New Feature: Add server-side channel unreads.

src/database/entities/channel.rs

@@ -128,6 +128,20 @@ impl Channel {
                 operation: "delete_many",
                 with: "channel_invites",
             })?;
+        
+        // Delete any unreads.
+        get_collection("channel_unreads")
+            .delete_many(
+                doc! {
+                    "_id.channel": id
+                },
+                None,
+            )
+            .await
+            .map_err(|_| Error::DatabaseError {
+                operation: "delete_many",
+                with: "channel_unreads",
+            })?;
 
         // Check if there are any attachments we need to delete.
         let message_ids = messages

src/database/entities/server.rs

@@ -180,6 +180,8 @@ impl Server {
                 })?;
         }
 
+        // ! FIXME: delete any unreads
+
         for with in &["server_members", "server_bans"] {
             get_collection(with)
                 .delete_many(

src/database/entities/sync.rs

@@ -1,3 +1,19 @@
 use std::collections::HashMap;
+use serde::{Serialize, Deserialize};
 
 pub type UserSettings = HashMap<String, (i64, String)>;
+
+#[derive(Serialize, Deserialize, Debug, Clone)]
+pub struct ChannelCompositeKey {
+    pub channel: String,
+    pub user: String,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone)]
+pub struct ChannelUnread {
+    #[serde(rename = "_id")]
+    pub id: ChannelCompositeKey,
+
+    pub last_id: String,
+    pub mentions: Option<Vec<String>>,
+}

src/database/entities/user.rs

@@ -253,4 +253,23 @@ impl User {
             .flatten()
             .collect::<Vec<String>>())
     }
+
+    /// Utility function to fetch unread objects for user.
+    pub async fn fetch_unreads(&self) -> Result<Vec<Document>> {
+        Ok(get_collection("channel_unreads")
+            .find(
+                doc! {
+                    "_id.user": &self.id
+                },
+                None
+            )
+            .await
+            .map_err(|_| Error::DatabaseError {
+                operation: "find_one",
+                with: "user_settings",
+            })?
+            .filter_map(async move |s| s.ok())
+            .collect::<Vec<Document>>()
+            .await)
+    }
 }