From fdb675bb6a10b139a79161dc99e93c2812a6a41b Mon Sep 17 00:00:00 2001
From: Samyak Jain <34437877+KaymasJain@users.noreply.github.com>
Date: Tue, 19 Nov 2019 03:08:54 +0530
Subject: [PATCH] MKR fee contract

---
 contracts/Read/InstaCdpFee.sol | 103 +++++++++++++++++++++++++++++++++
 1 file changed, 103 insertions(+)
 create mode 100644 contracts/Read/InstaCdpFee.sol

diff --git a/contracts/Read/InstaCdpFee.sol b/contracts/Read/InstaCdpFee.sol
new file mode 100644
index 0000000..81552ce
--- /dev/null
+++ b/contracts/Read/InstaCdpFee.sol
@@ -0,0 +1,103 @@
+pragma solidity ^0.5.0;
+
+interface TubInterface {
+    function tab(bytes32) external view returns (uint);
+    function rap(bytes32) external view returns (uint);
+    function pep() external view returns (PepInterface);
+    function cups(bytes32) external view returns (address, uint, uint, uint);
+}
+
+interface PepInterface {
+    function peek() external view returns (bytes32, bool);
+}
+
+interface InstaMcdAddress {
+    function dai() external view returns (address);
+    function gov() external view returns (address);
+    function saiTub() external view returns (address);
+    function weth() external view returns (address);
+    function sai() external view returns (address);
+}
+
+interface UniswapExchange {
+    function getEthToTokenOutputPrice(uint256 tokensBought) external view returns (uint256 ethSold);
+    function getTokenToEthOutputPrice(uint256 ethBought) external view returns (uint256 tokensSold);
+}
+
+interface UniswapFactoryInterface {
+    function getExchange(address token) external view returns (address exchange);
+}
+
+interface OtcInterface {
+    function getPayAmount(address, address, uint) external view returns (uint);
+}
+
+
+contract DSMath {
+
+    function add(uint x, uint y) internal pure returns (uint z) {
+        require((z = x + y) >= x, "math-not-safe");
+    }
+
+    function mul(uint x, uint y) internal pure returns (uint z) {
+        require(y == 0 || (z = x * y) / y == x, "math-not-safe");
+    }
+
+    uint constant WAD = 10 ** 18;
+    // uint constant RAY = 10 ** 27;
+
+    // function rmul(uint x, uint y) internal pure returns (uint z) {
+    //     z = add(mul(x, y), RAY / 2) / RAY;
+    // }
+
+    // function rdiv(uint x, uint y) internal pure returns (uint z) {
+    //     z = add(mul(x, RAY), y / 2) / y;
+    // }
+
+    function wdiv(uint x, uint y) internal pure returns (uint z) {
+        z = add(mul(x, WAD), y / 2) / y;
+    }
+
+}
+
+
+contract CdpFee is DSMath {
+
+    address public instaMcdAddress = 0x5092b94F61b1aa54969C67b58695a6fB15D70645;
+    address public otcAddr = 0x39755357759cE0d7f32dC8dC45414CCa409AE24e;
+    address public ethAddr = 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE;
+    address public uniMkrEx = 0x2C4Bd064b998838076fa341A83d007FC2FA50957;
+    address public uniFactory = 0xc0a47dFe034B400B47bDaD5FecDa2621de6c4d95;
+    address public peekAddr = 0x5C1fc813d9c1B5ebb93889B3d63bA24984CA44B7;
+    address public mkr = 0x9f8F72aA9304c8B593d555F12eF6589cC3A579A2;
+    address public weth = 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2;
+    
+    function getMkrRate() public view returns (uint mkrInUsd) {
+        (bytes32 val,) = PepInterface(peekAddr).peek();
+        mkrInUsd = uint(val);
+    }
+
+    function getBestMkrSwap(address srcTknAddr, uint destMkrAmt) public view returns(uint bestEx, uint srcAmt) {
+        uint oasisPrice = getOasisSwap(srcTknAddr, destMkrAmt);
+        uint uniswapPrice = getUniswapSwap(srcTknAddr, destMkrAmt);
+        srcAmt = oasisPrice < uniswapPrice ? oasisPrice : uniswapPrice;
+        bestEx = oasisPrice < uniswapPrice ? 0 : 1; // if 0 then use Oasis for Swap, if 1 then use Uniswap
+    }
+
+    function getOasisSwap(address tokenAddr, uint destMkrAmt) public view returns(uint srcAmt) {
+        address srcTknAddr = tokenAddr == ethAddr ? weth : tokenAddr;
+        srcAmt = OtcInterface(otcAddr).getPayAmount(srcTknAddr, mkr, destMkrAmt);
+    }
+
+    function getUniswapSwap(address srcTknAddr, uint destMkrAmt) public view returns(uint srcAmt) {
+        UniswapExchange mkrEx = UniswapExchange(uniMkrEx);
+        if (srcTknAddr == ethAddr) {
+            srcAmt = mkrEx.getEthToTokenOutputPrice(destMkrAmt);
+        } else {
+            address buyTknExAddr = UniswapFactoryInterface(uniFactory).getExchange(srcTknAddr);
+            UniswapExchange buyTknEx = UniswapExchange(buyTknExAddr);
+            srcAmt = buyTknEx.getTokenToEthOutputPrice(mkrEx.getEthToTokenOutputPrice(destMkrAmt)); //Check thrilok is this correct
+        }
+    }
+
+}
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