refactor(domain): algebraic NotificationKind — invalid states now unrepresentable

crates/adapters/postgres/migrations/008_rename_notifications_type.sql

@@ -0,0 +1 @@
+ALTER TABLE notifications RENAME COLUMN "type" TO notification_type;

crates/adapters/postgres/src/notification.rs

@@ -2,33 +2,11 @@ use crate::db_error::IntoDbResult;
 use async_trait::async_trait;
 use chrono::{DateTime, Utc};
 
-fn notif_type_from_str(s: &str) -> domain::models::notification::NotificationType {
-    use domain::models::notification::NotificationType;
-    match s {
-        "like" => NotificationType::Like,
-        "boost" => NotificationType::Boost,
-        "follow" => NotificationType::Follow,
-        "mention" => NotificationType::Mention,
-        _ => NotificationType::Reply,
-    }
-}
-
-fn notif_type_as_str(t: &domain::models::notification::NotificationType) -> &'static str {
-    use domain::models::notification::NotificationType;
-    match t {
-        NotificationType::Like => "like",
-        NotificationType::Boost => "boost",
-        NotificationType::Follow => "follow",
-        NotificationType::Mention => "mention",
-        NotificationType::Reply => "reply",
-    }
-}
-
 use domain::{
     errors::DomainError,
     models::{
         feed::{PageParams, Paginated},
-        notification::Notification,
+        notification::{Notification, NotificationKind},
     },
     ports::NotificationRepository,
     value_objects::{NotificationId, ThoughtId, UserId},
@@ -44,17 +22,83 @@ impl PgNotificationRepository {
     }
 }
 
+#[derive(sqlx::FromRow)]
+struct NotificationRow {
+    id: uuid::Uuid,
+    user_id: uuid::Uuid,
+    notification_type: String,
+    from_user_id: Option<uuid::Uuid>,
+    thought_id: Option<uuid::Uuid>,
+    read: bool,
+    created_at: DateTime<Utc>,
+}
+
+fn row_to_notification(r: NotificationRow) -> Result<Notification, DomainError> {
+    let from_user_id = r
+        .from_user_id
+        .map(UserId::from_uuid)
+        .ok_or_else(|| DomainError::Internal("notification missing from_user_id".into()))?;
+
+    let kind = match r.notification_type.as_str() {
+        "follow" => NotificationKind::Follow { from_user_id },
+        other => {
+            let thought_id = r.thought_id.map(ThoughtId::from_uuid).ok_or_else(|| {
+                DomainError::Internal(format!("notification type '{other}' missing thought_id"))
+            })?;
+            match other {
+                "like" => NotificationKind::Like {
+                    thought_id,
+                    from_user_id,
+                },
+                "boost" => NotificationKind::Boost {
+                    thought_id,
+                    from_user_id,
+                },
+                "reply" => NotificationKind::Reply {
+                    thought_id,
+                    from_user_id,
+                },
+                "mention" => NotificationKind::Mention {
+                    thought_id,
+                    from_user_id,
+                },
+                _ => {
+                    return Err(DomainError::Internal(format!(
+                        "unknown notification type: {other}"
+                    )))
+                }
+            }
+        }
+    };
+
+    Ok(Notification {
+        id: NotificationId::from_uuid(r.id),
+        user_id: UserId::from_uuid(r.user_id),
+        kind,
+        read: r.read,
+        created_at: r.created_at,
+    })
+}
+
 #[async_trait]
 impl NotificationRepository for PgNotificationRepository {
     async fn save(&self, n: &Notification) -> Result<(), DomainError> {
         sqlx::query(
-            "INSERT INTO notifications(id,user_id,type,from_user_id,thought_id,read,created_at) VALUES($1,$2,$3,$4,$5,$6,$7)"
+            "INSERT INTO notifications(id,user_id,notification_type,from_user_id,thought_id,read,created_at)
+             VALUES($1,$2,$3,$4,$5,$6,$7)
+             ON CONFLICT(id) DO NOTHING"
         )
-        .bind(n.id.as_uuid()).bind(n.user_id.as_uuid()).bind(notif_type_as_str(&n.notification_type))
+        .bind(n.id.as_uuid())
-        .bind(n.from_user_id.as_ref().map(|u| u.as_uuid()))
+        .bind(n.user_id.as_uuid())
-        .bind(n.thought_id.as_ref().map(|t| t.as_uuid()))
+        .bind(n.kind.kind_str())
-        .bind(n.read).bind(n.created_at)
+        .bind(n.kind.from_user_id().as_uuid())
-        .execute(&self.pool).await.into_domain().map(|_| ())
+        .bind(n.kind.thought_id().map(|t| t.as_uuid()))
+        .bind(n.read)
+        .bind(n.created_at)
+        .execute(&self.pool)
+        .await
+        .into_domain()
+        .map(|_| ())
     }
 
     async fn list_for_user(
@@ -67,32 +111,14 @@ impl NotificationRepository for PgNotificationRepository {
             .fetch_one(&self.pool)
             .await
             .into_domain()?;
-        #[derive(sqlx::FromRow)]
+        let rows = sqlx::query_as::<_, NotificationRow>(
-        struct Row {
+            "SELECT id,user_id,notification_type,from_user_id,thought_id,read,created_at FROM notifications WHERE user_id=$1 ORDER BY created_at DESC LIMIT $2 OFFSET $3"
-            id: uuid::Uuid,
-            user_id: uuid::Uuid,
-            r#type: String,
-            from_user_id: Option<uuid::Uuid>,
-            thought_id: Option<uuid::Uuid>,
-            read: bool,
-            created_at: DateTime<Utc>,
-        }
-        let rows = sqlx::query_as::<_, Row>(
-            "SELECT id,user_id,type,from_user_id,thought_id,read,created_at FROM notifications WHERE user_id=$1 ORDER BY created_at DESC LIMIT $2 OFFSET $3"
         ).bind(user_id.as_uuid()).bind(page.limit()).bind(page.offset())
         .fetch_all(&self.pool).await.into_domain()?;
         let items = rows
             .into_iter()
-            .map(|r| Notification {
+            .map(row_to_notification)
-                id: NotificationId::from_uuid(r.id),
+            .collect::<Result<Vec<_>, _>>()?;
-                user_id: UserId::from_uuid(r.user_id),
-                notification_type: notif_type_from_str(&r.r#type),
-                from_user_id: r.from_user_id.map(UserId::from_uuid),
-                thought_id: r.thought_id.map(ThoughtId::from_uuid),
-                read: r.read,
-                created_at: r.created_at,
-            })
-            .collect();
         Ok(Paginated {
             items,
             total,
@@ -139,7 +165,7 @@ mod tests {
     use chrono::Utc;
     use domain::ports::UserWriter;
     use domain::{
-        models::{notification::NotificationType, user::User},
+        models::{notification::NotificationKind, user::User},
         value_objects::*,
     };
 
@@ -158,14 +184,15 @@ mod tests {
     #[sqlx::test(migrations = "./migrations")]
     async fn save_and_list(pool: sqlx::PgPool) {
         let user = seed_user(&pool).await;
+        let from_user = seed_user(&pool).await;
         let repo = PgNotificationRepository::new(pool);
         use domain::models::feed::PageParams;
         let n = Notification {
             id: NotificationId::new(),
             user_id: user.id.clone(),
-            notification_type: NotificationType::Like,
+            kind: NotificationKind::Follow {
-            from_user_id: None,
+                from_user_id: from_user.id.clone(),
-            thought_id: None,
+            },
             read: false,
             created_at: Utc::now(),
         };
@@ -187,14 +214,15 @@ mod tests {
     #[sqlx::test(migrations = "./migrations")]
     async fn mark_all_read(pool: sqlx::PgPool) {
         let user = seed_user(&pool).await;
+        let from_user = seed_user(&pool).await;
         let repo = PgNotificationRepository::new(pool);
         use domain::models::feed::PageParams;
         let n = Notification {
             id: NotificationId::new(),
             user_id: user.id.clone(),
-            notification_type: NotificationType::Follow,
+            kind: NotificationKind::Follow {
-            from_user_id: None,
+                from_user_id: from_user.id.clone(),
-            thought_id: None,
+            },
             read: false,
             created_at: Utc::now(),
         };

crates/application/src/services/notification_event.rs

@@ -2,9 +2,9 @@ use chrono::Utc;
 use domain::{
     errors::DomainError,
     events::DomainEvent,
-    models::notification::{Notification, NotificationType},
+    models::notification::{Notification, NotificationKind},
     ports::{NotificationRepository, ThoughtRepository},
-    value_objects::{NotificationId, UserId},
+    value_objects::NotificationId,
 };
 use std::sync::Arc;
 
@@ -13,7 +13,10 @@ pub struct NotificationEventService {
     pub notifications: Arc<dyn NotificationRepository>,
 }
 
-fn is_self_action(thought_author: &UserId, actor: &UserId) -> bool {
+fn is_self_action(
+    thought_author: &domain::value_objects::UserId,
+    actor: &domain::value_objects::UserId,
+) -> bool {
     thought_author == actor
 }
 
@@ -36,9 +39,10 @@ impl NotificationEventService {
                     .save(&Notification {
                         id: NotificationId::new(),
                         user_id: thought.user_id,
-                        notification_type: NotificationType::Like,
+                        kind: NotificationKind::Like {
-                        from_user_id: Some(user_id.clone()),
+                            thought_id: thought_id.clone(),
-                        thought_id: Some(thought_id.clone()),
+                            from_user_id: user_id.clone(),
+                        },
                         read: false,
                         created_at: Utc::now(),
                     })
@@ -60,9 +64,10 @@ impl NotificationEventService {
                     .save(&Notification {
                         id: NotificationId::new(),
                         user_id: thought.user_id,
-                        notification_type: NotificationType::Boost,
+                        kind: NotificationKind::Boost {
-                        from_user_id: Some(user_id.clone()),
+                            thought_id: thought_id.clone(),
-                        thought_id: Some(thought_id.clone()),
+                            from_user_id: user_id.clone(),
+                        },
                         read: false,
                         created_at: Utc::now(),
                     })
@@ -76,9 +81,9 @@ impl NotificationEventService {
                     .save(&Notification {
                         id: NotificationId::new(),
                         user_id: following_id.clone(),
-                        notification_type: NotificationType::Follow,
+                        kind: NotificationKind::Follow {
-                        from_user_id: Some(follower_id.clone()),
+                            from_user_id: follower_id.clone(),
-                        thought_id: None,
+                        },
                         read: false,
                         created_at: Utc::now(),
                     })
@@ -104,9 +109,10 @@ impl NotificationEventService {
                     .save(&Notification {
                         id: NotificationId::new(),
                         user_id: original.user_id,
-                        notification_type: NotificationType::Reply,
+                        kind: NotificationKind::Reply {
-                        from_user_id: Some(user_id.clone()),
+                            thought_id: thought_id.clone(),
-                        thought_id: Some(thought_id.clone()),
+                            from_user_id: user_id.clone(),
+                        },
                         read: false,
                         created_at: Utc::now(),
                     })
@@ -121,9 +127,10 @@ impl NotificationEventService {
                     .save(&Notification {
                         id: NotificationId::new(),
                         user_id: mentioned_user_id.clone(),
-                        notification_type: NotificationType::Mention,
+                        kind: NotificationKind::Mention {
-                        from_user_id: Some(author_user_id.clone()),
+                            thought_id: thought_id.clone(),
-                        thought_id: Some(thought_id.clone()),
+                            from_user_id: author_user_id.clone(),
+                        },
                         read: false,
                         created_at: Utc::now(),
                     })
@@ -139,6 +146,7 @@ mod tests {
     use super::*;
     use domain::{
         models::{
+            notification::NotificationKind,
             thought::{Thought, Visibility},
             user::User,
         },
@@ -184,10 +192,7 @@ mod tests {
         .unwrap();
         let notifs = store.notifications.lock().unwrap();
         assert_eq!(notifs.len(), 1);
-        assert!(matches!(
+        assert!(matches!(notifs[0].kind, NotificationKind::Like { .. }));
-            notifs[0].notification_type,
-            NotificationType::Like
-        ));
     }
 
     #[tokio::test]
@@ -235,10 +240,7 @@ mod tests {
         .unwrap();
         let notifs = store.notifications.lock().unwrap();
         assert_eq!(notifs.len(), 1);
-        assert!(matches!(
+        assert!(matches!(notifs[0].kind, NotificationKind::Follow { .. }));
-            notifs[0].notification_type,
-            NotificationType::Follow
-        ));
     }
 
     #[tokio::test]
@@ -269,10 +271,7 @@ mod tests {
         .unwrap();
         let notifs = store.notifications.lock().unwrap();
         assert_eq!(notifs.len(), 1);
-        assert!(matches!(
+        assert!(matches!(notifs[0].kind, NotificationKind::Reply { .. }));
-            notifs[0].notification_type,
-            NotificationType::Reply
-        ));
     }
 
     #[tokio::test]

crates/domain/src/models/notification.rs

@@ -1,22 +1,66 @@
 use crate::value_objects::{NotificationId, ThoughtId, UserId};
 use chrono::{DateTime, Utc};
 
-#[derive(Debug, Clone, PartialEq, Eq)]
+#[derive(Debug, Clone, PartialEq)]
-pub enum NotificationType {
+pub enum NotificationKind {
-    Like,
+    Like {
-    Boost,
+        thought_id: ThoughtId,
-    Follow,
+        from_user_id: UserId,
-    Mention,
+    },
-    Reply,
+    Boost {
+        thought_id: ThoughtId,
+        from_user_id: UserId,
+    },
+    Reply {
+        thought_id: ThoughtId,
+        from_user_id: UserId,
+    },
+    Mention {
+        thought_id: ThoughtId,
+        from_user_id: UserId,
+    },
+    Follow {
+        from_user_id: UserId,
+    },
+}
+
+impl NotificationKind {
+    pub fn from_user_id(&self) -> &UserId {
+        match self {
+            Self::Like { from_user_id, .. } => from_user_id,
+            Self::Boost { from_user_id, .. } => from_user_id,
+            Self::Reply { from_user_id, .. } => from_user_id,
+            Self::Mention { from_user_id, .. } => from_user_id,
+            Self::Follow { from_user_id } => from_user_id,
+        }
+    }
+
+    pub fn thought_id(&self) -> Option<&ThoughtId> {
+        match self {
+            Self::Like { thought_id, .. } => Some(thought_id),
+            Self::Boost { thought_id, .. } => Some(thought_id),
+            Self::Reply { thought_id, .. } => Some(thought_id),
+            Self::Mention { thought_id, .. } => Some(thought_id),
+            Self::Follow { .. } => None,
+        }
+    }
+
+    pub fn kind_str(&self) -> &'static str {
+        match self {
+            Self::Like { .. } => "like",
+            Self::Boost { .. } => "boost",
+            Self::Reply { .. } => "reply",
+            Self::Mention { .. } => "mention",
+            Self::Follow { .. } => "follow",
+        }
+    }
 }
 
 #[derive(Debug, Clone)]
 pub struct Notification {
     pub id: NotificationId,
     pub user_id: UserId,
-    pub notification_type: NotificationType,
+    pub kind: NotificationKind,
-    pub from_user_id: Option<UserId>,
-    pub thought_id: Option<ThoughtId>,
     pub read: bool,
     pub created_at: DateTime<Utc>,
 }