From 2f7c3793c5160ed6eb01f6c677d3b4f1880f6d1d Mon Sep 17 00:00:00 2001
From: Jeremy Wall <jeremy@marzhillstudios.com>
Date: Sun, 12 Nov 2023 18:28:21 -0500
Subject: [PATCH] Add an api for retrieving the id of the element

---
 macros/src/lib.rs             | 20 ++++++++++++++------
 wasm-web-component/src/lib.rs |  6 ++++--
 2 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/macros/src/lib.rs b/macros/src/lib.rs
index 8fc3117..2d00bf5 100644
--- a/macros/src/lib.rs
+++ b/macros/src/lib.rs
@@ -285,21 +285,29 @@ fn expand_template_struct(item_struct: ItemStruct) -> TokenStream {
     );
     let trait_path = expand_crate_ref("wasm-web-component", parse_quote!(TemplateElement));
     let expanded = quote! {
-        use std::sync::Once;
+        use std::sync::OnceLock;
         use web_sys::Node;
-        static #struct_once_name: Once = Once::new();
+        static #struct_once_name: OnceLock<Option<String>> = OnceLock::new();
         #item_struct
         impl #trait_path for #struct_name {}
         impl #struct_name {
-            #[doc = "Defines this HtmlTemplateElement and adds it to the document exactly once. Subsequent calls are noops."]
-            pub fn define_once() { // TODO(jwall): Should this return the element?
-                #struct_once_name.call_once(|| {
+            #[doc = "Defines this HtmlTemplateElement and adds it to the document exactly once. Subsequent calls are noops. Returns the the template element id it exists on the template element."]
+            pub fn define_once() -> Option<&'static Option<String>> {
+                #struct_once_name.get_or_init(|| {
                     let template_element = Self::render();
+                    let id: Option<String> = template_element.get_attribute("id");
                     let body = web_sys::window().expect("Failed to get window")
                         .document().expect("Failed to get window document").
                         body().expect("Failed to get document body");
                     body.append_child(template_element.as_ref()).expect("Failed to add template element to document");
-                })
+                    return id;
+                });
+                return #struct_once_name.get();
+            }
+            
+            #[doc = "Returns the the template element id it exists. None if the element has not been defined yet. Some(&None) if the element has no id. Some(&Some(id)) if the element has an id."]
+            pub fn get_id() -> Option<&'static Option<String>> {
+                return #struct_once_name.get();
             }
         }
     };
diff --git a/wasm-web-component/src/lib.rs b/wasm-web-component/src/lib.rs
index a314121..e108181 100644
--- a/wasm-web-component/src/lib.rs
+++ b/wasm-web-component/src/lib.rs
@@ -334,13 +334,15 @@ mod tests {
                     .unwrap()
                     .into();
                 let el: HtmlTemplateElement = val.into();
-                el
+                el.set_attribute("id", "template-id").unwrap();
+                return el;
             }
         }
 
         let body = window().unwrap().document().unwrap().body().unwrap();
         assert!(!body.last_child().unwrap().has_type::<HtmlTemplateElement>());
-        MyTemplate::define_once();
+        let id = MyTemplate::define_once();
+        assert_eq!(id.unwrap(), &Some(String::from("template-id")));
         assert!(body.last_child().unwrap().has_type::<HtmlTemplateElement>());
     }
 }