From 8e4cbd88633f84847ad41a22bc69a12cca091f11 Mon Sep 17 00:00:00 2001
From: Samyak Jain <34437877+KaymasJain@users.noreply.github.com>
Date: Thu, 27 Aug 2020 20:23:04 +1000
Subject: [PATCH] chnaged exchange rate modal

---
 contracts/tokenPool.sol | 39 +++++++++++----------------------------
 1 file changed, 11 insertions(+), 28 deletions(-)

diff --git a/contracts/tokenPool.sol b/contracts/tokenPool.sol
index 698839f..5cda409 100644
--- a/contracts/tokenPool.sol
+++ b/contracts/tokenPool.sol
@@ -31,20 +31,6 @@ interface RateInterface {
 }
 
 contract PoolToken is ReentrancyGuard, DSMath, ERC20Pausable {
-    function convert36To18(uint _dec, uint256 _amt) public pure returns (uint256 amt) {
-        amt = (_amt / 10 ** (18 - _dec));
-    }
-
-    function convert18To36(uint _dec, uint256 _amt) public pure returns (uint256 amt) {
-        amt = mul(_amt, 10 ** (18 - _dec));
-    }
-
-    function convertDecTo18(uint _dec, uint256 _amt) internal pure returns (uint256 amt) {
-        amt = mul(_amt, 10 ** (18 - _dec));
-    }
-
-
-
     using SafeERC20 for IERC20;
 
     event LogDeploy(uint amount);
@@ -56,7 +42,6 @@ contract PoolToken is ReentrancyGuard, DSMath, ERC20Pausable {
     event LogPausePool(bool);
 
     IERC20 public immutable baseToken; // Base token. Eg:- DAI, USDC, etc.
-    uint256 public immutable baseDecimal; // Base token. Eg:- DAI, USDC, etc.
     RegistryInterface public immutable registry; // Pool Registry
     IndexInterface public constant instaIndex = IndexInterface(0x2971AdFa57b20E5a416aE5a708A8655A9c74f723); // Main Index
 
@@ -71,7 +56,6 @@ contract PoolToken is ReentrancyGuard, DSMath, ERC20Pausable {
         address _baseToken
     ) public ERC20(_name, _symbol) {
         baseToken = IERC20(_baseToken);
-        baseDecimal = ERC20(_baseToken).decimals();
         registry = RegistryInterface(_registry);
         exchangeRate = 10 ** uint(36 - ERC20(_baseToken).decimals());
     }
@@ -88,23 +72,22 @@ contract PoolToken is ReentrancyGuard, DSMath, ERC20Pausable {
     }
 
     function setExchangeRate() public isChief {
-      uint _previousRate = convert36To18(baseDecimal, exchangeRate);
+      uint _previousRate = exchangeRate;
       uint _totalToken = RateInterface(registry.poolLogic(address(this))).getTotalToken();
-      uint _currentRate = convertDecTo18(baseDecimal, wdiv(_totalToken, totalSupply()));
-      if (_currentRate < _previousRate) {
+      // should we add totalToken - insurance here or keep it on logic contract?
+      uint _currentRate = wdiv(totalSupply(), _totalToken);
+      if (_currentRate > _previousRate) {
         uint difTkn = sub(tokenBalance, _totalToken);
         insuranceAmt = sub(insuranceAmt, difTkn);
         _currentRate = _previousRate;
       } else {
         uint fee = registry.insureFee(address(this));
-        uint difRate = _currentRate - _previousRate;
-        uint insureFee = wmul(difRate, fee);
         uint insureFeeAmt = wmul(sub(_totalToken, tokenBalance), fee);
         insuranceAmt = add(insuranceAmt, insureFeeAmt);
-        _currentRate = sub(_currentRate, insureFee);
-        tokenBalance = sub(_totalToken, insuranceAmt);
+        tokenBalance = sub(_totalToken, insureFeeAmt);
+        _currentRate = wdiv(totalSupply(), tokenBalance);
       }
-      exchangeRate = convert18To36(baseDecimal, _currentRate);
+      exchangeRate = _currentRate;
       emit LogExchangeRate(exchangeRate, tokenBalance, insuranceAmt);
     }
 
@@ -122,7 +105,7 @@ contract PoolToken is ReentrancyGuard, DSMath, ERC20Pausable {
       require(_newTokenBal <= registry.poolCap(address(this)), "deposit-cap-reached");
 
       baseToken.safeTransferFrom(msg.sender, address(this), tknAmt);
-      uint _mintAmt = wdiv(tknAmt, exchangeRate);
+      uint _mintAmt = wmul(tknAmt, exchangeRate);
       _mint(msg.sender, _mintAmt);
 
       emit LogDeposit(tknAmt, _mintAmt);
@@ -132,14 +115,14 @@ contract PoolToken is ReentrancyGuard, DSMath, ERC20Pausable {
       uint poolBal = baseToken.balanceOf(address(this));
       require(tknAmt <= poolBal, "not-enough-liquidity-available");
       uint _bal = balanceOf(msg.sender);
-      uint _tknBal = wmul(_bal, exchangeRate);
+      uint _tknBal = wdiv(_bal, exchangeRate);
       uint _burnAmt;
       if (tknAmt == uint(-1)) {
         _burnAmt = _bal;
-        _tknAmt = wmul(_burnAmt, exchangeRate);
+        _tknAmt = wdiv(_burnAmt, exchangeRate);
       } else {
         require(tknAmt <= _tknBal, "balance-exceeded");
-        _burnAmt = wdiv(tknAmt, exchangeRate);
+        _burnAmt = wmul(tknAmt, exchangeRate);
         _tknAmt = tknAmt;
       }