use proc_macro2::TokenStream;
use quote::quote;
use syn::meta::ParseNestedMeta;
use syn::{Item, parse_macro_input};

pub fn specta(
	attr: proc_macro::TokenStream,
	item: proc_macro::TokenStream,
) -> proc_macro::TokenStream {
	let mut attrs = SpectaAttributes::default();
	let parser = syn::meta::parser(|meta| attrs.parse(&meta));
	parse_macro_input!(attr with parser);

	let input = parse_macro_input!(item as Item);

	let specta_rename = attrs.rename.map_or_else(TokenStream::new, |rename| {
		quote! {
			#[cfg_attr(feature = "specta", specta(rename = #rename))]
		}
	});

	let expanded = quote! {
		#[cfg_attr(feature = "specta", derive(specta::Type))]
		#specta_rename
		#input
	};

	expanded.into()
}

#[derive(Default)]
struct SpectaAttributes {
	rename: Option<String>,
}

impl SpectaAttributes {
	fn parse(&mut self, meta: &ParseNestedMeta) -> syn::Result<()> {
		if meta.path.is_ident("rename") {
			self.rename = Some(meta.value()?.to_string());
		}
		Ok(())
	}
}