tokenPool contract basics

contracts/Samyak/registry.sol

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+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.7.0;
+pragma experimental ABIEncoderV2;
+
+// TODO
+// function for adding and removing rate logics.
+// Added fee variable and required function to change it.
+// Link all the contract more properly.
+// Have to think more on pricePerToken function.
+
+interface IndexInterface {
+  function master() external view returns (address);
+}
+
+contract Registry {
+
+  event LogAddChief(address indexed chief);
+  event LogRemoveChief(address indexed chief);
+
+  IndexInterface public instaIndex;
+
+  mapping (address => bool) public chief;
+  mapping (address => address) public dsa;
+  mapping (address => address) public logic;
+
+  modifier isMaster() {
+    require(msg.sender == instaIndex.master(), "not-master");
+    _;
+  }
+
+  modifier isController() {
+    require(chief[msg.sender] || msg.sender == instaIndex.master(), "not-chief");
+    _;
+  }
+
+  constructor(address _index) public {
+    instaIndex = IndexInterface(_index);
+  }
+
+  /**
+    * @dev Enable New Chief.
+    * @param _chief Address of the new chief.
+  */
+  function enableChief(address _chief) external isMaster {
+    require(_chief != address(0), "address-not-valid");
+    require(!chief[_chief], "chief-already-enabled");
+    chief[_chief] = true;
+    emit LogAddChief(_chief);
+  }
+
+  /**
+    * @dev Disable Chief.
+    * @param _chief Address of the existing chief.
+  */
+  function disableChief(address _chief) external isMaster {
+    require(_chief != address(0), "address-not-valid");
+    require(chief[_chief], "chief-already-disabled");
+    delete chief[_chief];
+    emit LogRemoveChief(_chief);
+  }
+}

contracts/Samyak/tokenPool.sol

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+// SPDX-License-Identifier: MIT
+pragma solidity ^0.7.0;
+pragma experimental ABIEncoderV2;
+
+import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
+import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
+import "@openzeppelin/contracts/token/ERC20/SafeERC20.sol";
+
+import { DSMath } from "./../libs/safeMath.sol";
+
+// TODO - Add ReentrancyGuard lib
+
+interface AccountInterface {
+  function enable(address authority) external;
+  function cast(address[] calldata _targets, bytes[] calldata _datas, address _origin) external payable;
+}
+
+interface IndexInterface {
+  function master() external view returns (address);
+}
+
+interface RegistryInterface {
+  function chief(address) external view returns (bool);
+  function dsa(address) external view returns (address);
+  function rateLogic(address) external view returns (address);
+}
+
+interface RateInterface {
+  function pricePerToken() external view returns (uint);
+  function totalBalance() external view returns (uint);
+  function getTotalToken() external returns (uint totalUnderlyingTkn);
+}
+
+contract PoolToken is ERC20, DSMath {
+    using SafeERC20 for IERC20;
+
+    IERC20 public immutable baseToken;
+    RegistryInterface public immutable registry;
+    IndexInterface public immutable instaIndex;
+
+    uint private tokenBalance;
+    uint private tokenProfit;
+    uint private tokenCap;
+    uint public exchangeRate = 1000000000000000000; // initial 1 token = 1
+    address public settlementLogic;
+    uint public insuranceAmt;
+    
+    constructor(
+        address _registry,
+        address _index,
+        string memory _name,
+        string memory _symbol,
+        address _baseToken
+    ) public ERC20(_name, _symbol) {
+        // TODO - 0
+        baseToken = IERC20(_baseToken);
+        registry = RegistryInterface(_registry);
+        instaIndex = IndexInterface(_index);
+    }
+
+    modifier isMaster() {
+        require(msg.sender == instaIndex.master(), "not-master");
+        _;
+    }
+
+    modifier isChief() {
+        require(registry.chief(msg.sender) || msg.sender == instaIndex.master(), "not-chief");
+        _;
+    }
+    
+    uint dsaAmount;
+    function deploy(uint amount) public isChief {
+        address _dsa = registry.dsa(address(this));
+        baseToken.safeTransfer(_dsa, amount);
+        dsaAmount = add(dsaAmount, amount);
+    }
+
+    function claim(uint amount) public isChief {
+        // address _dsa = registry.dsa(address(this));
+        baseToken.safeTransferFrom(msg.sender, address(this), amount);
+        uint totalAmountWithProfit = RateInterface(address(0)).totalBalance(); // TODO - change to => totalBalanceDSA
+        uint _amount = wdiv(wmul(amount, dsaAmount), totalAmountWithProfit);
+        uint profit = sub(amount, _amount);
+        tokenProfit = add(tokenProfit, profit);
+        dsaAmount = sub(dsaAmount, _amount);
+    }
+
+    function getBalance() public view returns(uint) {
+        return sub(add(dsaAmount, baseToken.balanceOf(address(this))), tokenProfit);
+    }
+
+    function pricePerToken() public view returns(uint) {
+        return 1e18; // TODO - Link to rate logic contract
+    }
+
+    function setExchangeRate() public view isChief {
+        uint _previousRate = exchangeRate;
+        uint _totalToken = RateInterface(settlementLogic).getTotalToken();
+        uint _currentRate = wdiv(_totalToken, totalSupply());
+        if (_currentRate < _previousRate) {
+            uint difRate = _previousRate - _currentRate;
+            uint difTkn = wmul(_totalToken, difRate);
+            insuranceAmt = sub(insuranceAmt, difTkn);
+            _currentRate = _previousRate;
+        } else {
+            uint difRate = _currentRate - _previousRate;
+            uint insureFee = wmul(difRate, 100000000000000000); // 1e17
+            uint insureFeeAmt = wmul(_totalToken, insureRate);
+            insuranceAmt = add(insuranceAmt, insureFeeAmt);
+            _currentRate = sub(_currentRate, insureFee);
+        }
+        exchangeRate = _currentRate;
+    }
+
+    function settlement(address[] calldata _targets, bytes[] calldata _datas, address _origin) external view isChief {
+        address _dsa = registry.dsa(address(this));
+        if (_targets.length > 0 && _datas.length > 0) {
+            AccountInterface(_dsa).cast(_targets, _datas, _origin);
+        }
+        setExchangeRate();
+    }
+
+    function deposit(uint amount) public returns(uint) {
+        uint _newTokenBal = add(tokenBalance, amount);
+        require(_newTokenBal <= getBalance(), "deposit-cap-reached");
+
+        baseToken.safeTransferFrom(msg.sender, address(this), amount);
+        uint iAmt = wdiv(amount, exchangeRate);
+        _mint(msg.sender, iAmt);
+    }
+
+    function withdraw(address owner, uint iAmount) public returns (uint) {
+        // TODO - check balance before withdrawing
+        uint amount = wmul(iAmount, exchangeRate);
+        _burn(msg.sender, iAmount);
+
+        baseToken.safeTransfer(owner, amount);
+    }
+
+    function withdraw(uint amount) public returns (uint) {
+        return withdraw(msg.sender, amount);
+    }
+}