From d0e85b9c79f8d9c46eeaace26fefbecc42e94d23 Mon Sep 17 00:00:00 2001
From: Dmitry Lavrenov <lawrenowdima@gmail.com>
Date: Tue, 16 Apr 2024 14:28:19 +0300
Subject: [PATCH] Improve handling unbalanced funds

---
 crates/humanode-runtime/src/currency_swap.rs |  4 +--
 crates/humanode-runtime/src/lib.rs           |  2 +-
 crates/pallet-pot/src/lib.rs                 | 34 +++++++++++++-------
 3 files changed, 25 insertions(+), 15 deletions(-)

diff --git a/crates/humanode-runtime/src/currency_swap.rs b/crates/humanode-runtime/src/currency_swap.rs
index 8298a6f9b..bef19cd33 100644
--- a/crates/humanode-runtime/src/currency_swap.rs
+++ b/crates/humanode-runtime/src/currency_swap.rs
@@ -51,12 +51,12 @@ impl primitives_currency_swap_proxy::Config for EvmToNativeProxyConfig {
 
 pub type FeesPotProxy = primitives_currency_swap_proxy::SwapUnbalanced<
     EvmToNativeProxyConfig,
-    FeesPot,
+    pallet_pot::DepositUnbalancedCurrency<Self, FeesPot>,
     EvmToNativeSwapBridgePot,
 >;
 
 pub type TreasuryPotProxy = primitives_currency_swap_proxy::SwapUnbalanced<
     EvmToNativeProxyConfig,
-    TreasuryPot,
+    pallet_pot::DepositUnbalancedCurrency<Self, TreasuryPot>,
     EvmToNativeSwapBridgePot,
 >;
diff --git a/crates/humanode-runtime/src/lib.rs b/crates/humanode-runtime/src/lib.rs
index 97718fc8f..0b4f1f278 100644
--- a/crates/humanode-runtime/src/lib.rs
+++ b/crates/humanode-runtime/src/lib.rs
@@ -443,7 +443,7 @@ impl pallet_balances::Config for Runtime {
     type ReserveIdentifier = [u8; 8];
     /// The type for recording an account's balance.
     type Balance = Balance;
-    type DustRemoval = pallet_pot::OnUnbalancedOverCredit<Self, PotInstanceTreasury>;
+    type DustRemoval = pallet_pot::DepositUnbalancedFungible<Self, PotInstanceTreasury>;
     type ExistentialDeposit = ConstU128<500>;
     type AccountStore = System;
     type MaxLocks = ConstU32<50>;
diff --git a/crates/pallet-pot/src/lib.rs b/crates/pallet-pot/src/lib.rs
index d309be84e..07a10950e 100644
--- a/crates/pallet-pot/src/lib.rs
+++ b/crates/pallet-pot/src/lib.rs
@@ -5,11 +5,14 @@
 
 #![cfg_attr(not(feature = "std"), no_std)]
 
-use frame_support::traits::{
-    fungible::{Balanced, Credit, Inspect},
-    Imbalance, OnUnbalanced, StorageVersion,
+use frame_support::{
+    pallet_prelude::*,
+    traits::{
+        fungible::{Balanced, Credit, Inspect},
+        Currency, Imbalance, OnUnbalanced, StorageVersion,
+    },
+    PalletId,
 };
-use frame_support::{pallet_prelude::*, traits::Currency, PalletId};
 use frame_system::pallet_prelude::*;
 use sp_runtime::traits::{AccountIdConversion, CheckedSub, MaybeDisplay, Saturating};
 
@@ -197,30 +200,37 @@ impl<T: Config<I>, I: 'static> Pallet<T, I> {
     }
 }
 
-impl<T: Config<I>, I: 'static> OnUnbalanced<NegativeImbalanceOf<T, I>> for Pallet<T, I> {
+/// Handle unbalanced funds by depositing them into this pot.
+///
+/// Implementation for [`Currency`].
+pub struct DepositUnbalancedCurrency<T, I>(PhantomData<(T, I)>);
+
+impl<T: Config<I>, I: 'static> OnUnbalanced<NegativeImbalanceOf<T, I>>
+    for DepositUnbalancedCurrency<T, I>
+{
     fn on_nonzero_unbalanced(amount: NegativeImbalanceOf<T, I>) {
         let numeric_amount = amount.peek();
 
         // Must resolve into existing but better to be safe.
-        T::Currency::resolve_creating(&Self::account_id(), amount);
+        T::Currency::resolve_creating(&Pallet::<T, I>::account_id(), amount);
 
-        Self::deposit_event(Event::Deposit {
+        Pallet::<T, I>::deposit_event(Event::Deposit {
             value: numeric_amount,
         });
     }
 }
 
-/// A helper to handle `OnUnbalanced` implementation over `CreditOf`
-/// to avoid conflicting implmentation.
-pub struct OnUnbalancedOverCredit<T, I>(Pallet<T, I>);
+/// Handle unbalanced funds by depositing them into this pot.
+///
+/// Implementation for [`Fungible`].
+pub struct DepositUnbalancedFungible<T, I>(PhantomData<(T, I)>);
 
-impl<T: Config<I>, I: 'static> OnUnbalanced<CreditOf<T, I>> for OnUnbalancedOverCredit<T, I> {
+impl<T: Config<I>, I: 'static> OnUnbalanced<CreditOf<T, I>> for DepositUnbalancedFungible<T, I> {
     fn on_nonzero_unbalanced(amount: CreditOf<T, I>) {
         let numeric_amount = amount.peek();
 
         // Pot account already exists.
         let _ = T::Currency::resolve(&Pallet::<T, I>::account_id(), amount);
-        T::Currency::done_deposit(&Pallet::<T, I>::account_id(), numeric_amount);
 
         Pallet::<T, I>::deposit_event(Event::Deposit {
             value: numeric_amount,