openzeppelin-contracts/contracts/governance/extensions/GovernorVotesQuorumFractionUpgradeable.sol

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (governance/extensions/GovernorVotesQuorumFraction.sol)

pragma solidity ^0.8.0;

import "./GovernorVotesUpgradeable.sol";
import "../../proxy/utils/Initializable.sol";

/**
 * @dev Extension of {Governor} for voting weight extraction from an {ERC20Votes} token and a quorum expressed as a
 * fraction of the total supply.
 *
 * _Available since v4.3._
 */
abstract contract GovernorVotesQuorumFractionUpgradeable is Initializable, GovernorVotesUpgradeable {
    uint256 private _quorumNumerator;

    event QuorumNumeratorUpdated(uint256 oldQuorumNumerator, uint256 newQuorumNumerator);

    function __GovernorVotesQuorumFraction_init(uint256 quorumNumeratorValue) internal onlyInitializing {
        __GovernorVotesQuorumFraction_init_unchained(quorumNumeratorValue);
    }

    function __GovernorVotesQuorumFraction_init_unchained(uint256 quorumNumeratorValue) internal onlyInitializing {
        _updateQuorumNumerator(quorumNumeratorValue);
    }

    function quorumNumerator() public view virtual returns (uint256) {
        return _quorumNumerator;
    }

    function quorumDenominator() public view virtual returns (uint256) {
        return 100;
    }

    function quorum(uint256 blockNumber) public view virtual override returns (uint256) {
        return (token.getPastTotalSupply(blockNumber) * quorumNumerator()) / quorumDenominator();
    }

    function updateQuorumNumerator(uint256 newQuorumNumerator) external virtual onlyGovernance {
        _updateQuorumNumerator(newQuorumNumerator);
    }

    function _updateQuorumNumerator(uint256 newQuorumNumerator) internal virtual {
        require(
            newQuorumNumerator <= quorumDenominator(),
            "GovernorVotesQuorumFraction: quorumNumerator over quorumDenominator"
        );

        uint256 oldQuorumNumerator = _quorumNumerator;
        _quorumNumerator = newQuorumNumerator;

        emit QuorumNumeratorUpdated(oldQuorumNumerator, newQuorumNumerator);
    }

    /**
     * This empty reserved space is put in place to allow future versions to add new
     * variables without shifting down storage in the inheritance chain.
     * See https://docs.openzeppelin.com/contracts/4.x/upgradeable#storage_gaps
     */
    uint256[49] private __gap;
}