Handler to send emails to confirmed subscribers

src/routes.rs

@@ -1,7 +1,9 @@
 mod health_check;
+mod newsletters;
 mod subscriptions;
 mod subscriptions_confirm;
 
 pub use health_check::*;
+pub use newsletters::*;
 pub use subscriptions::*;
 pub use subscriptions_confirm::*;

src/routes/newsletters.rs

@@ -0,0 +1,110 @@
+use crate::{domain::SubscriberEmail, routes::error_chain_fmt, startup::AppState};
+use anyhow::Context;
+use axum::{
+    Json,
+    extract::State,
+    response::{IntoResponse, Response},
+};
+use reqwest::StatusCode;
+use sqlx::PgPool;
+
+#[derive(thiserror::Error)]
+pub enum PublishError {
+    #[error(transparent)]
+    UnexpectedError(#[from] anyhow::Error),
+}
+
+impl std::fmt::Debug for PublishError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        error_chain_fmt(self, f)
+    }
+}
+
+impl IntoResponse for PublishError {
+    fn into_response(self) -> Response {
+        #[derive(serde::Serialize)]
+        struct ErrorResponse<'a> {
+            message: &'a str,
+        }
+
+        tracing::error!("{:?}", self);
+
+        let status = match self {
+            PublishError::UnexpectedError(_) => StatusCode::INTERNAL_SERVER_ERROR,
+        };
+        let message = "An internal server error occured.";
+        (status, Json(ErrorResponse { message })).into_response()
+    }
+}
+
+#[derive(serde::Deserialize)]
+pub struct BodyData {
+    title: String,
+    content: Content,
+}
+
+#[derive(serde::Deserialize)]
+pub struct Content {
+    html: String,
+    text: String,
+}
+
+#[tracing::instrument(
+    name = "Publishing a newsletter",
+    skip(connection_pool, email_client, body)
+)]
+pub async fn publish_newsletter(
+    State(AppState {
+        connection_pool,
+        email_client,
+        ..
+    }): State<AppState>,
+    body: Json<BodyData>,
+) -> Result<Response, PublishError> {
+    let subscribers = get_confirmed_subscribers(&connection_pool).await?;
+    for subscriber in subscribers {
+        match subscriber {
+            Ok(ConfirmedSubscriber { email, .. }) => {
+                email_client
+                    .send_email(&email, &body.title, &body.content.html, &body.content.text)
+                    .await
+                    .with_context(|| {
+                        format!("Failed to send newsletter issue to {}", email.as_ref())
+                    })?;
+            }
+            Err(e) => {
+                tracing::warn!(
+                    "Skipping a confirmed subscriber. Their stored contact details are invalid: {}",
+                    e
+                )
+            }
+        }
+    }
+    Ok(StatusCode::OK.into_response())
+}
+
+#[allow(dead_code)]
+struct ConfirmedSubscriber {
+    name: String,
+    email: SubscriberEmail,
+}
+
+#[tracing::instrument(name = "Get confirmed subscribers", skip(connection_pool))]
+async fn get_confirmed_subscribers(
+    connection_pool: &PgPool,
+) -> Result<Vec<Result<ConfirmedSubscriber, anyhow::Error>>, anyhow::Error> {
+    let rows = sqlx::query!("SELECT name, email FROM subscriptions WHERE status = 'confirmed'")
+        .fetch_all(connection_pool)
+        .await?;
+    let confirmed_subscribers = rows
+        .into_iter()
+        .map(|r| match SubscriberEmail::parse(r.email) {
+            Ok(email) => Ok(ConfirmedSubscriber {
+                name: r.name,
+                email,
+            }),
+            Err(e) => Err(anyhow::anyhow!(e)),
+        })
+        .collect();
+    Ok(confirmed_subscribers)
+}

src/routes/subscriptions.rs

@@ -24,7 +24,10 @@ fn generate_subscription_token() -> String {
         .collect()
 }
 
-fn error_chain_fmt(e: &impl std::error::Error, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+pub fn error_chain_fmt(
+    e: &impl std::error::Error,
+    f: &mut std::fmt::Formatter,
+) -> std::fmt::Result {
     writeln!(f, "{}", e)?;
     let mut current = e.source();
     while let Some(cause) = current {
@@ -37,24 +40,12 @@ fn error_chain_fmt(e: &impl std::error::Error, f: &mut std::fmt::Formatter) -> s
     Ok(())
 }
 
-// #[derive(thiserror::Error)]
-// pub enum SubscribeError {
-//     #[error("Failed to store the confirmation token for a new subscriber.")]
-//     StoreToken(#[from] StoreTokenError),
-//     #[error("A database error occured.")]
-//     Database(#[from] sqlx::Error),
-//     #[error("Failed to send a confirmation email.")]
-//     SendEmail(#[from] reqwest::Error),
-//     #[error("{0}")]
-//     Validation(String),
-// }
-
 #[derive(thiserror::Error)]
 pub enum SubscribeError {
     #[error(transparent)]
     UnexpectedError(#[from] anyhow::Error),
     #[error("{0}")]
-    Validation(String),
+    ValidationError(String),
 }
 
 impl std::fmt::Debug for SubscribeError {
@@ -72,15 +63,9 @@ impl IntoResponse for SubscribeError {
 
         tracing::error!("{:?}", self);
 
-        // let status = match self {
-        //     SubscribeError::StoreToken(_)
-        //     | SubscribeError::Database(_)
-        //     | SubscribeError::SendEmail(_) => StatusCode::INTERNAL_SERVER_ERROR,
-        //     SubscribeError::Validation(_) => StatusCode::BAD_REQUEST,
-        // };
         let status = match self {
             SubscribeError::UnexpectedError(_) => StatusCode::INTERNAL_SERVER_ERROR,
-            SubscribeError::Validation(_) => StatusCode::BAD_REQUEST,
+            SubscribeError::ValidationError(_) => StatusCode::BAD_REQUEST,
         };
         let message = "An internal server error occured.";
         (status, Json(ErrorResponse { message })).into_response()
@@ -107,7 +92,7 @@ pub async fn subscribe(
         .begin()
         .await
         .context("Failed to acquire a Postgres connection from the pool.")?;
-    let new_subscriber = form.try_into().map_err(SubscribeError::Validation)?;
+    let new_subscriber = form.try_into().map_err(SubscribeError::ValidationError)?;
     let subscriber_id = insert_subscriber(&mut transaction, &new_subscriber)
         .await
         .context("Failed to insert new subscriber in the database.")?;

src/startup.rs

@@ -61,6 +61,7 @@ pub fn app(connection_pool: PgPool, email_client: EmailClient, base_url: String)
         .route("/health_check", get(health_check))
         .route("/subscriptions", post(subscribe))
         .route("/subscriptions/confirm", get(confirm))
+        .route("/newsletters", post(publish_newsletter))
         .layer(
             TraceLayer::new_for_http()
                 .make_span_with(|request: &Request<_>| {