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// This file is part of Substrate.

// Copyright (C) 2021-2022 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.

//! Provides functionality to embed a [`RuntimeVersion`](crate::RuntimeVersion) as custom section
//! into a WASM file.

use codec::Encode;
use parity_wasm::elements::{deserialize_buffer, serialize, Module};

#[derive(Clone, Copy, Eq, PartialEq, Debug, thiserror::Error)]
pub enum Error {
	#[error("Deserializing wasm failed")]
	Deserialize,
	#[error("Serializing wasm failed")]
	Serialize,
}

/// Embed the given `version` to the given `wasm` blob.
///
/// If there was already a runtime version embedded, this will be overwritten.
///
/// Returns the new WASM blob.
pub fn embed_runtime_version(
	wasm: &[u8],
	mut version: crate::RuntimeVersion,
) -> Result<Vec<u8>, Error> {
	let mut module: Module = deserialize_buffer(wasm).map_err(|_| Error::Deserialize)?;

	let apis = version
		.apis
		.iter()
		.map(Encode::encode)
		.flat_map(|v| v.into_iter())
		.collect::<Vec<u8>>();

	module.set_custom_section("runtime_apis", apis);

	version.apis.to_mut().clear();
	module.set_custom_section("runtime_version", version.encode());

	serialize(module).map_err(|_| Error::Serialize)
}