feat: Implement SplitSwapStrategyEncoder

The strategy works as follows:
- Manage approvals needed
- Compute min amount (if check amount is any):
  - if slippage is defined, apply slippage on the expected amount and take the min value between that and the check amount
  - if not, it's just the check amount
- Iterate through the swaps
  - call the corresponding swap encoder to encode the swap
  - add swap header (tokens indexes and split)
  - ple encode the swaps
- Add extra inputs (amounts, token addresses, min amount, (un)wrap, number of tokens and receiver)

Misc:
- Move executor address and selector encoding inside the SwapEncoder
- Add default executor_selector to SwapEncoder
- Pass router address inside the SplitSwapStrategyEncoder
- Move Permit2 inside the SplitSwapStrategyEncoder. It is a responsibility and a specificity of the strategy to need permit2 approvals

--- don't change below this line ---
ENG-4081 Took 1 hour 21 minutes

src/encoding/evm/approvals/permit2.rs

@@ -1,13 +1,14 @@
 use std::{str::FromStr, sync::Arc};
 
 use alloy::{
-    primitives::{aliases::U48, Address, Bytes as AlloyBytes, TxKind, U160},
+    primitives::{aliases::U48, Address, Bytes as AlloyBytes, ChainId, TxKind, U160, U256},
     providers::{Provider, RootProvider},
     rpc::types::{TransactionInput, TransactionRequest},
     signers::{local::PrivateKeySigner, SignerSync},
     transports::BoxTransport,
 };
-use alloy_primitives::{ChainId, Signature, U256};
+#[allow(deprecated)]
+use alloy_primitives::Signature;
 use alloy_sol_types::{eip712_domain, sol, SolStruct, SolValue};
 use chrono::Utc;
 use num_bigint::BigUint;
@@ -108,6 +109,7 @@ impl Permit2 {
         }
     }
     /// Creates permit single and signature
+    #[allow(deprecated)]
     pub fn get_permit(
         &self,
         spender: &Bytes,

src/encoding/evm/router_encoder.rs

@@ -1,5 +1,7 @@
 use std::str::FromStr;
 
+use alloy::signers::local::PrivateKeySigner;
+use alloy_primitives::ChainId;
 use num_bigint::BigUint;
 use tycho_core::Bytes;
 
@@ -9,37 +11,48 @@ use crate::encoding::{
     models::{NativeAction, Solution, Transaction},
     router_encoder::RouterEncoder,
     strategy_encoder::StrategySelector,
-    user_approvals_manager::{Approval, UserApprovalsManager},
 };
 
 #[allow(dead_code)]
-pub struct EVMRouterEncoder<S: StrategySelector, A: UserApprovalsManager> {
+pub struct EVMRouterEncoder<S: StrategySelector> {
     strategy_selector: S,
-    approvals_manager: A,
+    signer: Option<PrivateKeySigner>,
+    chain_id: ChainId,
     router_address: String,
 }
 
 #[allow(dead_code)]
-impl<S: StrategySelector, A: UserApprovalsManager> EVMRouterEncoder<S, A> {
+impl<S: StrategySelector> EVMRouterEncoder<S> {
-    pub fn new(strategy_selector: S, approvals_manager: A, router_address: String) -> Self {
+    pub fn new(
-        EVMRouterEncoder { strategy_selector, approvals_manager, router_address }
+        strategy_selector: S,
+        router_address: String,
+        signer: Option<PrivateKeySigner>,
+        chain_id: ChainId,
+    ) -> Result<Self, EncodingError> {
+        Ok(EVMRouterEncoder { strategy_selector, signer, chain_id, router_address })
     }
 }
-impl<S: StrategySelector, A: UserApprovalsManager> RouterEncoder<S, A> for EVMRouterEncoder<S, A> {
+impl<S: StrategySelector> RouterEncoder<S> for EVMRouterEncoder<S> {
     fn encode_router_calldata(
         &self,
         solutions: Vec<Solution>,
     ) -> Result<Vec<Transaction>, EncodingError> {
-        let _approvals_calldata = self.handle_approvals(&solutions)?; // TODO: where should we append this?
         let mut transactions: Vec<Transaction> = Vec::new();
         for solution in solutions.iter() {
             let exact_out = solution.exact_out;
             let straight_to_pool = solution.straight_to_pool;
-
+            let router_address = solution
-            let strategy = self
+                .router_address
-                .strategy_selector
+                .clone()
-                .select_strategy(solution);
+                .unwrap_or(Bytes::from_str(&self.router_address).map_err(|_| {
-            let method_calldata = strategy.encode_strategy((*solution).clone())?;
+                    EncodingError::FatalError("Invalid router address".to_string())
+                })?);
+            let strategy = self.strategy_selector.select_strategy(
+                solution,
+                self.signer.clone(),
+                self.chain_id,
+            )?;
+            let method_calldata = strategy.encode_strategy(solution.clone(), router_address)?;
 
             let contract_interaction = if straight_to_pool {
                 method_calldata
@@ -56,23 +69,4 @@ impl<S: StrategySelector, A: UserApprovalsManager> RouterEncoder<S, A> for EVMRo
         }
         Ok(transactions)
     }
-
-    fn handle_approvals(&self, solutions: &[Solution]) -> Result<Vec<Vec<u8>>, EncodingError> {
-        let mut approvals = Vec::new();
-        for solution in solutions.iter() {
-            approvals.push(Approval {
-                token: solution.given_token.clone(),
-                spender: solution
-                    .router_address
-                    .clone()
-                    .unwrap_or(Bytes::from_str(&self.router_address).map_err(|_| {
-                        EncodingError::FatalError("Invalid router address".to_string())
-                    })?),
-                amount: solution.given_amount.clone(),
-                owner: solution.sender.clone(),
-            });
-        }
-        self.approvals_manager
-            .encode_approvals(approvals)
-    }
 }

src/encoding/evm/strategy_encoder/encoder.rs

@@ -1,35 +1,150 @@
-use alloy_primitives::Address;
+use std::cmp::min;
+
+use alloy::signers::local::PrivateKeySigner;
+use alloy_primitives::{aliases::U24, map::HashSet, ChainId, U256, U8};
 use alloy_sol_types::SolValue;
+use num_bigint::BigUint;
+use tycho_core::Bytes;
 
 use crate::encoding::{
     errors::EncodingError,
-    evm::swap_encoder::SWAP_ENCODER_REGISTRY,
+    evm::{
-    models::{EncodingContext, Solution},
+        approvals::permit2::Permit2,
+        swap_encoder::SWAP_ENCODER_REGISTRY,
+        utils::{biguint_to_u256, bytes_to_address, percentage_to_uint24, ple_encode},
+    },
+    models::{EncodingContext, NativeAction, Solution},
     strategy_encoder::StrategyEncoder,
 };
 
 #[allow(dead_code)]
 pub trait EVMStrategyEncoder: StrategyEncoder {
-    fn encode_protocol_header(
+    fn encode_swap_header(
         &self,
+        token_in: U8,
+        token_out: U8,
+        split: U24,
         protocol_data: Vec<u8>,
-        executor_address: Address,
-        // Token indices, split, and token inclusion are only used for split swaps
-        token_in: u16,
-        token_out: u16,
-        split: u16, // not sure what should be the type of this :/
     ) -> Vec<u8> {
-        let args = (executor_address, token_in, token_out, split, protocol_data);
+        let mut encoded = Vec::new();
-        args.abi_encode()
+        encoded.push(token_in.to_be_bytes_vec()[0]);
+        encoded.push(token_out.to_be_bytes_vec()[0]);
+        encoded.extend_from_slice(&split.to_be_bytes_vec());
+        encoded.extend(protocol_data);
+        encoded
     }
 }
 
-pub struct SplitSwapStrategyEncoder {}
+pub struct SplitSwapStrategyEncoder {
+    permit2: Permit2,
+}
+
+impl SplitSwapStrategyEncoder {
+    pub fn new(signer: PrivateKeySigner, chain_id: ChainId) -> Result<Self, EncodingError> {
+        Ok(Self { permit2: Permit2::new(signer, chain_id)? })
+    }
+}
 impl EVMStrategyEncoder for SplitSwapStrategyEncoder {}
 impl StrategyEncoder for SplitSwapStrategyEncoder {
-    fn encode_strategy(&self, _solution: Solution) -> Result<Vec<u8>, EncodingError> {
+    fn encode_strategy(
-        todo!()
+        &self,
+        solution: Solution,
+        router_address: Bytes,
+    ) -> Result<Vec<u8>, EncodingError> {
+        let (permit, signature) = self.permit2.get_permit(
+            &router_address,
+            &solution.sender,
+            &solution.given_token,
+            &solution.given_amount,
+        )?;
+        let min_amount_out = if solution.check_amount.is_some() {
+            let mut min_amount_out = solution.check_amount.clone().unwrap();
+            if solution.slippage.is_some() {
+                let one_hundred = BigUint::from(100u32);
+                let slippage_percent = BigUint::from((solution.slippage.unwrap() * 100.0) as u32);
+                let multiplier = &one_hundred - slippage_percent;
+                let expected_amount_with_slippage =
+                    (&solution.expected_amount * multiplier) / one_hundred;
+                min_amount_out = min(min_amount_out, expected_amount_with_slippage);
+            }
+            min_amount_out
+        } else {
+            BigUint::ZERO
+        };
+
+        let tokens: Vec<Bytes> = solution
+            .swaps
+            .iter()
+            .flat_map(|swap| vec![swap.token_in.clone(), swap.token_out.clone()])
+            .collect::<HashSet<Bytes>>()
+            .into_iter()
+            .collect();
+
+        let mut swaps = vec![];
+        for swap in solution.swaps.iter() {
+            let registry = SWAP_ENCODER_REGISTRY.read().unwrap();
+            let swap_encoder = registry
+                .get_encoder(&swap.component.protocol_system)
+                .expect("Swap encoder not found");
+
+            let encoding_context = EncodingContext {
+                receiver: router_address.clone(),
+                exact_out: solution.exact_out,
+                router_address: router_address.clone(),
+            };
+            let protocol_data = swap_encoder.encode_swap(swap.clone(), encoding_context)?;
+            let swap_data = self.encode_swap_header(
+                U8::from(
+                    tokens
+                        .iter()
+                        .position(|t| *t == swap.token_in)
+                        .ok_or_else(|| {
+                            EncodingError::InvalidInput(
+                                "Token in not found in tokens array".to_string(),
+                            )
+                        })?,
+                ),
+                U8::from(
+                    tokens
+                        .iter()
+                        .position(|t| *t == swap.token_out)
+                        .ok_or_else(|| {
+                            EncodingError::InvalidInput(
+                                "Token out not found in tokens array".to_string(),
+                            )
+                        })?,
+                ),
+                percentage_to_uint24(swap.split),
+                protocol_data,
+            );
+            swaps.push(swap_data);
+        }
+
+        let encoded_swaps = ple_encode(swaps);
+        let (mut unwrap, mut wrap) = (false, false);
+        if solution.native_action.is_some() {
+            match solution.native_action.unwrap() {
+                NativeAction::Wrap => wrap = true,
+                NativeAction::Unwrap => unwrap = true,
+            }
+        }
+        let method_calldata = (
+            biguint_to_u256(&solution.given_amount),
+            bytes_to_address(&solution.given_token)?,
+            bytes_to_address(&solution.checked_token)?,
+            biguint_to_u256(&min_amount_out),
+            wrap,
+            unwrap,
+            U256::from(tokens.len()),
+            bytes_to_address(&solution.receiver)?,
+            permit,
+            signature.as_bytes().to_vec(),
+            encoded_swaps,
+        )
+            .abi_encode();
+        Ok(method_calldata)
     }
+
     fn selector(&self, _exact_out: bool) -> &str {
         "swap(uint256, address, uint256, bytes[])"
     }
@@ -40,7 +155,11 @@ impl StrategyEncoder for SplitSwapStrategyEncoder {
 pub struct StraightToPoolStrategyEncoder {}
 impl EVMStrategyEncoder for StraightToPoolStrategyEncoder {}
 impl StrategyEncoder for StraightToPoolStrategyEncoder {
-    fn encode_strategy(&self, solution: Solution) -> Result<Vec<u8>, EncodingError> {
+    fn encode_strategy(
+        &self,
+        solution: Solution,
+        _router_address: Bytes,
+    ) -> Result<Vec<u8>, EncodingError> {
         if solution.router_address.is_none() {
             return Err(EncodingError::InvalidInput(
                 "Router address is required for straight to pool solutions".to_string(),
@@ -75,3 +194,111 @@ impl StrategyEncoder for StraightToPoolStrategyEncoder {
         unimplemented!();
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use std::str::FromStr;
+
+    use alloy::hex::encode;
+    use alloy_primitives::B256;
+    use tycho_core::dto::ProtocolComponent;
+
+    use super::*;
+    use crate::encoding::models::Swap;
+
+    #[test]
+    fn test_split_swap_strategy_encoder() {
+        // Set up a mock private key for signing
+        let private_key =
+            B256::from_str("4c0883a69102937d6231471b5dbb6204fe512961708279feb1be6ae5538da033")
+                .expect("Invalid private key");
+        let signer = PrivateKeySigner::from_bytes(&private_key).expect("Failed to create signer");
+
+        let weth = Bytes::from_str("0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2").unwrap();
+        let dai = Bytes::from_str("0x6b175474e89094c44da98b954eedeac495271d0f").unwrap();
+
+        let swap = Swap {
+            component: ProtocolComponent {
+                id: "0x88e6A0c2dDD26FEEb64F039a2c41296FcB3f5640".to_string(),
+                protocol_system: "uniswap_v2".to_string(),
+                ..Default::default()
+            },
+            token_in: weth.clone(),
+            token_out: dai.clone(),
+            split: 0f64,
+        };
+
+        let encoder = SplitSwapStrategyEncoder::new(signer, 1).unwrap();
+        let solution = Solution {
+            exact_out: false,
+            given_token: weth,
+            given_amount: BigUint::from_str("1_000000000000000000").unwrap(),
+            checked_token: dai,
+            expected_amount: BigUint::from_str("3_000_000000000000000000").unwrap(),
+            check_amount: None,
+            sender: Bytes::from_str("0x2c6A3cd97c6283b95Ac8C5A4459eBB0d5Fd404F4").unwrap(),
+            receiver: Bytes::from_str("0x2c6A3cd97c6283b95Ac8C5A4459eBB0d5Fd404F4").unwrap(),
+            swaps: vec![swap],
+            ..Default::default()
+        };
+        let router_address = Bytes::from_str("0x2c6A3cd97c6283b95Ac8C5A4459eBB0d5Fd404F4").unwrap();
+
+        let calldata = encoder
+            .encode_strategy(solution, router_address)
+            .unwrap();
+
+        let expected_input = String::from(concat!(
+            "0000000000000000000000000000000000000000000000000000000000000020", // offset
+            "0000000000000000000000000000000000000000000000000de0b6b3a7640000", // amount out
+            "000000000000000000000000c02aaa39b223fe8d0a0e5c4f27ead9083c756cc2", // token in
+            "0000000000000000000000006b175474e89094c44da98b954eedeac495271d0f", // token out
+            "0000000000000000000000000000000000000000000000000000000000000000", // min amount out
+            "0000000000000000000000000000000000000000000000000000000000000000", // wrap
+            "0000000000000000000000000000000000000000000000000000000000000000", // unwrap
+            "0000000000000000000000000000000000000000000000000000000000000002", // tokens length
+            "0000000000000000000000002c6a3cd97c6283b95ac8c5a4459ebb0d5fd404f4", // receiver
+        ));
+        // after this there is the permit and because of the deadlines (that depend on block time)
+        // it's hard to assert
+        // "000000000000000000000000c02aaa39b223fe8d0a0e5c4f27ead9083c756cc2", // token in
+        // "0000000000000000000000000000000000000000000000000de0b6b3a7640000", // amount in
+        // "0000000000000000000000000000000000000000000000000000000067c205fe", // expiration
+        // "0000000000000000000000000000000000000000000000000000000000000000", // nonce
+        // "0000000000000000000000002c6a3cd97c6283b95ac8c5a4459ebb0d5fd404f4", // spender
+        // "00000000000000000000000000000000000000000000000000000000679a8006", // deadline
+        //  offsets???
+        // "0000000000000000000000000000000000000000000000000000000000000200",
+        // "0000000000000000000000000000000000000000000000000000000000000280",
+        // "0000000000000000000000000000000000000000000000000000000000000041",
+        //  signature
+        // "fc5bac4e27cd5d71c85d232d8c6b31ea924d2e0031091ff9a39579d9e49c214328ea34876961d9200af691373c71a174e166793d02241c76adb93c5f87fe0f381c",
+
+        let expected_swaps = String::from(concat!(
+            // ple encode adds aaalll of this :/ is it correct?
+            "0000000000000000000000000000000000000000000000000000000000000000",
+            "0000000000000000000000000000000000000000000000000000000000120000",
+            "0000000000000000000000000000000000000000000000000000000000020000",
+            "0000000000000000000000000000000000000000000000000000000000060000",
+            "000000000000000000000000000000000000000000000000000000000005b000",
+            "0000000000000000000000000000000000000000000000000000000000080000",
+            "0000000000000000000000000000000000000000000000000000000000000000",
+            "000000000000000000000000000000000000000000000000000000000005b",
+            // Swap header
+            "00",     // token in index
+            "01",     // token out index
+            "000000", // split
+            // Swap data
+            "5c2f5a71f67c01775180adc06909288b4c329308", // executor address
+            "bd0625ab",                                 // selector
+            "c02aaa39b223fe8d0a0e5c4f27ead9083c756cc2", // token in
+            "88e6a0c2ddd26feeb64f039a2c41296fcb3f5640", // component id
+            "2c6a3cd97c6283b95ac8c5a4459ebb0d5fd404f4", // receiver
+            "00",                                       // zero2one
+            "00",                                       // exact out
+            "0000000000",                               // padding
+        ));
+        let hex_calldata = encode(&calldata);
+        assert_eq!(hex_calldata[..576], expected_input);
+        assert_eq!(hex_calldata[1283..], expected_swaps);
+    }
+}

src/encoding/evm/strategy_encoder/selector.rs

@@ -1,4 +1,8 @@
+use alloy::signers::local::PrivateKeySigner;
+use alloy_primitives::ChainId;
+
 use crate::encoding::{
+    errors::EncodingError,
     evm::strategy_encoder::encoder::{SplitSwapStrategyEncoder, StraightToPoolStrategyEncoder},
     models::Solution,
     strategy_encoder::{StrategyEncoder, StrategySelector},
@@ -7,11 +11,21 @@ use crate::encoding::{
 pub struct EVMStrategySelector;
 
 impl StrategySelector for EVMStrategySelector {
-    fn select_strategy(&self, solution: &Solution) -> Box<dyn StrategyEncoder> {
+    fn select_strategy(
+        &self,
+        solution: &Solution,
+        signer: Option<PrivateKeySigner>,
+        chain_id: ChainId,
+    ) -> Result<Box<dyn StrategyEncoder>, EncodingError> {
         if solution.straight_to_pool {
-            Box::new(StraightToPoolStrategyEncoder {})
+            Ok(Box::new(StraightToPoolStrategyEncoder {}))
         } else {
-            Box::new(SplitSwapStrategyEncoder {})
+            let signer = signer.ok_or_else(|| {
+                EncodingError::FatalError(
+                    "Signer is required for SplitSwapStrategyEncoder".to_string(),
+                )
+            })?;
+            Ok(Box::new(SplitSwapStrategyEncoder::new(signer, chain_id).unwrap()))
         }
     }
 }

src/encoding/evm/swap_encoder/encoders.rs

@@ -42,6 +42,9 @@ impl SwapEncoder for UniswapV2SwapEncoder {
         // Token in address is always needed to perform a manual transfer from the router,
         // since no optimizations are performed that send from one pool to the next
         let args = (
+            Address::from_str(self.executor_address())
+                .map_err(|_| EncodingError::FatalError("Invalid executor address".to_string()))?,
+            self.executor_selector(),
             token_in_address,
             component_id,
             bytes_to_address(&encoding_context.receiver)?,
@@ -107,6 +110,9 @@ impl SwapEncoder for UniswapV3SwapEncoder {
             })?;
 
         let args = (
+            Address::from_str(self.executor_address())
+                .map_err(|_| EncodingError::FatalError("Invalid executor address".to_string()))?,
+            self.executor_selector(),
             token_in_address,
             token_out_address,
             pool_fee_u24,
@@ -155,6 +161,9 @@ impl SwapEncoder for BalancerV2SwapEncoder {
             .map_err(|_| EncodingError::FatalError("Invalid component ID".to_string()))?;
 
         let args = (
+            Address::from_str(self.executor_address())
+                .map_err(|_| EncodingError::FatalError("Invalid executor address".to_string()))?,
+            self.executor_selector(),
             bytes_to_address(&swap.token_in)?,
             bytes_to_address(&swap.token_out)?,
             component_id,
@@ -196,7 +205,8 @@ mod tests {
             exact_out: false,
             router_address: Bytes::zero(20),
         };
-        let encoder = UniswapV2SwapEncoder::new(String::from("0x"));
+        let encoder =
+            UniswapV2SwapEncoder::new(String::from("0x543778987b293C7E8Cf0722BB2e935ba6f4068D4"));
         let encoded_swap = encoder
             .encode_swap(swap, encoding_context)
             .unwrap();
@@ -204,6 +214,10 @@ mod tests {
         assert_eq!(
             hex_swap,
             String::from(concat!(
+                // executor address
+                "543778987b293c7e8cf0722bb2e935ba6f4068d4",
+                // executor selector
+                "bd0625ab",
                 // in token
                 "c02aaa39b223fe8d0a0e5c4f27ead9083c756cc2",
                 // component id
@@ -239,7 +253,8 @@ mod tests {
             exact_out: false,
             router_address: Bytes::zero(20),
         };
-        let encoder = UniswapV3SwapEncoder::new(String::from("0x"));
+        let encoder =
+            UniswapV3SwapEncoder::new(String::from("0x543778987b293C7E8Cf0722BB2e935ba6f4068D4"));
         let encoded_swap = encoder
             .encode_swap(swap, encoding_context)
             .unwrap();
@@ -247,6 +262,10 @@ mod tests {
         assert_eq!(
             hex_swap,
             String::from(concat!(
+                // executor address
+                "543778987b293c7e8cf0722bb2e935ba6f4068d4",
+                // executor selector
+                "bd0625ab",
                 // in token
                 "c02aaa39b223fe8d0a0e5c4f27ead9083c756cc2",
                 // out token
@@ -283,7 +302,8 @@ mod tests {
             exact_out: false,
             router_address: Bytes::zero(20),
         };
-        let encoder = BalancerV2SwapEncoder::new(String::from("0x"));
+        let encoder =
+            BalancerV2SwapEncoder::new(String::from("0x543778987b293C7E8Cf0722BB2e935ba6f4068D4"));
         let encoded_swap = encoder
             .encode_swap(swap, encoding_context)
             .unwrap();
@@ -292,6 +312,10 @@ mod tests {
         assert_eq!(
             hex_swap,
             String::from(concat!(
+                // executor address
+                "543778987b293c7e8cf0722bb2e935ba6f4068d4",
+                // executor selector
+                "bd0625ab",
                 // token in
                 "c02aaa39b223fe8d0a0e5c4f27ead9083c756cc2",
                 // token out

src/encoding/evm/utils.rs

@@ -1,4 +1,4 @@
-use alloy_primitives::{Address, Keccak256, U256};
+use alloy_primitives::{aliases::U24, Address, Keccak256, U256};
 use alloy_sol_types::SolValue;
 use num_bigint::BigUint;
 use tycho_core::Bytes;
@@ -13,7 +13,7 @@ pub fn bytes_to_address(address: &Bytes) -> Result<Address, EncodingError> {
     if address.len() == 20 {
         Ok(Address::from_slice(address))
     } else {
-        Err(EncodingError::InvalidInput(format!("Invalid ERC20 token address: {:?}", address)))
+        Err(EncodingError::InvalidInput(format!("Invalid address: {:?}", address)))
     }
 }
 
@@ -56,3 +56,12 @@ pub fn encode_input(selector: &str, mut encoded_args: Vec<u8>) -> Vec<u8> {
     call_data.extend(encoded_args);
     call_data
 }
+
+/// Converts a percentage to a `U24` value. The percentage is a `f64` value between 0 and 100.
+/// MAX_UINT24 corresponds to 100%.
+pub fn percentage_to_uint24(percentage: f64) -> U24 {
+    const MAX_UINT24: u32 = 16_777_215; // 2^24 - 1
+
+    let scaled = (percentage / 100.0) * (MAX_UINT24 as f64);
+    U24::from(scaled.round())
+}

src/encoding/models.rs

@@ -1,7 +1,7 @@
 use num_bigint::BigUint;
 use tycho_core::{dto::ProtocolComponent, Bytes};
 
-#[derive(Clone)]
+#[derive(Clone, Default, Debug)]
 #[allow(dead_code)]
 pub struct Solution {
     /// True if the solution is an exact output solution.
@@ -11,7 +11,7 @@ pub struct Solution {
     /// Amount of the given token.
     pub given_amount: BigUint,
     /// The token being bought (exact in) or sold (exact out).
-    checked_token: Bytes,
+    pub checked_token: Bytes,
     /// Expected amount of the bought token (exact in) or sold token (exact out).
     pub expected_amount: BigUint,
     /// Minimum amount to be checked for the solution to be valid.
@@ -35,14 +35,14 @@ pub struct Solution {
     pub native_action: Option<NativeAction>,
 }
 
-#[derive(Clone, PartialEq)]
+#[derive(Clone, PartialEq, Debug)]
 #[allow(dead_code)]
 pub enum NativeAction {
     Wrap,
     Unwrap,
 }
 
-#[derive(Clone)]
+#[derive(Clone, Debug)]
 #[allow(dead_code)]
 pub struct Swap {
     /// Protocol component from tycho indexer
@@ -51,7 +51,7 @@ pub struct Swap {
     pub token_in: Bytes,
     /// Token being output from the pool.
     pub token_out: Bytes,
-    /// Fraction of the amount to be swapped in this operation.
+    /// Percentage of the amount to be swapped in this operation.
     pub split: f64,
 }
 

src/encoding/router_encoder.rs

@@ -10,5 +10,4 @@ pub trait RouterEncoder<S: StrategySelector> {
         &self,
         solutions: Vec<Solution>,
     ) -> Result<Vec<Transaction>, EncodingError>;
-    fn handle_approvals(&self, solutions: &[Solution]) -> Result<Vec<Vec<u8>>, EncodingError>;
 }

src/encoding/strategy_encoder.rs

@@ -1,12 +1,25 @@
+use alloy::signers::local::PrivateKeySigner;
+use alloy_primitives::ChainId;
+use tycho_core::Bytes;
+
 use crate::encoding::{errors::EncodingError, models::Solution};
 
 #[allow(dead_code)]
 pub trait StrategyEncoder {
-    fn encode_strategy(&self, to_encode: Solution) -> Result<Vec<u8>, EncodingError>;
+    fn encode_strategy(
+        &self,
+        to_encode: Solution,
+        router_address: Bytes,
+    ) -> Result<Vec<u8>, EncodingError>;
     fn selector(&self, exact_out: bool) -> &str;
 }
 
 pub trait StrategySelector {
     #[allow(dead_code)]
-    fn select_strategy(&self, solution: &Solution) -> Box<dyn StrategyEncoder>;
+    fn select_strategy(
+        &self,
+        solution: &Solution,
+        signer: Option<PrivateKeySigner>,
+        chain_id: ChainId,
+    ) -> Result<Box<dyn StrategyEncoder>, EncodingError>;
 }

src/encoding/swap_encoder.rs

@@ -1,3 +1,6 @@
+use alloy_primitives::FixedBytes;
+use tycho_core::keccak256;
+
 use crate::encoding::{
     errors::EncodingError,
     models::{EncodingContext, Swap},
@@ -14,4 +17,9 @@ pub trait SwapEncoder: Sync + Send {
         encoding_context: EncodingContext,
     ) -> Result<Vec<u8>, EncodingError>;
     fn executor_address(&self) -> &str;
+
+    fn executor_selector(&self) -> FixedBytes<4> {
+        let hash = keccak256("swap(uint256,bytes)".as_bytes());
+        FixedBytes::<4>::from([hash[0], hash[1], hash[2], hash[3]])
+    }
 }