add big formula and prepare treasury redemption; not tested yet

Signed-off-by: Uncle Fatso <uncle.fatso@ghostchain.io>

src/Treasury.sol

@@ -4,10 +4,14 @@ pragma solidity ^0.8.20;
 import "@openzeppelin-contracts/token/ERC20/IERC20.sol";
 import "@openzeppelin-contracts/token/ERC20/extensions/IERC20Metadata.sol";
 import "@openzeppelin-contracts/token/ERC20/utils/SafeERC20.sol";
+
+import "@uniswap-v2-core-1.0.1/interfaces/IUniswapV2Factory.sol";
+import "@uniswap-v2-core-1.0.1/interfaces/IUniswapV2Pair.sol";
 import "@uniswap-v2-periphery-1.1.0-beta.0/interfaces/IUniswapV2Router02.sol";
 import "@uniswap-v2-periphery-1.1.0-beta.0/interfaces/IUniswapV2Router01.sol";
 
 import "./types/GhostAccessControlled.sol";
+import "./libraries/FixedPoint.sol";
 
 import "./interfaces/IFTSO.sol";
 import "./interfaces/ISTNK.sol";
@@ -211,58 +215,58 @@ contract GhostTreasury is GhostAccessControlled, ITreasury {
         emit Permissioned(toDisable, status, false);
     }
 
+    function _quantityToBeSwapped(uint256 xa, uint256 x1) internal pure returns (uint256) {
+        uint256 y1 = x1 * 1994 / 1000;
+        uint256 y2 = Babylonian.sqrt(y1**2 + 4 * xa * x1 * 997 / 1000);
+        return (y2 - y1) * 1000 / 1994;
+    }
+
     function redeemReserve(
         address router, // could be an issue
-        address token,
+        uint256 amount,
-        uint256 swapAmount,
+        uint256 slippage
-        uint256 liquidityAmount
     ) external onlyGovernor {
-        uint256 deadline = block.timestamp; // No delays in timestamp
         address weth = IUniswapV2Router01(router).WETH();
+        address pair = IUniswapV2Factory(IUniswapV2Router01(router).factory()).getPair(ftso, weth);
 
-        // Reconstruct path based on token address.
+        IERC20(weth).approve(router, amount + 1);
-        // Avoid user's input error.
+
+        (uint256 reserve0, uint256 reserve1,) = IUniswapV2Pair(pair).getReserves();
         address[] memory path;
-        if (token < weth) {
+        if (ftso < weth) {
-            path[0] = token;
+            path[0] = ftso;
             path[1] = weth;
+
+            reserve0 = reserve1 ^ reserve0;
+            reserve1 = reserve1 ^ reserve0;
+            reserve0 = reserve1 ^ reserve0;
         } else {
             path[0] = weth;
-            path[1] = token;
+            path[1] = ftso;
-        }
-
-        uint256 totalAmount = swapAmount + liquidityAmount;
-        if (IERC20(token).allowance(address(this), router) <= totalAmount) {
-            IERC20(token).approve(router, totalAmount + 1);
-        }
-
-        uint256[] memory amounts = IUniswapV2Router02(router).getAmountsOut(swapAmount, path);
-        uint256 amountOut = amounts[0];
-        if (token < weth) {
-            amountOut = amounts[1];
         }
 
+        uint256 amountIn = _quantityToBeSwapped(amount, reserve0);
+        uint256[] memory amounts = IUniswapV2Router02(router).getAmountsOut(amountIn, path);
         IUniswapV2Router02(router).swapExactTokensForTokens(
-            swapAmount,
+            amountIn,
-            amountOut,
+            amounts[0],
             path,
             address(this),
-            deadline
+            block.timestamp
         );
 
-        if (IERC20(weth).allowance(address(this), router) <= amountOut) {
+        amountIn = amount - amountIn;
-            IERC20(token).approve(router, amountOut + 1);
+        IERC20(ftso).approve(router, amountIn + 1);
-        }
 
         IUniswapV2Router02(router).addLiquidity(
             path[0],
             path[1],
-            liquidityAmount,
+            amountIn,
-            amountOut,
+            amounts[0],
-            liquidityAmount,
+            amountIn * (1e7 - slippage) / 1e7,
-            amountOut,
+            amounts[0] * (1e7 - slippage) / 1e7,
             address(this),
-            deadline
+            block.timestamp
         );
     }