balancer-v2-vault

// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.0;

import "@balancer-labs/v2-interfaces/contracts/vault/IVault.sol";
import "@balancer-labs/v2-interfaces/contracts/vault/IFlashLoanRecipient.sol";

contract Swap is IFlashLoanRecipient {
    IVault private constant vault = IVault(0xBA12222222228d8Ba445958a75a0704d566BF2C8);

    event eventLog(string eventName);

    function makeFlashLoan(
        IERC20[] memory tokens,
        uint256[] memory amounts,
        bytes memory userData
    ) external {
      vault.flashLoan(this, tokens, amounts, userData);
      emit eventLog("making flash...");
    }

    function receiveFlashLoan(
        IERC20[] memory tokens,
        uint256[] memory amounts,
        uint256[] memory feeAmounts,
        bytes memory userData
    ) external override {
        require(msg.sender == address(vault));

        //do something here...

        // return token0
        IERC20(tokens[0]).transfer(address(vault), amounts[0]);
        emit eventLog("receive done...");
    }
}