New Feature: Add server-side channel unreads.

src/routes/channels/channel_ack.rs

@@ -0,0 +1,53 @@
+use crate::notifications::events::ClientboundNotification;
+use crate::util::result::{Error, Result};
+use crate::database::*;
+
+use mongodb::bson::doc;
+use mongodb::options::UpdateOptions;
+
+#[put("/<target>/ack/<message>")]
+pub async fn req(user: User, target: Ref, message: Ref) -> Result<()> {
+    let target = target.fetch_channel().await?;
+
+    let perm = permissions::PermissionCalculator::new(&user)
+        .with_channel(&target)
+        .for_channel()
+        .await?;
+
+    if !perm.get_view() {
+        Err(Error::MissingPermission)?
+    }
+
+    let id = target.id();
+    get_collection("channel_unreads")
+        .update_one(
+            doc! {
+                "_id.channel": id,
+                "_id.user": &user.id
+            },
+            doc! {
+                "$unset": {
+                    "mentions": 1
+                },
+                "$set": {
+                    "last_id": &message.id
+                }
+            },
+            UpdateOptions::builder()
+                .upsert(true)
+                .build()
+        )
+        .await
+        .map_err(|_| Error::DatabaseError {
+            operation: "update_one",
+            with: "channel_unreads",
+        })?;
+    
+    ClientboundNotification::ChannelAck {
+        id: id.to_string(),
+        user: user.id.clone(),
+        message_id: message.id
+    }.publish(user.id);
+    
+    Ok(())
+}

src/routes/channels/mod.rs

@@ -1,5 +1,6 @@
 use rocket::Route;
 
+mod channel_ack;
 mod delete_channel;
 mod edit_channel;
 mod fetch_channel;
@@ -18,6 +19,7 @@ mod message_send;
 
 pub fn routes() -> Vec<Route> {
     routes![
+        channel_ack::req,
         fetch_channel::req,
         fetch_members::req,
         delete_channel::req,