[CLI] Remove some macros

Refactor the implementations for the following CLI methods in order to
avoid using macros:
- init_bridge
- relay_headers
- relay_parachains

Signed-off-by: Serban Iorga <serban@parity.io>

bridges/relays/bin-substrate/src/cli/bridge.rs

@@ -14,7 +14,10 @@
 // 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/>.
 
+use crate::cli::CliChain;
+use relay_substrate_client::{AccountKeyPairOf, Chain, TransactionSignScheme};
 use strum::{EnumString, EnumVariantNames};
+use substrate_relay_helper::finality::SubstrateFinalitySyncPipeline;
 
 #[derive(Debug, PartialEq, Eq, EnumString, EnumVariantNames)]
 #[strum(serialize_all = "kebab_case")]
@@ -218,3 +221,137 @@ macro_rules! select_full_bridge {
 		}
 	};
 }
+
+/// Minimal bridge representation that can be used from the CLI.
+/// It connects a source chain to a target chain.
+pub trait CliBridgeBase: Sized {
+	/// The source chain.
+	type Source: Chain + CliChain;
+	/// The target chain.
+	type Target: Chain
+		+ TransactionSignScheme<Chain = Self::Target>
+		+ CliChain<KeyPair = AccountKeyPairOf<Self::Target>>;
+}
+
+/// Bridge representation that can be used from the CLI.
+pub trait CliBridge: CliBridgeBase {
+	/// Finality proofs synchronization pipeline.
+	type Finality: SubstrateFinalitySyncPipeline<
+		SourceChain = Self::Source,
+		TargetChain = Self::Target,
+		TransactionSignScheme = Self::Target,
+	>;
+}
+
+//// `Millau` to `Rialto` bridge definition.
+pub struct MillauToRialtoCliBridge {}
+
+impl CliBridgeBase for MillauToRialtoCliBridge {
+	type Source = relay_millau_client::Millau;
+	type Target = relay_rialto_client::Rialto;
+}
+
+impl CliBridge for MillauToRialtoCliBridge {
+	type Finality = crate::chains::millau_headers_to_rialto::MillauFinalityToRialto;
+}
+
+//// `Rialto` to `Millau` bridge definition.
+pub struct RialtoToMillauCliBridge {}
+
+impl CliBridgeBase for RialtoToMillauCliBridge {
+	type Source = relay_rialto_client::Rialto;
+	type Target = relay_millau_client::Millau;
+}
+
+impl CliBridge for RialtoToMillauCliBridge {
+	type Finality = crate::chains::rialto_headers_to_millau::RialtoFinalityToMillau;
+}
+
+//// `Westend` to `Millau` bridge definition.
+pub struct WestendToMillauCliBridge {}
+
+impl CliBridgeBase for WestendToMillauCliBridge {
+	type Source = relay_westend_client::Westend;
+	type Target = relay_millau_client::Millau;
+}
+
+impl CliBridge for WestendToMillauCliBridge {
+	type Finality = crate::chains::westend_headers_to_millau::WestendFinalityToMillau;
+}
+
+//// `Rococo` to `Wococo` bridge definition.
+pub struct RococoToWococoCliBridge {}
+
+impl CliBridgeBase for RococoToWococoCliBridge {
+	type Source = relay_rococo_client::Rococo;
+	type Target = relay_wococo_client::Wococo;
+}
+
+impl CliBridge for RococoToWococoCliBridge {
+	type Finality = crate::chains::rococo_headers_to_wococo::RococoFinalityToWococo;
+}
+
+//// `Wococo` to `Rococo` bridge definition.
+pub struct WococoToRococoCliBridge {}
+
+impl CliBridgeBase for WococoToRococoCliBridge {
+	type Source = relay_wococo_client::Wococo;
+	type Target = relay_rococo_client::Rococo;
+}
+
+impl CliBridge for WococoToRococoCliBridge {
+	type Finality = crate::chains::wococo_headers_to_rococo::WococoFinalityToRococo;
+}
+
+//// `Kusama` to `Polkadot` bridge definition.
+pub struct KusamaToPolkadotCliBridge {}
+
+impl CliBridgeBase for KusamaToPolkadotCliBridge {
+	type Source = relay_kusama_client::Kusama;
+	type Target = relay_polkadot_client::Polkadot;
+}
+
+impl CliBridge for KusamaToPolkadotCliBridge {
+	type Finality = crate::chains::kusama_headers_to_polkadot::KusamaFinalityToPolkadot;
+}
+
+//// `Polkadot` to `Kusama`  bridge definition.
+pub struct PolkadotToKusamaCliBridge {}
+
+impl CliBridgeBase for PolkadotToKusamaCliBridge {
+	type Source = relay_polkadot_client::Polkadot;
+	type Target = relay_kusama_client::Kusama;
+}
+
+impl CliBridge for PolkadotToKusamaCliBridge {
+	type Finality = crate::chains::polkadot_headers_to_kusama::PolkadotFinalityToKusama;
+}
+
+//// `Millau` to `RialtoParachain`  bridge definition.
+pub struct MillauToRialtoParachainCliBridge {}
+
+impl CliBridgeBase for MillauToRialtoParachainCliBridge {
+	type Source = relay_millau_client::Millau;
+	type Target = relay_rialto_parachain_client::RialtoParachain;
+}
+
+impl CliBridge for MillauToRialtoParachainCliBridge {
+	type Finality =
+		crate::chains::millau_headers_to_rialto_parachain::MillauFinalityToRialtoParachain;
+}
+
+//// `RialtoParachain` to `Millau` bridge definition.
+pub struct RialtoParachainToMillauCliBridge {}
+
+impl CliBridgeBase for RialtoParachainToMillauCliBridge {
+	type Source = relay_rialto_parachain_client::RialtoParachain;
+	type Target = relay_millau_client::Millau;
+}
+
+//// `WestendParachain` to `Millau` bridge definition.
+pub struct WestmintToMillauCliBridge {}
+
+impl CliBridgeBase for WestmintToMillauCliBridge {
+	type Source = relay_westend_client::Westmint;
+	type Target = relay_millau_client::Millau;
+}