Bridge pot currency swap implementation

crates/bridge-pot-currency-swap/Cargo.toml

@@ -0,0 +1,15 @@
+[package]
+name = "bridge-pot-currency-swap"
+version = "0.1.0"
+edition = "2021"
+publish = false
+
+[dependencies]
+primitives-currency-swap = { version = "0.1", path = "../primitives-currency-swap", default-features = false }
+
+frame-support = { default-features = false, git = "https://github.com/humanode-network/substrate", branch = "locked/polkadot-v0.9.38" }
+
+[features]
+default = ["std"]
+std = ["frame-support/std", "primitives-currency-swap/std"]
+try-runtime = ["frame-support/try-runtime", "primitives-currency-swap/try-runtime"]

crates/bridge-pot-currency-swap/src/existence_optional.rs

@@ -0,0 +1,37 @@
+//! An implementation that does not require pot account existence and can potentially kill the
+//! pot account by withdrawing all the funds from it.
+
+use frame_support::{
+    sp_runtime::{traits::Convert, DispatchError},
+    traits::{Currency, ExistenceRequirement, Get, Imbalance, WithdrawReasons},
+};
+
+use super::{Config, CurrencySwap};
+
+/// A marker type for the implementation that does not require pot accounts existence.
+pub enum Marker {}
+
+impl<T: Config> primitives_currency_swap::CurrencySwap<T::AccountIdFrom, T::AccountIdTo>
+    for CurrencySwap<T, Marker>
+{
+    type From = T::CurrencyFrom;
+    type To = T::CurrencyTo;
+    type Error = DispatchError;
+
+    fn swap(
+        imbalance: <Self::From as Currency<T::AccountIdFrom>>::NegativeImbalance,
+    ) -> Result<<Self::To as Currency<T::AccountIdTo>>::NegativeImbalance, Self::Error> {
+        let amount = imbalance.peek();
+
+        T::CurrencyFrom::resolve_creating(&T::PotFrom::get(), imbalance);
+
+        let imbalance = T::CurrencyTo::withdraw(
+            &T::PotTo::get(),
+            T::BalanceCoverter::convert(amount),
+            WithdrawReasons::TRANSFER,
+            ExistenceRequirement::AllowDeath,
+        )?;
+
+        Ok(imbalance)
+    }
+}

crates/bridge-pot-currency-swap/src/existence_required.rs

@@ -0,0 +1,57 @@
+//! An implementation that requires and ensures pot account existence.
+
+use frame_support::{
+    sp_runtime::{traits::Convert, DispatchError},
+    traits::{Currency, ExistenceRequirement, Get, Imbalance, WithdrawReasons},
+};
+
+use super::{Config, CurrencySwap};
+
+/// A marker type for the implementation that requires pot accounts existence.
+pub enum Marker {}
+
+/// An error that can occur while doing the swap operation.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum Error<ImbalanceFrom> {
+    /// Unable to resolve the incoming balance into the corresponding pot.
+    ResolvingIncomingImbalance(ImbalanceFrom),
+    /// Unable to withdraw the outgoing balance from the corresponding pot.
+    IssuingOutgoingImbalance(DispatchError),
+}
+
+impl<T> From<Error<T>> for DispatchError {
+    fn from(value: Error<T>) -> Self {
+        match value {
+            Error::ResolvingIncomingImbalance(_) => DispatchError::NoProviders,
+            Error::IssuingOutgoingImbalance(err) => err,
+        }
+    }
+}
+
+impl<T: Config> primitives_currency_swap::CurrencySwap<T::AccountIdFrom, T::AccountIdTo>
+    for CurrencySwap<T, Marker>
+{
+    type From = T::CurrencyFrom;
+    type To = T::CurrencyTo;
+    type Error =
+        Error<<<T as Config>::CurrencyFrom as Currency<T::AccountIdFrom>>::NegativeImbalance>;
+
+    fn swap(
+        imbalance: <Self::From as Currency<T::AccountIdFrom>>::NegativeImbalance,
+    ) -> Result<<Self::To as Currency<T::AccountIdTo>>::NegativeImbalance, Self::Error> {
+        let amount = imbalance.peek();
+
+        T::CurrencyFrom::resolve_into_existing(&T::PotFrom::get(), imbalance)
+            .map_err(Error::ResolvingIncomingImbalance)?;
+
+        let imbalance = T::CurrencyTo::withdraw(
+            &T::PotTo::get(),
+            T::BalanceCoverter::convert(amount),
+            WithdrawReasons::TRANSFER,
+            ExistenceRequirement::KeepAlive,
+        )
+        .map_err(Error::IssuingOutgoingImbalance)?;
+
+        Ok(imbalance)
+    }
+}

crates/bridge-pot-currency-swap/src/lib.rs

@@ -0,0 +1,48 @@
+//! Bridge pot currency swap implementation.
+
+// Either generate code at stadard mode, or `no_std`, based on the `std` feature presence.
+#![cfg_attr(not(feature = "std"), no_std)]
+
+use frame_support::{
+    sp_runtime::traits::Convert,
+    sp_std::marker::PhantomData,
+    traits::{Currency, Get},
+};
+
+pub mod existence_optional;
+pub mod existence_required;
+
+pub use existence_optional::Marker as ExistenceOptional;
+pub use existence_required::Marker as ExistenceRequired;
+
+/// The config for the generic bridge pot currency swap logic.
+pub trait Config {
+    /// The type representing the account key for the currency to swap from.
+    type AccountIdFrom;
+
+    /// The type representing the account key for the currency to swap to.
+    type AccountIdTo;
+
+    /// The currency to swap from.
+    type CurrencyFrom: Currency<Self::AccountIdFrom>;
+
+    /// The currency to swap to.
+    type CurrencyTo: Currency<Self::AccountIdTo>;
+
+    /// The converter to determine how the balance amount should be converted from one currency to
+    /// another.
+    type BalanceCoverter: Convert<
+        <Self::CurrencyFrom as Currency<Self::AccountIdFrom>>::Balance,
+        <Self::CurrencyTo as Currency<Self::AccountIdTo>>::Balance,
+    >;
+
+    /// The account to land the balances to when receiving the funds as part of the swap operation.
+    type PotFrom: Get<Self::AccountIdFrom>;
+
+    /// The account to take the balances from when sending the funds as part of the swap operation.
+    type PotTo: Get<Self::AccountIdTo>;
+}
+
+/// A [`primitives_currency_swap::CurrencySwap`] implementation that does the swap using two
+/// "pot" accounts for each of end swapped currencies.
+pub struct CurrencySwap<T: Config, ExistenceRequirement>(PhantomData<(T, ExistenceRequirement)>);