From 9d497f0aaf0f54268d86a2f15abad7789fe33b80 Mon Sep 17 00:00:00 2001
From: Jacob Babich <jacob@katniss.top>
Date: Wed, 29 Nov 2023 13:30:51 -0500
Subject: [PATCH] implement an Atom RSS feed

---
 Cargo.lock                      |  2 ++
 Cargo.toml                      |  6 ++--
 src/routes/notifications/mod.rs | 57 ++++++++++++++++++++++++++++++---
 3 files changed, 58 insertions(+), 7 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 74bff86..f6997a5 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -184,7 +184,9 @@ version = "0.1.0"
 dependencies = [
  "atom_syndication",
  "axum",
+ "bytes",
  "error-stack",
+ "mime",
  "redb",
  "serde",
  "thiserror",
diff --git a/Cargo.toml b/Cargo.toml
index 01ef8c8..33ca823 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -4,9 +4,11 @@ version = "0.1.0"
 edition = "2021"
 
 [dependencies]
-atom_syndication = "0.12.2"
-axum = { version = "0.7.1", default-features = false, features = ["json", "tokio", "http2"] }
+atom_syndication = { version = "0.12.2" }
+axum = { version = "0.7.1", default-features = false, features = ["json", "tokio", "http2", "http1"] }
+bytes = "1.5.0"
 error-stack = "0.4.1"
+mime = "0.3.17"
 redb = "1.4.0"
 serde = { version = "1.0.193", features = ["derive"] }
 thiserror = "1.0.50"
diff --git a/src/routes/notifications/mod.rs b/src/routes/notifications/mod.rs
index 68d0101..7feab90 100644
--- a/src/routes/notifications/mod.rs
+++ b/src/routes/notifications/mod.rs
@@ -1,13 +1,60 @@
-use axum::{extract::State, response::IntoResponse, Router};
+use atom_syndication::{Feed, FeedBuilder};
+use axum::{
+    extract::State,
+    http::{header, HeaderValue, StatusCode},
+    response::{IntoResponse, Response},
+    Router,
+};
+use bytes::{BufMut, BytesMut};
 
 use crate::AppState;
 
-#[tracing::instrument(level = "trace")]
-async fn get(state: State<AppState>) -> impl IntoResponse {
-    "Hi, getter!"
+#[derive(Debug)]
+struct Atom(Feed);
+
+impl IntoResponse for Atom {
+    fn into_response(self) -> Response {
+        let buf = BytesMut::with_capacity(128).writer();
+        match self.0.write_to(buf) {
+            Ok(buf) => (
+                [(
+                    header::CONTENT_TYPE,
+                    HeaderValue::from_static("application/xml"),
+                )],
+                buf.into_inner().freeze(),
+            )
+                .into_response(),
+            Err(err) => (
+                StatusCode::INTERNAL_SERVER_ERROR,
+                [(
+                    header::CONTENT_TYPE,
+                    HeaderValue::from_static(mime::TEXT_PLAIN_UTF_8.as_ref()),
+                )],
+                err.to_string(),
+            )
+                .into_response(),
+        }
+    }
 }
 
-#[tracing::instrument(level = "trace")]
+impl From<Feed> for Atom {
+    fn from(inner: Feed) -> Self {
+        Self(inner)
+    }
+}
+
+#[tracing::instrument(level = "trace", ret)]
+async fn get(state: State<AppState>) -> impl IntoResponse {
+    let feed = FeedBuilder::default()
+        .title("My Notifications")
+        .subtitle(Some("Originally from my smartphone".into()))
+        .icon(Some("https://katniss.top/favicon.png".into()))
+        .build();
+
+    Atom(feed)
+}
+
+#[tracing::instrument(level = "trace", ret)]
 async fn post(state: State<AppState>) -> impl IntoResponse {
     "Hi, poster!"
 }