Building Flash Receiver

In the example below you can find a simple example for a flash receiver that can be used by the Flash Protocol.

We’ll define a function required by the Flash Protocol called receiveFlash and we’ll simply collect the yield and reward the staker with half of the yield amount in DAI. So if the user stakes 1000 $FLASH with 10% FPY, we’ll receive 100 $FLASH and we’ll send him 50 DAI.

Note

The code below is used only for example and testing. Do not use on production.

// SPDX-License-Identifier: GPL-3.0
pragma solidity ^0.6.0;

import '@openzeppelin/contracts/math/SafeMath.sol';
import './interfaces/ERC20.sol';

contract FlashReceiver {
    using SafeMath for uint256;

    address public constant FLASH_PROTOCOL = 0x2Fec418941c8E710372625Df48F32b69Cf4431A9;
    address public constant DAI_ADDRESS = 0x6b175474e89094c44da98b954eedeac495271d0f;

    modifier onlyFlashProtocol() {
        require(msg.sender == FLASH_PROTOCOL, 'Only FlashProtocol can call this');
        _;
    }

    function receiveFlash(
        uint256 amountIn,
        uint256 expireAfter,
        uint256 mintedAmount,
        address staker
    ) public override onlyFlashProtocol returns (uint256) {
        uint256 daiReward = mintedAmount.div(2);
        IERC20(DAI_ADDRESS).transfer(staker, daiReward);
        return daiReward;
    }
}

Now, if we deploy the contract we can use the contract address in the receiver field when calling stake and we’ll redirect the user’s yield to that contract. The result would be that the user will stake $FLASH and receive $DAI.