Collect shielded swap sus fees

Author: sug0

crates/sdk/src/args.rs

@@ -9,7 +9,8 @@ use std::time::Duration as StdDuration;
 use either::Either;
 use masp_primitives::transaction::components::sapling::builder::BuildParams;
 use masp_primitives::zip32::PseudoExtendedKey;
-use namada_core::address::Address;
+use namada_core::address::{Address, MASP};
+use namada_core::arith::checked;
 use namada_core::chain::{BlockHeight, ChainId, Epoch};
 use namada_core::collections::HashMap;
 use namada_core::dec::Dec;
@@ -669,6 +670,44 @@ impl TxOsmosisSwap<SdkTypes> {
             return Err(Error::Other("Swap has been cancelled".to_owned()));
         }
 
+        let frontend_sus_fee = 'frontend_sus_fee: {
+            let Some((target, fee_percentage)) = &transfer.frontend_sus_fee
+            else {
+                break 'frontend_sus_fee None;
+            };
+            if !swap_into_znam {
+                break 'frontend_sus_fee None;
+            }
+
+            let fee_receiver = match target {
+                crate::TransferTarget::Address(MASP)
+                | crate::TransferTarget::PaymentAddress(_)
+                | crate::TransferTarget::Ibc(_) => {
+                    return Err(Error::Other(
+                        "Only transparent sus fee receivers are supported in \
+                         Osmosis shielded swaps"
+                            .to_owned(),
+                    ));
+                }
+                crate::TransferTarget::Address(addr) => addr.clone(),
+            };
+            let remaining_amount_percentage =
+                checked!(Dec::one() - *fee_percentage)?;
+            let new_received_amount = tx::compute_raw_masp_frontend_sus_fee(
+                &trade_min_output_amount,
+                &remaining_amount_percentage,
+            )?;
+
+            Some(assert_json_obj(
+                serde_json::to_value(&NamadaMemo {
+                    namada: NamadaMemoData::VoluntaryFees {
+                        new_received_amount,
+                        fee_receiver,
+                    },
+                })
+                .unwrap(),
+            ))
+        };
         let cosmwasm_memo = Memo {
             wasm: Wasm {
                 contract: transfer.receiver.clone(),
@@ -683,7 +722,7 @@ impl TxOsmosisSwap<SdkTypes> {
                             local_recovery_addr,
                         },
                         route,
-                        final_memo: None,
+                        final_memo: frontend_sus_fee,
                     },
                 },
             },

crates/sdk/src/tx.rs

@@ -3631,9 +3631,29 @@ async fn compute_masp_frontend_sus_fee(
     token: &Address,
     force: bool,
 ) -> Result<namada_token::DenominatedAmount> {
-    let sus_fee_amt = namada_token::Amount::from_uint(
-        input_amount
-            .amount()
+    let sus_fee_amt =
+        compute_raw_masp_frontend_sus_fee(&input_amount.amount(), percentage)?;
+
+    // Validate the amount given
+    validate_amount(
+        context,
+        args::InputAmount::Unvalidated(DenominatedAmount::new(
+            sus_fee_amt,
+            input_amount.denom(),
+        )),
+        token,
+        force,
+    )
+    .await
+}
+
+/// Extract the raw amount for the masp frontend sustainability fee
+pub fn compute_raw_masp_frontend_sus_fee(
+    amount: &namada_token::Amount,
+    percentage: &namada_core::dec::Dec,
+) -> Result<namada_token::Amount> {
+    namada_token::Amount::from_uint(
+        amount
             .raw_amount()
             .checked_mul_div(
                 percentage.abs(),
@@ -3647,19 +3667,7 @@ async fn compute_masp_frontend_sus_fee(
             .0,
         0,
     )
-    .map_err(|e| Error::Other(e.to_string()))?;
-
-    // Validate the amount given
-    validate_amount(
-        context,
-        args::InputAmount::Unvalidated(DenominatedAmount::new(
-            sus_fee_amt,
-            input_amount.denom(),
-        )),
-        token,
-        force,
-    )
-    .await
+    .map_err(|e| Error::Other(e.to_string()))
 }
 
 /// Build a shielding transfer