Add initial vim mode mode switching

Co-authored-by: Nathan Sobo <nathan@zed.dev>

crates/vim/src/vim.rs

@@ -0,0 +1,98 @@
+mod editor_events;
+mod editor_utils;
+mod insert;
+mod mode;
+mod normal;
+#[cfg(test)]
+mod vim_tests;
+
+use collections::HashMap;
+use editor::Editor;
+use editor_utils::VimEditorExt;
+use gpui::{action, MutableAppContext, ViewContext, WeakViewHandle};
+
+use mode::Mode;
+use workspace::{self, Settings, Workspace};
+
+action!(SwitchMode, Mode);
+
+pub fn init(cx: &mut MutableAppContext) {
+    editor_events::init(cx);
+    insert::init(cx);
+    normal::init(cx);
+
+    cx.add_action(|_: &mut Workspace, action: &SwitchMode, cx| VimState::switch_mode(action, cx));
+
+    cx.observe_global::<Settings, _>(VimState::settings_changed)
+        .detach();
+}
+
+#[derive(Default)]
+pub struct VimState {
+    editors: HashMap<usize, WeakViewHandle<Editor>>,
+    active_editor: Option<WeakViewHandle<Editor>>,
+
+    enabled: bool,
+    mode: Mode,
+}
+
+impl VimState {
+    fn update_active_editor<S>(
+        cx: &mut MutableAppContext,
+        update: impl FnOnce(&mut Editor, &mut ViewContext<Editor>) -> S,
+    ) -> Option<S> {
+        cx.global::<Self>()
+            .active_editor
+            .clone()
+            .and_then(|ae| ae.upgrade(cx))
+            .map(|ae| ae.update(cx, update))
+    }
+
+    fn switch_mode(SwitchMode(mode): &SwitchMode, cx: &mut MutableAppContext) {
+        let active_editor = cx.update_default_global(|this: &mut Self, _| {
+            this.mode = *mode;
+            this.active_editor.clone()
+        });
+
+        if let Some(active_editor) = active_editor.and_then(|e| e.upgrade(cx)) {
+            active_editor.update(cx, |active_editor, cx| {
+                active_editor.set_keymap_context_layer::<Self>(mode.keymap_context_layer());
+                active_editor.set_input_enabled(*mode == Mode::Insert);
+                if *mode != Mode::Insert {
+                    active_editor.adjust_selections(cx);
+                }
+            });
+        }
+        VimState::update_cursor_shapes(cx);
+    }
+
+    fn settings_changed(cx: &mut MutableAppContext) {
+        cx.update_default_global(|this: &mut Self, cx| {
+            let settings = cx.global::<Settings>();
+            if this.enabled != settings.vim_mode {
+                this.enabled = settings.vim_mode;
+                this.mode = if settings.vim_mode {
+                    Mode::Normal
+                } else {
+                    Mode::Insert
+                };
+                Self::update_cursor_shapes(cx);
+            }
+        });
+    }
+
+    fn update_cursor_shapes(cx: &mut MutableAppContext) {
+        cx.defer(move |cx| {
+            cx.update_default_global(|this: &mut VimState, cx| {
+                let cursor_shape = this.mode.cursor_shape();
+                for editor in this.editors.values() {
+                    if let Some(editor) = editor.upgrade(cx) {
+                        editor.update(cx, |editor, cx| {
+                            editor.set_cursor_shape(cursor_shape, cx);
+                        });
+                    }
+                }
+            });
+        });
+    }
+}