Asset Conversion: Pool Account ID derivation with additional Pallet ID seed (#3250)

Introduce `PalletId` as an additional seed parameter for pool's account
id derivation.

The PR also introduces the `pallet_asset_conversion_ops` pallet with a
call to migrate a given pool to thew new account. Additionally
`fungibles::lifetime::ResetTeam` and `fungible::lifetime::Refund`
traits, to facilitate the migration of pools.

---------

Co-authored-by: command-bot <>

substrate/frame/assets/src/functions.rs

@@ -368,11 +368,14 @@ impl<T: Config<I>, I: 'static> Pallet<T, I> {
 		Ok(())
 	}
 
-	/// Returns a `DepositFrom` of an account only if balance is zero.
+	/// Refunds the `DepositFrom` of an account only if its balance is zero.
+	///
+	/// If the `maybe_check_caller` parameter is specified, it must match the account that provided
+	/// the deposit or must be the admin of the asset.
 	pub(super) fn do_refund_other(
 		id: T::AssetId,
 		who: &T::AccountId,
-		caller: &T::AccountId,
+		maybe_check_caller: Option<T::AccountId>,
 	) -> DispatchResult {
 		let mut account = Account::<T, I>::get(&id, &who).ok_or(Error::<T, I>::NoDeposit)?;
 		let (depositor, deposit) =
@@ -380,7 +383,9 @@ impl<T: Config<I>, I: 'static> Pallet<T, I> {
 		let mut details = Asset::<T, I>::get(&id).ok_or(Error::<T, I>::Unknown)?;
 		ensure!(details.status == AssetStatus::Live, Error::<T, I>::AssetNotLive);
 		ensure!(!account.status.is_frozen(), Error::<T, I>::Frozen);
-		ensure!(caller == &depositor || caller == &details.admin, Error::<T, I>::NoPermission);
+		if let Some(caller) = maybe_check_caller {
+			ensure!(caller == depositor || caller == details.admin, Error::<T, I>::NoPermission);
+		}
 		ensure!(account.balance.is_zero(), Error::<T, I>::WouldBurn);
 
 		T::Currency::unreserve(&depositor, deposit);
@@ -1013,4 +1018,28 @@ impl<T: Config<I>, I: 'static> Pallet<T, I> {
 			})
 			.collect::<Vec<_>>()
 	}
+
+	/// Reset the team for the asset with the given `id`.
+	///
+	/// ### Parameters
+	/// - `id`: The identifier of the asset for which the team is being reset.
+	/// - `owner`: The new `owner` account for the asset.
+	/// - `admin`: The new `admin` account for the asset.
+	/// - `issuer`: The new `issuer` account for the asset.
+	/// - `freezer`: The new `freezer` account for the asset.
+	pub(crate) fn do_reset_team(
+		id: T::AssetId,
+		owner: T::AccountId,
+		admin: T::AccountId,
+		issuer: T::AccountId,
+		freezer: T::AccountId,
+	) -> DispatchResult {
+		let mut d = Asset::<T, I>::get(&id).ok_or(Error::<T, I>::Unknown)?;
+		d.owner = owner;
+		d.admin = admin;
+		d.issuer = issuer;
+		d.freezer = freezer;
+		Asset::<T, I>::insert(&id, d);
+		Ok(())
+	}
 }

substrate/frame/assets/src/impl_fungibles.rs

@@ -308,3 +308,35 @@ impl<T: Config<I>, I: 'static> fungibles::InspectEnumerable<T::AccountId> for Pa
 		Asset::<T, I>::iter_keys()
 	}
 }
+
+impl<T: Config<I>, I: 'static> fungibles::roles::ResetTeam<T::AccountId> for Pallet<T, I> {
+	fn reset_team(
+		id: T::AssetId,
+		owner: T::AccountId,
+		admin: T::AccountId,
+		issuer: T::AccountId,
+		freezer: T::AccountId,
+	) -> DispatchResult {
+		Self::do_reset_team(id, owner, admin, issuer, freezer)
+	}
+}
+
+impl<T: Config<I>, I: 'static> fungibles::Refund<T::AccountId> for Pallet<T, I> {
+	type AssetId = T::AssetId;
+	type Balance = DepositBalanceOf<T, I>;
+	fn deposit_held(id: Self::AssetId, who: T::AccountId) -> Option<(T::AccountId, Self::Balance)> {
+		use ExistenceReason::*;
+		match Account::<T, I>::get(&id, &who).ok_or(Error::<T, I>::NoDeposit).ok()?.reason {
+			DepositHeld(b) => Some((who, b)),
+			DepositFrom(d, b) => Some((d, b)),
+			_ => None,
+		}
+	}
+	fn refund(id: Self::AssetId, who: T::AccountId) -> DispatchResult {
+		match Self::deposit_held(id.clone(), who.clone()) {
+			Some((d, _)) if d == who => Self::do_refund(id, who, false),
+			Some(..) => Self::do_refund_other(id, &who, None),
+			None => Err(Error::<T, I>::NoDeposit.into()),
+		}
+	}
+}

substrate/frame/assets/src/lib.rs

@@ -1644,7 +1644,7 @@ pub mod pallet {
 			let origin = ensure_signed(origin)?;
 			let who = T::Lookup::lookup(who)?;
 			let id: T::AssetId = id.into();
-			Self::do_refund_other(id, &who, &origin)
+			Self::do_refund_other(id, &who, Some(origin))
 		}
 
 		/// Disallow further unprivileged transfers of an asset `id` to and from an account `who`.