Merge pull request #346 from tranchess/dev-terry-flash-helper

Add FlashSwapRouterV3Helper

contracts/swap/FlashSwapRouterV3Helper.sol

@@ -0,0 +1,52 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+pragma solidity >=0.6.10 <0.8.0;
+
+import "./FlashSwapRouterV3.sol";
+
+contract FlashSwapRouterV3Helper {
+ FlashSwapRouterV3 public immutable flashSwapRouter;
+
+ constructor(address flashSwapRouter_) public {
+ flashSwapRouter = FlashSwapRouterV3(flashSwapRouter_);
+ }
+
+ /// @dev Only meant for an off-chain client to call with eth_call.
+ /// This function uses binary search to find the maximum `outR` in the range `[minOutR, maxOutR)`
+ /// such that `getBuyR(outR).quoteDelta <= inQuote`. When `inQuote` does not increase monotonically
+ /// with `outR`, this function does not guarantee to return the optimal solution.
+ ///
+ /// Although `FlashSwapRouterV3.getBuyR` is not a view function, it typically does not alter any
+ /// contract state. However, this function fails when `FlashSwapRouterV3.getBuyR` does modify some state.
+ function getBuyRFromQuote(
+ IFundV5 fund,
+ bool needWrap,
+ address queenSwapOrPrimaryMarketRouter,
+ address tokenQuote,
+ uint256 minOutR,
+ uint256 maxOutR,
+ uint256 inQuote
+ ) external returns (uint256 outR) {
+ while (minOutR < maxOutR - 1) {
+ uint256 midOutR = minOutR / 2 + maxOutR / 2;
+ (bool success, bytes memory data) = address(flashSwapRouter).call(
+ abi.encodeWithSelector(
+ FlashSwapRouterV3.getBuyR.selector,
+ fund,
+ needWrap,
+ queenSwapOrPrimaryMarketRouter,
+ tokenQuote,
+ midOutR
+ )
+ );
+ if (success) {
+ (uint256 quoteDelta, ) = abi.decode(data, (uint256, uint256));
+ if (quoteDelta <= inQuote) {
+ minOutR = midOutR;
+ continue;
+ }
+ }
+ maxOutR = midOutR;
+ }
+ return minOutR;
+ }
+}