Initial commit

backend/src/http/responders.rs

@@ -0,0 +1,157 @@
+use axum::{
+    http::StatusCode,
+    response::{IntoResponse, Response},
+    Json,
+};
+use serde::Serialize;
+
+use crate::error::{AppError, AppResult};
+
+/// Helper trait to convert error-centric results into the application's error type.
+pub trait IntoAppResult<T> {
+    fn into_app_result(self) -> AppResult<T>;
+}
+
+impl<T, E> IntoAppResult<T> for Result<T, E>
+where
+    AppError: From<E>,
+{
+    fn into_app_result(self) -> AppResult<T> {
+        self.map_err(AppError::from)
+    }
+}
+
+/// Extension helpers for optional values to map them into `AppResult`.
+pub trait OptionAppResultExt<T> {
+    fn or_not_found(self) -> AppResult<T>;
+    fn or_bad_request(self, message: impl Into<String>) -> AppResult<T>;
+}
+
+impl<T> OptionAppResultExt<T> for Option<T> {
+    fn or_not_found(self) -> AppResult<T> {
+        self.ok_or_else(AppError::not_found)
+    }
+
+    fn or_bad_request(self, message: impl Into<String>) -> AppResult<T> {
+        self.ok_or_else(|| AppError::bad_request(message))
+    }
+}
+
+/// Provides helpers for statements returning number of affected rows.
+pub trait RowsAffectedExt: Sized {
+    fn or_error(self, error: AppError) -> AppResult<usize>;
+    fn or_not_found(self) -> AppResult<usize> {
+        self.or_error(AppError::not_found())
+    }
+}
+
+impl RowsAffectedExt for usize {
+    fn or_error(self, error: AppError) -> AppResult<usize> {
+        if self == 0 {
+            Err(error)
+        } else {
+            Ok(self)
+        }
+    }
+}
+
+/// Wrapper providing a consistent JSON response with a status code.
+pub struct JsonResponse<T> {
+    status: StatusCode,
+    payload: T,
+}
+
+impl<T> JsonResponse<T> {
+    pub fn new(status: StatusCode, payload: T) -> Self {
+        Self { status, payload }
+    }
+
+    pub fn ok(payload: T) -> Self {
+        Self::new(StatusCode::OK, payload)
+    }
+
+    pub fn created(payload: T) -> Self {
+        Self::new(StatusCode::CREATED, payload)
+    }
+
+    pub fn accepted(payload: T) -> Self {
+        Self::new(StatusCode::ACCEPTED, payload)
+    }
+
+    pub fn into_inner(self) -> T {
+        self.payload
+    }
+
+    pub fn as_inner(&self) -> &T {
+        &self.payload
+    }
+}
+
+impl<T> From<T> for JsonResponse<T> {
+    fn from(value: T) -> Self {
+        Self::ok(value)
+    }
+}
+
+impl<T> IntoResponse for JsonResponse<T>
+where
+    T: Serialize,
+{
+    fn into_response(self) -> Response {
+        (self.status, Json(self.payload)).into_response()
+    }
+}
+
+/// Helper for returning empty responses with a status code.
+pub fn empty(status: StatusCode) -> AppResult<StatusCode> {
+    Ok(status)
+}
+
+/// Helper for returning `204 No Content`.
+pub fn no_content() -> AppResult<StatusCode> {
+    empty(StatusCode::NO_CONTENT)
+}
+
+/// Helper for returning JSON payloads with `200 OK`.
+pub fn ok_json<T>(value: T) -> AppResult<JsonResponse<T>>
+where
+    T: Serialize,
+{
+    Ok(JsonResponse::ok(value))
+}
+
+/// Helper for returning JSON payloads with `201 Created`.
+pub fn created_json<T>(value: T) -> AppResult<JsonResponse<T>>
+where
+    T: Serialize,
+{
+    Ok(JsonResponse::created(value))
+}
+
+/// Helper for returning JSON payloads with `202 Accepted`.
+pub fn accepted_json<T>(value: T) -> AppResult<JsonResponse<T>>
+where
+    T: Serialize,
+{
+    Ok(JsonResponse::accepted(value))
+}
+
+/// Standard wrapper for paginated responses.
+#[derive(Serialize)]
+pub struct PaginatedResponse<T, M>
+where
+    T: Serialize,
+    M: Serialize,
+{
+    pub data: T,
+    pub meta: M,
+}
+
+pub fn paginated_json<T, M>(data: T, meta: M) -> AppResult<JsonResponse<PaginatedResponse<T, M>>>
+where
+    T: Serialize,
+    M: Serialize,
+{
+    let payload = PaginatedResponse { data, meta };
+    Ok(JsonResponse::ok(payload))
+}