// Copyright 2015-2020 Parity Technologies (UK) Ltd.
// This file is part of Open Ethereum.

// Open Ethereum is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// Open Ethereum is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with Open Ethereum.  If not, see <http://www.gnu.org/licenses/>.

//! Defines the `ClientIoMessage` type, used pervasively throughout various parts of the project to
//! communicate between each other.

use std::fmt;
use bytes::Bytes;
use ethereum_types::H256;
use crate::snapshot::ManifestData;

/// Message type for external and internal events
#[derive(Debug)]
pub enum ClientIoMessage<C> {
	/// Best Block Hash in chain has been changed
	NewChainHead,
	/// A block is ready
	BlockVerified,
	/// Begin snapshot restoration
	BeginRestoration(ManifestData),
	/// Feed a state chunk to the snapshot service
	FeedStateChunk(H256, Bytes),
	/// Feed a block chunk to the snapshot service
	FeedBlockChunk(H256, Bytes),
	/// Take a snapshot for the block with given number.
	TakeSnapshot(u64),
	/// Execute wrapped Fn closure
	Execute(Callback<C>),
}

impl<C> ClientIoMessage<C> {
	/// Create new `ClientIoMessage` that can execute the wrapped Fn closure.
	pub fn execute<F: Fn(&C) + Send + Sync + 'static>(fun: F) -> Self {
		ClientIoMessage::Execute(Callback(Box::new(fun)))
	}
}

/// A wrapper around an Fn closure to invoke in the client thread.
pub struct Callback<C>(pub Box<dyn Fn(&C) + Send + Sync>);

impl<C> fmt::Debug for Callback<C> {
	fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
		write!(fmt, "<callback>")
	}
}
