Address Details

contract

pragma solidity ^0.5.13;

import "openzeppelin-solidity/contracts/math/Math.sol";
import "openzeppelin-solidity/contracts/math/SafeMath.sol";
import "openzeppelin-solidity/contracts/ownership/Ownable.sol";
import "openzeppelin-solidity/contracts/utils/Address.sol";
import "openzeppelin-solidity/contracts/utils/EnumerableSet.sol";

import "./interfaces/ILockedGold.sol";

import "../common/FixidityLib.sol";
import "../common/Initializable.sol";
import "../common/Signatures.sol";
import "../common/UsingRegistry.sol";
import "../common/interfaces/ICeloVersionedContract.sol";
import "../common/libraries/ReentrancyGuard.sol";

contract LockedGold is
  ILockedGold,
  ICeloVersionedContract,
  ReentrancyGuard,
  Initializable,
  UsingRegistry
{
  using SafeMath for uint256;
  using Address for address payable; // prettier-ignore
  using FixidityLib for FixidityLib.Fraction;
  using EnumerableSet for EnumerableSet.AddressSet;

  struct PendingWithdrawal {
    // The value of the pending withdrawal.
    uint256 value;
    // The timestamp at which the pending withdrawal becomes available.
    uint256 timestamp;
  }

  // NOTE: This contract does not store an account's locked gold that is being used in electing
  // validators.
  struct Balances {
    // The amount of locked gold that this account has that is not currently participating in
    // validator elections.
    uint256 nonvoting;
    // Gold that has been unlocked and will become available for withdrawal.
    PendingWithdrawal[] pendingWithdrawals;
  }

  struct DelegatedInfo {
    FixidityLib.Fraction percentage;
    uint256 currentAmount;
  }

  struct Delegated {
    EnumerableSet.AddressSet delegatees;
    // delegatees with how much percent delegatees are getting
    // Celo at the time of delegation/latest update
    mapping(address => DelegatedInfo) delegateesWithPercentagesAndAmount;
    FixidityLib.Fraction totalDelegatedCeloFraction;
  }

  mapping(address => Balances) internal balances;

  // Iterable map to store whitelisted identifiers.
  // Necessary to allow iterating over whitelisted IDs to check ID's address at runtime.
  mapping(bytes32 => bool) internal slashingMap;
  bytes32[] public slashingWhitelist;

  modifier onlySlasher {
    require(
      registry.isOneOf(slashingWhitelist, msg.sender),
      "Caller is not a whitelisted slasher."
    );
    _;
  }

  function isSlasher(address slasher) external view returns (bool) {
    return (registry.isOneOf(slashingWhitelist, slasher));
  }

  uint256 public totalNonvoting;
  uint256 public unlockingPeriod;

  // Info about delegator
  mapping(address => Delegated) delegatorInfo;
  // Celo that was delegated to this particular address
  mapping(address => uint256) public totalDelegatedCelo;

  // maximum amount of allowed delegatees
  uint256 maxDelegateesCount;

  event UnlockingPeriodSet(uint256 period);
  event GoldLocked(address indexed account, uint256 value);
  event GoldUnlocked(address indexed account, uint256 value, uint256 available);
  event GoldRelocked(address indexed account, uint256 value);
  event GoldWithdrawn(address indexed account, uint256 value);
  event SlasherWhitelistAdded(string indexed slasherIdentifier);
  event SlasherWhitelistRemoved(string indexed slasherIdentifier);
  event AccountSlashed(
    address indexed slashed,
    uint256 penalty,
    address indexed reporter,
    uint256 reward
  );
  event CeloDelegated(
    address indexed delegator,
    address indexed delegatee,
    uint256 percent,
    uint256 amount
  );
  event DelegatedCeloRevoked(
    address indexed delegator,
    address indexed delegatee,
    uint256 percent,
    uint256 amount
  );
  event MaxDelegateesCountSet(uint256 value);

  /**
  * @notice Returns the storage, major, minor, and patch version of the contract.
  * @return Storage version of the contract.
  * @return Major version of the contract.
  * @return Minor version of the contract.
  * @return Patch version of the contract.
  */
  function getVersionNumber() external pure returns (uint256, uint256, uint256, uint256) {
    return (1, 1, 4, 0);
  }

  /**
   * @notice Sets initialized == true on implementation contracts
   * @param test Set to true to skip implementation initialization
   */
  constructor(bool test) public Initializable(test) {}

  /**
   * @notice Used in place of the constructor to allow the contract to be upgradable via proxy.
   * @param registryAddress The address of the registry core smart contract.
   * @param _unlockingPeriod The unlocking period in seconds.
   */
  function initialize(address registryAddress, uint256 _unlockingPeriod) external initializer {
    _transferOwnership(msg.sender);
    setRegistry(registryAddress);
    setUnlockingPeriod(_unlockingPeriod);
    maxDelegateesCount = 10;
  }

  /**
   * @notice Sets the duration in seconds users must wait before withdrawing gold after unlocking.
   * @param value The unlocking period in seconds.
   */
  function setUnlockingPeriod(uint256 value) public onlyOwner {
    require(value != unlockingPeriod, "Unlocking period not changed");
    unlockingPeriod = value;
    emit UnlockingPeriodSet(value);
  }

  /**
   * @notice Sets max delegatees count.
   * @param value The max delegatees count.
   */
  function setMaxDelegateesCount(uint256 value) public onlyOwner {
    maxDelegateesCount = value;
    emit MaxDelegateesCountSet(value);
  }

  /**
   * @notice Locks gold to be used for voting.
   */
  function lock() external payable nonReentrant {
    require(
      getAccounts().isAccount(msg.sender),
      "Must first register address with Account.createAccount"
    );
    _incrementNonvotingAccountBalance(msg.sender, msg.value);
    _updateDelegatedAmount(msg.sender);
    emit GoldLocked(msg.sender, msg.value);
  }

  /**
   * @notice Increments the non-voting balance for an account.
   * @param account The account whose non-voting balance should be incremented.
   * @param value The amount by which to increment.
   * @dev Can only be called by the registered Election smart contract.
   */
  function incrementNonvotingAccountBalance(address account, uint256 value)
    external
    onlyRegisteredContract(ELECTION_REGISTRY_ID)
  {
    _incrementNonvotingAccountBalance(account, value);
  }

  /**
   * @notice Decrements the non-voting balance for an account.
   * @param account The account whose non-voting balance should be decremented.
   * @param value The amount by which to decrement.
   * @dev Can only be called by the registered "Election" smart contract.
   */
  function decrementNonvotingAccountBalance(address account, uint256 value)
    external
    onlyRegisteredContract(ELECTION_REGISTRY_ID)
  {
    _decrementNonvotingAccountBalance(account, value);
  }

  /**
   * @notice Increments the non-voting balance for an account.
   * @param account The account whose non-voting balance should be incremented.
   * @param value The amount by which to increment.
   */
  function _incrementNonvotingAccountBalance(address account, uint256 value) private {
    balances[account].nonvoting = balances[account].nonvoting.add(value);
    totalNonvoting = totalNonvoting.add(value);
  }

  /**
   * @notice Decrements the non-voting balance for an account.
   * @param account The account whose non-voting balance should be decremented.
   * @param value The amount by which to decrement.
   */
  function _decrementNonvotingAccountBalance(address account, uint256 value) private {
    balances[account].nonvoting = balances[account].nonvoting.sub(value);
    totalNonvoting = totalNonvoting.sub(value);
  }

  /**
   * @notice Unlocks gold that becomes withdrawable after the unlocking period.
   * @param value The amount of gold to unlock.
   */
  function unlock(uint256 value) external nonReentrant {
    require(
      getAccounts().isAccount(msg.sender),
      "Sender must be registered with Account.createAccount to lock or unlock"
    );
    Balances storage account = balances[msg.sender];

    uint256 totalLockedGold = getAccountTotalLockedGold(msg.sender);
    // Prevent unlocking gold when voting on governance proposals so that the gold cannot be
    // used to vote more than once.
    uint256 remainingLockedGold = totalLockedGold.sub(value);

    uint256 totalReferendumVotes = getGovernance().getAmountOfGoldUsedForVoting(msg.sender);
    require(
      remainingLockedGold >= totalReferendumVotes,
      "Not enough unlockable celo. Celo is locked in voting."
    );

    FixidityLib.Fraction memory delegatedPercentage = delegatorInfo[msg.sender]
      .totalDelegatedCeloFraction;

    if (FixidityLib.gt(delegatedPercentage, FixidityLib.newFixed(0))) {
      revokeFromDelegatedWhenUnlocking(msg.sender, value);
    }

    uint256 balanceRequirement = getValidators().getAccountLockedGoldRequirement(msg.sender);
    require(
      balanceRequirement == 0 || balanceRequirement <= remainingLockedGold,
      "Either account doesn't have enough locked Celo or locked Celo is being used for voting."
    );
    _decrementNonvotingAccountBalance(msg.sender, value);
    uint256 available = now.add(unlockingPeriod);
    // CERTORA: the slot containing the length could be MAX_UINT
    account.pendingWithdrawals.push(PendingWithdrawal(value, available));
    emit GoldUnlocked(msg.sender, value, available);
  }

  /**
   * @notice Relocks gold that has been unlocked but not withdrawn.
   * @param index The index of the pending withdrawal to relock from.
   * @param value The value to relock from the specified pending withdrawal.
   */
  function relock(uint256 index, uint256 value) external nonReentrant {
    require(
      getAccounts().isAccount(msg.sender),
      "Sender must be registered with Account.createAccount to lock or relock"
    );
    Balances storage account = balances[msg.sender];
    require(index < account.pendingWithdrawals.length, "Bad pending withdrawal index");
    PendingWithdrawal storage pendingWithdrawal = account.pendingWithdrawals[index];
    require(value <= pendingWithdrawal.value, "Requested value larger than pending value");
    if (value == pendingWithdrawal.value) {
      deletePendingWithdrawal(account.pendingWithdrawals, index);
    } else {
      pendingWithdrawal.value = pendingWithdrawal.value.sub(value);
    }
    _incrementNonvotingAccountBalance(msg.sender, value);
    _updateDelegatedAmount(msg.sender);
    emit GoldRelocked(msg.sender, value);
  }

  /**
   * @notice Withdraws gold that has been unlocked after the unlocking period has passed.
   * @param index The index of the pending withdrawal to withdraw.
   */
  function withdraw(uint256 index) external nonReentrant {
    require(
      getAccounts().isAccount(msg.sender),
      "Sender must be registered with Account.createAccount to withdraw"
    );
    Balances storage account = balances[msg.sender];
    require(index < account.pendingWithdrawals.length, "Bad pending withdrawal index");
    PendingWithdrawal storage pendingWithdrawal = account.pendingWithdrawals[index];
    require(now >= pendingWithdrawal.timestamp, "Pending withdrawal not available");
    uint256 value = pendingWithdrawal.value;
    deletePendingWithdrawal(account.pendingWithdrawals, index);
    require(value <= address(this).balance, "Inconsistent balance");
    msg.sender.sendValue(value);
    emit GoldWithdrawn(msg.sender, value);
  }

  /**
   * @notice Returns the total amount of locked gold in the system. Note that this does not include
   *   gold that has been unlocked but not yet withdrawn.
   * @return The total amount of locked gold in the system.
   */
  function getTotalLockedGold() external view returns (uint256) {
    return totalNonvoting.add(getElection().getTotalVotes());
  }

  /**
   * @notice Returns the total amount of locked gold not being used to vote in elections.
   * @return The total amount of locked gold not being used to vote in elections.
   */
  function getNonvotingLockedGold() external view returns (uint256) {
    return totalNonvoting;
  }

  /**
   * Delegates CELO to delegatee.
   * @param delegatee The delegatee account.
   * @param delegateFraction Fraction of total CELO that will be delegated from delegatee. Fixidity fraction
   */
  function delegateGovernanceVotes(address delegatee, uint256 delegateFraction) external {
    FixidityLib.Fraction memory percentageToDelegate = FixidityLib.wrap(delegateFraction);
    require(
      FixidityLib.lte(percentageToDelegate, FixidityLib.fixed1()),
      "Delegate fraction must be less than or equal to 1"
    );
    address delegatorAccount = getAccounts().voteSignerToAccount(msg.sender);
    address delegateeAccount = getAccounts().voteSignerToAccount(delegatee);

    IValidators validators = getValidators();
    require(!validators.isValidator(delegatorAccount), "Validators cannot delegate votes.");
    require(
      !validators.isValidatorGroup(delegatorAccount),
      "Validator groups cannot delegate votes."
    );

    Delegated storage delegated = delegatorInfo[delegatorAccount];
    delegated.delegatees.add(delegateeAccount);
    require(delegated.delegatees.length() <= maxDelegateesCount, "Too many delegatees");

    DelegatedInfo storage currentDelegateeInfo = delegated
      .delegateesWithPercentagesAndAmount[delegateeAccount];

    require(
      FixidityLib.gte(percentageToDelegate, currentDelegateeInfo.percentage),
      "Cannot decrease delegated amount - use revokeDelegatedGovernanceVotes."
    );

    FixidityLib.Fraction memory requestedToDelegate = delegated
      .totalDelegatedCeloFraction
      .subtract(currentDelegateeInfo.percentage)
      .add(percentageToDelegate);

    require(
      FixidityLib.lte(requestedToDelegate, FixidityLib.fixed1()),
      "Cannot delegate more than 100%"
    );

    uint256 totalLockedGold = getAccountTotalLockedGold(delegatorAccount);
    if (totalLockedGold == 0) {
      delegated.totalDelegatedCeloFraction = delegated
        .totalDelegatedCeloFraction
        .subtract(currentDelegateeInfo.percentage)
        .add(percentageToDelegate);
      currentDelegateeInfo.percentage = percentageToDelegate;

      emit CeloDelegated(
        delegatorAccount,
        delegateeAccount,
        FixidityLib.unwrap(percentageToDelegate),
        currentDelegateeInfo.currentAmount
      );
      return;
    }

    uint256 totalReferendumVotes = getGovernance().getAmountOfGoldUsedForVoting(delegatorAccount);

    if (totalReferendumVotes != 0) {
      FixidityLib.Fraction memory referendumVotesInPercents = FixidityLib.newFixedFraction(
        totalReferendumVotes,
        totalLockedGold
      );
      require(
        FixidityLib.lte(referendumVotesInPercents.add(requestedToDelegate), FixidityLib.fixed1()),
        "Cannot delegate votes that are voting in referendum"
      );
    }

    // amount that will really be delegated - whatever is already
    // delegated to this particular delagatee is already subracted from this
    uint256 amountToDelegate = FixidityLib
      .newFixed(totalLockedGold)
      .multiply(percentageToDelegate)
      .subtract(FixidityLib.newFixed(currentDelegateeInfo.currentAmount))
      .fromFixed();

    delegated.totalDelegatedCeloFraction = delegated
      .totalDelegatedCeloFraction
      .subtract(currentDelegateeInfo.percentage)
      .add(percentageToDelegate);
    currentDelegateeInfo.percentage = percentageToDelegate;

    currentDelegateeInfo.currentAmount = currentDelegateeInfo.currentAmount.add(amountToDelegate);
    totalDelegatedCelo[delegateeAccount] = totalDelegatedCelo[delegateeAccount].add(
      amountToDelegate
    );

    emit CeloDelegated(
      delegatorAccount,
      delegateeAccount,
      FixidityLib.unwrap(percentageToDelegate),
      currentDelegateeInfo.currentAmount
    );
  }

  /**
   * Revokes delegated CELO.
   * @param delegatee The delegatee acount.
   * @param revokeFraction Fraction of total CELO that will be revoked from delegatee. Fixidity fraction
   */
  function revokeDelegatedGovernanceVotes(address delegatee, uint256 revokeFraction) external {
    FixidityLib.Fraction memory percentageToRevoke = FixidityLib.wrap(revokeFraction);

    require(
      FixidityLib.lte(percentageToRevoke, FixidityLib.fixed1()),
      "Revoke fraction must be less than or equal to 1"
    );

    address delegatorAccount = getAccounts().voteSignerToAccount(msg.sender);
    Delegated storage delegated = delegatorInfo[delegatorAccount];
    require(
      FixidityLib.gte(delegated.totalDelegatedCeloFraction, percentageToRevoke),
      "Not enough total delegated percents"
    );

    address delegateeAccount = getAccounts().voteSignerToAccount(delegatee);
    _updateDelegatedAmount(delegatorAccount, delegateeAccount);

    DelegatedInfo storage currentDelegateeInfo = delegated
      .delegateesWithPercentagesAndAmount[delegateeAccount];

    require(
      FixidityLib.gte(currentDelegateeInfo.percentage, percentageToRevoke),
      "Not enough delegated percents"
    );

    currentDelegateeInfo.percentage = currentDelegateeInfo.percentage.subtract(percentageToRevoke);

    uint256 totalLockedGold = getAccountTotalLockedGold(delegatorAccount);

    uint256 amountToRevoke = FixidityLib.unwrap(currentDelegateeInfo.percentage) == 0
      ? currentDelegateeInfo.currentAmount
      : Math.min(
        FixidityLib.newFixed(totalLockedGold).multiply(percentageToRevoke).fromFixed(),
        currentDelegateeInfo.currentAmount
      );

    _decreaseDelegateeVotingPower(delegateeAccount, amountToRevoke, currentDelegateeInfo);

    delegated.totalDelegatedCeloFraction = delegated.totalDelegatedCeloFraction.subtract(
      percentageToRevoke
    );

    if (FixidityLib.unwrap(currentDelegateeInfo.percentage) == 0) {
      delegated.delegatees.remove(delegateeAccount);
    }

    emit DelegatedCeloRevoked(
      delegatorAccount,
      delegateeAccount,
      FixidityLib.unwrap(percentageToRevoke),
      amountToRevoke
    );
  }

  /**
   * Revokes amount during unlocking. It will revoke votes from voted proposals if necessary.
   * @param delegator The delegator account.
   * @param amountToRevoke The amount to revoke.
   */
  function revokeFromDelegatedWhenUnlocking(address delegator, uint256 amountToRevoke) private {
    address[] memory delegatees = getDelegateesOfDelegator(delegator);

    Delegated storage delegated = delegatorInfo[delegator];

    for (uint256 i = 0; i < delegatees.length; i = i.add(1)) {
      DelegatedInfo storage currentDelegateeInfo = delegated
        .delegateesWithPercentagesAndAmount[delegatees[i]];
      (uint256 expected, uint256 real) = _getDelegatorDelegateeExpectedAndRealAmount(
        delegator,
        delegatees[i]
      );
      uint256 delegateeAmountToRevoke = FixidityLib
        .newFixed(amountToRevoke)
        .multiply(currentDelegateeInfo.percentage)
        .fromFixed();
      delegateeAmountToRevoke = delegateeAmountToRevoke.sub(expected.sub(real));
      _decreaseDelegateeVotingPower(delegatees[i], delegateeAmountToRevoke, currentDelegateeInfo);
      emit DelegatedCeloRevoked(delegator, delegatees[i], 0, delegateeAmountToRevoke);
    }
  }

  /**
   * Decreases delegatee voting power when removing or unlocking delegated votes.
   * @param delegatee The delegatee.
   * @param amountToRevoke Amount to revoke.
   * @param delegateeInfo Delegatee info.
   */
  function _decreaseDelegateeVotingPower(
    address delegatee,
    uint256 amountToRevoke,
    DelegatedInfo storage delegateeInfo
  ) private {
    uint256 delegateeTotalVotingPower = getAccountTotalGovernanceVotingPower(delegatee);
    uint256 totalReferendumVotes = getGovernance().getAmountOfGoldUsedForVoting(delegatee);
    uint256 unusedReferendumVotes = delegateeTotalVotingPower.sub(totalReferendumVotes);
    if (unusedReferendumVotes < amountToRevoke) {
      getGovernance().removeVotesWhenRevokingDelegatedVotes(
        delegatee,
        delegateeTotalVotingPower.sub(amountToRevoke)
      );
    }
    delegateeInfo.currentAmount = delegateeInfo.currentAmount.sub(amountToRevoke);
    totalDelegatedCelo[delegatee] = totalDelegatedCelo[delegatee].sub(amountToRevoke);
  }

  /**
   * Updates real delegated amount to all delegator's delegatees.
   * There might be discrepancy because of validator rewards or extra locked gold.
   * @param delegator The delegator address.
   */
  function updateDelegatedAmount(address delegator) public {
    address delegatorAccount = getAccounts().voteSignerToAccount(delegator);
    _updateDelegatedAmount(delegatorAccount);
  }

  function _updateDelegatedAmount(address delegator) private {
    address delegatorAccount = getAccounts().voteSignerToAccount(delegator);
    EnumerableSet.AddressSet storage delegatees = delegatorInfo[delegatorAccount].delegatees;
    for (uint256 i = 0; i < delegatees.length(); i = i.add(1)) {
      _updateDelegatedAmount(delegatorAccount, delegatees.get(i));
    }
  }

  /**
   * Updates real delegated amount to delegatee.
   * There might be discrepancy because of validator rewards or extra locked gold.
   * Voting power will always be smaller or equal to what it is supposed to be.
   * @param delegator The delegator address.
   * @param delegatee The delegatee address.
   */
  function updateDelegatedAmount(address delegator, address delegatee) public returns (uint256) {
    address delegatorAccount = getAccounts().voteSignerToAccount(delegator);
    address delegateeAccount = getAccounts().voteSignerToAccount(delegatee);

    return _updateDelegatedAmount(delegatorAccount, delegateeAccount);
  }

  /**
   * Updates real delegated amount to delegatee.
   * There might be discrepancy because of validator rewards or extra locked gold.
   * Voting power will always be smaller or equal to what it is supposed to be.
   * @param delegator The delegator address.
   * @param delegatee The delegatee address.
   */
  function _updateDelegatedAmount(address delegator, address delegatee) internal returns (uint256) {
    Delegated storage delegated = delegatorInfo[delegator];
    require(
      FixidityLib.unwrap(delegated.totalDelegatedCeloFraction) != 0,
      "delegator is not delegating"
    );
    DelegatedInfo storage currentDelegateeInfo = delegated
      .delegateesWithPercentagesAndAmount[delegatee];
    require(
      FixidityLib.unwrap(currentDelegateeInfo.percentage) != 0,
      "delegator is not delegating for delegatee"
    );

    (uint256 expected, uint256 real) = getDelegatorDelegateeExpectedAndRealAmount(
      delegator,
      delegatee
    );

    currentDelegateeInfo.currentAmount = expected;
    totalDelegatedCelo[delegatee] = totalDelegatedCelo[delegatee].sub(real).add(expected);

    return expected;
  }

  /**
   * Returns how many percents of CELO is account delegating.
   * @param account The account address.
   */
  function getAccountTotalDelegatedFraction(address account) public view returns (uint256) {
    Delegated storage delegated = delegatorInfo[account];
    return FixidityLib.unwrap(delegated.totalDelegatedCeloFraction);
  }

  /**
   * @notice Returns the total amount of locked gold for an account.
   * @param account The account.
   * @return The total amount of locked gold for an account.
   */
  function getAccountTotalLockedGold(address account) public view returns (uint256) {
    uint256 total = balances[account].nonvoting;
    return total.add(getElection().getTotalVotesByAccount(account));
  }

  /**
   * @notice Returns the total amount of locked gold + delegated gold for an account.
   * @param account The account.
   * @return The total amount of locked gold + delegated gold for an account.
   */
  function getAccountTotalGovernanceVotingPower(address account) public view returns (uint256) {
    FixidityLib.Fraction memory availableUndelegatedPercents = FixidityLib.fixed1().subtract(
      FixidityLib.wrap(getAccountTotalDelegatedFraction(account))
    );
    uint256 totalLockedGold = getAccountTotalLockedGold(account);

    uint256 availableForVoting = FixidityLib
      .newFixed(totalLockedGold)
      .multiply(availableUndelegatedPercents)
      .fromFixed();

    return availableForVoting.add(totalDelegatedCelo[account]);
  }

  /**
 * Return percentage and amount that delegator assigned to delegateee.
 * Please note that amount doesn't have to be up to date. 
 * In such case please use `updateDelegatedBalance`.
 * @param delegator The delegator address.
 * @param delegatee The delegatee address.
 * @return fraction The fraction that is delegator asigning to delegatee.
 * @return currentAmount The current actual Celo amount that is assigned to delegatee.
 */
  function getDelegatorDelegateeInfo(address delegator, address delegatee)
    external
    view
    returns (uint256 fraction, uint256 currentAmount)
  {
    DelegatedInfo storage currentDelegateeInfo = delegatorInfo[delegator]
      .delegateesWithPercentagesAndAmount[delegatee];

    fraction = FixidityLib.unwrap(currentDelegateeInfo.percentage);
    currentAmount = currentDelegateeInfo.currentAmount;
  }

  /**
   * Returns expected vs real delegated amount. 
   * If there is a discrepancy it can be fixed by calling `updateDelegatedAmount` function.
   * @param delegator The delegator address.
   * @param delegatee The delegatee address.
   * @return expected The expected amount.
   * @return real The real amount. 
   */
  function getDelegatorDelegateeExpectedAndRealAmount(address delegator, address delegatee)
    public
    view
    returns (uint256 expected, uint256 real)
  {
    address delegatorAccount = getAccounts().voteSignerToAccount(delegator);
    address delegateeAccount = getAccounts().voteSignerToAccount(delegatee);

    (expected, real) = _getDelegatorDelegateeExpectedAndRealAmount(
      delegatorAccount,
      delegateeAccount
    );
  }

  /**
   * Returns expected vs real delegated amount. 
   * If there is a discrepancy it can be fixed by calling `updateDelegatedAmount` function.
   * @param delegator The delegator address.
   * @param delegatee The delegatee address.
   * @return expected The expected amount.
   * @return real The real amount. 
   */
  function _getDelegatorDelegateeExpectedAndRealAmount(address delegator, address delegatee)
    private
    view
    returns (uint256 expected, uint256 real)
  {
    DelegatedInfo storage currentDelegateeInfo = delegatorInfo[delegator]
      .delegateesWithPercentagesAndAmount[delegatee];

    uint256 amountToDelegate = FixidityLib
      .newFixed(getAccountTotalLockedGold(delegator))
      .multiply(currentDelegateeInfo.percentage)
      .fromFixed();

    expected = amountToDelegate;
    real = currentDelegateeInfo.currentAmount;
  }

  /**
   * Retuns all delegatees of delegator
   * @param delegator The delegator address.
   */
  function getDelegateesOfDelegator(address delegator) public view returns (address[] memory) {
    address[] memory values = delegatorInfo[delegator].delegatees.enumerate();
    return values;
  }

  /**
   * @notice Returns the total amount of non-voting locked gold for an account.
   * @param account The account.
   * @return The total amount of non-voting locked gold for an account.
   */
  function getAccountNonvotingLockedGold(address account) external view returns (uint256) {
    return balances[account].nonvoting;
  }

  /**
   * @notice Returns the pending withdrawals from unlocked gold for an account.
   * @param account The address of the account.
   * @return The value for each pending withdrawal.
   * @return The timestamp for each pending withdrawal.
   */
  function getPendingWithdrawals(address account)
    external
    view
    returns (uint256[] memory, uint256[] memory)
  {
    require(
      getAccounts().isAccount(account),
      "Unknown account: only registered accounts have pending withdrawals"
    );
    uint256 length = balances[account].pendingWithdrawals.length;
    uint256[] memory values = new uint256[](length);
    uint256[] memory timestamps = new uint256[](length);
    for (uint256 i = 0; i < length; i = i.add(1)) {
      PendingWithdrawal memory pendingWithdrawal = (balances[account].pendingWithdrawals[i]);
      values[i] = pendingWithdrawal.value;
      timestamps[i] = pendingWithdrawal.timestamp;
    }
    return (values, timestamps);
  }

  /**
   * @notice Returns the pending withdrawal at a given index for a given account.
   * @param account The address of the account.
   * @param index The index of the pending withdrawal.
   * @return The value of the pending withdrawal.
   * @return The timestamp of the pending withdrawal.
   */
  function getPendingWithdrawal(address account, uint256 index)
    external
    view
    returns (uint256, uint256)
  {
    require(
      getAccounts().isAccount(account),
      "Unknown account: only registered accounts have pending withdrawals"
    );
    require(index < balances[account].pendingWithdrawals.length, "Bad pending withdrawal index");
    PendingWithdrawal memory pendingWithdrawal = (balances[account].pendingWithdrawals[index]);

    return (pendingWithdrawal.value, pendingWithdrawal.timestamp);
  }

  /**
    * @notice Returns the number of pending withdrawals for the specified account.
    * @param account The address of the account.
    * @return The count of pending withdrawals.
    */
  function getTotalPendingWithdrawalsCount(address account) external view returns (uint256) {
    return balances[account].pendingWithdrawals.length;
  }

  /**
   * @notice Returns the total amount to withdraw from unlocked gold for an account.
   * @param account The address of the account.
   * @return Total amount to withdraw.
   */
  function getTotalPendingWithdrawals(address account) external view returns (uint256) {
    uint256 pendingWithdrawalSum = 0;
    PendingWithdrawal[] memory withdrawals = balances[account].pendingWithdrawals;
    for (uint256 i = 0; i < withdrawals.length; i = i.add(1)) {
      pendingWithdrawalSum = pendingWithdrawalSum.add(withdrawals[i].value);
    }
    return pendingWithdrawalSum;
  }

  function getSlashingWhitelist() external view returns (bytes32[] memory) {
    return slashingWhitelist;
  }

  /**
   * @notice Deletes a pending withdrawal.
   * @param list The list of pending withdrawals from which to delete.
   * @param index The index of the pending withdrawal to delete.
   */
  function deletePendingWithdrawal(PendingWithdrawal[] storage list, uint256 index) private {
    uint256 lastIndex = list.length.sub(1);
    list[index] = list[lastIndex];
    list.length = lastIndex;
  }

  /**
   * @notice Adds `slasher` to whitelist of approved slashing addresses.
   * @param slasherIdentifier Identifier to whitelist.
   */
  function addSlasher(string calldata slasherIdentifier) external onlyOwner {
    bytes32 keyBytes = keccak256(abi.encodePacked(slasherIdentifier));
    require(registry.getAddressFor(keyBytes) != address(0), "Identifier is not registered");
    require(!slashingMap[keyBytes], "Cannot add slasher ID twice.");
    slashingWhitelist.push(keyBytes);
    slashingMap[keyBytes] = true;
    emit SlasherWhitelistAdded(slasherIdentifier);
  }

  /**
   * @notice Removes `slasher` from whitelist of approved slashing addresses.
   * @param slasherIdentifier Identifier to remove from whitelist.
   * @param index Index of the provided identifier in slashingWhiteList array.
   */
  function removeSlasher(string calldata slasherIdentifier, uint256 index) external onlyOwner {
    bytes32 keyBytes = keccak256(abi.encodePacked(slasherIdentifier));
    require(slashingMap[keyBytes], "Cannot remove slasher ID not yet added.");
    require(index < slashingWhitelist.length, "Provided index exceeds whitelist bounds.");
    require(slashingWhitelist[index] == keyBytes, "Index doesn't match identifier");
    slashingWhitelist[index] = slashingWhitelist[slashingWhitelist.length - 1];
    slashingWhitelist.pop();
    slashingMap[keyBytes] = false;
    emit SlasherWhitelistRemoved(slasherIdentifier);
  }

  /**
   * @notice Slashes `account` by reducing its nonvoting locked gold by `penalty`.
   *         If there is not enough nonvoting locked gold to slash, calls into
   *         `Election.slashVotes` to slash the remaining gold. If `account` does not have
   *         `penalty` worth of locked gold, slashes `account`'s total locked gold.
   *         Also sends `reward` gold to the reporter, and penalty-reward to the Community Fund.
   * @param account Address of account being slashed.
   * @param penalty Amount to slash account.
   * @param reporter Address of account reporting the slasher.
   * @param reward Reward to give reporter.
   * @param lessers The groups receiving fewer votes than i'th group, or 0 if the i'th group has
   *                the fewest votes of any validator group.
   * @param greaters The groups receiving more votes than the i'th group, or 0 if the i'th group
   *                 has the most votes of any validator group.
   * @param indices The indices of the i'th group in `account`'s voting list.
   * @dev Fails if `reward` is greater than `account`'s total locked gold.
   */
  function slash(
    address account,
    uint256 penalty,
    address reporter,
    uint256 reward,
    address[] calldata lessers,
    address[] calldata greaters,
    uint256[] calldata indices
  ) external onlySlasher {
    uint256 maxSlash = Math.min(penalty, getAccountTotalLockedGold(account));
    require(maxSlash >= reward, "reward cannot exceed penalty.");
    // `reporter` receives the reward in locked CELO, so it must be given to an account
    // There is no reward for slashing via the GovernanceSlasher, and `reporter`
    // is set to 0x0.
    if (reporter != address(0)) {
      reporter = getAccounts().signerToAccount(reporter);
    }
    // Local scoping is required to avoid Solc "stack too deep" error from too many locals.
    {
      uint256 nonvotingBalance = balances[account].nonvoting;
      uint256 difference = 0;
      // If not enough nonvoting, revoke the difference
      if (nonvotingBalance < maxSlash) {
        difference = maxSlash.sub(nonvotingBalance);
        require(
          getElection().forceDecrementVotes(account, difference, lessers, greaters, indices) ==
            difference,
          "Cannot revoke enough voting gold."
        );
      }
      // forceDecrementVotes does not increment nonvoting account balance, so we can't double count
      _decrementNonvotingAccountBalance(account, maxSlash.sub(difference));
      _incrementNonvotingAccountBalance(reporter, reward);
    }
    address communityFund = registry.getAddressForOrDie(GOVERNANCE_REGISTRY_ID);
    address payable communityFundPayable = address(uint160(communityFund));
    require(maxSlash.sub(reward) <= address(this).balance, "Inconsistent balance");
    communityFundPayable.sendValue(maxSlash.sub(reward));
    emit AccountSlashed(account, maxSlash, reporter, reward);
  }
}
        

pragma solidity ^0.5.0;

/*
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with GSN meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
contract Context {
    // Empty internal constructor, to prevent people from mistakenly deploying
    // an instance of this contract, which should be used via inheritance.
    constructor () internal { }
    // solhint-disable-previous-line no-empty-blocks

    function _msgSender() internal view returns (address payable) {
        return msg.sender;
    }

    function _msgData() internal view returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}
          

pragma solidity ^0.5.0;

/**
 * @dev Elliptic Curve Digital Signature Algorithm (ECDSA) operations.
 *
 * These functions can be used to verify that a message was signed by the holder
 * of the private keys of a given address.
 */
library ECDSA {
    /**
     * @dev Returns the address that signed a hashed message (`hash`) with
     * `signature`. This address can then be used for verification purposes.
     *
     * The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
     * this function rejects them by requiring the `s` value to be in the lower
     * half order, and the `v` value to be either 27 or 28.
     *
     * NOTE: This call _does not revert_ if the signature is invalid, or
     * if the signer is otherwise unable to be retrieved. In those scenarios,
     * the zero address is returned.
     *
     * IMPORTANT: `hash` _must_ be the result of a hash operation for the
     * verification to be secure: it is possible to craft signatures that
     * recover to arbitrary addresses for non-hashed data. A safe way to ensure
     * this is by receiving a hash of the original message (which may otherwise
     * be too long), and then calling {toEthSignedMessageHash} on it.
     */
    function recover(bytes32 hash, bytes memory signature) internal pure returns (address) {
        // Check the signature length
        if (signature.length != 65) {
            return (address(0));
        }

        // Divide the signature in r, s and v variables
        bytes32 r;
        bytes32 s;
        uint8 v;

        // ecrecover takes the signature parameters, and the only way to get them
        // currently is to use assembly.
        // solhint-disable-next-line no-inline-assembly
        assembly {
            r := mload(add(signature, 0x20))
            s := mload(add(signature, 0x40))
            v := byte(0, mload(add(signature, 0x60)))
        }

        // EIP-2 still allows signature malleability for ecrecover(). Remove this possibility and make the signature
        // unique. Appendix F in the Ethereum Yellow paper (https://ethereum.github.io/yellowpaper/paper.pdf), defines
        // the valid range for s in (281): 0 < s < secp256k1n ÷ 2 + 1, and for v in (282): v ∈ {27, 28}. Most
        // signatures from current libraries generate a unique signature with an s-value in the lower half order.
        //
        // If your library generates malleable signatures, such as s-values in the upper range, calculate a new s-value
        // with 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141 - s1 and flip v from 27 to 28 or
        // vice versa. If your library also generates signatures with 0/1 for v instead 27/28, add 27 to v to accept
        // these malleable signatures as well.
        if (uint256(s) > 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0) {
            return address(0);
        }

        if (v != 27 && v != 28) {
            return address(0);
        }

        // If the signature is valid (and not malleable), return the signer address
        return ecrecover(hash, v, r, s);
    }

    /**
     * @dev Returns an Ethereum Signed Message, created from a `hash`. This
     * replicates the behavior of the
     * https://github.com/ethereum/wiki/wiki/JSON-RPC#eth_sign[`eth_sign`]
     * JSON-RPC method.
     *
     * See {recover}.
     */
    function toEthSignedMessageHash(bytes32 hash) internal pure returns (bytes32) {
        // 32 is the length in bytes of hash,
        // enforced by the type signature above
        return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n32", hash));
    }
}
          

pragma solidity ^0.5.0;

/**
 * @dev Standard math utilities missing in the Solidity language.
 */
library Math {
    /**
     * @dev Returns the largest of two numbers.
     */
    function max(uint256 a, uint256 b) internal pure returns (uint256) {
        return a >= b ? a : b;
    }

    /**
     * @dev Returns the smallest of two numbers.
     */
    function min(uint256 a, uint256 b) internal pure returns (uint256) {
        return a < b ? a : b;
    }

    /**
     * @dev Returns the average of two numbers. The result is rounded towards
     * zero.
     */
    function average(uint256 a, uint256 b) internal pure returns (uint256) {
        // (a + b) / 2 can overflow, so we distribute
        return (a / 2) + (b / 2) + ((a % 2 + b % 2) / 2);
    }
}
          

pragma solidity ^0.5.0;

/**
 * @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, 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) {
        return sub(a, b, "SafeMath: subtraction overflow");
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     * - Subtraction cannot overflow.
     *
     * _Available since v2.4.0._
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }

    /**
     * @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) {
        // 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 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts 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) {
        return div(a, b, "SafeMath: division by zero");
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts with custom message 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.
     *
     * _Available since v2.4.0._
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        // Solidity only automatically asserts when dividing by 0
        require(b > 0, errorMessage);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts 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) {
        return mod(a, b, "SafeMath: modulo by zero");
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts with custom message 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.
     *
     * _Available since v2.4.0._
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}
          

pragma solidity ^0.5.0;

import "../GSN/Context.sol";
/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor () internal {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), msgSender);
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(isOwner(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Returns true if the caller is the current owner.
     */
    function isOwner() public view returns (bool) {
        return _msgSender() == _owner;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = address(0);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public onlyOwner {
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     */
    function _transferOwnership(address newOwner) internal {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}
          

pragma solidity ^0.5.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP. Does not include
 * the optional functions; to access them see {ERC20Detailed}.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}
          

pragma solidity ^0.5.5;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following 
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // According to EIP-1052, 0x0 is the value returned for not-yet created accounts
        // and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
        // for accounts without code, i.e. `keccak256('')`
        bytes32 codehash;
        bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
        // solhint-disable-next-line no-inline-assembly
        assembly { codehash := extcodehash(account) }
        return (codehash != accountHash && codehash != 0x0);
    }

    /**
     * @dev Converts an `address` into `address payable`. Note that this is
     * simply a type cast: the actual underlying value is not changed.
     *
     * _Available since v2.4.0._
     */
    function toPayable(address account) internal pure returns (address payable) {
        return address(uint160(account));
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     *
     * _Available since v2.4.0._
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        // solhint-disable-next-line avoid-call-value
        (bool success, ) = recipient.call.value(amount)("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }
}
          

pragma solidity ^0.5.0;

/**
 * @dev Library for managing
 * https://en.wikipedia.org/wiki/Set_(abstract_data_type)[sets] of primitive
 * types.
 *
 * Sets have the following properties:
 *
 * - Elements are added, removed, and checked for existence in constant time
 * (O(1)).
 * - Elements are enumerated in O(n). No guarantees are made on the ordering.
 *
 * As of v2.5.0, only `address` sets are supported.
 *
 * Include with `using EnumerableSet for EnumerableSet.AddressSet;`.
 *
 * _Available since v2.5.0._
 *
 * @author Alberto Cuesta Cañada
 */
library EnumerableSet {

    struct AddressSet {
        // Position of the value in the `values` array, plus 1 because index 0
        // means a value is not in the set.
        mapping (address => uint256) index;
        address[] values;
    }

    /**
     * @dev Add a value to a set. O(1).
     * Returns false if the value was already in the set.
     */
    function add(AddressSet storage set, address value)
        internal
        returns (bool)
    {
        if (!contains(set, value)){
            set.index[value] = set.values.push(value);
            return true;
        } else {
            return false;
        }
    }

    /**
     * @dev Removes a value from a set. O(1).
     * Returns false if the value was not present in the set.
     */
    function remove(AddressSet storage set, address value)
        internal
        returns (bool)
    {
        if (contains(set, value)){
            uint256 toDeleteIndex = set.index[value] - 1;
            uint256 lastIndex = set.values.length - 1;

            // If the element we're deleting is the last one, we can just remove it without doing a swap
            if (lastIndex != toDeleteIndex) {
                address lastValue = set.values[lastIndex];

                // Move the last value to the index where the deleted value is
                set.values[toDeleteIndex] = lastValue;
                // Update the index for the moved value
                set.index[lastValue] = toDeleteIndex + 1; // All indexes are 1-based
            }

            // Delete the index entry for the deleted value
            delete set.index[value];

            // Delete the old entry for the moved value
            set.values.pop();

            return true;
        } else {
            return false;
        }
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(AddressSet storage set, address value)
        internal
        view
        returns (bool)
    {
        return set.index[value] != 0;
    }

    /**
     * @dev Returns an array with all values in the set. O(N).
     * Note that there are no guarantees on the ordering of values inside the
     * array, and it may change when more values are added or removed.

     * WARNING: This function may run out of gas on large sets: use {length} and
     * {get} instead in these cases.
     */
    function enumerate(AddressSet storage set)
        internal
        view
        returns (address[] memory)
    {
        address[] memory output = new address[](set.values.length);
        for (uint256 i; i < set.values.length; i++){
            output[i] = set.values[i];
        }
        return output;
    }

    /**
     * @dev Returns the number of elements on the set. O(1).
     */
    function length(AddressSet storage set)
        internal
        view
        returns (uint256)
    {
        return set.values.length;
    }

   /** @dev Returns the element stored at position `index` in the set. O(1).
    * Note that there are no guarantees on the ordering of values inside the
    * array, and it may change when more values are added or removed.
    *
    * Requirements:
    *
    * - `index` must be strictly less than {length}.
    */
    function get(AddressSet storage set, uint256 index)
        internal
        view
        returns (address)
    {
        return set.values[index];
    }
}
          

// SPDX-License-Identifier: LGPL-3.0-only
pragma solidity >=0.5.13 <0.9.0;

/**
 * @title FixidityLib
 * @author Gadi Guy, Alberto Cuesta Canada
 * @notice This library provides fixed point arithmetic with protection against
 * overflow.
 * All operations are done with uint256 and the operands must have been created
 * with any of the newFrom* functions, which shift the comma digits() to the
 * right and check for limits, or with wrap() which expects a number already
 * in the internal representation of a fraction.
 * When using this library be sure to use maxNewFixed() as the upper limit for
 * creation of fixed point numbers.
 * @dev All contained functions are pure and thus marked internal to be inlined
 * on consuming contracts at compile time for gas efficiency.
 */
library FixidityLib {
  struct Fraction {
    uint256 value;
  }

  /**
   * @notice Number of positions that the comma is shifted to the right.
   */
  function digits() internal pure returns (uint8) {
    return 24;
  }

  uint256 private constant FIXED1_UINT = 1000000000000000000000000;

  /**
   * @notice This is 1 in the fixed point units used in this library.
   * @dev Test fixed1() equals 10^digits()
   * Hardcoded to 24 digits.
   */
  function fixed1() internal pure returns (Fraction memory) {
    return Fraction(FIXED1_UINT);
  }

  /**
   * @notice Wrap a uint256 that represents a 24-decimal fraction in a Fraction
   * struct.
   * @param x Number that already represents a 24-decimal fraction.
   * @return A Fraction struct with contents x.
   */
  function wrap(uint256 x) internal pure returns (Fraction memory) {
    return Fraction(x);
  }

  /**
   * @notice Unwraps the uint256 inside of a Fraction struct.
   */
  function unwrap(Fraction memory x) internal pure returns (uint256) {
    return x.value;
  }

  /**
   * @notice The amount of decimals lost on each multiplication operand.
   * @dev Test mulPrecision() equals sqrt(fixed1)
   */
  function mulPrecision() internal pure returns (uint256) {
    return 1000000000000;
  }

  /**
   * @notice Maximum value that can be converted to fixed point. Optimize for deployment.
   * @dev
   * Test maxNewFixed() equals maxUint256() / fixed1()
   */
  function maxNewFixed() internal pure returns (uint256) {
    return 115792089237316195423570985008687907853269984665640564;
  }

  /**
   * @notice Converts a uint256 to fixed point Fraction
   * @dev Test newFixed(0) returns 0
   * Test newFixed(1) returns fixed1()
   * Test newFixed(maxNewFixed()) returns maxNewFixed() * fixed1()
   * Test newFixed(maxNewFixed()+1) fails
   */
  function newFixed(uint256 x) internal pure returns (Fraction memory) {
    require(x <= maxNewFixed(), "can't create fixidity number larger than maxNewFixed()");
    return Fraction(x * FIXED1_UINT);
  }

  /**
   * @notice Converts a uint256 in the fixed point representation of this
   * library to a non decimal. All decimal digits will be truncated.
   */
  function fromFixed(Fraction memory x) internal pure returns (uint256) {
    return x.value / FIXED1_UINT;
  }

  /**
   * @notice Converts two uint256 representing a fraction to fixed point units,
   * equivalent to multiplying dividend and divisor by 10^digits().
   * @param numerator numerator must be <= maxNewFixed()
   * @param denominator denominator must be <= maxNewFixed() and denominator can't be 0
   * @dev
   * Test newFixedFraction(1,0) fails
   * Test newFixedFraction(0,1) returns 0
   * Test newFixedFraction(1,1) returns fixed1()
   * Test newFixedFraction(1,fixed1()) returns 1
   */
  function newFixedFraction(uint256 numerator, uint256 denominator)
    internal
    pure
    returns (Fraction memory)
  {
    Fraction memory convertedNumerator = newFixed(numerator);
    Fraction memory convertedDenominator = newFixed(denominator);
    return divide(convertedNumerator, convertedDenominator);
  }

  /**
   * @notice Returns the integer part of a fixed point number.
   * @dev
   * Test integer(0) returns 0
   * Test integer(fixed1()) returns fixed1()
   * Test integer(newFixed(maxNewFixed())) returns maxNewFixed()*fixed1()
   */
  function integer(Fraction memory x) internal pure returns (Fraction memory) {
    return Fraction((x.value / FIXED1_UINT) * FIXED1_UINT); // Can't overflow
  }

  /**
   * @notice Returns the fractional part of a fixed point number.
   * In the case of a negative number the fractional is also negative.
   * @dev
   * Test fractional(0) returns 0
   * Test fractional(fixed1()) returns 0
   * Test fractional(fixed1()-1) returns 10^24-1
   */
  function fractional(Fraction memory x) internal pure returns (Fraction memory) {
    return Fraction(x.value - (x.value / FIXED1_UINT) * FIXED1_UINT); // Can't overflow
  }

  /**
   * @notice x+y.
   * @dev The maximum value that can be safely used as an addition operator is defined as
   * maxFixedAdd = maxUint256()-1 / 2, or
   * 57896044618658097711785492504343953926634992332820282019728792003956564819967.
   * Test add(maxFixedAdd,maxFixedAdd) equals maxFixedAdd + maxFixedAdd
   * Test add(maxFixedAdd+1,maxFixedAdd+1) throws
   */
  function add(Fraction memory x, Fraction memory y) internal pure returns (Fraction memory) {
    uint256 z = x.value + y.value;
    require(z >= x.value, "add overflow detected");
    return Fraction(z);
  }

  /**
   * @notice x-y.
   * @dev
   * Test subtract(6, 10) fails
   */
  function subtract(Fraction memory x, Fraction memory y) internal pure returns (Fraction memory) {
    require(x.value >= y.value, "substraction underflow detected");
    return Fraction(x.value - y.value);
  }

  /**
   * @notice x*y. If any of the operators is higher than the max multiplier value it
   * might overflow.
   * @dev The maximum value that can be safely used as a multiplication operator
   * (maxFixedMul) is calculated as sqrt(maxUint256()*fixed1()),
   * or 340282366920938463463374607431768211455999999999999
   * Test multiply(0,0) returns 0
   * Test multiply(maxFixedMul,0) returns 0
   * Test multiply(0,maxFixedMul) returns 0
   * Test multiply(fixed1()/mulPrecision(),fixed1()*mulPrecision()) returns fixed1()
   * Test multiply(maxFixedMul,maxFixedMul) is around maxUint256()
   * Test multiply(maxFixedMul+1,maxFixedMul+1) fails
   */
  function multiply(Fraction memory x, Fraction memory y) internal pure returns (Fraction memory) {
    if (x.value == 0 || y.value == 0) return Fraction(0);
    if (y.value == FIXED1_UINT) return x;
    if (x.value == FIXED1_UINT) return y;

    // Separate into integer and fractional parts
    // x = x1 + x2, y = y1 + y2
    uint256 x1 = integer(x).value / FIXED1_UINT;
    uint256 x2 = fractional(x).value;
    uint256 y1 = integer(y).value / FIXED1_UINT;
    uint256 y2 = fractional(y).value;

    // (x1 + x2) * (y1 + y2) = (x1 * y1) + (x1 * y2) + (x2 * y1) + (x2 * y2)
    uint256 x1y1 = x1 * y1;
    if (x1 != 0) require(x1y1 / x1 == y1, "overflow x1y1 detected");

    // x1y1 needs to be multiplied back by fixed1
    // solium-disable-next-line mixedcase
    uint256 fixed_x1y1 = x1y1 * FIXED1_UINT;
    if (x1y1 != 0) require(fixed_x1y1 / x1y1 == FIXED1_UINT, "overflow x1y1 * fixed1 detected");
    x1y1 = fixed_x1y1;

    uint256 x2y1 = x2 * y1;
    if (x2 != 0) require(x2y1 / x2 == y1, "overflow x2y1 detected");

    uint256 x1y2 = x1 * y2;
    if (x1 != 0) require(x1y2 / x1 == y2, "overflow x1y2 detected");

    x2 = x2 / mulPrecision();
    y2 = y2 / mulPrecision();
    uint256 x2y2 = x2 * y2;
    if (x2 != 0) require(x2y2 / x2 == y2, "overflow x2y2 detected");

    // result = fixed1() * x1 * y1 + x1 * y2 + x2 * y1 + x2 * y2 / fixed1();
    Fraction memory result = Fraction(x1y1);
    result = add(result, Fraction(x2y1)); // Add checks for overflow
    result = add(result, Fraction(x1y2)); // Add checks for overflow
    result = add(result, Fraction(x2y2)); // Add checks for overflow
    return result;
  }

  /**
   * @notice 1/x
   * @dev
   * Test reciprocal(0) fails
   * Test reciprocal(fixed1()) returns fixed1()
   * Test reciprocal(fixed1()*fixed1()) returns 1 // Testing how the fractional is truncated
   * Test reciprocal(1+fixed1()*fixed1()) returns 0 // Testing how the fractional is truncated
   * Test reciprocal(newFixedFraction(1, 1e24)) returns newFixed(1e24)
   */
  function reciprocal(Fraction memory x) internal pure returns (Fraction memory) {
    require(x.value != 0, "can't call reciprocal(0)");
    return Fraction((FIXED1_UINT * FIXED1_UINT) / x.value); // Can't overflow
  }

  /**
   * @notice x/y. If the dividend is higher than the max dividend value, it
   * might overflow. You can use multiply(x,reciprocal(y)) instead.
   * @dev The maximum value that can be safely used as a dividend (maxNewFixed) is defined as
   * divide(maxNewFixed,newFixedFraction(1,fixed1())) is around maxUint256().
   * This yields the value 115792089237316195423570985008687907853269984665640564.
   * Test maxNewFixed equals maxUint256()/fixed1()
   * Test divide(maxNewFixed,1) equals maxNewFixed*(fixed1)
   * Test divide(maxNewFixed+1,multiply(mulPrecision(),mulPrecision())) throws
   * Test divide(fixed1(),0) fails
   * Test divide(maxNewFixed,1) = maxNewFixed*(10^digits())
   * Test divide(maxNewFixed+1,1) throws
   */
  function divide(Fraction memory x, Fraction memory y) internal pure returns (Fraction memory) {
    require(y.value != 0, "can't divide by 0");
    uint256 X = x.value * FIXED1_UINT;
    require(X / FIXED1_UINT == x.value, "overflow at divide");
    return Fraction(X / y.value);
  }

  /**
   * @notice x > y
   */
  function gt(Fraction memory x, Fraction memory y) internal pure returns (bool) {
    return x.value > y.value;
  }

  /**
   * @notice x >= y
   */
  function gte(Fraction memory x, Fraction memory y) internal pure returns (bool) {
    return x.value >= y.value;
  }

  /**
   * @notice x < y
   */
  function lt(Fraction memory x, Fraction memory y) internal pure returns (bool) {
    return x.value < y.value;
  }

  /**
   * @notice x <= y
   */
  function lte(Fraction memory x, Fraction memory y) internal pure returns (bool) {
    return x.value <= y.value;
  }

  /**
   * @notice x == y
   */
  function equals(Fraction memory x, Fraction memory y) internal pure returns (bool) {
    return x.value == y.value;
  }

  /**
   * @notice x <= 1
   */
  function isProperFraction(Fraction memory x) internal pure returns (bool) {
    return lte(x, fixed1());
  }
}
          

// SPDX-License-Identifier: LGPL-3.0-only
pragma solidity >=0.5.13 <0.9.0;

contract Initializable {
  bool public initialized;

  constructor(bool testingDeployment) public {
    if (!testingDeployment) {
      initialized = true;
    }
  }

  modifier initializer() {
    require(!initialized, "contract already initialized");
    initialized = true;
    _;
  }
}
          

pragma solidity ^0.5.13;

import "openzeppelin-solidity/contracts/cryptography/ECDSA.sol";

library Signatures {
  /**
  * @notice Given a signed address, returns the signer of the address.
  * @param message The address that was signed.
  * @param v The recovery id of the incoming ECDSA signature.
  * @param r Output value r of the ECDSA signature.
  * @param s Output value s of the ECDSA signature.
  */
  function getSignerOfAddress(address message, uint8 v, bytes32 r, bytes32 s)
    public
    pure
    returns (address)
  {
    bytes32 hash = keccak256(abi.encodePacked(message));
    return getSignerOfMessageHash(hash, v, r, s);
  }

  /**
  * @notice Given a message hash, returns the signer of the address.
  * @param messageHash The hash of a message.
  * @param v The recovery id of the incoming ECDSA signature.
  * @param r Output value r of the ECDSA signature.
  * @param s Output value s of the ECDSA signature.
  */
  function getSignerOfMessageHash(bytes32 messageHash, uint8 v, bytes32 r, bytes32 s)
    public
    pure
    returns (address)
  {
    bytes memory signature = new bytes(65);
    // Concatenate (r, s, v) into signature.
    assembly {
      mstore(add(signature, 32), r)
      mstore(add(signature, 64), s)
      mstore8(add(signature, 96), v)
    }
    bytes32 prefixedHash = ECDSA.toEthSignedMessageHash(messageHash);
    return ECDSA.recover(prefixedHash, signature);
  }

  /**
  * @notice Given a domain separator and a structHash, construct the typed data hash
  * @param eip712DomainSeparator Context specific domain separator
  * @param structHash hash of the typed data struct
  * @return The EIP712 typed data hash
  */
  function toEthSignedTypedDataHash(bytes32 eip712DomainSeparator, bytes32 structHash)
    public
    pure
    returns (bytes32)
  {
    return keccak256(abi.encodePacked("\x19\x01", eip712DomainSeparator, structHash));
  }

  /**
  * @notice Given a domain separator and a structHash and a signature return the signer
  * @param eip712DomainSeparator Context specific domain separator
  * @param structHash hash of the typed data struct
  * @param v The recovery id of the incoming ECDSA signature.
  * @param r Output value r of the ECDSA signature.
  * @param s Output value s of the ECDSA signature.
  */
  function getSignerOfTypedDataHash(
    bytes32 eip712DomainSeparator,
    bytes32 structHash,
    uint8 v,
    bytes32 r,
    bytes32 s
  ) public pure returns (address) {
    bytes memory signature = new bytes(65);
    // Concatenate (r, s, v) into signature.
    assembly {
      mstore(add(signature, 32), r)
      mstore(add(signature, 64), s)
      mstore8(add(signature, 96), v)
    }
    bytes32 prefixedHash = toEthSignedTypedDataHash(eip712DomainSeparator, structHash);
    return ECDSA.recover(prefixedHash, signature);
  }
}
          

// SPDX-License-Identifier: LGPL-3.0-only
pragma solidity ^0.5.13;

import "openzeppelin-solidity/contracts/ownership/Ownable.sol";
import "openzeppelin-solidity/contracts/token/ERC20/IERC20.sol";

import "./interfaces/IAccounts.sol";
import "./interfaces/IFeeCurrencyWhitelist.sol";
import "./interfaces/IFreezer.sol";
import "./interfaces/IRegistry.sol";

import "../governance/interfaces/IElection.sol";
import "../governance/interfaces/IGovernance.sol";
import "../governance/interfaces/ILockedGold.sol";
import "../governance/interfaces/IValidators.sol";

import "../identity/interfaces/IRandom.sol";
import "../identity/interfaces/IAttestations.sol";

import "../../lib/mento-core/contracts/interfaces/IExchange.sol";
import "../../lib/mento-core/contracts/interfaces/IReserve.sol";
import "../../lib/mento-core/contracts/interfaces/IStableToken.sol";
import "../stability/interfaces/ISortedOracles.sol";

contract UsingRegistry is Ownable {
  event RegistrySet(address indexed registryAddress);

  // solhint-disable state-visibility
  bytes32 constant ACCOUNTS_REGISTRY_ID = keccak256(abi.encodePacked("Accounts"));
  bytes32 constant ATTESTATIONS_REGISTRY_ID = keccak256(abi.encodePacked("Attestations"));
  bytes32 constant DOWNTIME_SLASHER_REGISTRY_ID = keccak256(abi.encodePacked("DowntimeSlasher"));
  bytes32 constant DOUBLE_SIGNING_SLASHER_REGISTRY_ID = keccak256(
    abi.encodePacked("DoubleSigningSlasher")
  );
  bytes32 constant ELECTION_REGISTRY_ID = keccak256(abi.encodePacked("Election"));
  bytes32 constant EXCHANGE_REGISTRY_ID = keccak256(abi.encodePacked("Exchange"));
  bytes32 constant FEE_CURRENCY_WHITELIST_REGISTRY_ID = keccak256(
    abi.encodePacked("FeeCurrencyWhitelist")
  );
  bytes32 constant FREEZER_REGISTRY_ID = keccak256(abi.encodePacked("Freezer"));
  bytes32 constant GOLD_TOKEN_REGISTRY_ID = keccak256(abi.encodePacked("GoldToken"));
  bytes32 constant GOVERNANCE_REGISTRY_ID = keccak256(abi.encodePacked("Governance"));
  bytes32 constant GOVERNANCE_SLASHER_REGISTRY_ID = keccak256(
    abi.encodePacked("GovernanceSlasher")
  );
  bytes32 constant LOCKED_GOLD_REGISTRY_ID = keccak256(abi.encodePacked("LockedGold"));
  bytes32 constant RESERVE_REGISTRY_ID = keccak256(abi.encodePacked("Reserve"));
  bytes32 constant RANDOM_REGISTRY_ID = keccak256(abi.encodePacked("Random"));
  bytes32 constant SORTED_ORACLES_REGISTRY_ID = keccak256(abi.encodePacked("SortedOracles"));
  bytes32 constant STABLE_TOKEN_REGISTRY_ID = keccak256(abi.encodePacked("StableToken"));
  bytes32 constant VALIDATORS_REGISTRY_ID = keccak256(abi.encodePacked("Validators"));
  // solhint-enable state-visibility

  IRegistry public registry;

  modifier onlyRegisteredContract(bytes32 identifierHash) {
    require(registry.getAddressForOrDie(identifierHash) == msg.sender, "only registered contract");
    _;
  }

  modifier onlyRegisteredContracts(bytes32[] memory identifierHashes) {
    require(registry.isOneOf(identifierHashes, msg.sender), "only registered contracts");
    _;
  }

  /**
   * @notice Updates the address pointing to a Registry contract.
   * @param registryAddress The address of a registry contract for routing to other contracts.
   */
  function setRegistry(address registryAddress) public onlyOwner {
    require(registryAddress != address(0), "Cannot register the null address");
    registry = IRegistry(registryAddress);
    emit RegistrySet(registryAddress);
  }

  function getAccounts() internal view returns (IAccounts) {
    return IAccounts(registry.getAddressForOrDie(ACCOUNTS_REGISTRY_ID));
  }

  function getAttestations() internal view returns (IAttestations) {
    return IAttestations(registry.getAddressForOrDie(ATTESTATIONS_REGISTRY_ID));
  }

  function getElection() internal view returns (IElection) {
    return IElection(registry.getAddressForOrDie(ELECTION_REGISTRY_ID));
  }

  function getExchange() internal view returns (IExchange) {
    return IExchange(registry.getAddressForOrDie(EXCHANGE_REGISTRY_ID));
  }

  function getFeeCurrencyWhitelistRegistry() internal view returns (IFeeCurrencyWhitelist) {
    return IFeeCurrencyWhitelist(registry.getAddressForOrDie(FEE_CURRENCY_WHITELIST_REGISTRY_ID));
  }

  function getFreezer() internal view returns (IFreezer) {
    return IFreezer(registry.getAddressForOrDie(FREEZER_REGISTRY_ID));
  }

  function getGoldToken() internal view returns (IERC20) {
    return IERC20(registry.getAddressForOrDie(GOLD_TOKEN_REGISTRY_ID));
  }

  function getGovernance() internal view returns (IGovernance) {
    return IGovernance(registry.getAddressForOrDie(GOVERNANCE_REGISTRY_ID));
  }

  function getLockedGold() internal view returns (ILockedGold) {
    return ILockedGold(registry.getAddressForOrDie(LOCKED_GOLD_REGISTRY_ID));
  }

  function getRandom() internal view returns (IRandom) {
    return IRandom(registry.getAddressForOrDie(RANDOM_REGISTRY_ID));
  }

  function getReserve() internal view returns (IReserve) {
    return IReserve(registry.getAddressForOrDie(RESERVE_REGISTRY_ID));
  }

  function getSortedOracles() internal view returns (ISortedOracles) {
    return ISortedOracles(registry.getAddressForOrDie(SORTED_ORACLES_REGISTRY_ID));
  }

  function getStableToken() internal view returns (IStableToken) {
    return IStableToken(registry.getAddressForOrDie(STABLE_TOKEN_REGISTRY_ID));
  }

  function getValidators() internal view returns (IValidators) {
    return IValidators(registry.getAddressForOrDie(VALIDATORS_REGISTRY_ID));
  }
}
          

// SPDX-License-Identifier: LGPL-3.0-only
pragma solidity >=0.5.13 <0.9.0;

interface IAccounts {
  function isAccount(address) external view returns (bool);
  function voteSignerToAccount(address) external view returns (address);
  function validatorSignerToAccount(address) external view returns (address);
  function attestationSignerToAccount(address) external view returns (address);
  function signerToAccount(address) external view returns (address);
  function getAttestationSigner(address) external view returns (address);
  function getValidatorSigner(address) external view returns (address);
  function getVoteSigner(address) external view returns (address);
  function hasAuthorizedVoteSigner(address) external view returns (bool);
  function hasAuthorizedValidatorSigner(address) external view returns (bool);
  function hasAuthorizedAttestationSigner(address) external view returns (bool);

  function setAccountDataEncryptionKey(bytes calldata) external;
  function setMetadataURL(string calldata) external;
  function setName(string calldata) external;
  function setWalletAddress(address, uint8, bytes32, bytes32) external;
  function setAccount(string calldata, bytes calldata, address, uint8, bytes32, bytes32) external;

  function getDataEncryptionKey(address) external view returns (bytes memory);
  function getWalletAddress(address) external view returns (address);
  function getMetadataURL(address) external view returns (string memory);
  function batchGetMetadataURL(address[] calldata)
    external
    view
    returns (uint256[] memory, bytes memory);
  function getName(address) external view returns (string memory);

  function authorizeVoteSigner(address, uint8, bytes32, bytes32) external;
  function authorizeValidatorSigner(address, uint8, bytes32, bytes32) external;
  function authorizeValidatorSignerWithPublicKey(address, uint8, bytes32, bytes32, bytes calldata)
    external;
  function authorizeValidatorSignerWithKeys(
    address,
    uint8,
    bytes32,
    bytes32,
    bytes calldata,
    bytes calldata,
    bytes calldata
  ) external;
  function authorizeAttestationSigner(address, uint8, bytes32, bytes32) external;
  function createAccount() external returns (bool);

  function setPaymentDelegation(address, uint256) external;
  function getPaymentDelegation(address) external view returns (address, uint256);
  function isSigner(address, address, bytes32) external view returns (bool);
}
          

// SPDX-License-Identifier: LGPL-3.0-only
pragma solidity >=0.5.13 <0.9.0;

interface ICeloVersionedContract {
  /**
   * @notice Returns the storage, major, minor, and patch version of the contract.
    * @return Storage version of the contract.
    * @return Major version of the contract.
    * @return Minor version of the contract.
    * @return Patch version of the contract.
   */
  function getVersionNumber() external pure returns (uint256, uint256, uint256, uint256);
}
          

// SPDX-License-Identifier: LGPL-3.0-only
pragma solidity >=0.5.13 <0.9.0;

interface IFeeCurrencyWhitelist {
  function addToken(address) external;
  function getWhitelist() external view returns (address[] memory);
}
          

// SPDX-License-Identifier: LGPL-3.0-only
pragma solidity >=0.5.13 <0.9.0;

interface IFreezer {
  function isFrozen(address) external view returns (bool);
}
          

// SPDX-License-Identifier: LGPL-3.0-only
pragma solidity >=0.5.13 <0.9.0;

interface IRegistry {
  function setAddressFor(string calldata, address) external;
  function getAddressForOrDie(bytes32) external view returns (address);
  function getAddressFor(bytes32) external view returns (address);
  function getAddressForStringOrDie(string calldata identifier) external view returns (address);
  function getAddressForString(string calldata identifier) external view returns (address);
  function isOneOf(bytes32[] calldata, address) external view returns (bool);
}
          

pragma solidity ^0.5.13;

/**
 * @title Helps contracts guard against reentrancy attacks.
 * @author Remco Bloemen <remco@2π.com>, Eenae <alexey@mixbytes.io>
 * @dev If you mark a function `nonReentrant`, you should also
 * mark it `external`.
 */
contract ReentrancyGuard {
  /// @dev counter to allow mutex lock with only one SSTORE operation
  uint256 private _guardCounter;

  constructor() internal {
    // The counter starts at one to prevent changing it from zero to a non-zero
    // value, which is a more expensive operation.
    _guardCounter = 1;
  }

  /**
   * @dev Prevents a contract from calling itself, directly or indirectly.
   * Calling a `nonReentrant` function from another `nonReentrant`
   * function is not supported. It is possible to prevent this from happening
   * by making the `nonReentrant` function external, and make it call a
   * `private` function that does the actual work.
   */
  modifier nonReentrant() {
    _guardCounter += 1;
    uint256 localCounter = _guardCounter;
    _;
    require(localCounter == _guardCounter, "reentrant call");
  }
}
          

// SPDX-License-Identifier: LGPL-3.0-only
pragma solidity >=0.5.13 <0.9.0;

interface IElection {
  function electValidatorSigners() external view returns (address[] memory);
  function electNValidatorSigners(uint256, uint256) external view returns (address[] memory);
  function vote(address, uint256, address, address) external returns (bool);
  function activate(address) external returns (bool);
  function revokeActive(address, uint256, address, address, uint256) external returns (bool);
  function revokeAllActive(address, address, address, uint256) external returns (bool);
  function revokePending(address, uint256, address, address, uint256) external returns (bool);
  function markGroupIneligible(address) external;
  function markGroupEligible(address, address, address) external;
  function allowedToVoteOverMaxNumberOfGroups(address) external returns (bool);
  function forceDecrementVotes(
    address,
    uint256,
    address[] calldata,
    address[] calldata,
    uint256[] calldata
  ) external returns (uint256);
  function setAllowedToVoteOverMaxNumberOfGroups(bool flag) external;

  // view functions
  function getElectableValidators() external view returns (uint256, uint256);
  function getElectabilityThreshold() external view returns (uint256);
  function getNumVotesReceivable(address) external view returns (uint256);
  function getTotalVotes() external view returns (uint256);
  function getActiveVotes() external view returns (uint256);
  function getTotalVotesByAccount(address) external view returns (uint256);
  function getPendingVotesForGroupByAccount(address, address) external view returns (uint256);
  function getActiveVotesForGroupByAccount(address, address) external view returns (uint256);
  function getTotalVotesForGroupByAccount(address, address) external view returns (uint256);
  function getActiveVoteUnitsForGroupByAccount(address, address) external view returns (uint256);
  function getTotalVotesForGroup(address) external view returns (uint256);
  function getActiveVotesForGroup(address) external view returns (uint256);
  function getPendingVotesForGroup(address) external view returns (uint256);
  function getGroupEligibility(address) external view returns (bool);
  function getGroupEpochRewards(address, uint256, uint256[] calldata)
    external
    view
    returns (uint256);
  function getGroupsVotedForByAccount(address) external view returns (address[] memory);
  function getEligibleValidatorGroups() external view returns (address[] memory);
  function getTotalVotesForEligibleValidatorGroups()
    external
    view
    returns (address[] memory, uint256[] memory);
  function getCurrentValidatorSigners() external view returns (address[] memory);
  function canReceiveVotes(address, uint256) external view returns (bool);
  function hasActivatablePendingVotes(address, address) external view returns (bool);
  function validatorSignerAddressFromCurrentSet(uint256 index) external view returns (address);
  function numberValidatorsInCurrentSet() external view returns (uint256);

  // only owner
  function setElectableValidators(uint256, uint256) external returns (bool);
  function setMaxNumGroupsVotedFor(uint256) external returns (bool);
  function setElectabilityThreshold(uint256) external returns (bool);

  // only VM
  function distributeEpochRewards(address, uint256, address, address) external;
}
          

// SPDX-License-Identifier: LGPL-3.0-only
pragma solidity >=0.5.13 <0.9.0;

interface IGovernance {
  function removeVotesWhenRevokingDelegatedVotes(address account, uint256 maxAmountAllowed)
    external;
  function votePartially(
    uint256 proposalId,
    uint256 index,
    uint256 yesVotes,
    uint256 noVotes,
    uint256 abstainVotes
  ) external returns (bool);

  function isVoting(address) external view returns (bool);
  function getAmountOfGoldUsedForVoting(address account) external view returns (uint256);

  function getProposal(uint256 proposalId)
    external
    view
    returns (address, uint256, uint256, uint256, string memory, uint256, bool);

  function getReferendumStageDuration() external view returns (uint256);
}
          

// SPDX-License-Identifier: LGPL-3.0-only
pragma solidity >=0.5.13 <0.9.0;

interface ILockedGold {
  function lock() external payable;
  function incrementNonvotingAccountBalance(address, uint256) external;
  function decrementNonvotingAccountBalance(address, uint256) external;
  function getAccountTotalLockedGold(address) external view returns (uint256);
  function getTotalLockedGold() external view returns (uint256);
  function getPendingWithdrawals(address)
    external
    view
    returns (uint256[] memory, uint256[] memory);
  function getPendingWithdrawal(address account, uint256 index)
    external
    view
    returns (uint256, uint256);
  function getTotalPendingWithdrawals(address) external view returns (uint256);
  function unlock(uint256) external;
  function relock(uint256, uint256) external;
  function withdraw(uint256) external;
  function slash(
    address account,
    uint256 penalty,
    address reporter,
    uint256 reward,
    address[] calldata lessers,
    address[] calldata greaters,
    uint256[] calldata indices
  ) external;
  function isSlasher(address) external view returns (bool);

  function getAccountTotalDelegatedFraction(address account) external view returns (uint256);

  function getAccountTotalGovernanceVotingPower(address account) external view returns (uint256);
  function unlockingPeriod() external view returns (uint256);
  function getAccountNonvotingLockedGold(address account) external view returns (uint256);
}
          

// SPDX-License-Identifier: LGPL-3.0-only
pragma solidity >=0.5.13 <0.9.0;

interface IValidators {
  function registerValidator(bytes calldata, bytes calldata, bytes calldata)
    external
    returns (bool);
  function deregisterValidator(uint256) external returns (bool);
  function affiliate(address) external returns (bool);
  function deaffiliate() external returns (bool);
  function updateBlsPublicKey(bytes calldata, bytes calldata) external returns (bool);
  function registerValidatorGroup(uint256) external returns (bool);
  function deregisterValidatorGroup(uint256) external returns (bool);
  function addMember(address) external returns (bool);
  function addFirstMember(address, address, address) external returns (bool);
  function removeMember(address) external returns (bool);
  function reorderMember(address, address, address) external returns (bool);
  function updateCommission() external;
  function setNextCommissionUpdate(uint256) external;
  function resetSlashingMultiplier() external;

  // only owner
  function setCommissionUpdateDelay(uint256) external;
  function setMaxGroupSize(uint256) external returns (bool);
  function setMembershipHistoryLength(uint256) external returns (bool);
  function setValidatorScoreParameters(uint256, uint256) external returns (bool);
  function setGroupLockedGoldRequirements(uint256, uint256) external returns (bool);
  function setValidatorLockedGoldRequirements(uint256, uint256) external returns (bool);
  function setSlashingMultiplierResetPeriod(uint256) external;

  // view functions
  function getMaxGroupSize() external view returns (uint256);
  function getCommissionUpdateDelay() external view returns (uint256);
  function getValidatorScoreParameters() external view returns (uint256, uint256);
  function getMembershipHistory(address)
    external
    view
    returns (uint256[] memory, address[] memory, uint256, uint256);
  function calculateEpochScore(uint256) external view returns (uint256);
  function calculateGroupEpochScore(uint256[] calldata) external view returns (uint256);
  function getAccountLockedGoldRequirement(address) external view returns (uint256);
  function meetsAccountLockedGoldRequirements(address) external view returns (bool);
  function getValidatorBlsPublicKeyFromSigner(address) external view returns (bytes memory);
  function getValidator(address account)
    external
    view
    returns (bytes memory, bytes memory, address, uint256, address);
  function getValidatorGroup(address)
    external
    view
    returns (address[] memory, uint256, uint256, uint256, uint256[] memory, uint256, uint256);
  function getGroupNumMembers(address) external view returns (uint256);
  function getTopGroupValidators(address, uint256) external view returns (address[] memory);
  function getGroupsNumMembers(address[] calldata accounts)
    external
    view
    returns (uint256[] memory);
  function getNumRegisteredValidators() external view returns (uint256);
  function groupMembershipInEpoch(address, uint256, uint256) external view returns (address);

  // only registered contract
  function updateEcdsaPublicKey(address, address, bytes calldata) external returns (bool);
  function updatePublicKeys(address, address, bytes calldata, bytes calldata, bytes calldata)
    external
    returns (bool);
  function getValidatorLockedGoldRequirements() external view returns (uint256, uint256);
  function getGroupLockedGoldRequirements() external view returns (uint256, uint256);
  function getRegisteredValidators() external view returns (address[] memory);
  function getRegisteredValidatorSigners() external view returns (address[] memory);
  function getRegisteredValidatorGroups() external view returns (address[] memory);
  function isValidatorGroup(address) external view returns (bool);
  function isValidator(address) external view returns (bool);
  function getValidatorGroupSlashingMultiplier(address) external view returns (uint256);
  function getMembershipInLastEpoch(address) external view returns (address);
  function getMembershipInLastEpochFromSigner(address) external view returns (address);

  // only VM
  function updateValidatorScoreFromSigner(address, uint256) external;
  function distributeEpochPaymentsFromSigner(address, uint256) external returns (uint256);

  // only slasher
  function forceDeaffiliateIfValidator(address) external;
  function halveSlashingMultiplier(address) external;

}
          

// SPDX-License-Identifier: LGPL-3.0-only
pragma solidity >=0.5.13 <0.9.0;

interface IAttestations {
  function revoke(bytes32, uint256) external;
  function withdraw(address) external;

  // view functions
  function getUnselectedRequest(bytes32, address) external view returns (uint32, uint32, address);
  function getAttestationIssuers(bytes32, address) external view returns (address[] memory);
  function getAttestationStats(bytes32, address) external view returns (uint32, uint32);
  function batchGetAttestationStats(bytes32[] calldata)
    external
    view
    returns (uint256[] memory, address[] memory, uint64[] memory, uint64[] memory);
  function getAttestationState(bytes32, address, address)
    external
    view
    returns (uint8, uint32, address);
  function getCompletableAttestations(bytes32, address)
    external
    view
    returns (uint32[] memory, address[] memory, uint256[] memory, bytes memory);
  function getAttestationRequestFee(address) external view returns (uint256);
  function getMaxAttestations() external view returns (uint256);
  function validateAttestationCode(bytes32, address, uint8, bytes32, bytes32)
    external
    view
    returns (address);
  function lookupAccountsForIdentifier(bytes32) external view returns (address[] memory);
  function requireNAttestationsRequested(bytes32, address, uint32) external view;

  // only owner
  function setAttestationRequestFee(address, uint256) external;
  function setAttestationExpiryBlocks(uint256) external;
  function setSelectIssuersWaitBlocks(uint256) external;
  function setMaxAttestations(uint256) external;
}
          

// SPDX-License-Identifier: LGPL-3.0-only
pragma solidity >=0.5.13 <0.9.0;

interface IRandom {
  function revealAndCommit(bytes32, bytes32, address) external;
  function randomnessBlockRetentionWindow() external view returns (uint256);
  function random() external view returns (bytes32);
  function getBlockRandomness(uint256) external view returns (bytes32);
}
          

// SPDX-License-Identifier: LGPL-3.0-only
pragma solidity >=0.5.13 <0.9.0;

interface ISortedOracles {
  function addOracle(address, address) external;
  function removeOracle(address, address, uint256) external;
  function report(address, uint256, address, address) external;
  function removeExpiredReports(address, uint256) external;
  function isOldestReportExpired(address token) external view returns (bool, address);
  function numRates(address) external view returns (uint256);
  function medianRate(address) external view returns (uint256, uint256);
  function numTimestamps(address) external view returns (uint256);
  function medianTimestamp(address) external view returns (uint256);
}
          

pragma solidity ^0.5.13;

interface IExchange {
    function buy(
        uint256,
        uint256,
        bool
    ) external returns (uint256);

    function sell(
        uint256,
        uint256,
        bool
    ) external returns (uint256);

    function exchange(
        uint256,
        uint256,
        bool
    ) external returns (uint256);

    function setUpdateFrequency(uint256) external;

    function getBuyTokenAmount(uint256, bool) external view returns (uint256);

    function getSellTokenAmount(uint256, bool) external view returns (uint256);

    function getBuyAndSellBuckets(bool) external view returns (uint256, uint256);
}
          

pragma solidity ^0.5.13;

interface IReserve {
    function setTobinTaxStalenessThreshold(uint256) external;

    function addToken(address) external returns (bool);

    function removeToken(address, uint256) external returns (bool);

    function transferGold(address payable, uint256) external returns (bool);

    function transferExchangeGold(address payable, uint256) external returns (bool);

    function getReserveGoldBalance() external view returns (uint256);

    function getUnfrozenReserveGoldBalance() external view returns (uint256);

    function getOrComputeTobinTax() external returns (uint256, uint256);

    function getTokens() external view returns (address[] memory);

    function getReserveRatio() external view returns (uint256);

    function addExchangeSpender(address) external;

    function removeExchangeSpender(address, uint256) external;

    function addSpender(address) external;

    function removeSpender(address) external;
}
          

pragma solidity ^0.5.13;

/**
 * @title This interface describes the functions specific to Celo Stable Tokens, and in the
 * absence of interface inheritance is intended as a companion to IERC20.sol and ICeloToken.sol.
 */
interface IStableToken {
    function mint(address, uint256) external returns (bool);

    function burn(uint256) external returns (bool);

    function setInflationParameters(uint256, uint256) external;

    function valueToUnits(uint256) external view returns (uint256);

    function unitsToValue(uint256) external view returns (uint256);

    function getInflationParameters()
        external
        view
        returns (
            uint256,
            uint256,
            uint256,
            uint256
        );

    // NOTE: duplicated with IERC20.sol, remove once interface inheritance is supported.
    function balanceOf(address) external view returns (uint256);
}