Prelude/Main: rework hook system

youmubot-prelude/src/hook.rs

@@ -0,0 +1,24 @@
+use crate::{async_trait, future, Context, Result};
+use serenity::model::channel::Message;
+
+/// Hook represents the asynchronous hook that is run on every message.
+#[async_trait]
+pub trait Hook: Send + Sync {
+    async fn call(&mut self, ctx: &Context, message: &Message) -> Result<()>;
+}
+
+#[async_trait]
+impl<T> Hook for T
+where
+    T: for<'a> FnMut(
+            &'a Context,
+            &'a Message,
+        )
+            -> std::pin::Pin<Box<dyn future::Future<Output = Result<()>> + 'a + Send>>
+        + Send
+        + Sync,
+{
+    async fn call(&mut self, ctx: &Context, message: &Message) -> Result<()> {
+        self(ctx, message).await
+    }
+}

youmubot-prelude/src/lib.rs

@@ -5,11 +5,13 @@ use std::sync::Arc;
 
 pub mod announcer;
 pub mod args;
+pub mod hook;
 pub mod pagination;
 pub mod setup;
 
 pub use announcer::{Announcer, AnnouncerHandler};
 pub use args::{Duration, UsernameArg};
+pub use hook::Hook;
 pub use pagination::paginate;
 
 /// Re-exporting async_trait helps with implementing Announcer.