Refactor mode indicator to remove itself

One of the problems we had is that the status_bar shows a gap between
items, and we want to not add an additional gap for an invisible status
indicator.

crates/vim/src/vim.rs

@@ -118,6 +118,7 @@ pub fn observe_keystrokes(cx: &mut WindowContext) {
 pub struct Vim {
     active_editor: Option<WeakViewHandle<Editor>>,
     editor_subscription: Option<Subscription>,
+    mode_indicator: Option<ViewHandle<ModeIndicator>>,
 
     enabled: bool,
     state: VimState,
@@ -177,6 +178,10 @@ impl Vim {
         self.state.mode = mode;
         self.state.operator_stack.clear();
 
+        if let Some(mode_indicator) = &self.mode_indicator {
+            mode_indicator.update(cx, |mode_indicator, cx| mode_indicator.set_mode(mode, cx))
+        }
+
         // Sync editor settings like clip mode
         self.sync_vim_settings(cx);
 
@@ -259,6 +264,51 @@ impl Vim {
         }
     }
 
+    fn sync_mode_indicator(cx: &mut AppContext) {
+        cx.spawn(|mut cx| async move {
+            let workspace = match cx.update(|cx| {
+                cx.update_active_window(|cx| {
+                    cx.root_view()
+                        .downcast_ref::<Workspace>()
+                        .map(|workspace| workspace.downgrade())
+                })
+            }) {
+                Some(Some(workspace)) => workspace,
+                _ => {
+                    return Ok(());
+                }
+            };
+
+            workspace.update(&mut cx, |workspace, cx| {
+                Vim::update(cx, |vim, cx| {
+                    workspace.status_bar().update(cx, |status_bar, cx| {
+                        let current_position = status_bar.position_of_item::<ModeIndicator>();
+                        if vim.enabled && current_position.is_none() {
+                            if vim.mode_indicator.is_none() {
+                                vim.mode_indicator =
+                                    Some(cx.add_view(|_| ModeIndicator::new(vim.state.mode)));
+                            };
+                            let mode_indicator = vim.mode_indicator.as_ref().unwrap();
+                            // TODO: would it be better to depend on the diagnostics crate
+                            // so we can pass the type directly?
+                            let position = status_bar.position_of_named_item("DiagnosticIndicator");
+                            if let Some(position) = position {
+                                status_bar.insert_item_after(position, mode_indicator.clone(), cx)
+                            } else {
+                                status_bar.add_left_item(mode_indicator.clone(), cx)
+                            }
+                        } else if !vim.enabled {
+                            if let Some(position) = current_position {
+                                status_bar.remove_item_at(position, cx)
+                            }
+                        }
+                    })
+                })
+            })
+        })
+        .detach_and_log_err(cx);
+    }
+
     fn set_enabled(&mut self, enabled: bool, cx: &mut AppContext) {
         if self.enabled != enabled {
             self.enabled = enabled;
@@ -309,6 +359,8 @@ impl Vim {
                 self.unhook_vim_settings(editor, cx);
             }
         });
+
+        Vim::sync_mode_indicator(cx);
     }
 
     fn unhook_vim_settings(&self, editor: &mut Editor, cx: &mut ViewContext<Editor>) {