use proc_macro::TokenStream;
use quote::quote;
use syn::{parse_macro_input, ItemFn};

extern crate proc_macro;

#[proc_macro]
pub fn plugin(metadata: TokenStream) -> TokenStream {
    emit_plugin_api().into()
}

#[proc_macro_attribute]
pub fn plugin_init(attribute: TokenStream, item: TokenStream) -> TokenStream {
    let input = parse_macro_input!(item as ItemFn);

    let func = input.sig.ident.clone();

    quote! {
        #[doc(hidden)]
        #[no_mangle]
        unsafe extern "C" fn __plugin_init() {
            #func(&mut ::giterated_plugin::local::PluginStackBuilder::new()).unwrap()
        }

        #input
    }
    .into()
}

fn emit_plugin_api() -> impl Into<TokenStream> {
    quote! {
        #[doc(hidden)]
        #[no_mangle]
        unsafe extern "C" fn __load_runtime_vtable(vtable: &'static ::giterated_plugin::abi::vtable::VTable<::giterated_plugin::abi::vtable::runtime::RuntimeHandle>) {
            todo!("runtime vtable insertion is not implemented")
        }

        #[doc(hidden)]
        #[no_mangle]
        unsafe extern "C" fn __get_plugin_vtable() -> &'static ::giterated_plugin::abi::vtable::VTable<::giterated_plugin::abi::vtable::plugin::Plugin> {
            unsafe extern "C" fn plugin_name() -> ::giterated_plugin::abi::FfiSliceRef<str> {
                ::giterated_plugin::abi::FfiSliceRef::static_ref("plugin name")
            }

            unsafe extern "C" fn plugin_version() -> ::giterated_plugin::abi::FfiSliceRef<str> {
                ::giterated_plugin::abi::FfiSliceRef::static_ref("0.0.1")
            }

            unsafe extern "C" fn type_metadata() -> ::giterated_plugin::abi::value_ex::FfiValueRefUntyped {
                todo!()
            }

            static PLUGIN_VTABLE: ::giterated_plugin::abi::vtable::plugin::PluginVTable = ::giterated_plugin::abi::vtable::plugin::PluginVTable {
                plugin_name,
                plugin_version,
                type_metadata
            };

            ::giterated_plugin::abi::vtable::VTable::new(&PLUGIN_VTABLE)
        }
    }
}