[Bridge] Add polkadot parachain pot (#917)

cstrml/bridge-transfer/src/lib.rs

@@ -124,6 +124,28 @@ decl_module! {
 			<bridge::Module<T>>::transfer_fungible(dest_id, T::BridgeTokenId::get(), recipient, U256::from(amount.saturating_sub(fee).saturated_into::<u128>()))
 		}
 
+		/// Transfers some amount of the native token to some recipient on a (whitelisted) destination chain.
+		#[weight = 195_000_000]
+		pub fn transfer_to_polkadot_parachain(origin, amount: BalanceOf<T>, recipient: Vec<u8>) -> DispatchResult {
+			let source = ensure_signed(origin)?;
+			// Set polkadot parachain chain id to 101
+			let dest_id = 101u8;
+			ensure!(<bridge::Module<T>>::chain_whitelisted(dest_id), Error::<T>::InvalidTransfer);
+			let polkadot_parachain_pot = <bridge::Module<T>>::polkadot_parachain_pot();
+			ensure!(BridgeFee::<T>::contains_key(&dest_id), Error::<T>::FeeOptionsMissiing);
+			let (min_fee, fee_scale) = Self::bridge_fee(dest_id);
+			let fee_estimated = amount * fee_scale.into() / 1000u32.into();
+			let fee = if fee_estimated > min_fee {
+				fee_estimated
+			} else {
+				min_fee
+			};
+			ensure!(amount > fee, Error::<T>::LessThanFee);
+			T::Currency::transfer(&source, &polkadot_parachain_pot, amount.into(), AllowDeath)?;
+
+			<bridge::Module<T>>::transfer_fungible(dest_id, T::BridgeTokenId::get(), recipient, U256::from(amount.saturating_sub(fee).saturated_into::<u128>()))
+		}
+
 		//
 		// Executable calls. These can be triggered by a bridge transfer initiated on another chain
 		//
@@ -144,5 +166,14 @@ decl_module! {
 			<T as Config>::Currency::transfer(&elrond_pot, &to, amount.into(), AllowDeath)?;
 			Ok(())
 		}
+
+		/// Executes a simple currency transfer using the bridge account as the source
+		#[weight = 195_000_000]
+		pub fn transfer_from_polkadot_parachain(origin, to: T::AccountId, amount: BalanceOf<T>, _rid: [u8; 32]) -> DispatchResult {
+			let _ = T::BridgeOrigin::ensure_origin(origin)?;
+			let polkadot_parachain_pot = <bridge::Module<T>>::polkadot_parachain_pot();
+			<T as Config>::Currency::transfer(&polkadot_parachain_pot, &to, amount.into(), AllowDeath)?;
+			Ok(())
+		}
 	}
 }

cstrml/bridge/src/lib.rs

@@ -30,6 +30,7 @@ mod tests;
 const DEFAULT_RELAYER_THRESHOLD: u32 = 1;
 const MODULE_ID: ModuleId = ModuleId(*b"crust/bg");
 const ELROND_ID: ModuleId = ModuleId(*b"elrondbg");
+const PARACHAIN_ID: ModuleId = ModuleId(*b"parac/bg");
 
 
 /// Helper function to concatenate a chain ID and some bytes to produce a resource ID.
@@ -214,6 +215,7 @@ decl_module! {
 		const ProposalLifetime: T::BlockNumber = T::ProposalLifetime::get();
 		const BridgeAccountId: T::AccountId = MODULE_ID.into_account();
 		const ElrondAccountId: T::AccountId = ELROND_ID.into_account();
+		const PolkadotParachainAccountId: T::AccountId = PARACHAIN_ID.into_account();
 
 		fn deposit_event() = default;
 
@@ -358,6 +360,11 @@ impl<T: Config> Module<T> {
 		ELROND_ID.into_account()
 	}
 
+	/// Provides an AccountId for the pallet to store polkadot parachain bridge.
+	pub fn polkadot_parachain_pot() -> T::AccountId {
+		PARACHAIN_ID.into_account()
+	}
+
 	/// Asserts if a resource is registered
 	pub fn resource_exists(id: [u8; 32]) -> bool {
 		return Self::resources(id) != None;