refactor(users): content negotiation at GET /users/{username}; move lookup_handler; rename get_me_following

crates/presentation/src/handlers/users.rs

@@ -6,13 +6,15 @@ use crate::{
 };
 use api_types::{
     requests::{PaginationQuery, UpdateProfileRequest},
-    responses::{ErrorResponse, UserResponse},
+    responses::{ErrorResponse, RemoteActorResponse, UserResponse},
 };
 use application::use_cases::feed::list_users;
 use application::use_cases::profile::{get_user_by_username, update_profile};
 use application::use_cases::search::search_users;
 use axum::{
     extract::{Path, Query, State},
+    http::{header, HeaderMap},
+    response::{IntoResponse, Response},
     Json,
 };
 
@@ -28,8 +30,19 @@ pub async fn get_user(
     State(s): State<AppState>,
     Path(username): Path<String>,
     OptionalAuthUser(viewer): OptionalAuthUser,
-) -> Result<Json<UserResponse>, ApiError> {
+    headers: HeaderMap,
+) -> Result<Response, ApiError> {
     let user = get_user_by_username(&*s.users, &username).await?;
+
+    let accept = headers
+        .get(header::ACCEPT)
+        .and_then(|v| v.to_str().ok())
+        .unwrap_or("");
+
+    if accept.contains("application/activity+json") {
+        let json = s.federation.actor_json(&user.id).await?;
+        Ok(([(header::CONTENT_TYPE, "application/activity+json")], json).into_response())
+    } else {
         let is_followed = if let Some(viewer_id) = viewer {
             s.follows.find(&viewer_id, &user.id).await?.is_some()
         } else {
@@ -37,7 +50,8 @@ pub async fn get_user(
         };
         let mut resp = to_user_response(&user);
         resp.is_followed_by_viewer = is_followed;
-    Ok(Json(resp))
+        Ok(Json(resp).into_response())
+    }
 }
 
 #[utoipa::path(
@@ -92,7 +106,7 @@ pub async fn get_me(
     Ok(Json(to_user_response(&user)))
 }
 
-pub async fn get_me_following_list(
+pub async fn get_me_following(
     State(s): State<AppState>,
     AuthUser(uid): AuthUser,
     Query(q): Query<PaginationQuery>,
@@ -170,3 +184,135 @@ pub async fn get_user_count(
     let count = s.users.count().await?;
     Ok(Json(serde_json::json!({ "count": count })))
 }
+
+#[derive(serde::Deserialize)]
+pub struct LookupQuery {
+    pub handle: String,
+}
+
+pub async fn lookup_handler(
+    State(s): State<AppState>,
+    Query(q): Query<LookupQuery>,
+) -> Result<Json<RemoteActorResponse>, ApiError> {
+    let actor = s.federation.lookup_actor(&q.handle).await?;
+    Ok(Json(RemoteActorResponse {
+        handle: actor.handle,
+        display_name: actor.display_name,
+        avatar_url: actor.avatar_url,
+        url: actor.url,
+    }))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use async_trait::async_trait;
+    use axum::{
+        body::Body,
+        http::{header, Request},
+        routing::get,
+        Router,
+    };
+    use domain::{
+        errors::DomainError,
+        ports::{AuthService, GeneratedToken, PasswordHasher},
+        testing::TestStore,
+        value_objects::{PasswordHash, UserId},
+    };
+    use std::sync::Arc;
+    use tower::ServiceExt;
+
+    struct NoOpAuth;
+    impl AuthService for NoOpAuth {
+        fn generate_token(&self, _uid: &UserId) -> Result<GeneratedToken, DomainError> {
+            Err(DomainError::Internal("noop".into()))
+        }
+        fn validate_token(&self, _token: &str) -> Result<UserId, DomainError> {
+            Err(DomainError::Unauthorized)
+        }
+    }
+
+    struct NoOpHasher;
+    #[async_trait]
+    impl PasswordHasher for NoOpHasher {
+        async fn hash(&self, _plain: &str) -> Result<PasswordHash, DomainError> {
+            Err(DomainError::Internal("noop".into()))
+        }
+        async fn verify(&self, _plain: &str, _hash: &PasswordHash) -> Result<bool, DomainError> {
+            Ok(false)
+        }
+    }
+
+    fn make_state() -> crate::state::AppState {
+        let store = Arc::new(TestStore::default());
+        crate::state::AppState {
+            users: store.clone(),
+            thoughts: store.clone(),
+            likes: store.clone(),
+            boosts: store.clone(),
+            follows: store.clone(),
+            blocks: store.clone(),
+            tags: store.clone(),
+            api_keys: store.clone(),
+            top_friends: store.clone(),
+            notifications: store.clone(),
+            remote_actors: store.clone(),
+            feed: store.clone(),
+            search: store.clone(),
+            auth: Arc::new(NoOpAuth),
+            hasher: Arc::new(NoOpHasher),
+            events: store.clone(),
+            federation: store.clone(),
+        }
+    }
+
+    fn app() -> Router {
+        Router::new()
+            .route("/users/{username}", get(get_user))
+            .route("/users/lookup", get(lookup_handler))
+            .with_state(make_state())
+    }
+
+    #[tokio::test]
+    async fn get_unknown_user_returns_404() {
+        let resp = app()
+            .oneshot(
+                Request::builder()
+                    .uri("/users/nobody")
+                    .body(Body::empty())
+                    .unwrap(),
+            )
+            .await
+            .unwrap();
+        assert_eq!(resp.status(), 404);
+    }
+
+    #[tokio::test]
+    async fn get_user_with_ap_accept_returns_404_when_actor_not_found() {
+        let resp = app()
+            .oneshot(
+                Request::builder()
+                    .uri("/users/nobody")
+                    .header(header::ACCEPT, "application/activity+json")
+                    .body(Body::empty())
+                    .unwrap(),
+            )
+            .await
+            .unwrap();
+        assert_eq!(resp.status(), 404);
+    }
+
+    #[tokio::test]
+    async fn lookup_unknown_handle_returns_404() {
+        let resp = app()
+            .oneshot(
+                Request::builder()
+                    .uri("/users/lookup?handle=%40alice%40example.com")
+                    .body(Body::empty())
+                    .unwrap(),
+            )
+            .await
+            .unwrap();
+        assert_eq!(resp.status(), 404);
+    }
+}

crates/presentation/src/routes.rs

@@ -20,10 +20,7 @@ pub fn router() -> Router<AppState> {
                 .patch(users::patch_profile)
                 .put(users::patch_profile),
         )
-        .route(
+        .route("/users/me/following-list", get(users::get_me_following))
-            "/users/me/following-list",
-            get(users::get_me_following_list),
-        )
         .route("/users/me/top-friends", put(social::put_top_friends))
         // /users/{username} is owned by the AP router (returns AP actor JSON for federation).
         // The REST user profile lives at /users/{username}/profile to avoid the conflict.