pragma ever-solidity >= 0.68.0;

pragma AbiHeader expire;
pragma AbiHeader pubkey;

import "../libraries/UtilityErrors.tsol";

contract InternalOwner {
    address public owner;

    event OwnershipTransferred(address previousOwner, address newOwner);

    modifier onlyOwner() {
        require(
            msg.sender == owner && msg.sender.value != 0,
            UtilityErrors.CALLER_IS_NOT_OWNER
        );
        _;
    }

    /*
        @dev Internal function for setting owner
        Can be used in child contracts
    */
    function setOwnership(address newOwner) internal {
        address oldOwner = owner;

        owner = newOwner;

        emit OwnershipTransferred(oldOwner, newOwner);
    }

    /*
        @dev Transfer ownership to the new owner
    */
    function transferOwnership(address newOwner) external onlyOwner {
        require(
            newOwner != address.makeAddrStd(0, 0),
            UtilityErrors.INVALID_NEW_OWNER
        );

        setOwnership(newOwner);
    }

    /*
        @dev Renounce ownership. Can't be aborted!
    */
    function renounceOwnership() external onlyOwner {
        address newOwner = address.makeAddrStd(0, 0);

        setOwnership(newOwner);
    }
}