData> for MyEventHandler {
/// async fn handle(&self, event: &Event<MyEventData>) -> Result<(), BasuError> {
/// // Handle the event here
/// // ...
/// Ok(())
/// }
/// }
///
/// let event_bus = EventBus::<MyEventData>::new();
/// let handler = MyEventHandler;
/// let handler_id = event_bus.subscribe("my_event", Box::new(handler)).await;
/// let event_data = MyEventData { /* initialize your event data */ };
/// let event = Event::new(event_data);
///
/// event_bus.publish("my_event", &event).await?;
/// ```
pub async fn publish(&self, event_type: &str, event_data: &Event<T>) -> Result<(), BasuError> {
let event_handler_map = self.event_handler_map.lock().await;
match event_handler_map.get(event_type) {
Some(handler_map) => {
let handler_map = handler_map.lock().await;
let futures = handler_map.iter().map(|(_id, h)| h.handle(event_data));
futures::future::try_join_all(futures)
.await
.map(|_| ())
.map_err(Into::into)
}
None => Err(BasuError::EventTypeNotFOUND),
}
}
/// List all registered event types.
/// It returns a Vec that contains the names of the registered event types.
///
/// ```no_run
/// struct MyEventData {
/// // Define your event data structure here
/// }
///
/// struct MyEventHandler;
///
/// #[async_trait]
/// impl Handle<MyEventData> for MyEventHandler {
/// async fn handle(&self, event: &Event<MyEventData>) -> Result<(), BasuError> {
/// // Handle the event here
/// // ...
/// Ok(())
/// }
/// }
///
/// let event_bus = EventBus::<MyEventData>::new();
/// let handler = MyEventHandler;
/// let _handler_id = event_bus.subscribe("my_event", Box::new(handler)).await;
///
/// let event_types = event_bus.list().await;
/// for event_type in event_types {
/// println!("Registered event type: {}", event_type);
/// }
///```
pub async fn list(&self) -> Vec<String> {
let event_handler_map = self.event_handler_map.lock().await;
event_handler_map.keys().cloned().collect()
}
/// Get the number of registered handlers for a specific event type.
///
/// ```no_run
/// struct MyEventData {
/// // Define your event data structure here
/// }
///
/// let event_bus = EventBus::<EventData>::new();
///
/// let event_type = "my_event";
/// let handler_count = event_bus.get_handler_count(event_type).await?;
///
/// println!("Number of handlers for event '{}': {}", event_type, handler_count);
/// ```
pub async fn get_handler_count(&self, event_type: &str) -> Result<usize, BasuError> {
let event_handler_map = self.event_handler_map.lock().await;
match event_handler_map.get(event_type) {
Some(handler_map) => {
let handler_map = handler_map.lock().await;
Ok(handler_map.len())
}
None => Err(BasuError::EventTypeNotFOUND),
}
}
/// Clear all event handlers from the event bus.
/// It removes all registered event handlers.
///
/// ```no_run
/// struct MyEventData {
/// // Define your event data structure here
/// }
///
/// struct MyEventHandler;
///
/// #[async_trait]
/// impl Handle<MyEventData> for MyEventHandler {
/// async fn handle(&self, event: &Event<MyEventData>) -> Result<(), BasuError> {
/// // Handle the event here
/// // ...
/// Ok(())
/// }
/// }
///
/// let event_bus = EventBus::<MyEventData>::new();
/// let handler = MyEventHandler;
/// let _handler_id = event_bus.subscribe("my_event", Box::new(handler)).await;
///
/// event_bus.clear().await;
///
/// println!("All event handlers cleared");
/// ```
///
/// **Note:** The `clear` method removes all event handlers and makes the event bus empty.
pub async fn clear(&self) {
let mut event_handler_map = self.event_handler_map.lock().await;
event_handler_map.clear();
}
}