Add shorthand for meta()

Signed-off-by: eternal-flame-AD <yume@yumechi.jp>

src/evaluate/chain/meta.rs

@@ -4,6 +4,7 @@ use serde::{Deserialize, Serialize};
 
 use crate::{
     delegate,
+    evaluate::{Disposition, Evaluator},
     model::ap::{AnyObject, NoteObject},
     APRequestInfo, HasAppState,
 };
@@ -14,6 +15,15 @@ pub struct Meta<E: IntoResponse + 'static, I: HasAppState<E>> {
     _marker: std::marker::PhantomData<E>,
 }
 
+impl<E: IntoResponse + 'static, I: HasAppState<E>> Meta<E, I> {
+    pub fn new(inner: I) -> Self {
+        Self {
+            inner,
+            _marker: std::marker::PhantomData,
+        }
+    }
+}
+
 pub fn extract_host(act: &APRequestInfo) -> Option<String> {
     act.activity
         .as_ref()
@@ -50,3 +60,26 @@ pub struct MetaItem {
     instance_host: Option<String>,
     attributed_to: Option<String>,
 }
+
+#[async_trait::async_trait]
+impl<
+        E: IntoResponse + Serialize + Send + Sync + 'static,
+        I: HasAppState<E> + Evaluator<E> + Sync,
+    > Evaluator<E> for Meta<E, I>
+{
+    fn name() -> &'static str {
+        "ExtractMeta"
+    }
+    async fn evaluate<'r>(
+        &self,
+        ctx: Option<serde_json::Value>,
+        info: &APRequestInfo<'r>,
+    ) -> (Disposition<E>, Option<serde_json::Value>) {
+        let ctx = ctx.map(|mut c| {
+            c["meta"] = serde_json::to_value(extract_meta(info)).unwrap();
+            c
+        });
+
+        self.inner.evaluate(ctx, info).await
+    }
+}

src/lib.rs

@@ -17,6 +17,7 @@ use axum::{
 };
 use client::ClientCache;
 use evaluate::chain::audit::{Audit, AuditOptions};
+use evaluate::chain::meta::Meta;
 use evaluate::{
     Disposition, Evaluator, ERR_BAD_REQUEST, ERR_INTERNAL_SERVER_ERROR, ERR_PAYLOAD_TOO_LARGE,
     ERR_SERVICE_TEMPORARILY_UNAVAILABLE,
@@ -103,6 +104,15 @@ pub trait HasAppState<E: IntoResponse + 'static>: Clone {
     {
         Audit::new(self, opts)
     }
+
+    /// Wrap the evaluator in a meta chain.
+    fn extract_meta(self) -> Meta<E, Self>
+    where
+        Self: Sized + Send + Sync + Evaluator<E>,
+        E: Send + Sync,
+    {
+        Meta::new(self.clone())
+    }
 }
 
 /// Application state.

src/main.rs

@@ -29,6 +29,7 @@ async fn build_state<E: IntoResponse + Clone + Serialize + Send + Sync + 'static
     _args: &Args,
 ) -> impl HasAppState<E> + Evaluator<E> {
     base.audited(AuditOptions::new(PathBuf::from("inbox_audit")))
+        .extract_meta()
 }
 
 #[tokio::main]
@@ -41,9 +42,9 @@ async fn main() {
     let args = Args::parse();
 
     let state = build_state::<MisskeyError>(
-        Arc::new(BaseAppState::new(
+        Arc::new(
-            args.backend.parse().expect("Invalid backend URL"),
+            BaseAppState::new(args.backend.parse().expect("Invalid backend URL")).with_empty_ctx(),
-        )),
+        ),
         &args,
     )
     .await;