feat: Support in between swaps optimizations

--- don't change below this line ---
ENG-4314 Took 31 seconds

foundry/test/TychoRouterSequentialSwap.t.sol

@@ -340,4 +340,100 @@ contract TychoRouterSequentialSwapTest is TychoRouterTestSetup {
         tychoRouter.exposedSequentialSwap(amountIn, pleEncode(swaps));
         assertEq(IERC20(USDC_ADDR).balanceOf(tychoRouterAddr), 99889294);
     }
+
+    function testUSV3USV2Integration() public {
+        // Performs a sequential swap from WETH to USDC though WBTC and DAI using USV3 and USV2 pools
+        //
+        //   WETH ──(USV3)──> WBTC ───(USV2)──> USDC
+        deal(WETH_ADDR, ALICE, 1 ether);
+        uint256 balanceBefore = IERC20(USDC_ADDR).balanceOf(ALICE);
+
+        // Approve permit2
+        vm.startPrank(ALICE);
+        IERC20(WETH_ADDR).approve(tychoRouterAddr, type(uint256).max);
+        // Encoded solution generated using `test_uniswap_v3_uniswap_v2`
+        (bool success,) = tychoRouterAddr.call(
+            hex"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"
+        );
+
+        vm.stopPrank();
+
+        uint256 balanceAfter = IERC20(USDC_ADDR).balanceOf(ALICE);
+
+        assertTrue(success, "Call Failed");
+        assertEq(balanceAfter - balanceBefore, 2554299052);
+        assertEq(IERC20(WETH_ADDR).balanceOf(tychoRouterAddr), 0);
+    }
+
+    function testUSV3USV3Integration() public {
+        // Performs a sequential swap from WETH to USDC though WBTC using USV3 pools
+        //
+        //   WETH ──(USV3)──> WBTC ───(USV3)──> USDC
+        deal(WETH_ADDR, ALICE, 1 ether);
+        uint256 balanceBefore = IERC20(USDC_ADDR).balanceOf(ALICE);
+
+        // Approve permit2
+        vm.startPrank(ALICE);
+        IERC20(WETH_ADDR).approve(tychoRouterAddr, type(uint256).max);
+        // Encoded solution generated using `test_uniswap_v3_uniswap_v3`
+        (bool success,) = tychoRouterAddr.call(
+            hex"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"
+        );
+
+        vm.stopPrank();
+
+        uint256 balanceAfter = IERC20(USDC_ADDR).balanceOf(ALICE);
+
+        assertTrue(success, "Call Failed");
+        assertEq(balanceAfter - balanceBefore, 2647438249);
+        assertEq(IERC20(WETH_ADDR).balanceOf(tychoRouterAddr), 0);
+    }
+
+    function testUSV3CurveIntegration() public {
+        // Performs a sequential swap from WETH to USDT though WBTC using USV3 and Curve pools
+        //
+        //   WETH ──(USV3)──> WBTC ───(USV3)──> USDT
+        deal(WETH_ADDR, ALICE, 1 ether);
+        uint256 balanceBefore = IERC20(USDT_ADDR).balanceOf(ALICE);
+
+        // Approve permit2
+        vm.startPrank(ALICE);
+        IERC20(WETH_ADDR).approve(tychoRouterAddr, type(uint256).max);
+        // Encoded solution generated using `test_uniswap_v3_curve`
+        (bool success,) = tychoRouterAddr.call(
+            hex"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"
+        );
+
+        vm.stopPrank();
+
+        uint256 balanceAfter = IERC20(USDT_ADDR).balanceOf(ALICE);
+
+        assertTrue(success, "Call Failed");
+        assertEq(balanceAfter - balanceBefore, 2650183330);
+        assertEq(IERC20(WETH_ADDR).balanceOf(tychoRouterAddr), 0);
+    }
+
+    function testBalancerV2USV2Integration() public {
+        // Performs a sequential swap from WETH to USDC though WBTC using Balancer v2 and USV2 pools
+        //
+        //   WETH ──(balancer)──> WBTC ───(USV2)──> USDC
+        deal(WETH_ADDR, ALICE, 1 ether);
+        uint256 balanceBefore = IERC20(USDT_ADDR).balanceOf(ALICE);
+
+        // Approve permit2
+        vm.startPrank(ALICE);
+        IERC20(WETH_ADDR).approve(tychoRouterAddr, type(uint256).max);
+        // Encoded solution generated using `test_uniswap_v3_curve`
+        (bool success,) = tychoRouterAddr.call(
+            hex"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"
+        );
+
+        vm.stopPrank();
+
+        uint256 balanceAfter = IERC20(USDC_ADDR).balanceOf(ALICE);
+
+        assertTrue(success, "Call Failed");
+        assertEq(balanceAfter - balanceBefore, 2549391308);
+        assertEq(IERC20(WETH_ADDR).balanceOf(tychoRouterAddr), 0);
+    }
 }

src/encoding/evm/constants.rs

@@ -13,7 +13,7 @@ pub const PROTOCOL_SPECIFIC_CONFIG: &str =
 pub static GROUPABLE_PROTOCOLS: LazyLock<HashSet<&'static str>> = LazyLock::new(|| {
     let mut set = HashSet::new();
     set.insert("uniswap_v4");
-    set.insert("balancer_v3");
+    set.insert("vm:balancer_v3");
     set.insert("ekubo_v2");
     set
 });
@@ -23,18 +23,21 @@ pub static IN_TRANSFER_OPTIMIZABLE_PROTOCOLS: LazyLock<HashSet<&'static str>> =
     LazyLock::new(|| {
         let mut set = HashSet::new();
         set.insert("uniswap_v2");
+        set.insert("sushiswap_v2");
+        set.insert("pancakeswap_v2");
         set.insert("uniswap_v3");
+        set.insert("pancakeswap_v3");
         set.insert("ekubo_v2");
         set
     });
 
-/// These protocols expect funds to be in the router at the time of swap.
+// These protocols do not support chained swaps from the same protocol. This is the case for uniswap
-pub static PROTOCOLS_EXPECTING_FUNDS_IN_ROUTER: LazyLock<HashSet<&'static str>> =
+// v3 because of the callback logic. The only way for this to work it would be to call the second
+// swap during the callback of the first swap. This is currently not supported.
+pub static PROTOCOLS_NOT_OPTIMIZED_CHAINED_SWAPS: LazyLock<HashSet<&'static str>> =
     LazyLock::new(|| {
         let mut set = HashSet::new();
-        set.insert("vm:curve");
+        set.insert("uniswap_v3");
-        set.insert("balancer_v2");
+        set.insert("pancakeswap_v3");
-        // TODO remove uniswap_v4 when we add callback support for transfer optimizations
-        set.insert("uniswap_v4");
         set
     });

src/encoding/evm/group_swaps.rs

@@ -255,7 +255,7 @@ mod tests {
 
         let swap_weth_wbtc = Swap {
             component: ProtocolComponent {
-                protocol_system: "balancer_v3".to_string(),
+                protocol_system: "vm:balancer_v3".to_string(),
                 ..Default::default()
             },
             token_in: weth.clone(),
@@ -264,7 +264,7 @@ mod tests {
         };
         let swap_wbtc_usdc = Swap {
             component: ProtocolComponent {
-                protocol_system: "balancer_v3".to_string(),
+                protocol_system: "vm:balancer_v3".to_string(),
                 ..Default::default()
             },
             token_in: wbtc.clone(),
@@ -306,7 +306,7 @@ mod tests {
                     swaps: vec![swap_weth_wbtc, swap_wbtc_usdc],
                     input_token: weth.clone(),
                     output_token: usdc.clone(),
-                    protocol_system: "balancer_v3".to_string(),
+                    protocol_system: "vm:balancer_v3".to_string(),
                     split: 0.5f64,
                 },
                 SwapGroup {

src/encoding/evm/strategy_encoder/strategy_encoders.rs

@@ -8,6 +8,7 @@ use crate::encoding::{
     errors::EncodingError,
     evm::{
         approvals::permit2::Permit2,
+        constants::{IN_TRANSFER_OPTIMIZABLE_PROTOCOLS, PROTOCOLS_NOT_OPTIMIZED_CHAINED_SWAPS},
         group_swaps::group_swaps,
         strategy_encoder::{
             strategy_validators::{SequentialSwapValidator, SplitSwapValidator, SwapValidator},
@@ -133,6 +134,7 @@ impl StrategyEncoder for SingleSwapStrategyEncoder {
                 self.wrapped_address.clone(),
                 self.permit2.clone().is_some(),
                 wrap,
+                false,
             );
 
             let encoding_context = EncodingContext {
@@ -289,6 +291,7 @@ impl StrategyEncoder for SequentialSwapStrategyEncoder {
         }
 
         let mut swaps = vec![];
+        let mut next_in_between_swap_optimization = true;
         for (i, grouped_swap) in grouped_swaps.iter().enumerate() {
             let protocol = grouped_swap.protocol_system.clone();
             let swap_encoder = self
@@ -300,12 +303,31 @@ impl StrategyEncoder for SequentialSwapStrategyEncoder {
                     ))
                 })?;
 
-            // if it is the last swap and there isn't an unwrap at the end, we can set the receiver
+            let in_between_swap_optimization = next_in_between_swap_optimization;
-            // to the final user
+            let next_swap = grouped_swaps.get(i + 1);
-            let swap_receiver = if i == grouped_swaps.len() - 1 && !unwrap {
+            // if there is a next swap
-                solution.receiver.clone()
+            let swap_receiver = if let Some(next) = next_swap {
-            } else {
+                // if the protocol of the next swap supports transfer in optimization
+                if IN_TRANSFER_OPTIMIZABLE_PROTOCOLS.contains(&next.protocol_system.as_str()) {
+                    // if the protocol does not allow for chained swaps, we can't optimize the
+                    // receiver of this swap nor the transfer in of the next swap
+                    if PROTOCOLS_NOT_OPTIMIZED_CHAINED_SWAPS
+                        .contains(&next.protocol_system.as_str()) &&
+                        PROTOCOLS_NOT_OPTIMIZED_CHAINED_SWAPS.contains(protocol.as_str())
+                    {
+                        next_in_between_swap_optimization = false;
                         self.router_address.clone()
+                    } else {
+                        Bytes::from_str(&next.swaps[0].component.id.clone()).map_err(|_| {
+                            EncodingError::FatalError("Invalid component id".to_string())
+                        })?
+                    }
+                } else {
+                    // the protocol of the next swap does not support transfer in optimization
+                    self.router_address.clone()
+                }
+            } else {
+                solution.receiver.clone() // last swap - there is not next swap
             };
 
             let mut grouped_protocol_data: Vec<u8> = vec![];
@@ -317,6 +339,7 @@ impl StrategyEncoder for SequentialSwapStrategyEncoder {
                     self.wrapped_address.clone(),
                     self.permit2.clone().is_some(),
                     wrap,
+                    in_between_swap_optimization,
                 );
 
                 let encoding_context = EncodingContext {
@@ -553,6 +576,7 @@ impl StrategyEncoder for SplitSwapStrategyEncoder {
                     self.wrapped_address.clone(),
                     self.permit2.clone().is_some(),
                     wrap,
+                    false,
                 );
 
                 let encoding_context = EncodingContext {
@@ -1148,12 +1172,15 @@ mod tests {
         println!("test_split_swap_strategy_encoder_complex_route: {}", _hex_calldata);
     }
 
+    mod sequential {
+        use super::*;
+
         #[test]
         fn test_sequential_swap_strategy_encoder_complex_route() {
             // Note: This test does not assert anything. It is only used to obtain integration test
             // data for our router solidity test.
             //
-        // Performs a split swap from WETH to USDC though WBTC and DAI using USV2 pools
+            // Performs a sequential swap from WETH to USDC though WBTC using USV2 pools
             //
             //   WETH ───(USV2)──> WBTC ───(USV2)──> USDC
 
@@ -1216,7 +1243,7 @@ mod tests {
 
         #[test]
         fn test_sequential_swap_strategy_encoder_no_permit2() {
-        // Performs a split swap from WETH to USDC though WBTC and DAI using USV2 pools
+            // Performs a sequential swap from WETH to USDC though WBTC using USV2 pools
             //
             //   WETH ───(USV2)──> WBTC ───(USV2)──> USDC
 
@@ -1277,7 +1304,7 @@ mod tests {
                 "0000000000000000000000000000000000000000000000000de0b6b3a7640000", // amount in
                 "000000000000000000000000c02aaa39b223fe8d0a0e5c4f27ead9083c756cc2", // token in
                 "000000000000000000000000a0b86991c6218b36c1d19d4a2e9eb0ce3606eb48", // token ou
-            "00000000000000000000000000000000000000000000000000000000018f61ec", // min amount out
+                "00000000000000000000000000000000000000000000000000000000018f61ec", /* min amount out */
                 "0000000000000000000000000000000000000000000000000000000000000000", // wrap
                 "0000000000000000000000000000000000000000000000000000000000000000", // unwrap
                 "000000000000000000000000cd09f75e2bf2a4d11f3ab23f1389fcc1621c0cc2", // receiver
@@ -1289,7 +1316,7 @@ mod tests {
                 "5615deb798bb3e4dfa0139dfa1b3d433cc23b72f", // executor address
                 "c02aaa39b223fe8d0a0e5c4f27ead9083c756cc2", // token in
                 "bb2b8038a1640196fbe3e38816f3e67cba72d940", // component id
-            "3ede3eca2a72b3aecc820e955b36f38437d01395", // receiver (router)
+                "004375dff511095cc5a197a54140a24efef3a416", // receiver (next pool)
                 "00",                                       // zero to one
                 "01",                                       // transfer type
                 // swap 2
@@ -1299,13 +1326,312 @@ mod tests {
                 "004375dff511095cc5a197a54140a24efef3a416",         // component id
                 "cd09f75e2bf2a4d11f3ab23f1389fcc1621c0cc2",         // receiver (final user)
                 "01",                                               // zero to one
-            "00",                                               // transfer type
+                "05",                                               // transfer type - None
                 "000000000000000000000000000000000000000000000000", // padding
             ));
 
             assert_eq!(hex_calldata, expected);
         }
 
+        #[test]
+        fn test_uniswap_v3_uniswap_v2() {
+            // Note: This test does not assert anything. It is only used to obtain integration test
+            // data for our router solidity test.
+            //
+            // Performs a sequential swap from WETH to USDC though WBTC using USV3 and USV2
+            // pools
+            //
+            //   WETH ───(USV3)──> WBTC ───(USV2)──> USDC
+
+            let weth = weth();
+            let wbtc = Bytes::from_str("0x2260fac5e5542a773aa44fbcfedf7c193bc2c599").unwrap();
+            let usdc = Bytes::from_str("0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48").unwrap();
+
+            let swap_weth_wbtc = Swap {
+                component: ProtocolComponent {
+                    id: "0xCBCdF9626bC03E24f779434178A73a0B4bad62eD".to_string(),
+                    protocol_system: "uniswap_v3".to_string(),
+                    static_attributes: {
+                        let mut attrs = HashMap::new();
+                        attrs.insert(
+                            "fee".to_string(),
+                            Bytes::from(BigInt::from(3000).to_signed_bytes_be()),
+                        );
+                        attrs
+                    },
+                    ..Default::default()
+                },
+                token_in: weth.clone(),
+                token_out: wbtc.clone(),
+                split: 0f64,
+            };
+            let swap_wbtc_usdc = Swap {
+                component: ProtocolComponent {
+                    id: "0x004375Dff511095CC5A197A54140a24eFEF3A416".to_string(),
+                    protocol_system: "uniswap_v2".to_string(),
+                    ..Default::default()
+                },
+                token_in: wbtc.clone(),
+                token_out: usdc.clone(),
+                split: 0f64,
+            };
+            let swap_encoder_registry = get_swap_encoder_registry();
+            let encoder = SequentialSwapStrategyEncoder::new(
+                eth_chain(),
+                swap_encoder_registry,
+                None,
+                Bytes::from_str("0x3Ede3eCa2a72B3aeCC820E955B36f38437D01395").unwrap(),
+            )
+            .unwrap();
+            let solution = Solution {
+                exact_out: false,
+                given_token: weth,
+                given_amount: BigUint::from_str("1_000000000000000000").unwrap(),
+                checked_token: usdc,
+                expected_amount: None,
+                checked_amount: Some(BigUint::from_str("26173932").unwrap()),
+                sender: Bytes::from_str("0xcd09f75E2BF2A4d11F3AB23f1389FcC1621c0cc2").unwrap(),
+                receiver: Bytes::from_str("0xcd09f75E2BF2A4d11F3AB23f1389FcC1621c0cc2").unwrap(),
+                swaps: vec![swap_weth_wbtc, swap_wbtc_usdc],
+                ..Default::default()
+            };
+
+            let (calldata, _) = encoder
+                .encode_strategy(solution)
+                .unwrap();
+
+            let _hex_calldata = encode(&calldata);
+            println!("test_uniswap_v3_uniswap_v2: {}", _hex_calldata);
+        }
+
+        #[test]
+        fn test_uniswap_v3_uniswap_v3() {
+            // Note: This test does not assert anything. It is only used to obtain integration test
+            // data for our router solidity test.
+            //
+            // Performs a sequential swap from WETH to USDC though WBTC using USV3 pools
+            // There is no optimization between the two USV3 pools, this is currently not supported.
+            //
+            //   WETH ───(USV3)──> WBTC ───(USV3)──> USDC
+
+            let weth = weth();
+            let wbtc = Bytes::from_str("0x2260fac5e5542a773aa44fbcfedf7c193bc2c599").unwrap();
+            let usdc = Bytes::from_str("0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48").unwrap();
+
+            let swap_weth_wbtc = Swap {
+                component: ProtocolComponent {
+                    id: "0xCBCdF9626bC03E24f779434178A73a0B4bad62eD".to_string(),
+                    protocol_system: "uniswap_v3".to_string(),
+                    static_attributes: {
+                        let mut attrs = HashMap::new();
+                        attrs.insert(
+                            "fee".to_string(),
+                            Bytes::from(BigInt::from(3000).to_signed_bytes_be()),
+                        );
+                        attrs
+                    },
+                    ..Default::default()
+                },
+                token_in: weth.clone(),
+                token_out: wbtc.clone(),
+                split: 0f64,
+            };
+            let swap_wbtc_usdc = Swap {
+                component: ProtocolComponent {
+                    id: "0x99ac8cA7087fA4A2A1FB6357269965A2014ABc35".to_string(),
+                    protocol_system: "uniswap_v3".to_string(),
+                    static_attributes: {
+                        let mut attrs = HashMap::new();
+                        attrs.insert(
+                            "fee".to_string(),
+                            Bytes::from(BigInt::from(3000).to_signed_bytes_be()),
+                        );
+                        attrs
+                    },
+                    ..Default::default()
+                },
+                token_in: wbtc.clone(),
+                token_out: usdc.clone(),
+                split: 0f64,
+            };
+            let swap_encoder_registry = get_swap_encoder_registry();
+            let encoder = SequentialSwapStrategyEncoder::new(
+                eth_chain(),
+                swap_encoder_registry,
+                None,
+                Bytes::from_str("0x3Ede3eCa2a72B3aeCC820E955B36f38437D01395").unwrap(),
+            )
+            .unwrap();
+            let solution = Solution {
+                exact_out: false,
+                given_token: weth,
+                given_amount: BigUint::from_str("1_000000000000000000").unwrap(),
+                checked_token: usdc,
+                expected_amount: None,
+                checked_amount: Some(BigUint::from_str("26173932").unwrap()),
+                sender: Bytes::from_str("0xcd09f75E2BF2A4d11F3AB23f1389FcC1621c0cc2").unwrap(),
+                receiver: Bytes::from_str("0xcd09f75E2BF2A4d11F3AB23f1389FcC1621c0cc2").unwrap(),
+                swaps: vec![swap_weth_wbtc, swap_wbtc_usdc],
+                ..Default::default()
+            };
+
+            let (calldata, _) = encoder
+                .encode_strategy(solution)
+                .unwrap();
+
+            let _hex_calldata = encode(&calldata);
+            println!("test_uniswap_v3_uniswap_v3: {}", _hex_calldata);
+        }
+
+        #[test]
+        fn test_uniswap_v3_curve() {
+            // Note: This test does not assert anything. It is only used to obtain integration test
+            // data for our router solidity test.
+            //
+            // Performs a sequential swap from WETH to USDT though WBTC using USV3 and curve
+            // pools
+            //
+            //   WETH ───(USV3)──> WBTC ───(curve)──> USDT
+
+            let weth = weth();
+            let wbtc = Bytes::from_str("0x2260fac5e5542a773aa44fbcfedf7c193bc2c599").unwrap();
+            let usdt = Bytes::from_str("0xdAC17F958D2ee523a2206206994597C13D831ec7").unwrap();
+
+            let swap_weth_wbtc = Swap {
+                component: ProtocolComponent {
+                    id: "0xCBCdF9626bC03E24f779434178A73a0B4bad62eD".to_string(),
+                    protocol_system: "uniswap_v3".to_string(),
+                    static_attributes: {
+                        let mut attrs = HashMap::new();
+                        attrs.insert(
+                            "fee".to_string(),
+                            Bytes::from(BigInt::from(3000).to_signed_bytes_be()),
+                        );
+                        attrs
+                    },
+                    ..Default::default()
+                },
+                token_in: weth.clone(),
+                token_out: wbtc.clone(),
+                split: 0f64,
+            };
+
+            let swap_wbtc_usdt = Swap {
+                component: ProtocolComponent {
+                    id: String::from("0xD51a44d3FaE010294C616388b506AcdA1bfAAE46"),
+                    protocol_system: String::from("vm:curve"),
+                    static_attributes: {
+                        let mut attrs: HashMap<String, Bytes> = HashMap::new();
+                        attrs.insert(
+                            "factory".into(),
+                            Bytes::from(
+                                "0x0000000000000000000000000000000000000000"
+                                    .as_bytes()
+                                    .to_vec(),
+                            ),
+                        );
+                        attrs
+                    },
+                    ..Default::default()
+                },
+                token_in: wbtc.clone(),
+                token_out: usdt.clone(),
+                split: 0f64,
+            };
+            let swap_encoder_registry = get_swap_encoder_registry();
+            let encoder = SequentialSwapStrategyEncoder::new(
+                eth_chain(),
+                swap_encoder_registry,
+                None,
+                Bytes::from_str("0x3Ede3eCa2a72B3aeCC820E955B36f38437D01395").unwrap(),
+            )
+            .unwrap();
+            let solution = Solution {
+                exact_out: false,
+                given_token: weth,
+                given_amount: BigUint::from_str("1_000000000000000000").unwrap(),
+                checked_token: usdt,
+                expected_amount: None,
+                checked_amount: Some(BigUint::from_str("26173932").unwrap()),
+                sender: Bytes::from_str("0xcd09f75E2BF2A4d11F3AB23f1389FcC1621c0cc2").unwrap(),
+                receiver: Bytes::from_str("0xcd09f75E2BF2A4d11F3AB23f1389FcC1621c0cc2").unwrap(),
+                swaps: vec![swap_weth_wbtc, swap_wbtc_usdt],
+                ..Default::default()
+            };
+
+            let (calldata, _) = encoder
+                .encode_strategy(solution)
+                .unwrap();
+
+            let _hex_calldata = encode(&calldata);
+            println!("test_uniswap_v3_curve: {}", _hex_calldata);
+        }
+
+        #[test]
+        fn test_balancer_v2_uniswap_v2() {
+            // Note: This test does not assert anything. It is only used to obtain integration test
+            // data for our router solidity test.
+            //
+            // Performs a sequential swap from WETH to USDC though WBTC using balancer and USV2
+            // pools
+            //
+            //   WETH ───(balancer)──> WBTC ───(USV2)──> USDC
+
+            let weth = weth();
+            let wbtc = Bytes::from_str("0x2260fac5e5542a773aa44fbcfedf7c193bc2c599").unwrap();
+            let usdc = Bytes::from_str("0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48").unwrap();
+
+            let swap_weth_wbtc = Swap {
+                component: ProtocolComponent {
+                    id: "0xa6f548df93de924d73be7d25dc02554c6bd66db500020000000000000000000e"
+                        .to_string(),
+                    protocol_system: "vm:balancer_v2".to_string(),
+                    ..Default::default()
+                },
+                token_in: weth.clone(),
+                token_out: wbtc.clone(),
+                split: 0f64,
+            };
+
+            let swap_wbtc_usdc = Swap {
+                component: ProtocolComponent {
+                    id: "0x004375Dff511095CC5A197A54140a24eFEF3A416".to_string(),
+                    protocol_system: "uniswap_v2".to_string(),
+                    ..Default::default()
+                },
+                token_in: wbtc.clone(),
+                token_out: usdc.clone(),
+                split: 0f64,
+            };
+            let swap_encoder_registry = get_swap_encoder_registry();
+            let encoder = SequentialSwapStrategyEncoder::new(
+                eth_chain(),
+                swap_encoder_registry,
+                None,
+                Bytes::from_str("0x3Ede3eCa2a72B3aeCC820E955B36f38437D01395").unwrap(),
+            )
+            .unwrap();
+            let solution = Solution {
+                exact_out: false,
+                given_token: weth,
+                given_amount: BigUint::from_str("1_000000000000000000").unwrap(),
+                checked_token: usdc,
+                expected_amount: None,
+                checked_amount: Some(BigUint::from_str("26173932").unwrap()),
+                sender: Bytes::from_str("0xcd09f75E2BF2A4d11F3AB23f1389FcC1621c0cc2").unwrap(),
+                receiver: Bytes::from_str("0xcd09f75E2BF2A4d11F3AB23f1389FcC1621c0cc2").unwrap(),
+                swaps: vec![swap_weth_wbtc, swap_wbtc_usdc],
+                ..Default::default()
+            };
+
+            let (calldata, _) = encoder
+                .encode_strategy(solution)
+                .unwrap();
+
+            let _hex_calldata = encode(&calldata);
+            println!("test_balancer_v2_uniswap_v2: {}", _hex_calldata);
+        }
+    }
     #[test]
     fn test_split_encoding_strategy_usv4() {
         // Performs a sequential swap from USDC to PEPE though ETH using two consecutive USV4 pools

src/encoding/evm/strategy_encoder/transfer_optimizations.rs

@@ -1,13 +1,14 @@
 use tycho_common::Bytes;
 
 use crate::encoding::{
-    evm::constants::{IN_TRANSFER_OPTIMIZABLE_PROTOCOLS, PROTOCOLS_EXPECTING_FUNDS_IN_ROUTER},
+    evm::constants::IN_TRANSFER_OPTIMIZABLE_PROTOCOLS,
     models::{Swap, TransferType},
 };
 
 /// A trait that defines how the tokens will be transferred into the given pool given the solution.
 pub trait TransferOptimization {
     /// Returns the transfer method that should be used for the given swap and solution.
+    #[allow(clippy::too_many_arguments)]
     fn get_transfer_type(
         &self,
         swap: Swap,
@@ -16,22 +17,22 @@ pub trait TransferOptimization {
         wrapped_token: Bytes,
         permit2: bool,
         wrap: bool,
+        in_between_swap_optimization: bool,
     ) -> TransferType {
-        let send_funds_to_pool: bool =
+        let in_transfer_optimizable: bool =
             IN_TRANSFER_OPTIMIZABLE_PROTOCOLS.contains(&swap.component.protocol_system.as_str());
-        let funds_expected_in_router: bool =
-            PROTOCOLS_EXPECTING_FUNDS_IN_ROUTER.contains(&swap.component.protocol_system.as_str());
 
-        // In the case of wrapping, check if the swap's token in is the wrapped token to
-        // determine if it's the first swap. Otherwise, compare to the given token.
         let is_first_swap = swap.token_in == given_token;
 
         if swap.token_in == native_token {
             // Funds are already in router. All protocols currently take care of native transfers.
             TransferType::None
         } else if (swap.token_in == wrapped_token) && wrap {
+            // Wrapping already happened in the router so we can just use a normal transfer.
             TransferType::TransferToProtocol
-        } else if is_first_swap && send_funds_to_pool {
+            // first swap
+        } else if is_first_swap {
+            if in_transfer_optimizable {
                 if permit2 {
                     // Transfer from swapper to pool using permit2.
                     TransferType::TransferPermit2ToProtocol
@@ -39,14 +40,17 @@ pub trait TransferOptimization {
                     // Transfer from swapper to pool.
                     TransferType::TransferFromToProtocol
                 }
-        } else if is_first_swap && funds_expected_in_router {
+            } else if permit2 {
-            if permit2 {
                 // Transfer from swapper to router using permit2.
                 TransferType::TransferPermit2ToRouter
             } else {
                 // Transfer from swapper to router.
                 TransferType::TransferFromToRouter
             }
+        // all other swaps
+        } else if !in_transfer_optimizable || in_between_swap_optimization {
+            // funds should already be in the router or in the next pool
+            TransferType::None
         } else {
             TransferType::TransferToProtocol
         }
@@ -93,7 +97,7 @@ mod tests {
         };
         let strategy = MockStrategy {};
         let transfer_method =
-            strategy.get_transfer_type(swap.clone(), weth(), eth(), weth(), true, false);
+            strategy.get_transfer_type(swap.clone(), weth(), eth(), weth(), true, false, false);
         assert_eq!(transfer_method, TransferType::TransferPermit2ToProtocol);
     }
 
@@ -111,7 +115,7 @@ mod tests {
         };
         let strategy = MockStrategy {};
         let transfer_method =
-            strategy.get_transfer_type(swap.clone(), weth(), eth(), weth(), false, false);
+            strategy.get_transfer_type(swap.clone(), weth(), eth(), weth(), false, false, false);
         assert_eq!(transfer_method, TransferType::TransferFromToProtocol);
     }
 
@@ -130,7 +134,7 @@ mod tests {
         };
         let strategy = MockStrategy {};
         let transfer_method =
-            strategy.get_transfer_type(swap.clone(), eth(), eth(), weth(), false, false);
+            strategy.get_transfer_type(swap.clone(), eth(), eth(), weth(), false, false, false);
         assert_eq!(transfer_method, TransferType::None);
     }
 
@@ -149,7 +153,7 @@ mod tests {
         };
         let strategy = MockStrategy {};
         let transfer_method =
-            strategy.get_transfer_type(swap.clone(), eth(), eth(), weth(), false, true);
+            strategy.get_transfer_type(swap.clone(), eth(), eth(), weth(), false, true, false);
         assert_eq!(transfer_method, TransferType::TransferToProtocol);
     }
 
@@ -168,7 +172,45 @@ mod tests {
         };
         let strategy = MockStrategy {};
         let transfer_method =
-            strategy.get_transfer_type(swap.clone(), weth(), eth(), weth(), false, false);
+            strategy.get_transfer_type(swap.clone(), weth(), eth(), weth(), false, false, false);
         assert_eq!(transfer_method, TransferType::TransferToProtocol);
     }
+
+    #[test]
+    fn test_not_first_swap_funds_in_router() {
+        // Not the first swap and the protocol requires the funds to be in the router (which they
+        // already are, so the transfer type is None)
+        let swap = Swap {
+            component: ProtocolComponent {
+                protocol_system: "vm:curve".to_string(),
+                ..Default::default()
+            },
+            token_in: usdc(),
+            token_out: dai(),
+            split: 0f64,
+        };
+        let strategy = MockStrategy {};
+        let transfer_method =
+            strategy.get_transfer_type(swap.clone(), weth(), eth(), weth(), false, false, false);
+        assert_eq!(transfer_method, TransferType::None);
+    }
+
+    #[test]
+    fn test_not_first_swap_in_between_swap_optimization() {
+        // Not the first swap and the in between swaps are optimized. The funds should already be in
+        // the next pool or in the router
+        let swap = Swap {
+            component: ProtocolComponent {
+                protocol_system: "uniswap_v2".to_string(),
+                ..Default::default()
+            },
+            token_in: usdc(),
+            token_out: dai(),
+            split: 0f64,
+        };
+        let strategy = MockStrategy {};
+        let transfer_method =
+            strategy.get_transfer_type(swap.clone(), weth(), eth(), weth(), false, false, true);
+        assert_eq!(transfer_method, TransferType::None);
+    }
 }