code cleanup & multi-channel support

backend/src/messenger/cache.rs

@@ -51,8 +51,8 @@ pub async fn initialise(
 ) -> Result<(), Box<dyn std::error::Error>> {
     let key = format!("messages:{}", channel_id);
 
-    let length: usize = cache.llen(&key).await?;
-    if length < 100 {
+    // less than 100 messages in cache?
+    if cache.llen::<_, i32>(&key).await? < 100 {
         // Fetch from Postgres
         let messages = sqlx::query!(
             "SELECT u.username, u.display_name, u.id, m.content, m.created_at
@@ -68,14 +68,12 @@ pub async fn initialise(
 
         // Populate cache (in reverse order so oldest is at the end)
         for msg in messages.into_iter().rev() {
-            let chat_msg = ChatMsg {
+            let msg_json = serde_json::to_string(&ChatMsg {
                 display_name: Some(msg.display_name.unwrap_or(msg.username)),
                 user_id: msg.id as usize,
                 text: msg.content,
                 timestamp: (msg.created_at.unwrap().unix_timestamp_nanos() / 1_000_000) as usize,
-            };
-
-            let msg_json = serde_json::to_string(&chat_msg)?;
+            })?;
 
             cache.lpush::<_, _, ()>(&key, &msg_json).await?;
         }