From cf41c472c6ee146db2440b2a2a567aada40184b4 Mon Sep 17 00:00:00 2001
From: domenicodev <domenico.romeo3919@gmail.com>
Date: Wed, 17 Jan 2024 15:24:18 +0100
Subject: [PATCH] fix: Initial code review fixes

---
 evm/src/integral/IntegralSwapAdapter.sol | 50 ++++++++++++++++--------
 evm/test/IntegralSwapAdapter.t.sol       | 19 ---------
 2 files changed, 34 insertions(+), 35 deletions(-)

diff --git a/evm/src/integral/IntegralSwapAdapter.sol b/evm/src/integral/IntegralSwapAdapter.sol
index 85e9037..67ab0bb 100644
--- a/evm/src/integral/IntegralSwapAdapter.sol
+++ b/evm/src/integral/IntegralSwapAdapter.sol
@@ -8,6 +8,7 @@ import {SafeERC20} from "openzeppelin-contracts/contracts/token/ERC20/utils/Safe
 /// @dev Integral submitted deadline of 3600 seconds (1 hour) to Paraswap, but it is not strictly necessary to be this long
 /// as the contract allows less durations, we use 1000 seconds (15 minutes) as a deadline
 uint256 constant SWAP_DEADLINE_SEC = 1000;
+uint256 constant STANDARD_TOKEN_DECIMALS = 10**18;
 
 /// @title Integral Swap Adapter
 contract IntegralSwapAdapter is ISwapAdapter {
@@ -33,12 +34,43 @@ contract IntegralSwapAdapter is ISwapAdapter {
         uint256[] memory _specifiedAmounts
     ) external view override returns (Fraction[] memory _prices) {
         _prices = new Fraction[](_specifiedAmounts.length);
+        uint256 price = getPriceAt(address(_sellToken), address(_buyToken));
         
         for (uint256 i = 0; i < _specifiedAmounts.length; i++) {
-            _prices[i] = getPriceAt(address(_sellToken), address(_buyToken));
+            _prices[i] = price;
         }
     }
 
+    /// @notice Get swap price including fee
+    /// @param sellToken token to sell
+    /// @param buyToken token to buy
+    function getPriceAt(address sellToken, address buyToken) internal view returns(Fraction memory) {
+        uint256 priceWithoutFee = relayer.getPriceByTokenAddresses(address(sellToken), address(buyToken));
+        ITwapFactory factory = ITwapFactory(relayer.factory());
+        address pairAddress = factory.getPair(address(sellToken), address(buyToken));
+
+        // get swapFee formatted; swapFee is a constant
+        uint256 swapFeeFormatted = (STANDARD_TOKEN_DECIMALS - relayer.swapFee(pairAddress));
+
+        // get token decimals
+        uint256 sellTokenDecimals = 10**ERC20(sellToken).decimals();
+        uint256 buyTokenDecimals = 10**ERC20(buyToken).decimals();
+
+        /**
+         * @dev
+         * Denominator works as a "standardizer" for the price rather than a reserve value
+         * as Integral takes prices from oracles and do not operate with reserves;
+         * it is therefore used to maintain integrity for the Fraction division,
+         * as numerator and denominator could have different token decimals(es. ETH(18)-USDC(6)).
+         * Both numerator and denominator are also multiplied by STANDARD_TOKEN_DECIMALS
+         * to ensure that precision losses are minimized or null.
+         */
+        return Fraction(
+            priceWithoutFee * STANDARD_TOKEN_DECIMALS,
+            STANDARD_TOKEN_DECIMALS * sellTokenDecimals * swapFeeFormatted / buyTokenDecimals
+        );
+    }
+
     /// @inheritdoc ISwapAdapter
     function swap(
         bytes32,
@@ -154,7 +186,7 @@ contract IntegralSwapAdapter is ISwapAdapter {
             to: msg.sender,
             submitDeadline: uint32(block.timestamp + SWAP_DEADLINE_SEC),
             amountIn: amount,
-            amountOutMin: amountOut
+            amountOutMin: 0
         }));
 
         return amountOut;
@@ -190,20 +222,6 @@ contract IntegralSwapAdapter is ISwapAdapter {
 
         return amountIn;
     }
-
-    /// @notice Get swap price including fee
-    /// @param sellToken token to sell
-    /// @param buyToken token to buy
-    function getPriceAt(address sellToken, address buyToken) internal view returns(Fraction memory) {
-        uint256 priceWithoutFee = relayer.getPriceByTokenAddresses(address(sellToken), address(buyToken));
-        ITwapFactory factory = ITwapFactory(relayer.factory());
-        address pairAddress = factory.getPair(address(sellToken), address(buyToken));
-
-        return Fraction(
-            priceWithoutFee * 10**18,
-            10**(ERC20(sellToken).decimals()) * 10**18 * (10**18 - relayer.swapFee(pairAddress)) / 10**(ERC20(buyToken).decimals())
-        );
-    }
 }
 
 interface ITwapRelayer {
diff --git a/evm/test/IntegralSwapAdapter.t.sol b/evm/test/IntegralSwapAdapter.t.sol
index 65b8fd5..3d41885 100644
--- a/evm/test/IntegralSwapAdapter.t.sol
+++ b/evm/test/IntegralSwapAdapter.t.sol
@@ -49,25 +49,6 @@ contract IntegralSwapAdapterTest is Test, ISwapAdapterTypes {
             assertGt(prices[i].denominator, 0);
         }
     }
-
-    function testPriceKeepingIntegral() public {
-        bytes32 pair = bytes32(bytes20(USDC_WETH_PAIR));
-        uint256[] memory amounts = new uint256[](TEST_ITERATIONS);
-
-        for (uint256 i = 0; i < TEST_ITERATIONS; i++) {
-            amounts[i] = 1000 * i * 10 ** 15;
-        }
-
-        Fraction[] memory prices = adapter.price(pair, WETH, USDC, amounts);
-
-        for (uint256 i = 0; i < TEST_ITERATIONS - 1; i++) {
-            Fraction memory reducedPrice0 = Fraction(prices[i].numerator / 10**18, prices[i].denominator / 10**18);
-            Fraction memory reducedPrice1 = Fraction(prices[i + 1].numerator / 10**18, prices[i + 1].denominator / 10**18);
-            assertEq(reducedPrice0.compareFractions(reducedPrice1), 0);
-            assertGt(prices[i].denominator, 0);
-            assertGt(prices[i + 1].denominator, 0);
-        }
-    }
  
     /// @dev Since TwapRelayer's calculateAmountOut function is internal, and using quoteSell would
     /// revert the transaction if calculateAmountOut is not enough,