Avoid duplicate function definitions

Avoid duplicate function definitions for:
- ensure_owner_or_root()
- ensure_not_halted()
- set_owner()
- set_operating_mode() / set_operational()

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

bridges/primitives/runtime/src/lib.rs

@@ -18,11 +18,16 @@
 
 #![cfg_attr(not(feature = "std"), no_std)]
 
-use codec::Encode;
-use frame_support::{RuntimeDebug, StorageHasher};
+use codec::{Decode, Encode, FullCodec};
+use frame_support::{
+	log, pallet_prelude::DispatchResult, PalletError, RuntimeDebug, StorageHasher, StorageValue,
+};
+use frame_system::RawOrigin;
+use scale_info::TypeInfo;
 use sp_core::{hash::H256, storage::StorageKey};
 use sp_io::hashing::blake2_256;
-use sp_std::{convert::TryFrom, vec, vec::Vec};
+use sp_runtime::traits::BadOrigin;
+use sp_std::{convert::TryFrom, fmt::Debug, vec, vec::Vec};
 
 pub use chain::{
 	AccountIdOf, AccountPublicOf, BalanceOf, BlockNumberOf, Chain, EncodedOrDecodedCall, HashOf,
@@ -257,6 +262,79 @@ pub fn storage_value_key(pallet_prefix: &str, value_name: &str) -> StorageKey {
 	StorageKey(final_key)
 }
 
+/// Error generated by the `OwnedBridgeModule` trait.
+#[derive(Encode, Decode, TypeInfo, PalletError)]
+pub enum OwnedBridgeModuleError {
+	/// All pallet operations are halted.
+	Halted,
+}
+
+/// Bridge module that has owner and operating mode
+pub trait OwnedBridgeModule<T: frame_system::Config> {
+	/// The target that will be used when publishing logs related to this module.
+	const LOG_TARGET: &'static str;
+	const OPERATING_MODE_KEY: &'static str;
+
+	type OwnerStorage: StorageValue<T::AccountId, Query = Option<T::AccountId>>;
+	type OperatingMode: Copy + Debug + FullCodec;
+	type OperatingModeStorage: StorageValue<Self::OperatingMode>;
+
+	/// Check if the module is halted.
+	fn is_halted() -> bool;
+
+	/// Ensure that the origin is either root, or `PalletOwner`.
+	fn ensure_owner_or_root(origin: T::Origin) -> Result<(), BadOrigin> {
+		match origin.into() {
+			Ok(RawOrigin::Root) => Ok(()),
+			Ok(RawOrigin::Signed(ref signer))
+				if Self::OwnerStorage::get().as_ref() == Some(signer) =>
+				Ok(()),
+			_ => Err(BadOrigin),
+		}
+	}
+
+	/// Ensure that the module is not halted.
+	fn ensure_not_halted() -> Result<(), OwnedBridgeModuleError> {
+		match Self::is_halted() {
+			true => Err(OwnedBridgeModuleError::Halted),
+			false => Ok(()),
+		}
+	}
+
+	/// Change the owner of the module.
+	fn set_owner(origin: T::Origin, maybe_owner: Option<T::AccountId>) -> DispatchResult {
+		Self::ensure_owner_or_root(origin)?;
+		match maybe_owner {
+			Some(owner) => {
+				Self::OwnerStorage::put(&owner);
+				log::info!(target: Self::LOG_TARGET, "Setting pallet Owner to: {:?}", owner);
+			},
+			None => {
+				Self::OwnerStorage::kill();
+				log::info!(target: Self::LOG_TARGET, "Removed Owner of pallet.");
+			},
+		}
+
+		Ok(())
+	}
+
+	/// Halt or resume all/some module operations.
+	fn set_operating_mode(
+		origin: T::Origin,
+		operating_mode: Self::OperatingMode,
+	) -> DispatchResult {
+		Self::ensure_owner_or_root(origin)?;
+		Self::OperatingModeStorage::put(operating_mode);
+		log::info!(
+			target: Self::LOG_TARGET,
+			"Setting operating mode ( {} = {:?}).",
+			Self::OPERATING_MODE_KEY,
+			operating_mode
+		);
+		Ok(())
+	}
+}
+
 #[cfg(test)]
 mod tests {
 	use super::*;