Feature/refferal contract

contracts/Referral.sol

@@ -0,0 +1,118 @@
+/* Copyright (C) 2020 PlotX.io
+
+  This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+    along with this program.  If not, see http://www.gnu.org/licenses/ */
+
+pragma solidity 0.5.7;
+
+import "./PlotXToken.sol";
+import "./external/openzeppelin-solidity/math/SafeMath.sol";
+import "./external/openzeppelin-solidity/token/ERC20/ERC20.sol";
+
+interface IbLOTToken {
+  function mint(address account, uint256 amount) external returns (bool);
+}
+
+contract Referral {
+
+  using SafeMath for uint256;
+  IbLOTToken bLotToken;
+  PlotXToken public plotToken;
+  address public owner;
+  address public signer;
+  uint public endDate;
+  uint public remainingbudget;
+  uint public refferalAmount;
+
+
+  /// @dev mapping to maintain if user have claimed or not
+  mapping(address => bool) public userClaimed;
+
+  /**
+   * @dev modifier that allows only the owner to execute the function
+   */
+  modifier onlyOwner() {
+    require(owner == msg.sender, "Not owner");
+        _;
+  }
+
+  /**     
+   * @dev Constructor     
+   * @param _plotToken The address of plot token       
+   * @param _bLotToken The address of BLot token   
+   * @param _endDate user can claim thier allocated amounts before this time.
+   * @param _budget total amount of BLot to be minted
+   */
+  constructor(address _plotToken, address _bLotToken, address _signer, uint _endDate, uint _budget, uint _refferalAmount) public
+  {
+    require(_plotToken != address(0),"Cannot be null address");
+    require(_bLotToken != address(0),"Cannot be null address");
+    require(_signer != address(0),"Cannot be null address");
+    require(_refferalAmount != 0,"Cannot be zero referral amount");
+    require(_budget >= _refferalAmount,"Cannot be less than referral amount");
+    require(_endDate > now,"End date cannot be past time");
+    plotToken = PlotXToken(_plotToken);
+    bLotToken = IbLOTToken(_bLotToken);
+    owner = msg.sender;
+    signer = _signer;
+    endDate = _endDate;
+    remainingbudget = _budget;
+    refferalAmount = _refferalAmount;
+    plotToken.approve(address(bLotToken), _budget);
+  }
+
+  /**
+   * @dev Allows owner to take back left over plot token after end date.
+   */
+  function takeLeftOverPlot() external onlyOwner {
+    require(endDate <= now, "Callable only after end date");
+    plotToken.transfer(owner, plotToken.balanceOf(address(this)));
+  }
+
+  /**
+   * @dev Allows users to claim their allocated tokens.
+   * user should claim before end date.
+   */
+  function claim(bytes calldata hash, uint8 v, bytes32 r, bytes32 s) external {
+    require(endDate > now, "Callable only before end date");
+    require(!userClaimed[msg.sender], "Already claimed");
+    require(msg.sender == abi.decode(hash, (address)));
+    require(isValidSignature(hash, v, r, s));
+    userClaimed[msg.sender] = true;
+    bLotToken.mint(msg.sender, refferalAmount);
+  } 
+
+  /**
+   * @dev Verifies signature.
+   * @param hash order hash
+   * @param v argument from vrs hash.
+   * @param r argument from vrs hash.
+   * @param s argument from vrs hash.
+   */  
+  function isValidSignature(bytes memory hash, uint8 v, bytes32 r, bytes32 s) public view returns(bool) {
+    bytes memory prefix = "\x19Ethereum Signed Message:\n32";
+    bytes32 prefixedHash = keccak256(abi.encodePacked(prefix, hash));
+    address _signer = ecrecover(prefixedHash, v, r, s);
+    return (_signer == signer);
+  }
+
+  /**
+   * @dev Allows owner to transfer ownership to other address.
+   * @param _newOwner new owner address
+   */
+  function tranferOwnership(address _newOwner) external onlyOwner {
+    require(_newOwner != address(0), "Can not be null address");
+    owner = _newOwner;
+  }
+
+}