abstract contract Governance is MGovernance {
    event LogNominatedGovernor(address nominatedGovernor);
    event LogNewGovernorAccepted(address acceptedGovernor);
    event LogRemovedGovernor(address removedGovernor);
    event LogNominationCancelled();

    function getGovernanceInfo() internal view virtual returns (GovernanceInfoStruct storage);

    /*
      Current code intentionally prevents governance re-initialization.
      This may be a problem in an upgrade situation, in a case that the upgrade-to implementation
      performs an initialization (for real) and within that calls initGovernance().

      Possible workarounds:
      1. Clearing the governance info altogether by changing the MAIN_GOVERNANCE_INFO_TAG.
         This will remove existing main governance information.
      2. Modify the require part in this function, so that it will exit quietly
         when trying to re-initialize (uncomment the lines below).
    */
    function initGovernance() internal {
        GovernanceInfoStruct storage gub = getGovernanceInfo();
        require(!gub.initialized, "ALREADY_INITIALIZED");
        gub.initialized = true; // to ensure addGovernor() won't fail.
        // Add the initial governer.
        addGovernor(msg.sender);
    }

    function isGovernor(address testGovernor) internal view override returns (bool) {
        GovernanceInfoStruct storage gub = getGovernanceInfo();
        return gub.effectiveGovernors[testGovernor];
    }

    /*
      Cancels the nomination of a governor candidate.
    */
    function cancelNomination() internal onlyGovernance {
        GovernanceInfoStruct storage gub = getGovernanceInfo();
        gub.candidateGovernor = address(0x0);
        emit LogNominationCancelled();
    }

    function nominateNewGovernor(address newGovernor) internal onlyGovernance {
        GovernanceInfoStruct storage gub = getGovernanceInfo();
        require(!isGovernor(newGovernor), "ALREADY_GOVERNOR");
        gub.candidateGovernor = newGovernor;
        emit LogNominatedGovernor(newGovernor);
    }

    /*
      The addGovernor is called in two cases:
      1. by acceptGovernance when a new governor accepts its role.
      2. by initGovernance to add the initial governor.
      The difference is that the init path skips the nominate step
      that would fail because of the onlyGovernance modifier.
    */
    function addGovernor(address newGovernor) private {
        require(!isGovernor(newGovernor), "ALREADY_GOVERNOR");
        GovernanceInfoStruct storage gub = getGovernanceInfo();
        gub.effectiveGovernors[newGovernor] = true;
    }

    function acceptGovernance() internal {
        // The new governor was proposed as a candidate by the current governor.
        GovernanceInfoStruct storage gub = getGovernanceInfo();
        require(msg.sender == gub.candidateGovernor, "ONLY_CANDIDATE_GOVERNOR");

        // Update state.
        addGovernor(gub.candidateGovernor);
        gub.candidateGovernor = address(0x0);

        // Send a notification about the change of governor.
        emit LogNewGovernorAccepted(msg.sender);
    }

    /*
      Remove a governor from office.
    */
    function removeGovernor(address governorForRemoval) internal onlyGovernance {
        require(msg.sender != governorForRemoval, "GOVERNOR_SELF_REMOVE");
        GovernanceInfoStruct storage gub = getGovernanceInfo();
        require(isGovernor(governorForRemoval), "NOT_GOVERNOR");
        gub.effectiveGovernors[governorForRemoval] = false;
        emit LogRemovedGovernor(governorForRemoval);
    }
}
/*
 Implements Generic Governance, applicable for both proxy and main contract, and possibly others.
 Notes:
 The use of the same function names by both the Proxy and a delegated implementation
 is not possible since calling the implementation functions is done via the default function
 of the Proxy. For this reason, for example, the implementation of MainContract (MainGovernance)
 exposes mainIsGovernor, which calls the internal isGovernor method.
 */
function addGovernor(address newGovernor) private {
    require(!isGovernor(newGovernor), "ALREADY_GOVERNOR");
    GovernanceInfoStruct storage gub = getGovernanceInfo();
    gub.effectiveGovernors[newGovernor] = true;
}

/*
 The addGovernor is called in two cases:
 1. by acceptGovernance when a new governor accepts its role.
 2. by initGovernance to add the initial governor.
 The difference is that the init path skips the nominate step
 that would fail because of the onlyGovernance modifier.
 */