assistant: Add action footer and refine slash command popover (#16360)

- [x] Put the slash command popover on the footer
- [x] Refine the popover (change it to a picker)
- [x] Add more options dropdown on the assistant's toolbar
- [x] Add quote selection button on the footer

---

Release Notes:

- N/A

---------

Co-authored-by: Piotr Osiewicz <24362066+osiewicz@users.noreply.github.com>
Co-authored-by: Nate Butler <iamnbutler@gmail.com>
Co-authored-by: Kirill Bulatov <mail4score@gmail.com>

crates/assistant/src/slash_command_picker.rs

@@ -0,0 +1,201 @@
+use assistant_slash_command::SlashCommandRegistry;
+use gpui::DismissEvent;
+use gpui::WeakView;
+use picker::PickerEditorPosition;
+
+use std::sync::Arc;
+use ui::ListItemSpacing;
+
+use gpui::SharedString;
+use gpui::Task;
+use picker::{Picker, PickerDelegate};
+use ui::{prelude::*, ListItem, PopoverMenu, PopoverMenuHandle, PopoverTrigger};
+
+use crate::assistant_panel::ContextEditor;
+
+#[derive(IntoElement)]
+pub struct SlashCommandSelector<T: PopoverTrigger> {
+    handle: Option<PopoverMenuHandle<Picker<SlashCommandDelegate>>>,
+    registry: Arc<SlashCommandRegistry>,
+    active_context_editor: WeakView<ContextEditor>,
+    trigger: T,
+    info_text: Option<SharedString>,
+}
+
+#[derive(Clone)]
+struct SlashCommandInfo {
+    name: SharedString,
+    description: SharedString,
+}
+
+pub struct SlashCommandDelegate {
+    all_commands: Vec<SlashCommandInfo>,
+    filtered_commands: Vec<SlashCommandInfo>,
+    active_context_editor: WeakView<ContextEditor>,
+    selected_index: usize,
+}
+
+impl<T: PopoverTrigger> SlashCommandSelector<T> {
+    pub fn new(
+        registry: Arc<SlashCommandRegistry>,
+        active_context_editor: WeakView<ContextEditor>,
+        trigger: T,
+    ) -> Self {
+        SlashCommandSelector {
+            handle: None,
+            registry,
+            active_context_editor,
+            trigger,
+            info_text: None,
+        }
+    }
+
+    pub fn with_handle(mut self, handle: PopoverMenuHandle<Picker<SlashCommandDelegate>>) -> Self {
+        self.handle = Some(handle);
+        self
+    }
+
+    pub fn with_info_text(mut self, text: impl Into<SharedString>) -> Self {
+        self.info_text = Some(text.into());
+        self
+    }
+}
+
+impl PickerDelegate for SlashCommandDelegate {
+    type ListItem = ListItem;
+
+    fn match_count(&self) -> usize {
+        self.filtered_commands.len()
+    }
+
+    fn selected_index(&self) -> usize {
+        self.selected_index
+    }
+
+    fn set_selected_index(&mut self, ix: usize, cx: &mut ViewContext<Picker<Self>>) {
+        self.selected_index = ix.min(self.filtered_commands.len().saturating_sub(1));
+        cx.notify();
+    }
+
+    fn placeholder_text(&self, _cx: &mut WindowContext) -> Arc<str> {
+        "Select a command...".into()
+    }
+
+    fn update_matches(&mut self, query: String, cx: &mut ViewContext<Picker<Self>>) -> Task<()> {
+        let all_commands = self.all_commands.clone();
+        cx.spawn(|this, mut cx| async move {
+            let filtered_commands = cx
+                .background_executor()
+                .spawn(async move {
+                    if query.is_empty() {
+                        all_commands
+                    } else {
+                        all_commands
+                            .into_iter()
+                            .filter(|model_info| {
+                                model_info
+                                    .name
+                                    .to_lowercase()
+                                    .contains(&query.to_lowercase())
+                            })
+                            .collect()
+                    }
+                })
+                .await;
+
+            this.update(&mut cx, |this, cx| {
+                this.delegate.filtered_commands = filtered_commands;
+                this.delegate.set_selected_index(0, cx);
+                cx.notify();
+            })
+            .ok();
+        })
+    }
+
+    fn confirm(&mut self, _secondary: bool, cx: &mut ViewContext<Picker<Self>>) {
+        if let Some(command) = self.filtered_commands.get(self.selected_index) {
+            self.active_context_editor
+                .update(cx, |context_editor, cx| {
+                    context_editor.insert_command(&command.name, cx)
+                })
+                .ok();
+            cx.emit(DismissEvent);
+        }
+    }
+
+    fn dismissed(&mut self, _cx: &mut ViewContext<Picker<Self>>) {}
+
+    fn editor_position(&self) -> PickerEditorPosition {
+        PickerEditorPosition::End
+    }
+
+    fn render_match(
+        &self,
+        ix: usize,
+        selected: bool,
+        _: &mut ViewContext<Picker<Self>>,
+    ) -> Option<Self::ListItem> {
+        let command_info = self.filtered_commands.get(ix)?;
+
+        Some(
+            ListItem::new(ix)
+                .inset(true)
+                .spacing(ListItemSpacing::Sparse)
+                .selected(selected)
+                .child(
+                    h_flex().w_full().min_w(px(220.)).child(
+                        v_flex()
+                            .child(
+                                Label::new(format!("/{}", command_info.name))
+                                    .size(LabelSize::Small),
+                            )
+                            .child(
+                                Label::new(command_info.description.clone())
+                                    .size(LabelSize::Small)
+                                    .color(Color::Muted),
+                            ),
+                    ),
+                ),
+        )
+    }
+}
+
+impl<T: PopoverTrigger> RenderOnce for SlashCommandSelector<T> {
+    fn render(self, cx: &mut WindowContext) -> impl IntoElement {
+        let all_models = self
+            .registry
+            .featured_command_names()
+            .into_iter()
+            .filter_map(|command_name| {
+                let command = self.registry.command(&command_name)?;
+                let menu_text = SharedString::from(Arc::from(command.menu_text()));
+                Some(SlashCommandInfo {
+                    name: command_name.into(),
+                    description: menu_text,
+                })
+            })
+            .collect::<Vec<_>>();
+
+        let delegate = SlashCommandDelegate {
+            all_commands: all_models.clone(),
+            active_context_editor: self.active_context_editor.clone(),
+            filtered_commands: all_models,
+            selected_index: 0,
+        };
+
+        let picker_view = cx.new_view(|cx| {
+            let picker = Picker::uniform_list(delegate, cx).max_height(Some(rems(20.).into()));
+            picker
+        });
+
+        PopoverMenu::new("model-switcher")
+            .menu(move |_cx| Some(picker_view.clone()))
+            .trigger(self.trigger)
+            .attach(gpui::AnchorCorner::TopLeft)
+            .anchor(gpui::AnchorCorner::BottomLeft)
+            .offset(gpui::Point {
+                x: px(0.0),
+                y: px(-16.0),
+            })
+    }
+}