Flatten back the structure (#837)

* Remove chains.

* Move relay clients.

* Flatten generic.

* Fix fmt.

bridges/relays/client-substrate/src/error.rs

@@ -0,0 +1,81 @@
+// Copyright 2019-2020 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/>.
+
+//! Substrate node RPC errors.
+
+use jsonrpsee_types::error::Error as RpcError;
+use relay_utils::MaybeConnectionError;
+use sc_rpc_api::system::Health;
+
+/// Result type used by Substrate client.
+pub type Result<T> = std::result::Result<T, Error>;
+
+/// Errors that can occur only when interacting with
+/// a Substrate node through RPC.
+#[derive(Debug)]
+pub enum Error {
+	/// An error that can occur when making a request to
+	/// an JSON-RPC server.
+	RpcError(RpcError),
+	/// The response from the server could not be SCALE decoded.
+	ResponseParseFailed(codec::Error),
+	/// The Substrate bridge pallet has not yet been initialized.
+	UninitializedBridgePallet,
+	/// Account does not exist on the chain.
+	AccountDoesNotExist,
+	/// The client we're connected to is not synced, so we can't rely on its state.
+	ClientNotSynced(Health),
+	/// Custom logic error.
+	Custom(String),
+}
+
+impl From<RpcError> for Error {
+	fn from(error: RpcError) -> Self {
+		Error::RpcError(error)
+	}
+}
+
+impl MaybeConnectionError for Error {
+	fn is_connection_error(&self) -> bool {
+		matches!(
+			*self,
+			Error::RpcError(RpcError::TransportError(_))
+				// right now if connection to the ws server is dropped (after it is already established),
+				// we're getting this error
+				| Error::RpcError(RpcError::Internal(_))
+				| Error::ClientNotSynced(_),
+		)
+	}
+}
+
+impl From<Error> for String {
+	fn from(error: Error) -> String {
+		error.to_string()
+	}
+}
+
+impl ToString for Error {
+	fn to_string(&self) -> String {
+		match self {
+			Self::RpcError(e) => e.to_string(),
+			Self::ResponseParseFailed(e) => e.to_string(),
+			Self::UninitializedBridgePallet => "The Substrate bridge pallet has not been initialized yet.".into(),
+			Self::AccountDoesNotExist => "Account does not exist on the chain".into(),
+			Self::ClientNotSynced(health) => format!("Substrate client is not synced: {}", health),
+			Self::Custom(e) => e.clone(),
+		}
+	}
+}