pragma solidity ^0.6.0;

contract AdminAuth {

    address public owner;
    address public admin;

    modifier onlyOwner() {
        require(owner == msg.sender);
        _;
    }

    constructor() public {
        owner = msg.sender;
    }

    /// @notice Admin is set by owner first time, after that admin is super role and has permission to change owner
    /// @param _admin Address of multisig that becomes admin
    function setAdminByOwner(address _admin) public {
        require(msg.sender == owner);
        require(admin == address(0));

        admin = _admin;
    }

    /// @notice Admin is able to set new admin
    /// @param _admin Address of multisig that becomes new admin
    function setAdminByAdmin(address _admin) public {
        require(msg.sender == admin);

        admin = _admin;
    }

    /// @notice Admin is able to change owner
    /// @param _owner Address of new owner
    function setOwnerByAdmin(address _owner) public {
        require(msg.sender == admin);

        owner = _owner;
    }
}

contract ZrxAllowlist is AdminAuth {

    mapping (address => bool) public zrxAllowlist;

    function setAllowlistAddr(address _zrxAddr, bool _state) public onlyOwner {
        zrxAllowlist[_zrxAddr] = _state;
    }

    function isZrxAddr(address _zrxAddr) public view returns (bool) {
        return zrxAllowlist[_zrxAddr];
    }
}