ChainportCongressMembersRegistry

// Sources flattened with hardhat v2.11.2 https://hardhat.org

// File contracts/libraries/SafeMath.sol


pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        uint256 c = a + b;
        if (c < a) return (false, 0);
        return (true, c);
    }

    /**
     * @dev Returns the substraction of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b > a) return (false, 0);
        return (true, a - b);
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) return (true, 0);
        uint256 c = a * b;
        if (c / a != b) return (false, 0);
        return (true, c);
    }

    /**
     * @dev Returns the division of two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b == 0) return (false, 0);
        return (true, a / b);
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b == 0) return (false, 0);
        return (true, a % b);
    }

    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");
        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a, "SafeMath: subtraction overflow");
        return a - b;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        if (a == 0) return 0;
        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");
        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0, "SafeMath: division by zero");
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0, "SafeMath: modulo by zero");
        return a % b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {trySub}.
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        return a - b;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryDiv}.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting with custom message when dividing by zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryMod}.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        return a % b;
    }
}


// File contracts/governance/ChainportCongressMembersRegistry.sol

pragma solidity ^0.6.12;

/**
 * ChainportCongressMembersRegistry contract.
 * @author Nikola Madjarevic
 * Date created: 21.3.21.
 * Github: madjarevicn
 */
contract ChainportCongressMembersRegistry {

    using SafeMath for *;

    /// @notice The name of this contract
    string public constant name = "ChainportCongressMembersRegistry";

    /// @notice Event to fire every time someone is added or removed from members
    event MembershipChanged(address member, bool isMember);

    /// @notice Chainport congress pointer
    address public chainportCongress;

    //The minimum number of voting members that must be in attendance
    uint256 minimalQuorum;

    // Mapping to check if the member is belonging to congress
    mapping (address => bool) isMemberInCongress;

    // Mapping address to member info
    mapping(address => Member) public address2Member;

    // Mapping to store all members addresses
    address[] public allMembers;


    struct Member {
        bytes32 name;
        uint memberSince;
    }

    modifier onlyChainportCongress {
        require(msg.sender == chainportCongress);
        _;
    }

    /**
     * @param initialCongressMembers is the array containing addresses of initial members
     */
    constructor(
        address[] memory initialCongressMembers,
        bytes32[] memory initialCongressMemberNames,
        address _chainportCongress
    )
    public
    {
        uint length = initialCongressMembers.length;

        for(uint i=0; i<length; i++) {
            addMemberInternal(
                initialCongressMembers[i],
                initialCongressMemberNames[i]
            );
        }

        chainportCongress = _chainportCongress;
    }


    function changeMinimumQuorum(
        uint newMinimumQuorum
    )
    external
    onlyChainportCongress
    {
        require(newMinimumQuorum > 0);
        minimalQuorum = newMinimumQuorum;
    }

    /**
     * Add member
     *
     * Make `targetMember` a member named `memberName`
     *
     * @param targetMember ethereum address to be added
     * @param memberName public name for that member
     */
    function addMember(
        address targetMember,
        bytes32 memberName
    )
    external
    onlyChainportCongress
    {
        addMemberInternal(targetMember, memberName);
    }


    function addMemberInternal(
        address targetMember,
        bytes32 memberName
    )
    internal
    {
        //Require that this member is not already a member of congress
        require(isMemberInCongress[targetMember] == false);
        // Update basic member information
        address2Member[targetMember] = Member({
        memberSince: block.timestamp,
        name: memberName
        });
        // Add member to list of all members
        allMembers.push(targetMember);
        // Update minimum quorum
        minimalQuorum = allMembers.length.sub(1);
        // Mark that user is member in congress
        isMemberInCongress[targetMember] = true;
        // Fire an event
        emit MembershipChanged(targetMember, true);
    }

    /**
     * Remove member
     *
     * @notice Remove membership from `targetMember`
     *
     * @param targetMember ethereum address to be removed
     */
    function removeMember(
        address targetMember
    )
    external
    onlyChainportCongress
    {
        require(isMemberInCongress[targetMember] == true);

        uint length = allMembers.length;

        uint i=0;

        // Find selected member
        while(allMembers[i] != targetMember) {
            if(i == length) {
                revert();
            }
            i++;
        }

        // Move the last member to this place
        allMembers[i] = allMembers[length-1];

        // Remove the last member
        allMembers.pop();

        //Remove him from state mapping
        isMemberInCongress[targetMember] = false;

        //Remove his state to empty member
        address2Member[targetMember] = Member({
        memberSince: block.timestamp,
        name: "0x0"
        });

        //Reduce 1 member from quorum
        minimalQuorum = minimalQuorum.sub(1);

        // Emit event that member is removed.
        emit MembershipChanged(targetMember, false);
    }

    /**
     * @notice Function which will be exposed and congress will use it as "modifier"
     * @param _address is the address we're willing to check if it belongs to congress
     * @return true/false depending if it is either a member or not
     */
    function isMember(
        address _address
    )
    external
    view
    returns (bool)
    {
        return isMemberInCongress[_address];
    }

    /// @notice Getter for length for how many members are currently
    /// @return length of members
    function getNumberOfMembers()
    external
    view
    returns (uint)
    {
        return allMembers.length;
    }

    /// @notice Function to get addresses of all members in congress
    /// @return array of addresses
    function getAllMemberAddresses()
    external
    view
    returns (address[] memory)
    {
        return allMembers;
    }

    /// Get member information
    function getMemberInfo(
        address _member
    )
    external
    view
    returns (address, bytes32, uint)
    {
        Member memory member = address2Member[_member];
        return (
        _member,
        member.name,
        member.memberSince
        );
    }

    function getMinimalQuorum()
    external
    view
    returns (uint256)
    {
        return minimalQuorum;
    }
}