Add api for updating searcher with selected component (#3659)

Implements [#182593882](https://www.pivotaltracker.com/story/show/182633582).

Adds API for updating Searcher with the selected suggestion. To-dos are left in the places where this will be implemented in a subsequent PR for the next task.

**Example of the debug output generated by typing into the searcher.**

![ShowSearcherInputLog](https://user-images.githubusercontent.com/1428930/186120851-7292824c-7c6e-444e-8453-5f2d234f3244.png)

**Example of the debug output generated by selecting something in the searcher.**

![ShowSearcherSelectionLog](https://user-images.githubusercontent.com/1428930/186120857-d9610eba-04fd-4e65-bb9e-71ec7bfe361d.png)

# Important Notes
For testing/QA set the `app/gui/src/lib.rs:145` logging initialization to `DEBUG` to see the console output.

[ci no changelog needed]

app/gui/src/controller/searcher.rs

@@ -607,7 +607,7 @@ impl Searcher {
     /// in a new action list (the appropriate notification will be emitted).
     #[profile(Debug)]
     pub fn set_input(&self, new_input: String) -> FallibleResult {
-        debug!(self.logger, "Manually setting input to {new_input}.");
+        tracing::debug!("Manually setting input to {}.", new_input);
         let parsed_input = ParsedInput::new(new_input, self.ide.parser())?;
         let old_expr = self.data.borrow().input.expression.repr();
         let new_expr = parsed_input.expression.repr();
@@ -696,6 +696,18 @@ impl Searcher {
         }
     }
 
+    /// Preview the suggestion in the searcher.
+    pub fn preview_entry_as_suggestion(&self, index: usize) {
+        tracing::debug!("Previewing entry: {:?}", index);
+        //TODO[MM] the actual functionality here will be implemented as part of task #182634050.
+    }
+
+    /// Use action at given index as a suggestion. The exact outcome depends on the action's type.
+    pub fn preview_suggestion(&self, selected_suggestion: action::Suggestion) {
+        //TODO[MM] the actual functionality here will be implemented as part of task #182634050.
+        tracing::debug!("Previewing suggestion: {:?}", selected_suggestion);
+    }
+
     /// Execute given action.
     ///
     /// If the action results in adding new node to the graph, or changing an exiting node, its id
@@ -754,6 +766,20 @@ impl Searcher {
         self.execute_action(action.clone_ref())
     }
 
+    /// Preview the action in the searcher.
+    #[profile(Task)]
+    pub fn preview_action_by_index(&self, index: usize) -> FallibleResult<()> {
+        //TODO[MM] the actual functionality here will be implemented as part of task #182634050.
+        let error = || NoSuchAction { index };
+        let action = {
+            let data = self.data.borrow();
+            let list = data.actions.list().ok_or_else(error)?;
+            list.get_cloned(index).ok_or_else(error)?.action
+        };
+        tracing::debug!("Previewing action: {:?}", action);
+        Ok(())
+    }
+
     /// Check if the first fragment in the input (i.e. the one representing the called function)
     /// is still unmodified.
     ///

app/gui/src/presenter/searcher.rs

@@ -117,6 +117,12 @@ impl Model {
         }
     }
 
+    /// Should be called if an entry is selected but not used yet. Only used for the old searcher
+    /// API.
+    fn entry_selected_as_suggestion(&self, entry_id: view::searcher::entry::Id) {
+        self.controller.preview_entry_as_suggestion(entry_id);
+    }
+
     fn commit_editing(&self, entry_id: Option<view::searcher::entry::Id>) -> Option<AstNodeId> {
         let result = match entry_id {
             Some(id) => self.controller.execute_action_by_index(id),
@@ -132,9 +138,25 @@ impl Model {
         provider::create_providers_from_controller(&self.logger, &self.controller)
     }
 
+    fn suggestion_for_entry_id(&self, id: list_panel::EntryId) -> FallibleResult<Suggestion> {
+        let component: FallibleResult<_> =
+            self.component_by_view_id(id).ok_or_else(|| NoSuchComponent(id).into());
+        Ok(match component?.data {
+            component::Data::FromDatabase { entry, .. } =>
+                Suggestion::FromDatabase(entry.clone_ref()),
+            component::Data::Virtual { snippet } => Suggestion::Hardcoded(snippet.clone_ref()),
+        })
+    }
+
+    /// Should be called if a suggestion is selected but not used yet.
+    fn suggestion_selected(&self, entry_id: list_panel::EntryId) {
+        let suggestion = self.suggestion_for_entry_id(entry_id).unwrap();
+        self.controller.preview_suggestion(suggestion);
+    }
+
     fn suggestion_accepted(
         &self,
-        id: view::component_browser::list_panel::EntryId,
+        id: list_panel::EntryId,
     ) -> Option<(ViewNodeId, node_view::Expression)> {
         let component: FallibleResult<_> =
             self.component_by_view_id(id).ok_or_else(|| NoSuchComponent(id).into());
@@ -321,6 +343,7 @@ impl Searcher {
                     trace documentation.frp.display_documentation;
 
                     eval_ list_view.suggestion_accepted([]analytics::remote_log_event("component_browser::suggestion_accepted"));
+                    eval list_view.suggestion_selected((entry) model.suggestion_selected(*entry));
                 }
             }
             SearcherVariant::OldNodeSearcher(searcher) => {
@@ -333,6 +356,8 @@ impl Searcher {
                     used_as_suggestion <- searcher.used_as_suggestion.filter_map(|entry| *entry);
                     new_input <- used_as_suggestion.filter_map(f!((e) model.entry_used_as_suggestion(*e)));
                     graph.set_node_expression <+ new_input;
+                    eval searcher.selected_entry([model](entry)
+                        if let Some(id) = entry { model.entry_selected_as_suggestion(*id)});
 
                     eval_ searcher.used_as_suggestion([]analytics::remote_log_event("searcher::used_as_suggestion"));
                 }

app/gui/view/component-browser/searcher-list-panel/src/lib.rs

@@ -916,6 +916,8 @@ define_endpoints_2! {
         selected(Option<Selected>),
         suggestion_accepted(EntryId),
         expression_accepted(EntryId),
+        /// The last selected suggestion.
+        suggestion_selected(EntryId),
         header_accepted(GroupId),
         size(Vector2),
     }
@@ -968,7 +970,9 @@ impl component::Frp<Model> for Frp {
             eval_ on_hover ( model.on_hover() );
             eval_ on_hover_end ( model.on_hover_end() );
 
-            output.selected <+ groups.selected.map(|op| op.as_ref().map(Selected::from_wrapper_event));
+            selected <- groups.selected.map(|op| op.as_ref().map(Selected::from_wrapper_event));
+            output.selected <+ selected;
+            output.suggestion_selected <+ selected.map(|selected| selected.and_then(|selected| selected.as_entry_id())).unwrap();
             output.suggestion_accepted <+ groups.suggestion_accepted.map(EntryId::from_wrapper_event);
             output.expression_accepted <+ groups.expression_accepted.map(EntryId::from_wrapper_event);
             output.header_accepted <+ groups.header_accepted;