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

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)]
-pub enum NotificationType {
-    Like,
-    Boost,
-    Follow,
-    Mention,
-    Reply,
+#[derive(Debug, Clone, PartialEq)]
+pub enum NotificationKind {
+    Like {
+        thought_id: ThoughtId,
+        from_user_id: UserId,
+    },
+    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 from_user_id: Option<UserId>,
-    pub thought_id: Option<ThoughtId>,
+    pub kind: NotificationKind,
     pub read: bool,
     pub created_at: DateTime<Utc>,
 }