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src/routes/subscriptions.rs

@@ -41,28 +41,33 @@ pub async fn subscribe(
         .begin()
         .await
         .context("Failed to acquire a Postgres connection from the pool.")?;
-    let subscriber_id = insert_subscriber(&mut transaction, &new_subscriber)
+    if let Some(subscriber_id) = insert_subscriber(&mut transaction, &new_subscriber)
         .await
-        .context("Failed to insert new subscriber in the database.")?;
-    let subscription_token = generate_token();
-    store_token(&mut transaction, &subscription_token, &subscriber_id)
+        .context("Failed to insert new subscriber in the database.")
+        .map_err(AppError::unexpected_message)?
+    {
+        let subscription_token = generate_token();
+        store_token(&mut transaction, &subscription_token, &subscriber_id)
+            .await
+            .context("Failed to store the confirmation token for a new subscriber.")
+            .map_err(AppError::unexpected_message)?;
+        send_confirmation_email(
+            &email_client,
+            &new_subscriber,
+            &base_url,
+            &subscription_token,
+        )
         .await
-        .context("Failed to store the confirmation token for a new subscriber.")?;
-    send_confirmation_email(
-        &email_client,
-        &new_subscriber,
-        &base_url,
-        &subscription_token,
-    )
-    .await
-    .context("Failed to send a confirmation email.")?;
+        .context("Failed to send a confirmation email.")?;
+
+        transaction
+            .commit()
+            .await
+            .context("Failed to commit the database transaction to store a new subscriber.")?;
+    }
 
-    transaction
-        .commit()
-        .await
-        .context("Failed to commit the database transaction to store a new subscriber.")?;
     let template = MessageTemplate::Success {
-        message: "A confirmation email has been sent.".to_string(),
+        message: "You'll receive a confirmation email shortly.".to_string(),
     };
     Ok(Html(template.render().unwrap()).into_response())
 }
@@ -74,7 +79,15 @@ pub async fn subscribe(
 pub async fn insert_subscriber(
     transaction: &mut Transaction<'_, Postgres>,
     new_subscriber: &NewSubscriber,
-) -> Result<Uuid, sqlx::Error> {
+) -> Result<Option<Uuid>, sqlx::Error> {
+    let query = sqlx::query!(
+        "SELECT id FROM subscriptions WHERE email = $1",
+        new_subscriber.email.as_ref()
+    );
+    let existing = transaction.fetch_optional(query).await?;
+    if existing.is_some() {
+        return Ok(None);
+    }
     let subscriber_id = Uuid::new_v4();
     let query = sqlx::query!(
         r#"
@@ -86,7 +99,7 @@ pub async fn insert_subscriber(
         Utc::now()
     );
     transaction.execute(query).await?;
-    Ok(subscriber_id)
+    Ok(Some(subscriber_id))
 }
 
 #[tracing::instrument(