Add Wococo<>Rococo Header Relayer (#925)

* Add Wococo primitives crate

* Add more Wococo boilerplate code

* Add CLI support for initializing the Wococo<>Rococo bridge

* Add support for relaying headers between Rococo and Wococo

* Fix test

* RustFmt

* Fix compilation issues related to enum naming

* Bump Rococo `spec_version`

* Remove stray Westend references

bridges/relays/bin-substrate/src/chains/rococo_headers_to_wococo.rs

@@ -0,0 +1,60 @@
+// Copyright 2019-2021 Parity Technologies (UK) Ltd.
+// This file is part of Parity Bridges Common.
+
+// Parity Bridges Common 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.
+
+// Parity Bridges Common 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 Parity Bridges Common.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Rococo-to-Wococo headers sync entrypoint.
+
+use crate::finality_pipeline::{SubstrateFinalitySyncPipeline, SubstrateFinalityToSubstrate};
+
+use bp_header_chain::justification::GrandpaJustification;
+use codec::Encode;
+use relay_rococo_client::{Rococo, SyncHeader as RococoSyncHeader};
+use relay_substrate_client::{Chain, TransactionSignScheme};
+use relay_utils::metrics::MetricsParams;
+use relay_wococo_client::{SigningParams as WococoSigningParams, Wococo};
+use sp_core::{Bytes, Pair};
+
+/// Rococo-to-Wococo finality sync pipeline.
+pub(crate) type RococoFinalityToWococo = SubstrateFinalityToSubstrate<Rococo, Wococo, WococoSigningParams>;
+
+impl SubstrateFinalitySyncPipeline for RococoFinalityToWococo {
+	const BEST_FINALIZED_SOURCE_HEADER_ID_AT_TARGET: &'static str = bp_rococo::BEST_FINALIZED_ROCOCO_HEADER_METHOD;
+
+	type TargetChain = Wococo;
+
+	fn customize_metrics(params: MetricsParams) -> anyhow::Result<MetricsParams> {
+		crate::chains::add_polkadot_kusama_price_metrics::<Self>(params)
+	}
+
+	fn transactions_author(&self) -> bp_wococo::AccountId {
+		(*self.target_sign.public().as_array_ref()).into()
+	}
+
+	fn make_submit_finality_proof_transaction(
+		&self,
+		transaction_nonce: <Wococo as Chain>::Index,
+		header: RococoSyncHeader,
+		proof: GrandpaJustification<bp_rococo::Header>,
+	) -> Bytes {
+		let call = bp_wococo::Call::BridgeGrandpaRococo(bp_wococo::BridgeGrandpaRococoCall::submit_finality_proof(
+			header.into_inner(),
+			proof,
+		));
+		let genesis_hash = *self.target_client.genesis_hash();
+		let transaction = Wococo::sign_transaction(genesis_hash, &self.target_sign, transaction_nonce, call);
+
+		Bytes(transaction.encode())
+	}
+}