Implement basic chat functionality

rc_chat_room/src/operations/user_online.rs

@@ -0,0 +1,36 @@
+use crate::SimpleChatFunc;
+use polariton::operation::{ParameterTable, Typed};
+
+const USERNAME_PARAM_KEY: u8 = 22; // str; in & out
+const DISPLAY_NAME_PARAM_KEY: u8 = 30; // str; out
+const CAN_SEND_DM_PARAM_KEY: u8 = 27; // int; out
+
+#[allow(dead_code)]
+#[repr(u8)]
+enum CanSendMessageResult {
+    Ok = 0,
+    UserDoesNotExist = 1,
+    UserOffline = 2,
+}
+
+
+pub(super) fn is_online_provider(chat_system: crate::state::ChatImpl) -> SimpleChatFunc<14, crate::UserTy, impl (Fn(ParameterTable, &crate::UserTy, &crate::state::ChatImpl) -> Result<ParameterTable, i16>) + Sync + Sync> {
+    SimpleChatFunc::new(|params, _: &crate::UserTy, chat_system| {
+        let mut params = params.to_dict();
+        if let Some(Typed::Str(user_name)) = params.get(&USERNAME_PARAM_KEY) {
+            let username = user_name.string.clone();
+            params.insert(DISPLAY_NAME_PARAM_KEY, Typed::Str(username.clone().into()));
+            if chat_system.system().is_user_online(&username) {
+                params.insert(CAN_SEND_DM_PARAM_KEY, Typed::Int(CanSendMessageResult::Ok as _));
+                Ok(params.into())
+            } else {
+                log::debug!("User {} is not online", username);
+                params.insert(CAN_SEND_DM_PARAM_KEY, Typed::Int(CanSendMessageResult::UserOffline as _));
+                //params.insert(CAN_SEND_DM_PARAM_KEY, Typed::Int(CanSendMessageResult::Ok as _));
+                Ok(params.into())
+            }
+        } else {
+            Err(rc_core::data::error_codes::ChatErrorCodes::UnexpectedError as _)
+        }
+    }, chat_system)
+}