// Copyright Moonsong Labs

// This file is part of Moonkit.

// Moonkit 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.

// Moonkit 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 Moonkit.  If not, see <http://www.gnu.org/licenses/>.

//! A convenient interface over the digests used in nimbus.

//!

//! Currently Nimbus has two digests;

//! 1. A consensus digest that contains the block author identity

//!    This information is copied from the author inehrent.

//!    This may be replaced with a pre-runtime digest in the future.

//! 2. A seal digest that contains a signature over the rest of the

//!    block including the first digest.

use crate::{NimbusId, NimbusSignature, NIMBUS_ENGINE_ID};

use parity_scale_codec::Encode;

use sp_runtime::generic::DigestItem;

/// A digest item which is usable with aura consensus.

pub trait CompatibleDigestItem: Sized {

	/// Construct a pre-runtime digest from the given AuthorId

	fn nimbus_pre_digest(author: NimbusId) -> Self;

	/// If this item is a nimbus pre-runtime digest, return the author

	fn as_nimbus_pre_digest(&self) -> Option<NimbusId>;

	/// Construct a seal digest item from the given signature

	fn nimbus_seal(signature: NimbusSignature) -> Self;

	/// If this item is a nimbus seal, return the signature.

	fn as_nimbus_seal(&self) -> Option<NimbusSignature>;

	/// This will be deprecated in the future

	/// Construct a consensus digest from the given AuthorId

	fn nimbus_consensus_digest(author: NimbusId) -> Self;

	/// This will be deprecated in the future

	/// If this item is a nimbus consensus digest, return the author

	fn as_nimbus_consensus_digest(&self) -> Option<NimbusId>;

}

impl CompatibleDigestItem for DigestItem {

	// Remove this once deprecated

	// Remove this once deprecated. I don't think it is used anyway.

	// Notice that it calls the pre_runtime helper function.

}