// This file is part of Substrate.

// Copyright (C) Parity Technologies (UK) Ltd.
// SPDX-License-Identifier: Apache-2.0

// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// 	http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

use crate::pallet::Def;

///
/// * implement the trait `sp_runtime::BuildStorage`
pub fn expand_genesis_build(def: &mut Def) -> proc_macro2::TokenStream {
	let genesis_config = if let Some(genesis_config) = &def.genesis_config {
		genesis_config
	} else {
		return Default::default()
	};
	let genesis_build = def.genesis_build.as_ref().expect("Checked by def parser");

	let frame_support = &def.frame_support;
	let type_impl_gen = &genesis_config.gen_kind.type_impl_gen(genesis_build.attr_span);
	let gen_cfg_ident = &genesis_config.genesis_config;
	let gen_cfg_use_gen = &genesis_config.gen_kind.type_use_gen(genesis_build.attr_span);

	let where_clause = &genesis_build.where_clause;

	quote::quote_spanned!(genesis_build.attr_span =>
		#[cfg(feature = "std")]
			impl<#type_impl_gen> #frame_support::sp_runtime::BuildStorage for #gen_cfg_ident<#gen_cfg_use_gen> #where_clause
			{
				fn assimilate_storage(&self, storage: &mut #frame_support::sp_runtime::Storage) -> std::result::Result<(), std::string::String> {
					#frame_support::__private::BasicExternalities::execute_with_storage(storage, || {
						self.build();
						Ok(())
					})
				}
			}
	)
}
