use proc_macro::TokenStream;
use quote::quote;
use syn::{parse::Parser, parse_macro_input, DeriveInput};

#[proc_macro_attribute]
pub fn uses_base_template(_attr: TokenStream, item: TokenStream) -> TokenStream {
	let mut input = parse_macro_input!(item as DeriveInput);
	
	let base_template_field = syn::Field::parse_named
		.parse2(
			quote! {
				pub base_template: BaseTemplate
			}
			.into(),
		)
		.unwrap();

	match &mut input.data {
		syn::Data::Struct(ref mut struct_data) => {
			match &mut struct_data.fields {
				syn::Fields::Named(fields) => {
					fields.named.push(base_template_field);
				}
				_ => (),
			}
			return quote! {
				#input
			}
			.into();
		}
		_ => {
			panic!("bad")
		}
	};
}