pragma solidity ^0.5.2;


/**
 * @title ERC20 interface
 * @dev see https://eips.ethereum.org/EIPS/eip-20
 */
interface IERC20 {
    function transfer(address to, uint256 value) external returns (bool);

    function approve(address spender, uint256 value) external returns (bool);

    function transferFrom(address from, address to, uint256 value) external returns (bool);

    function totalSupply() external view returns (uint256);

    function balanceOf(address who) external view returns (uint256);

    function allowance(address owner, address spender) external view returns (uint256);

    event Transfer(address indexed from, address indexed to, uint256 value);

    event Approval(address indexed owner, address indexed spender, uint256 value);
}



/**
 * @title SafeMath
 * @dev Unsigned math operations with safety checks that revert on error
 */
library SafeMath {
    /**
     * @dev Multiplies two unsigned integers, reverts on 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-solidity/pull/522
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b);

        return c;
    }

    /**
     * @dev Integer division of two unsigned integers truncating the quotient, reverts on division by zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        // Solidity only automatically asserts when dividing by 0
        require(b > 0);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
     * @dev Subtracts two unsigned integers, reverts on overflow (i.e. if subtrahend is greater than minuend).
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a);
        uint256 c = a - b;

        return c;
    }

    /**
     * @dev Adds two unsigned integers, reverts on overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a);

        return c;
    }

    /**
     * @dev Divides two unsigned integers and returns the remainder (unsigned integer modulo),
     * reverts when dividing by zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b != 0);
        return a % b;
    }
}



interface IGovernance {
    function update(address target, bytes calldata data) external;
}



contract Governable {
    IGovernance public governance;

    constructor(address _governance) public {
        governance = IGovernance(_governance);
    }

    modifier onlyGovernance() {
        _assertGovernance();
        _;
    }

    function _assertGovernance() private view {
        require(
            msg.sender == address(governance),
            "Only governance contract is authorized"
        );
    }
}



contract IWithdrawManager {
    function createExitQueue(address token) external;

    function verifyInclusion(
        bytes calldata data,
        uint8 offset,
        bool verifyTxInclusion
    ) external view returns (uint256 age);

    function addExitToQueue(
        address exitor,
        address childToken,
        address rootToken,
        uint256 exitAmountOrTokenId,
        bytes32 txHash,
        bool isRegularExit,
        uint256 priority
    ) external;

    function addInput(
        uint256 exitId,
        uint256 age,
        address utxoOwner,
        address token
    ) external;

    function challengeExit(
        uint256 exitId,
        uint256 inputId,
        bytes calldata challengeData,
        address adjudicatorPredicate
    ) external;
}




contract Registry is Governable {
    // @todo hardcode constants
    bytes32 private constant WETH_TOKEN = keccak256("wethToken");
    bytes32 private constant DEPOSIT_MANAGER = keccak256("depositManager");
    bytes32 private constant STAKE_MANAGER = keccak256("stakeManager");
    bytes32 private constant VALIDATOR_SHARE = keccak256("validatorShare");
    bytes32 private constant WITHDRAW_MANAGER = keccak256("withdrawManager");
    bytes32 private constant CHILD_CHAIN = keccak256("childChain");
    bytes32 private constant STATE_SENDER = keccak256("stateSender");
    bytes32 private constant SLASHING_MANAGER = keccak256("slashingManager");

    address public erc20Predicate;
    address public erc721Predicate;

    mapping(bytes32 => address) public contractMap;
    mapping(address => address) public rootToChildToken;
    mapping(address => address) public childToRootToken;
    mapping(address => bool) public proofValidatorContracts;
    mapping(address => bool) public isERC721;

    enum Type {Invalid, ERC20, ERC721, Custom}
    struct Predicate {
        Type _type;
    }
    mapping(address => Predicate) public predicates;

    event TokenMapped(address indexed rootToken, address indexed childToken);
    event ProofValidatorAdded(address indexed validator, address indexed from);
    event ProofValidatorRemoved(address indexed validator, address indexed from);
    event PredicateAdded(address indexed predicate, address indexed from);
    event PredicateRemoved(address indexed predicate, address indexed from);
    event ContractMapUpdated(bytes32 indexed key, address indexed previousContract, address indexed newContract);

    constructor(address _governance) public Governable(_governance) {}

    function updateContractMap(bytes32 _key, address _address) external onlyGovernance {
        emit ContractMapUpdated(_key, contractMap[_key], _address);
        contractMap[_key] = _address;
    }

    /**
     * @dev Map root token to child token
     * @param _rootToken Token address on the root chain
     * @param _childToken Token address on the child chain
     * @param _isERC721 Is the token being mapped ERC721
     */
    function mapToken(
        address _rootToken,
        address _childToken,
        bool _isERC721
    ) external onlyGovernance {
        require(_rootToken != address(0x0) && _childToken != address(0x0), "INVALID_TOKEN_ADDRESS");
        rootToChildToken[_rootToken] = _childToken;
        childToRootToken[_childToken] = _rootToken;
        isERC721[_rootToken] = _isERC721;
        IWithdrawManager(contractMap[WITHDRAW_MANAGER]).createExitQueue(_rootToken);
        emit TokenMapped(_rootToken, _childToken);
    }

    function addErc20Predicate(address predicate) public onlyGovernance {
        require(predicate != address(0x0), "Can not add null address as predicate");
        erc20Predicate = predicate;
        addPredicate(predicate, Type.ERC20);
    }

    function addErc721Predicate(address predicate) public onlyGovernance {
        erc721Predicate = predicate;
        addPredicate(predicate, Type.ERC721);
    }

    function addPredicate(address predicate, Type _type) public onlyGovernance {
        require(predicates[predicate]._type == Type.Invalid, "Predicate already added");
        predicates[predicate]._type = _type;
        emit PredicateAdded(predicate, msg.sender);
    }

    function removePredicate(address predicate) public onlyGovernance {
        require(predicates[predicate]._type != Type.Invalid, "Predicate does not exist");
        delete predicates[predicate];
        emit PredicateRemoved(predicate, msg.sender);
    }

    function getValidatorShareAddress() public view returns (address) {
        return contractMap[VALIDATOR_SHARE];
    }

    function getWethTokenAddress() public view returns (address) {
        return contractMap[WETH_TOKEN];
    }

    function getDepositManagerAddress() public view returns (address) {
        return contractMap[DEPOSIT_MANAGER];
    }

    function getStakeManagerAddress() public view returns (address) {
        return contractMap[STAKE_MANAGER];
    }

    function getSlashingManagerAddress() public view returns (address) {
        return contractMap[SLASHING_MANAGER];
    }

    function getWithdrawManagerAddress() public view returns (address) {
        return contractMap[WITHDRAW_MANAGER];
    }

    function getChildChainAndStateSender() public view returns (address, address) {
        return (contractMap[CHILD_CHAIN], contractMap[STATE_SENDER]);
    }

    function isTokenMapped(address _token) public view returns (bool) {
        return rootToChildToken[_token] != address(0x0);
    }

    function isTokenMappedAndIsErc721(address _token) public view returns (bool) {
        require(isTokenMapped(_token), "TOKEN_NOT_MAPPED");
        return isERC721[_token];
    }

    function isTokenMappedAndGetPredicate(address _token) public view returns (address) {
        if (isTokenMappedAndIsErc721(_token)) {
            return erc721Predicate;
        }
        return erc20Predicate;
    }

    function isChildTokenErc721(address childToken) public view returns (bool) {
        address rootToken = childToRootToken[childToken];
        require(rootToken != address(0x0), "Child token is not mapped");
        return isERC721[rootToken];
    }
}



contract Lockable {
    bool public locked;

    modifier onlyWhenUnlocked() {
        _assertUnlocked();
        _;
    }

    function _assertUnlocked() private view {
        require(!locked, "locked");
    }

    function lock() public {
        locked = true;
    }

    function unlock() public {
        locked = false;
    }
}




contract GovernanceLockable is Lockable, Governable {
    constructor(address governance) public Governable(governance) {}

    function lock() public onlyGovernance {
        super.lock();
    }

    function unlock() public onlyGovernance {
        super.unlock();
    }
}



contract IStakeManager {
    // validator replacement
    function startAuction(
        uint256 validatorId,
        uint256 amount,
        bool acceptDelegation,
        bytes calldata signerPubkey
    ) external;

    function confirmAuctionBid(uint256 validatorId, uint256 heimdallFee) external;

    function transferFunds(
        uint256 validatorId,
        uint256 amount,
        address delegator
    ) external returns (bool);

    function delegationDeposit(
        uint256 validatorId,
        uint256 amount,
        address delegator
    ) external returns (bool);

    function unstake(uint256 validatorId) external;

    function totalStakedFor(address addr) external view returns (uint256);

    function stakeFor(
        address user,
        uint256 amount,
        uint256 heimdallFee,
        bool acceptDelegation,
        bytes memory signerPubkey
    ) public;

    function checkSignatures(
        uint256 blockInterval,
        bytes32 voteHash,
        bytes32 stateRoot,
        address proposer,
        uint[3][] calldata sigs
    ) external returns (uint256);

    function updateValidatorState(uint256 validatorId, int256 amount) public;

    function ownerOf(uint256 tokenId) public view returns (address);

    function slash(bytes calldata slashingInfoList) external returns (uint256);

    function validatorStake(uint256 validatorId) public view returns (uint256);

    function epoch() public view returns (uint256);

    function getRegistry() public view returns (address);

    function withdrawalDelay() public view returns (uint256);

    function delegatedAmount(uint256 validatorId) public view returns(uint256);

    function decreaseValidatorDelegatedAmount(uint256 validatorId, uint256 amount) public;

    function withdrawDelegatorsReward(uint256 validatorId) public returns(uint256);

    function delegatorsReward(uint256 validatorId) public view returns(uint256);

    function dethroneAndStake(
        address auctionUser,
        uint256 heimdallFee,
        uint256 validatorId,
        uint256 auctionAmount,
        bool acceptDelegation,
        bytes calldata signerPubkey
    ) external;
}



/**
 * @title Ownable
 * @dev The Ownable contract has an owner address, and provides basic authorization control
 * functions, this simplifies the implementation of "user permissions".
 */
contract Ownable {
    address private _owner;

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

    /**
     * @dev The Ownable constructor sets the original `owner` of the contract to the sender
     * account.
     */
    constructor () internal {
        _owner = msg.sender;
        emit OwnershipTransferred(address(0), _owner);
    }

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

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(isOwner());
        _;
    }

    /**
     * @return true if `msg.sender` is the owner of the contract.
     */
    function isOwner() public view returns (bool) {
        return msg.sender == _owner;
    }

    /**
     * @dev Allows the current owner to relinquish control of the contract.
     * It will not be possible to call the functions with the `onlyOwner`
     * modifier anymore.
     * @notice 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 Allows the current owner to transfer control of the contract to a newOwner.
     * @param newOwner The address to transfer ownership to.
     */
    function transferOwnership(address newOwner) public onlyOwner {
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers control of the contract to a newOwner.
     * @param newOwner The address to transfer ownership to.
     */
    function _transferOwnership(address newOwner) internal {
        require(newOwner != address(0));
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}



/**
 * @title RootChainable
 */
contract RootChainable is Ownable {
    address public rootChain;

    // Rootchain changed
    event RootChainChanged(
        address indexed previousRootChain,
        address indexed newRootChain
    );

    // only root chain
    modifier onlyRootChain() {
        require(msg.sender == rootChain);
        _;
    }

    /**
   * @dev Allows the current owner to change root chain address.
   * @param newRootChain The address to new rootchain.
   */
    function changeRootChain(address newRootChain) public onlyOwner {
        require(newRootChain != address(0));
        emit RootChainChanged(rootChain, newRootChain);
        rootChain = newRootChain;
    }
}





// dummy interface to avoid cyclic dependency
contract IStakeManagerLocal {
    enum Status {Inactive, Active, Locked, Unstaked}

    struct Validator {
        uint256 amount;
        uint256 reward;
        uint256 activationEpoch;
        uint256 deactivationEpoch;
        uint256 jailTime;
        address signer;
        address contractAddress;
        Status status;
    }

    mapping(uint256 => Validator) public validators;
    bytes32 public accountStateRoot;
    uint256 public activeAmount; // delegation amount from validator contract
    uint256 public validatorRewards;

    function currentValidatorSetTotalStake() public view returns (uint256);

    // signer to Validator mapping
    function signerToValidator(address validatorAddress)
        public
        view
        returns (uint256);

    function isValidator(uint256 validatorId) public view returns (bool);
}

contract StakingInfo is Ownable {
    using SafeMath for uint256;
    mapping(uint256 => uint256) public validatorNonce;

    /// @dev Emitted when validator stakes in '_stakeFor()' in StakeManager.
    /// @param signer validator address.
    /// @param validatorId unique integer to identify a validator.
    /// @param nonce to synchronize the events in heimdal.
    /// @param activationEpoch validator's first epoch as proposer.
    /// @param amount staking amount.
    /// @param total total staking amount.
    /// @param signerPubkey public key of the validator
    event Staked(
        address indexed signer,
        uint256 indexed validatorId,
        uint256 nonce,
        uint256 indexed activationEpoch,
        uint256 amount,
        uint256 total,
        bytes signerPubkey
    );

    /// @dev Emitted when validator unstakes in 'unstakeClaim()'
    /// @param user address of the validator.
    /// @param validatorId unique integer to identify a validator.
    /// @param amount staking amount.
    /// @param total total staking amount.
    event Unstaked(
        address indexed user,
        uint256 indexed validatorId,
        uint256 amount,
        uint256 total
    );

    /// @dev Emitted when validator unstakes in '_unstake()'.
    /// @param user address of the validator.
    /// @param validatorId unique integer to identify a validator.
    /// @param nonce to synchronize the events in heimdal.
    /// @param deactivationEpoch last epoch for validator.
    /// @param amount staking amount.
    event UnstakeInit(
        address indexed user,
        uint256 indexed validatorId,
        uint256 nonce,
        uint256 deactivationEpoch,
        uint256 indexed amount
    );

    /// @dev Emitted when the validator public key is updated in 'updateSigner()'.
    /// @param validatorId unique integer to identify a validator.
    /// @param nonce to synchronize the events in heimdal.
    /// @param oldSigner old address of the validator.
    /// @param newSigner new address of the validator.
    /// @param signerPubkey public key of the validator.
    event SignerChange(
        uint256 indexed validatorId,
        uint256 nonce,
        address indexed oldSigner,
        address indexed newSigner,
        bytes signerPubkey
    );
    event Restaked(uint256 indexed validatorId, uint256 amount, uint256 total);
    event Jailed(
        uint256 indexed validatorId,
        uint256 indexed exitEpoch,
        address indexed signer
    );
    event UnJailed(uint256 indexed validatorId, address indexed signer);
    event Slashed(uint256 indexed nonce, uint256 indexed amount);
    event ThresholdChange(uint256 newThreshold, uint256 oldThreshold);
    event DynastyValueChange(uint256 newDynasty, uint256 oldDynasty);
    event ProposerBonusChange(
        uint256 newProposerBonus,
        uint256 oldProposerBonus
    );

    event RewardUpdate(uint256 newReward, uint256 oldReward);

    /// @dev Emitted when validator confirms the auction bid and at the time of restaking in confirmAuctionBid() and restake().
    /// @param validatorId unique integer to identify a validator.
    /// @param nonce to synchronize the events in heimdal.
    /// @param newAmount the updated stake amount.
    event StakeUpdate(
        uint256 indexed validatorId,
        uint256 indexed nonce,
        uint256 indexed newAmount
    );
    event ClaimRewards(
        uint256 indexed validatorId,
        uint256 indexed amount,
        uint256 indexed totalAmount
    );
    event StartAuction(
        uint256 indexed validatorId,
        uint256 indexed amount,
        uint256 indexed auctionAmount
    );
    event ConfirmAuction(
        uint256 indexed newValidatorId,
        uint256 indexed oldValidatorId,
        uint256 indexed amount
    );
    event TopUpFee(address indexed user, uint256 indexed fee);
    event ClaimFee(address indexed user, uint256 indexed fee);
    // Delegator events
    event ShareMinted(
        uint256 indexed validatorId,
        address indexed user,
        uint256 indexed amount,
        uint256 tokens
    );
    event ShareBurned(
        uint256 indexed validatorId,
        address indexed user,
        uint256 indexed amount,
        uint256 tokens
    );
    event DelegatorClaimedRewards(
        uint256 indexed validatorId,
        address indexed user,
        uint256 indexed rewards
    );
    event DelegatorRestaked(
        uint256 indexed validatorId,
        address indexed user,
        uint256 indexed totalStaked
    );
    event DelegatorUnstaked(
        uint256 indexed validatorId,
        address indexed user,
        uint256 amount
    );
    event UpdateCommissionRate(
        uint256 indexed validatorId,
        uint256 indexed newCommissionRate,
        uint256 indexed oldCommissionRate
    );

    Registry public registry;

    modifier onlyValidatorContract(uint256 validatorId) {
        address _contract;
        (, , , , , , _contract, ) = IStakeManagerLocal(
            registry.getStakeManagerAddress()
        )
            .validators(validatorId);
        require(_contract == msg.sender,
        "Invalid sender, not validator");
        _;
    }

    modifier StakeManagerOrValidatorContract(uint256 validatorId) {
        address _contract;
        address _stakeManager = registry.getStakeManagerAddress();
        (, , , , , , _contract, ) = IStakeManagerLocal(_stakeManager).validators(
            validatorId
        );
        require(_contract == msg.sender || _stakeManager == msg.sender,
        "Invalid sender, not stake manager or validator contract");
        _;
    }

    modifier onlyStakeManager() {
        require(registry.getStakeManagerAddress() == msg.sender,
        "Invalid sender, not stake manager");
        _;
    }
    modifier onlySlashingManager() {
        require(registry.getSlashingManagerAddress() == msg.sender,
        "Invalid sender, not slashing manager");
        _;
    }

    constructor(address _registry) public {
        registry = Registry(_registry);
    }

    function updateNonce(
        uint256[] calldata validatorIds,
        uint256[] calldata nonces
    ) external onlyOwner {
        require(validatorIds.length == nonces.length, "args length mismatch");

        for (uint256 i = 0; i < validatorIds.length; ++i) {
            validatorNonce[validatorIds[i]] = nonces[i];
        }
    } 

    function logStaked(
        address signer,
        bytes memory signerPubkey,
        uint256 validatorId,
        uint256 activationEpoch,
        uint256 amount,
        uint256 total
    ) public onlyStakeManager {
        validatorNonce[validatorId] = validatorNonce[validatorId].add(1);
        emit Staked(
            signer,
            validatorId,
            validatorNonce[validatorId],
            activationEpoch,
            amount,
            total,
            signerPubkey
        );
    }

    function logUnstaked(
        address user,
        uint256 validatorId,
        uint256 amount,
        uint256 total
    ) public onlyStakeManager {
        emit Unstaked(user, validatorId, amount, total);
    }

    function logUnstakeInit(
        address user,
        uint256 validatorId,
        uint256 deactivationEpoch,
        uint256 amount
    ) public onlyStakeManager {
        validatorNonce[validatorId] = validatorNonce[validatorId].add(1);
        emit UnstakeInit(
            user,
            validatorId,
            validatorNonce[validatorId],
            deactivationEpoch,
            amount
        );
    }

    function logSignerChange(
        uint256 validatorId,
        address oldSigner,
        address newSigner,
        bytes memory signerPubkey
    ) public onlyStakeManager {
        validatorNonce[validatorId] = validatorNonce[validatorId].add(1);
        emit SignerChange(
            validatorId,
            validatorNonce[validatorId],
            oldSigner,
            newSigner,
            signerPubkey
        );
    }

    function logRestaked(uint256 validatorId, uint256 amount, uint256 total)
        public
        onlyStakeManager
    {
        emit Restaked(validatorId, amount, total);
    }

    function logJailed(uint256 validatorId, uint256 exitEpoch, address signer)
        public
        onlyStakeManager
    {
        emit Jailed(validatorId, exitEpoch, signer);
    }

    function logUnjailed(uint256 validatorId, address signer)
        public
        onlyStakeManager
    {
        emit UnJailed(validatorId, signer);
    }

    function logSlashed(uint256 nonce, uint256 amount)
        public
        onlySlashingManager
    {
        emit Slashed(nonce, amount);
    }

    function logThresholdChange(uint256 newThreshold, uint256 oldThreshold)
        public
        onlyStakeManager
    {
        emit ThresholdChange(newThreshold, oldThreshold);
    }

    function logDynastyValueChange(uint256 newDynasty, uint256 oldDynasty)
        public
        onlyStakeManager
    {
        emit DynastyValueChange(newDynasty, oldDynasty);
    }

    function logProposerBonusChange(
        uint256 newProposerBonus,
        uint256 oldProposerBonus
    ) public onlyStakeManager {
        emit ProposerBonusChange(newProposerBonus, oldProposerBonus);
    }

    function logRewardUpdate(uint256 newReward, uint256 oldReward)
        public
        onlyStakeManager
    {
        emit RewardUpdate(newReward, oldReward);
    }

    function logStakeUpdate(uint256 validatorId)
        public
        StakeManagerOrValidatorContract(validatorId)
    {
        validatorNonce[validatorId] = validatorNonce[validatorId].add(1);
        emit StakeUpdate(
            validatorId,
            validatorNonce[validatorId],
            totalValidatorStake(validatorId)
        );
    }

    function logClaimRewards(
        uint256 validatorId,
        uint256 amount,
        uint256 totalAmount
    ) public onlyStakeManager {
        emit ClaimRewards(validatorId, amount, totalAmount);
    }

    function logStartAuction(
        uint256 validatorId,
        uint256 amount,
        uint256 auctionAmount
    ) public onlyStakeManager {
        emit StartAuction(validatorId, amount, auctionAmount);
    }

    function logConfirmAuction(
        uint256 newValidatorId,
        uint256 oldValidatorId,
        uint256 amount
    ) public onlyStakeManager {
        emit ConfirmAuction(newValidatorId, oldValidatorId, amount);
    }

    function logTopUpFee(address user, uint256 fee) public onlyStakeManager {
        emit TopUpFee(user, fee);
    }

    function logClaimFee(address user, uint256 fee) public onlyStakeManager {
        emit ClaimFee(user, fee);
    }

    function getStakerDetails(uint256 validatorId)
        public
        view
        returns (
            uint256 amount,
            uint256 reward,
            uint256 activationEpoch,
            uint256 deactivationEpoch,
            address signer,
            uint256 _status
        )
    {
        IStakeManagerLocal stakeManager = IStakeManagerLocal(
            registry.getStakeManagerAddress()
        );
        address _contract;
        IStakeManagerLocal.Status status;
        (
            amount,
            reward,
            activationEpoch,
            deactivationEpoch,
            ,
            signer,
            _contract,
            status
        ) = stakeManager.validators(validatorId);
        _status = uint256(status);
        if (_contract != address(0x0)) {
            reward += IStakeManagerLocal(_contract).validatorRewards();
        }
    }

    function totalValidatorStake(uint256 validatorId)
        public
        view
        returns (uint256 validatorStake)
    {
        address contractAddress;
        (validatorStake, , , , , , contractAddress, ) = IStakeManagerLocal(
            registry.getStakeManagerAddress()
        )
            .validators(validatorId);
        if (contractAddress != address(0x0)) {
            validatorStake += IStakeManagerLocal(contractAddress).activeAmount();
        }
    }

    function getAccountStateRoot()
        public
        view
        returns (bytes32 accountStateRoot)
    {
        accountStateRoot = IStakeManagerLocal(registry.getStakeManagerAddress())
            .accountStateRoot();
    }

    function getValidatorContractAddress(uint256 validatorId)
        public
        view
        returns (address ValidatorContract)
    {
        (, , , , , , ValidatorContract, ) = IStakeManagerLocal(
            registry.getStakeManagerAddress()
        )
            .validators(validatorId);
    }

    // validator Share contract logging func
    function logShareMinted(
        uint256 validatorId,
        address user,
        uint256 amount,
        uint256 tokens
    ) public onlyValidatorContract(validatorId) {
        emit ShareMinted(validatorId, user, amount, tokens);
    }

    function logShareBurned(
        uint256 validatorId,
        address user,
        uint256 amount,
        uint256 tokens
    ) public onlyValidatorContract(validatorId) {
        emit ShareBurned(validatorId, user, amount, tokens);
    }

    function logDelegatorClaimRewards(
        uint256 validatorId,
        address user,
        uint256 rewards
    ) public onlyValidatorContract(validatorId) {
        emit DelegatorClaimedRewards(validatorId, user, rewards);
    }

    function logDelegatorRestaked(
        uint256 validatorId,
        address user,
        uint256 totalStaked
    ) public onlyValidatorContract(validatorId) {
        emit DelegatorRestaked(validatorId, user, totalStaked);
    }

    function logDelegatorUnstaked(uint256 validatorId, address user, uint256 amount)
        public
        onlyValidatorContract(validatorId)
    {
        emit DelegatorUnstaked(validatorId, user, amount);
    }

    // deprecated
    function logUpdateCommissionRate(
        uint256 validatorId,
        uint256 newCommissionRate,
        uint256 oldCommissionRate
    ) public onlyValidatorContract(validatorId) {
        emit UpdateCommissionRate(
            validatorId,
            newCommissionRate,
            oldCommissionRate
        );
    }
}



/**
 * @title IERC165
 * @dev https://eips.ethereum.org/EIPS/eip-165
 */
interface IERC165 {
    /**
     * @notice Query if a contract implements an interface
     * @param interfaceId The interface identifier, as specified in ERC-165
     * @dev Interface identification is specified in ERC-165. This function
     * uses less than 30,000 gas.
     */
    function supportsInterface(bytes4 interfaceId) external view returns (bool);
}



/**
 * @title ERC721 Non-Fungible Token Standard basic interface
 * @dev see https://eips.ethereum.org/EIPS/eip-721
 */
contract IERC721 is IERC165 {
    event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);
    event Approval(address indexed owner, address indexed approved, uint256 indexed tokenId);
    event ApprovalForAll(address indexed owner, address indexed operator, bool approved);

    function balanceOf(address owner) public view returns (uint256 balance);
    function ownerOf(uint256 tokenId) public view returns (address owner);

    function approve(address to, uint256 tokenId) public;
    function getApproved(uint256 tokenId) public view returns (address operator);

    function setApprovalForAll(address operator, bool _approved) public;
    function isApprovedForAll(address owner, address operator) public view returns (bool);

    function transferFrom(address from, address to, uint256 tokenId) public;
    function safeTransferFrom(address from, address to, uint256 tokenId) public;

    function safeTransferFrom(address from, address to, uint256 tokenId, bytes memory data) public;
}



/**
 * @title ERC721 token receiver interface
 * @dev Interface for any contract that wants to support safeTransfers
 * from ERC721 asset contracts.
 */
contract IERC721Receiver {
    /**
     * @notice Handle the receipt of an NFT
     * @dev The ERC721 smart contract calls this function on the recipient
     * after a `safeTransfer`. This function MUST return the function selector,
     * otherwise the caller will revert the transaction. The selector to be
     * returned can be obtained as `this.onERC721Received.selector`. This
     * function MAY throw to revert and reject the transfer.
     * Note: the ERC721 contract address is always the message sender.
     * @param operator The address which called `safeTransferFrom` function
     * @param from The address which previously owned the token
     * @param tokenId The NFT identifier which is being transferred
     * @param data Additional data with no specified format
     * @return bytes4 `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`
     */
    function onERC721Received(address operator, address from, uint256 tokenId, bytes memory data)
    public returns (bytes4);
}



/**
 * Utility library of inline functions on addresses
 */
library Address {
    /**
     * Returns whether the target address is a contract
     * @dev This function will return false if invoked during the constructor of a contract,
     * as the code is not actually created until after the constructor finishes.
     * @param account address of the account to check
     * @return whether the target address is a contract
     */
    function isContract(address account) internal view returns (bool) {
        uint256 size;
        // XXX Currently there is no better way to check if there is a contract in an address
        // than to check the size of the code at that address.
        // See https://ethereum.stackexchange.com/a/14016/36603
        // for more details about how this works.
        // TODO Check this again before the Serenity release, because all addresses will be
        // contracts then.
        // solhint-disable-next-line no-inline-assembly
        assembly { size := extcodesize(account) }
        return size > 0;
    }
}



/**
 * @title Counters
 * @author Matt Condon (@shrugs)
 * @dev Provides counters that can only be incremented or decremented by one. This can be used e.g. to track the number
 * of elements in a mapping, issuing ERC721 ids, or counting request ids
 *
 * Include with `using Counters for Counters.Counter;`
 * Since it is not possible to overflow a 256 bit integer with increments of one, `increment` can skip the SafeMath
 * overflow check, thereby saving gas. This does assume however correct usage, in that the underlying `_value` is never
 * directly accessed.
 */
library Counters {
    using SafeMath for uint256;

    struct Counter {
        // This variable should never be directly accessed by users of the library: interactions must be restricted to
        // the library's function. As of Solidity v0.5.2, this cannot be enforced, though there is a proposal to add
        // this feature: see https://github.com/ethereum/solidity/issues/4637
        uint256 _value; // default: 0
    }

    function current(Counter storage counter) internal view returns (uint256) {
        return counter._value;
    }

    function increment(Counter storage counter) internal {
        counter._value += 1;
    }

    function decrement(Counter storage counter) internal {
        counter._value = counter._value.sub(1);
    }
}



/**
 * @title ERC165
 * @author Matt Condon (@shrugs)
 * @dev Implements ERC165 using a lookup table.
 */
contract ERC165 is IERC165 {
    bytes4 private constant _INTERFACE_ID_ERC165 = 0x01ffc9a7;
    /*
     * 0x01ffc9a7 ===
     *     bytes4(keccak256('supportsInterface(bytes4)'))
     */

    /**
     * @dev a mapping of interface id to whether or not it's supported
     */
    mapping(bytes4 => bool) private _supportedInterfaces;

    /**
     * @dev A contract implementing SupportsInterfaceWithLookup
     * implement ERC165 itself
     */
    constructor () internal {
        _registerInterface(_INTERFACE_ID_ERC165);
    }

    /**
     * @dev implement supportsInterface(bytes4) using a lookup table
     */
    function supportsInterface(bytes4 interfaceId) external view returns (bool) {
        return _supportedInterfaces[interfaceId];
    }

    /**
     * @dev internal method for registering an interface
     */
    function _registerInterface(bytes4 interfaceId) internal {
        require(interfaceId != 0xffffffff);
        _supportedInterfaces[interfaceId] = true;
    }
}








/**
 * @title ERC721 Non-Fungible Token Standard basic implementation
 * @dev see https://eips.ethereum.org/EIPS/eip-721
 */
contract ERC721 is ERC165, IERC721 {
    using SafeMath for uint256;
    using Address for address;
    using Counters for Counters.Counter;

    // Equals to `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`
    // which can be also obtained as `IERC721Receiver(0).onERC721Received.selector`
    bytes4 private constant _ERC721_RECEIVED = 0x150b7a02;

    // Mapping from token ID to owner
    mapping (uint256 => address) private _tokenOwner;

    // Mapping from token ID to approved address
    mapping (uint256 => address) private _tokenApprovals;

    // Mapping from owner to number of owned token
    mapping (address => Counters.Counter) private _ownedTokensCount;

    // Mapping from owner to operator approvals
    mapping (address => mapping (address => bool)) private _operatorApprovals;

    bytes4 private constant _INTERFACE_ID_ERC721 = 0x80ac58cd;
    /*
     * 0x80ac58cd ===
     *     bytes4(keccak256('balanceOf(address)')) ^
     *     bytes4(keccak256('ownerOf(uint256)')) ^
     *     bytes4(keccak256('approve(address,uint256)')) ^
     *     bytes4(keccak256('getApproved(uint256)')) ^
     *     bytes4(keccak256('setApprovalForAll(address,bool)')) ^
     *     bytes4(keccak256('isApprovedForAll(address,address)')) ^
     *     bytes4(keccak256('transferFrom(address,address,uint256)')) ^
     *     bytes4(keccak256('safeTransferFrom(address,address,uint256)')) ^
     *     bytes4(keccak256('safeTransferFrom(address,address,uint256,bytes)'))
     */

    constructor () public {
        // register the supported interfaces to conform to ERC721 via ERC165
        _registerInterface(_INTERFACE_ID_ERC721);
    }

    /**
     * @dev Gets the balance of the specified address
     * @param owner address to query the balance of
     * @return uint256 representing the amount owned by the passed address
     */
    function balanceOf(address owner) public view returns (uint256) {
        require(owner != address(0));
        return _ownedTokensCount[owner].current();
    }

    /**
     * @dev Gets the owner of the specified token ID
     * @param tokenId uint256 ID of the token to query the owner of
     * @return address currently marked as the owner of the given token ID
     */
    function ownerOf(uint256 tokenId) public view returns (address) {
        address owner = _tokenOwner[tokenId];
        require(owner != address(0));
        return owner;
    }

    /**
     * @dev Approves another address to transfer the given token ID
     * The zero address indicates there is no approved address.
     * There can only be one approved address per token at a given time.
     * Can only be called by the token owner or an approved operator.
     * @param to address to be approved for the given token ID
     * @param tokenId uint256 ID of the token to be approved
     */
    function approve(address to, uint256 tokenId) public {
        address owner = ownerOf(tokenId);
        require(to != owner);
        require(msg.sender == owner || isApprovedForAll(owner, msg.sender));

        _tokenApprovals[tokenId] = to;
        emit Approval(owner, to, tokenId);
    }

    /**
     * @dev Gets the approved address for a token ID, or zero if no address set
     * Reverts if the token ID does not exist.
     * @param tokenId uint256 ID of the token to query the approval of
     * @return address currently approved for the given token ID
     */
    function getApproved(uint256 tokenId) public view returns (address) {
        require(_exists(tokenId));
        return _tokenApprovals[tokenId];
    }

    /**
     * @dev Sets or unsets the approval of a given operator
     * An operator is allowed to transfer all tokens of the sender on their behalf
     * @param to operator address to set the approval
     * @param approved representing the status of the approval to be set
     */
    function setApprovalForAll(address to, bool approved) public {
        require(to != msg.sender);
        _operatorApprovals[msg.sender][to] = approved;
        emit ApprovalForAll(msg.sender, to, approved);
    }

    /**
     * @dev Tells whether an operator is approved by a given owner
     * @param owner owner address which you want to query the approval of
     * @param operator operator address which you want to query the approval of
     * @return bool whether the given operator is approved by the given owner
     */
    function isApprovedForAll(address owner, address operator) public view returns (bool) {
        return _operatorApprovals[owner][operator];
    }

    /**
     * @dev Transfers the ownership of a given token ID to another address
     * Usage of this method is discouraged, use `safeTransferFrom` whenever possible
     * Requires the msg.sender to be the owner, approved, or operator
     * @param from current owner of the token
     * @param to address to receive the ownership of the given token ID
     * @param tokenId uint256 ID of the token to be transferred
     */
    function transferFrom(address from, address to, uint256 tokenId) public {
        require(_isApprovedOrOwner(msg.sender, tokenId));

        _transferFrom(from, to, tokenId);
    }

    /**
     * @dev Safely transfers the ownership of a given token ID to another address
     * If the target address is a contract, it must implement `onERC721Received`,
     * which is called upon a safe transfer, and return the magic value
     * `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`; otherwise,
     * the transfer is reverted.
     * Requires the msg.sender to be the owner, approved, or operator
     * @param from current owner of the token
     * @param to address to receive the ownership of the given token ID
     * @param tokenId uint256 ID of the token to be transferred
     */
    function safeTransferFrom(address from, address to, uint256 tokenId) public {
        safeTransferFrom(from, to, tokenId, "");
    }

    /**
     * @dev Safely transfers the ownership of a given token ID to another address
     * If the target address is a contract, it must implement `onERC721Received`,
     * which is called upon a safe transfer, and return the magic value
     * `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`; otherwise,
     * the transfer is reverted.
     * Requires the msg.sender to be the owner, approved, or operator
     * @param from current owner of the token
     * @param to address to receive the ownership of the given token ID
     * @param tokenId uint256 ID of the token to be transferred
     * @param _data bytes data to send along with a safe transfer check
     */
    function safeTransferFrom(address from, address to, uint256 tokenId, bytes memory _data) public {
        transferFrom(from, to, tokenId);
        require(_checkOnERC721Received(from, to, tokenId, _data));
    }

    /**
     * @dev Returns whether the specified token exists
     * @param tokenId uint256 ID of the token to query the existence of
     * @return bool whether the token exists
     */
    function _exists(uint256 tokenId) internal view returns (bool) {
        address owner = _tokenOwner[tokenId];
        return owner != address(0);
    }

    /**
     * @dev Returns whether the given spender can transfer a given token ID
     * @param spender address of the spender to query
     * @param tokenId uint256 ID of the token to be transferred
     * @return bool whether the msg.sender is approved for the given token ID,
     * is an operator of the owner, or is the owner of the token
     */
    function _isApprovedOrOwner(address spender, uint256 tokenId) internal view returns (bool) {
        address owner = ownerOf(tokenId);
        return (spender == owner || getApproved(tokenId) == spender || isApprovedForAll(owner, spender));
    }

    /**
     * @dev Internal function to mint a new token
     * Reverts if the given token ID already exists
     * @param to The address that will own the minted token
     * @param tokenId uint256 ID of the token to be minted
     */
    function _mint(address to, uint256 tokenId) internal {
        require(to != address(0));
        require(!_exists(tokenId));

        _tokenOwner[tokenId] = to;
        _ownedTokensCount[to].increment();

        emit Transfer(address(0), to, tokenId);
    }

    /**
     * @dev Internal function to burn a specific token
     * Reverts if the token does not exist
     * Deprecated, use _burn(uint256) instead.
     * @param owner owner of the token to burn
     * @param tokenId uint256 ID of the token being burned
     */
    function _burn(address owner, uint256 tokenId) internal {
        require(ownerOf(tokenId) == owner);

        _clearApproval(tokenId);

        _ownedTokensCount[owner].decrement();
        _tokenOwner[tokenId] = address(0);

        emit Transfer(owner, address(0), tokenId);
    }

    /**
     * @dev Internal function to burn a specific token
     * Reverts if the token does not exist
     * @param tokenId uint256 ID of the token being burned
     */
    function _burn(uint256 tokenId) internal {
        _burn(ownerOf(tokenId), tokenId);
    }

    /**
     * @dev Internal function to transfer ownership of a given token ID to another address.
     * As opposed to transferFrom, this imposes no restrictions on msg.sender.
     * @param from current owner of the token
     * @param to address to receive the ownership of the given token ID
     * @param tokenId uint256 ID of the token to be transferred
     */
    function _transferFrom(address from, address to, uint256 tokenId) internal {
        require(ownerOf(tokenId) == from);
        require(to != address(0));

        _clearApproval(tokenId);

        _ownedTokensCount[from].decrement();
        _ownedTokensCount[to].increment();

        _tokenOwner[tokenId] = to;

        emit Transfer(from, to, tokenId);
    }

    /**
     * @dev Internal function to invoke `onERC721Received` on a target address
     * The call is not executed if the target address is not a contract
     * @param from address representing the previous owner of the given token ID
     * @param to target address that will receive the tokens
     * @param tokenId uint256 ID of the token to be transferred
     * @param _data bytes optional data to send along with the call
     * @return bool whether the call correctly returned the expected magic value
     */
    function _checkOnERC721Received(address from, address to, uint256 tokenId, bytes memory _data)
        internal returns (bool)
    {
        if (!to.isContract()) {
            return true;
        }

        bytes4 retval = IERC721Receiver(to).onERC721Received(msg.sender, from, tokenId, _data);
        return (retval == _ERC721_RECEIVED);
    }

    /**
     * @dev Private function to clear current approval of a given token ID
     * @param tokenId uint256 ID of the token to be transferred
     */
    function _clearApproval(uint256 tokenId) private {
        if (_tokenApprovals[tokenId] != address(0)) {
            _tokenApprovals[tokenId] = address(0);
        }
    }
}



/**
 * @title ERC-721 Non-Fungible Token Standard, optional enumeration extension
 * @dev See https://eips.ethereum.org/EIPS/eip-721
 */
contract IERC721Enumerable is IERC721 {
    function totalSupply() public view returns (uint256);
    function tokenOfOwnerByIndex(address owner, uint256 index) public view returns (uint256 tokenId);

    function tokenByIndex(uint256 index) public view returns (uint256);
}





/**
 * @title ERC-721 Non-Fungible Token with optional enumeration extension logic
 * @dev See https://eips.ethereum.org/EIPS/eip-721
 */
contract ERC721Enumerable is ERC165, ERC721, IERC721Enumerable {
    // Mapping from owner to list of owned token IDs
    mapping(address => uint256[]) private _ownedTokens;

    // Mapping from token ID to index of the owner tokens list
    mapping(uint256 => uint256) private _ownedTokensIndex;

    // Array with all token ids, used for enumeration
    uint256[] private _allTokens;

    // Mapping from token id to position in the allTokens array
    mapping(uint256 => uint256) private _allTokensIndex;

    bytes4 private constant _INTERFACE_ID_ERC721_ENUMERABLE = 0x780e9d63;
    /*
     * 0x780e9d63 ===
     *     bytes4(keccak256('totalSupply()')) ^
     *     bytes4(keccak256('tokenOfOwnerByIndex(address,uint256)')) ^
     *     bytes4(keccak256('tokenByIndex(uint256)'))
     */

    /**
     * @dev Constructor function
     */
    constructor () public {
        // register the supported interface to conform to ERC721Enumerable via ERC165
        _registerInterface(_INTERFACE_ID_ERC721_ENUMERABLE);
    }

    /**
     * @dev Gets the token ID at a given index of the tokens list of the requested owner
     * @param owner address owning the tokens list to be accessed
     * @param index uint256 representing the index to be accessed of the requested tokens list
     * @return uint256 token ID at the given index of the tokens list owned by the requested address
     */
    function tokenOfOwnerByIndex(address owner, uint256 index) public view returns (uint256) {
        require(index < balanceOf(owner));
        return _ownedTokens[owner][index];
    }

    /**
     * @dev Gets the total amount of tokens stored by the contract
     * @return uint256 representing the total amount of tokens
     */
    function totalSupply() public view returns (uint256) {
        return _allTokens.length;
    }

    /**
     * @dev Gets the token ID at a given index of all the tokens in this contract
     * Reverts if the index is greater or equal to the total number of tokens
     * @param index uint256 representing the index to be accessed of the tokens list
     * @return uint256 token ID at the given index of the tokens list
     */
    function tokenByIndex(uint256 index) public view returns (uint256) {
        require(index < totalSupply());
        return _allTokens[index];
    }

    /**
     * @dev Internal function to transfer ownership of a given token ID to another address.
     * As opposed to transferFrom, this imposes no restrictions on msg.sender.
     * @param from current owner of the token
     * @param to address to receive the ownership of the given token ID
     * @param tokenId uint256 ID of the token to be transferred
     */
    function _transferFrom(address from, address to, uint256 tokenId) internal {
        super._transferFrom(from, to, tokenId);

        _removeTokenFromOwnerEnumeration(from, tokenId);

        _addTokenToOwnerEnumeration(to, tokenId);
    }

    /**
     * @dev Internal function to mint a new token
     * Reverts if the given token ID already exists
     * @param to address the beneficiary that will own the minted token
     * @param tokenId uint256 ID of the token to be minted
     */
    function _mint(address to, uint256 tokenId) internal {
        super._mint(to, tokenId);

        _addTokenToOwnerEnumeration(to, tokenId);

        _addTokenToAllTokensEnumeration(tokenId);
    }

    /**
     * @dev Internal function to burn a specific token
     * Reverts if the token does not exist
     * Deprecated, use _burn(uint256) instead
     * @param owner owner of the token to burn
     * @param tokenId uint256 ID of the token being burned
     */
    function _burn(address owner, uint256 tokenId) internal {
        super._burn(owner, tokenId);

        _removeTokenFromOwnerEnumeration(owner, tokenId);
        // Since tokenId will be deleted, we can clear its slot in _ownedTokensIndex to trigger a gas refund
        _ownedTokensIndex[tokenId] = 0;

        _removeTokenFromAllTokensEnumeration(tokenId);
    }

    /**
     * @dev Gets the list of token IDs of the requested owner
     * @param owner address owning the tokens
     * @return uint256[] List of token IDs owned by the requested address
     */
    function _tokensOfOwner(address owner) internal view returns (uint256[] storage) {
        return _ownedTokens[owner];
    }

    /**
     * @dev Private function to add a token to this extension's ownership-tracking data structures.
     * @param to address representing the new owner of the given token ID
     * @param tokenId uint256 ID of the token to be added to the tokens list of the given address
     */
    function _addTokenToOwnerEnumeration(address to, uint256 tokenId) private {
        _ownedTokensIndex[tokenId] = _ownedTokens[to].length;
        _ownedTokens[to].push(tokenId);
    }

    /**
     * @dev Private function to add a token to this extension's token tracking data structures.
     * @param tokenId uint256 ID of the token to be added to the tokens list
     */
    function _addTokenToAllTokensEnumeration(uint256 tokenId) private {
        _allTokensIndex[tokenId] = _allTokens.length;
        _allTokens.push(tokenId);
    }

    /**
     * @dev Private function to remove a token from this extension's ownership-tracking data structures. Note that
     * while the token is not assigned a new owner, the _ownedTokensIndex mapping is _not_ updated: this allows for
     * gas optimizations e.g. when performing a transfer operation (avoiding double writes).
     * This has O(1) time complexity, but alters the order of the _ownedTokens array.
     * @param from address representing the previous owner of the given token ID
     * @param tokenId uint256 ID of the token to be removed from the tokens list of the given address
     */
    function _removeTokenFromOwnerEnumeration(address from, uint256 tokenId) private {
        // To prevent a gap in from's tokens array, we store the last token in the index of the token to delete, and
        // then delete the last slot (swap and pop).

        uint256 lastTokenIndex = _ownedTokens[from].length.sub(1);
        uint256 tokenIndex = _ownedTokensIndex[tokenId];

        // When the token to delete is the last token, the swap operation is unnecessary
        if (tokenIndex != lastTokenIndex) {
            uint256 lastTokenId = _ownedTokens[from][lastTokenIndex];

            _ownedTokens[from][tokenIndex] = lastTokenId; // Move the last token to the slot of the to-delete token
            _ownedTokensIndex[lastTokenId] = tokenIndex; // Update the moved token's index
        }

        // This also deletes the contents at the last position of the array
        _ownedTokens[from].length--;

        // Note that _ownedTokensIndex[tokenId] hasn't been cleared: it still points to the old slot (now occupied by
        // lastTokenId, or just over the end of the array if the token was the last one).
    }

    /**
     * @dev Private function to remove a token from this extension's token tracking data structures.
     * This has O(1) time complexity, but alters the order of the _allTokens array.
     * @param tokenId uint256 ID of the token to be removed from the tokens list
     */
    function _removeTokenFromAllTokensEnumeration(uint256 tokenId) private {
        // To prevent a gap in the tokens array, we store the last token in the index of the token to delete, and
        // then delete the last slot (swap and pop).

        uint256 lastTokenIndex = _allTokens.length.sub(1);
        uint256 tokenIndex = _allTokensIndex[tokenId];

        // When the token to delete is the last token, the swap operation is unnecessary. However, since this occurs so
        // rarely (when the last minted token is burnt) that we still do the swap here to avoid the gas cost of adding
        // an 'if' statement (like in _removeTokenFromOwnerEnumeration)
        uint256 lastTokenId = _allTokens[lastTokenIndex];

        _allTokens[tokenIndex] = lastTokenId; // Move the last token to the slot of the to-delete token
        _allTokensIndex[lastTokenId] = tokenIndex; // Update the moved token's index

        // This also deletes the contents at the last position of the array
        _allTokens.length--;
        _allTokensIndex[tokenId] = 0;
    }
}



/**
 * @title ERC-721 Non-Fungible Token Standard, optional metadata extension
 * @dev See https://eips.ethereum.org/EIPS/eip-721
 */
contract IERC721Metadata is IERC721 {
    function name() external view returns (string memory);
    function symbol() external view returns (string memory);
    function tokenURI(uint256 tokenId) external view returns (string memory);
}





contract ERC721Metadata is ERC165, ERC721, IERC721Metadata {
    // Token name
    string private _name;

    // Token symbol
    string private _symbol;

    // Optional mapping for token URIs
    mapping(uint256 => string) private _tokenURIs;

    bytes4 private constant _INTERFACE_ID_ERC721_METADATA = 0x5b5e139f;
    /*
     * 0x5b5e139f ===
     *     bytes4(keccak256('name()')) ^
     *     bytes4(keccak256('symbol()')) ^
     *     bytes4(keccak256('tokenURI(uint256)'))
     */

    /**
     * @dev Constructor function
     */
    constructor (string memory name, string memory symbol) public {
        _name = name;
        _symbol = symbol;

        // register the supported interfaces to conform to ERC721 via ERC165
        _registerInterface(_INTERFACE_ID_ERC721_METADATA);
    }

    /**
     * @dev Gets the token name
     * @return string representing the token name
     */
    function name() external view returns (string memory) {
        return _name;
    }

    /**
     * @dev Gets the token symbol
     * @return string representing the token symbol
     */
    function symbol() external view returns (string memory) {
        return _symbol;
    }

    /**
     * @dev Returns an URI for a given token ID
     * Throws if the token ID does not exist. May return an empty string.
     * @param tokenId uint256 ID of the token to query
     */
    function tokenURI(uint256 tokenId) external view returns (string memory) {
        require(_exists(tokenId));
        return _tokenURIs[tokenId];
    }

    /**
     * @dev Internal function to set the token URI for a given token
     * Reverts if the token ID does not exist
     * @param tokenId uint256 ID of the token to set its URI
     * @param uri string URI to assign
     */
    function _setTokenURI(uint256 tokenId, string memory uri) internal {
        require(_exists(tokenId));
        _tokenURIs[tokenId] = uri;
    }

    /**
     * @dev Internal function to burn a specific token
     * Reverts if the token does not exist
     * Deprecated, use _burn(uint256) instead
     * @param owner owner of the token to burn
     * @param tokenId uint256 ID of the token being burned by the msg.sender
     */
    function _burn(address owner, uint256 tokenId) internal {
        super._burn(owner, tokenId);

        // Clear metadata (if any)
        if (bytes(_tokenURIs[tokenId]).length != 0) {
            delete _tokenURIs[tokenId];
        }
    }
}





/**
 * @title Full ERC721 Token
 * This implementation includes all the required and some optional functionality of the ERC721 standard
 * Moreover, it includes approve all functionality using operator terminology
 * @dev see https://eips.ethereum.org/EIPS/eip-721
 */
contract ERC721Full is ERC721, ERC721Enumerable, ERC721Metadata {
    constructor (string memory name, string memory symbol) public ERC721Metadata(name, symbol) {
        // solhint-disable-previous-line no-empty-blocks
    }
}




contract StakingNFT is ERC721Full, Ownable {
    constructor(string memory name, string memory symbol)
        public
        ERC721Full(name, symbol)
    {
        // solhint-disable-previous-line no-empty-blocks
    }

    function mint(address to, uint256 tokenId) public onlyOwner {
        require(
            balanceOf(to) == 0,
            "Validators MUST NOT own multiple stake position"
        );
        _mint(to, tokenId);
    }

    function burn(uint256 tokenId) public onlyOwner {
        _burn(tokenId);
    }

    function _transferFrom(address from, address to, uint256 tokenId) internal {
        require(
            balanceOf(to) == 0,
            "Validators MUST NOT own multiple stake position"
        );
        super._transferFrom(from, to, tokenId);
    }
}


/*
 * SPDX-License-Identitifer:    MIT
 */


// See https://github.com/ethereum/EIPs/blob/master/EIPS/eip-897.md

interface ERCProxy {
    function proxyType() external pure returns (uint256 proxyTypeId);
    function implementation() external view returns (address codeAddr);
}



contract DelegateProxyForwarder {
    function delegatedFwd(address _dst, bytes memory _calldata) internal {
        // solium-disable-next-line security/no-inline-assembly
        assembly {
            let result := delegatecall(
                sub(gas, 10000),
                _dst,
                add(_calldata, 0x20),
                mload(_calldata),
                0,
                0
            )
            let size := returndatasize

            let ptr := mload(0x40)
            returndatacopy(ptr, 0, size)

            // revert instead of invalid() bc if the underlying call failed with invalid() it already wasted gas.
            // if the call returned error data, forward it
            switch result
                case 0 {
                    revert(ptr, size)
                }
                default {
                    return(ptr, size)
                }
        }
    }
    
    function isContract(address _target) internal view returns (bool) {
        if (_target == address(0)) {
            return false;
        }

        uint256 size;
        assembly {
            size := extcodesize(_target)
        }
        return size > 0;
    }
}




contract DelegateProxy is ERCProxy, DelegateProxyForwarder {
    function proxyType() external pure returns (uint256 proxyTypeId) {
        // Upgradeable proxy
        proxyTypeId = 2;
    }

    function implementation() external view returns (address);
}



contract UpgradableProxy is DelegateProxy {
    event ProxyUpdated(address indexed _new, address indexed _old);
    event OwnerUpdate(address _new, address _old);

    bytes32 constant IMPLEMENTATION_SLOT = keccak256("matic.network.proxy.implementation");
    bytes32 constant OWNER_SLOT = keccak256("matic.network.proxy.owner");

    constructor(address _proxyTo) public {
        setOwner(msg.sender);
        setImplementation(_proxyTo);
    }

    function() external payable {
        // require(currentContract != 0, "If app code has not been set yet, do not call");
        // Todo: filter out some calls or handle in the end fallback
        delegatedFwd(loadImplementation(), msg.data);
    }

    modifier onlyProxyOwner() {
        require(loadOwner() == msg.sender, "NOT_OWNER");
        _;
    }

    function owner() external view returns(address) {
        return loadOwner();
    }

    function loadOwner() internal view returns(address) {
        address _owner;
        bytes32 position = OWNER_SLOT;
        assembly {
            _owner := sload(position)
        }
        return _owner;
    }

    function implementation() external view returns (address) {
        return loadImplementation();
    }

    function loadImplementation() internal view returns(address) {
        address _impl;
        bytes32 position = IMPLEMENTATION_SLOT;
        assembly {
            _impl := sload(position)
        }
        return _impl;
    }

    function transferOwnership(address newOwner) public onlyProxyOwner {
        require(newOwner != address(0), "ZERO_ADDRESS");
        emit OwnerUpdate(newOwner, loadOwner());
        setOwner(newOwner);
    }

    function setOwner(address newOwner) private {
        bytes32 position = OWNER_SLOT;
        assembly {
            sstore(position, newOwner)
        }
    }

    function updateImplementation(address _newProxyTo) public onlyProxyOwner {
        require(_newProxyTo != address(0x0), "INVALID_PROXY_ADDRESS");
        require(isContract(_newProxyTo), "DESTINATION_ADDRESS_IS_NOT_A_CONTRACT");

        emit ProxyUpdated(_newProxyTo, loadImplementation());
        
        setImplementation(_newProxyTo);
    }

    function updateAndCall(address _newProxyTo, bytes memory data) payable public onlyProxyOwner {
        updateImplementation(_newProxyTo);

        (bool success, bytes memory returnData) = address(this).call.value(msg.value)(data);
        require(success, string(returnData));
    }

    function setImplementation(address _newProxyTo) private {
        bytes32 position = IMPLEMENTATION_SLOT;
        assembly {
            sstore(position, _newProxyTo)
        }
    }
}




contract ValidatorShareProxy is UpgradableProxy {
    constructor(address _registry) public UpgradableProxy(_registry) {}

    function loadImplementation() internal view returns (address) {
        return Registry(super.loadImplementation()).getValidatorShareAddress();
    }
}




/**
 * @title Standard ERC20 token
 *
 * @dev Implementation of the basic standard token.
 * https://eips.ethereum.org/EIPS/eip-20
 * Originally based on code by FirstBlood:
 * https://github.com/Firstbloodio/token/blob/master/smart_contract/FirstBloodToken.sol
 *
 * This implementation emits additional Approval events, allowing applications to reconstruct the allowance status for
 * all accounts just by listening to said events. Note that this isn't required by the specification, and other
 * compliant implementations may not do it.
 */
contract ERC20 is IERC20 {
    using SafeMath for uint256;

    mapping (address => uint256) private _balances;

    mapping (address => mapping (address => uint256)) private _allowed;

    uint256 private _totalSupply;

    /**
     * @dev Total number of tokens in existence
     */
    function totalSupply() public view returns (uint256) {
        return _totalSupply;
    }

    /**
     * @dev Gets the balance of the specified address.
     * @param owner The address to query the balance of.
     * @return A uint256 representing the amount owned by the passed address.
     */
    function balanceOf(address owner) public view returns (uint256) {
        return _balances[owner];
    }

    /**
     * @dev Function to check the amount of tokens that an owner allowed to a spender.
     * @param owner address The address which owns the funds.
     * @param spender address The address which will spend the funds.
     * @return A uint256 specifying the amount of tokens still available for the spender.
     */
    function allowance(address owner, address spender) public view returns (uint256) {
        return _allowed[owner][spender];
    }

    /**
     * @dev Transfer token to a specified address
     * @param to The address to transfer to.
     * @param value The amount to be transferred.
     */
    function transfer(address to, uint256 value) public returns (bool) {
        _transfer(msg.sender, to, value);
        return true;
    }

    /**
     * @dev Approve the passed address to spend the specified amount of tokens on behalf of msg.sender.
     * 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
     * @param spender The address which will spend the funds.
     * @param value The amount of tokens to be spent.
     */
    function approve(address spender, uint256 value) public returns (bool) {
        _approve(msg.sender, spender, value);
        return true;
    }

    /**
     * @dev Transfer tokens from one address to another.
     * Note that while this function emits an Approval event, this is not required as per the specification,
     * and other compliant implementations may not emit the event.
     * @param from address The address which you want to send tokens from
     * @param to address The address which you want to transfer to
     * @param value uint256 the amount of tokens to be transferred
     */
    function transferFrom(address from, address to, uint256 value) public returns (bool) {
        _transfer(from, to, value);
        _approve(from, msg.sender, _allowed[from][msg.sender].sub(value));
        return true;
    }

    /**
     * @dev Increase the amount of tokens that an owner allowed to a spender.
     * approve should be called when _allowed[msg.sender][spender] == 0. To increment
     * allowed value is better to use this function to avoid 2 calls (and wait until
     * the first transaction is mined)
     * From MonolithDAO Token.sol
     * Emits an Approval event.
     * @param spender The address which will spend the funds.
     * @param addedValue The amount of tokens to increase the allowance by.
     */
    function increaseAllowance(address spender, uint256 addedValue) public returns (bool) {
        _approve(msg.sender, spender, _allowed[msg.sender][spender].add(addedValue));
        return true;
    }

    /**
     * @dev Decrease the amount of tokens that an owner allowed to a spender.
     * approve should be called when _allowed[msg.sender][spender] == 0. To decrement
     * allowed value is better to use this function to avoid 2 calls (and wait until
     * the first transaction is mined)
     * From MonolithDAO Token.sol
     * Emits an Approval event.
     * @param spender The address which will spend the funds.
     * @param subtractedValue The amount of tokens to decrease the allowance by.
     */
    function decreaseAllowance(address spender, uint256 subtractedValue) public returns (bool) {
        _approve(msg.sender, spender, _allowed[msg.sender][spender].sub(subtractedValue));
        return true;
    }

    /**
     * @dev Transfer token for a specified addresses
     * @param from The address to transfer from.
     * @param to The address to transfer to.
     * @param value The amount to be transferred.
     */
    function _transfer(address from, address to, uint256 value) internal {
        require(to != address(0));

        _balances[from] = _balances[from].sub(value);
        _balances[to] = _balances[to].add(value);
        emit Transfer(from, to, value);
    }

    /**
     * @dev Internal function that mints an amount of the token and assigns it to
     * an account. This encapsulates the modification of balances such that the
     * proper events are emitted.
     * @param account The account that will receive the created tokens.
     * @param value The amount that will be created.
     */
    function _mint(address account, uint256 value) internal {
        require(account != address(0));

        _totalSupply = _totalSupply.add(value);
        _balances[account] = _balances[account].add(value);
        emit Transfer(address(0), account, value);
    }

    /**
     * @dev Internal function that burns an amount of the token of a given
     * account.
     * @param account The account whose tokens will be burnt.
     * @param value The amount that will be burnt.
     */
    function _burn(address account, uint256 value) internal {
        require(account != address(0));

        _totalSupply = _totalSupply.sub(value);
        _balances[account] = _balances[account].sub(value);
        emit Transfer(account, address(0), value);
    }

    /**
     * @dev Approve an address to spend another addresses' tokens.
     * @param owner The address that owns the tokens.
     * @param spender The address that will spend the tokens.
     * @param value The number of tokens that can be spent.
     */
    function _approve(address owner, address spender, uint256 value) internal {
        require(spender != address(0));
        require(owner != address(0));

        _allowed[owner][spender] = value;
        emit Approval(owner, spender, value);
    }

    /**
     * @dev Internal function that burns an amount of the token of a given
     * account, deducting from the sender's allowance for said account. Uses the
     * internal burn function.
     * Emits an Approval event (reflecting the reduced allowance).
     * @param account The account whose tokens will be burnt.
     * @param value The amount that will be burnt.
     */
    function _burnFrom(address account, uint256 value) internal {
        _burn(account, value);
        _approve(account, msg.sender, _allowed[account][msg.sender].sub(value));
    }
}



contract ERC20NonTradable is ERC20 {
    function _approve(
        address owner,
        address spender,
        uint256 value
    ) internal {
        revert("disabled");
    }
}



contract Initializable {
    bool inited = false;

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




contract IStakeManagerEventsHub {
    struct Validator {
        uint256 amount;
        uint256 reward;
        uint256 activationEpoch;
        uint256 deactivationEpoch;
        uint256 jailTime;
        address signer;
        address contractAddress;
    }

    mapping(uint256 => Validator) public validators;
}

contract EventsHub is Initializable {
    Registry public registry;

    modifier onlyValidatorContract(uint256 validatorId) {
        address _contract;
        (, , , , , , _contract) = IStakeManagerEventsHub(registry.getStakeManagerAddress()).validators(validatorId);
        require(_contract == msg.sender, "not validator");
        _;
    }

    modifier onlyStakeManager() {
        require(registry.getStakeManagerAddress() == msg.sender,
        "Invalid sender, not stake manager");
        _;
    }

    function initialize(Registry _registry) external initializer {
        registry = _registry;
    }

    event ShareBurnedWithId(
        uint256 indexed validatorId,
        address indexed user,
        uint256 indexed amount,
        uint256 tokens,
        uint256 nonce
    );

    function logShareBurnedWithId(
        uint256 validatorId,
        address user,
        uint256 amount,
        uint256 tokens,
        uint256 nonce
    ) public onlyValidatorContract(validatorId) {
        emit ShareBurnedWithId(validatorId, user, amount, tokens, nonce);
    }

    event DelegatorUnstakeWithId(
        uint256 indexed validatorId,
        address indexed user,
        uint256 amount,
        uint256 nonce
    );

    function logDelegatorUnstakedWithId(
        uint256 validatorId,
        address user,
        uint256 amount,
        uint256 nonce
    ) public onlyValidatorContract(validatorId) {
        emit DelegatorUnstakeWithId(validatorId, user, amount, nonce);
    }

    event RewardParams(
        uint256 rewardDecreasePerCheckpoint,
        uint256 maxRewardedCheckpoints,
        uint256 checkpointRewardDelta
    );

    function logRewardParams(
        uint256 rewardDecreasePerCheckpoint,
        uint256 maxRewardedCheckpoints,
        uint256 checkpointRewardDelta
    ) public onlyStakeManager {
        emit RewardParams(rewardDecreasePerCheckpoint, maxRewardedCheckpoints, checkpointRewardDelta);
    }

    event UpdateCommissionRate(
        uint256 indexed validatorId,
        uint256 indexed newCommissionRate,
        uint256 indexed oldCommissionRate
    );

    function logUpdateCommissionRate(
        uint256 validatorId,
        uint256 newCommissionRate,
        uint256 oldCommissionRate
    ) public onlyStakeManager {
        emit UpdateCommissionRate(
            validatorId,
            newCommissionRate,
            oldCommissionRate
        );
    }

    event SharesTransfer(
        uint256 indexed validatorId,
        address indexed from,
        address indexed to,
        uint256 value
    );

    function logSharesTransfer(
        uint256 validatorId,
        address from,
        address to,
        uint256 value
    ) public onlyValidatorContract(validatorId) {
        emit SharesTransfer(validatorId, from, to, value);
    }
}




contract OwnableLockable is Lockable, Ownable {
    function lock() public onlyOwner {
        super.lock();
    }

    function unlock() public onlyOwner {
        super.unlock();
    }
}



// note this contract interface is only for stakeManager use
contract IValidatorShare {
    function withdrawRewards() public;

    function unstakeClaimTokens() public;

    function getLiquidRewards(address user) public view returns (uint256);
    
    function owner() public view returns (address);

    function restake() public returns(uint256, uint256);

    function unlock() external;

    function lock() external;

    function drain(
        address token,
        address payable destination,
        uint256 amount
    ) external;

    function slash(uint256 valPow, uint256 delegatedAmount, uint256 totalAmountToSlash) external returns (uint256);

    function updateDelegation(bool delegation) external;

    function migrateOut(address user, uint256 amount) external;

    function migrateIn(address user, uint256 amount) external;
}











contract ValidatorShare is IValidatorShare, ERC20NonTradable, OwnableLockable, Initializable {
    struct DelegatorUnbond {
        uint256 shares;
        uint256 withdrawEpoch;
    }

    uint256 constant EXCHANGE_RATE_PRECISION = 100;
    // maximum matic possible, even if rate will be 1 and all matic will be staken in one go, it will result in 10 ^ 58 shares
    uint256 constant EXCHANGE_RATE_HIGH_PRECISION = 10**29;
    uint256 constant MAX_COMMISION_RATE = 100;
    uint256 constant REWARD_PRECISION = 10**25;

    StakingInfo public stakingLogger;
    IStakeManager public stakeManager;
    uint256 public validatorId;
    uint256 public validatorRewards_deprecated;
    uint256 public commissionRate_deprecated;
    uint256 public lastCommissionUpdate_deprecated;
    uint256 public minAmount;

    uint256 public totalStake_deprecated;
    uint256 public rewardPerShare;
    uint256 public activeAmount;

    bool public delegation;

    uint256 public withdrawPool;
    uint256 public withdrawShares;

    mapping(address => uint256) amountStaked_deprecated; // deprecated, keep for foundation delegators
    mapping(address => DelegatorUnbond) public unbonds;
    mapping(address => uint256) public initalRewardPerShare;

    mapping(address => uint256) public unbondNonces;
    mapping(address => mapping(uint256 => DelegatorUnbond)) public unbonds_new;

    EventsHub public eventsHub;

    // onlyOwner will prevent this contract from initializing, since it's owner is going to be 0x0 address
    function initialize(
        uint256 _validatorId,
        address _stakingLogger,
        address _stakeManager
    ) external initializer {
        validatorId = _validatorId;
        stakingLogger = StakingInfo(_stakingLogger);
        stakeManager = IStakeManager(_stakeManager);
        _transferOwnership(_stakeManager);
        _getOrCacheEventsHub();

        minAmount = 10**18;
        delegation = true;
    }

    /**
        Public View Methods
    */

    function exchangeRate() public view returns (uint256) {
        uint256 totalShares = totalSupply();
        uint256 precision = _getRatePrecision();
        return totalShares == 0 ? precision : stakeManager.delegatedAmount(validatorId).mul(precision).div(totalShares);
    }

    function getTotalStake(address user) public view returns (uint256, uint256) {
        uint256 shares = balanceOf(user);
        uint256 rate = exchangeRate();
        if (shares == 0) {
            return (0, rate);
        }

        return (rate.mul(shares).div(_getRatePrecision()), rate);
    }

    function withdrawExchangeRate() public view returns (uint256) {
        uint256 precision = _getRatePrecision();
        if (validatorId < 8) {
            // fix of potentially broken withdrawals for future unbonding
            // foundation validators have no slashing enabled and thus we can return default exchange rate
            // because without slashing rate will stay constant
            return precision;
        }

        uint256 _withdrawShares = withdrawShares;
        return _withdrawShares == 0 ? precision : withdrawPool.mul(precision).div(_withdrawShares);
    }

    function getLiquidRewards(address user) public view returns (uint256) {
        return _calculateReward(user, getRewardPerShare());
    }

    function getRewardPerShare() public view returns (uint256) {
        return _calculateRewardPerShareWithRewards(stakeManager.delegatorsReward(validatorId));
    }

    /**
        Public Methods
     */

    function buyVoucher(uint256 _amount, uint256 _minSharesToMint) public returns(uint256 amountToDeposit) {
        _withdrawAndTransferReward(msg.sender);
        
        amountToDeposit = _buyShares(_amount, _minSharesToMint, msg.sender);
        require(stakeManager.delegationDeposit(validatorId, amountToDeposit, msg.sender), "deposit failed");
        
        return amountToDeposit;
    }

    function restake() public returns(uint256, uint256) {
        address user = msg.sender;
        uint256 liquidReward = _withdrawReward(user);
        uint256 amountRestaked;

        require(liquidReward >= minAmount, "Too small rewards to restake");

        if (liquidReward != 0) {
            amountRestaked = _buyShares(liquidReward, 0, user);

            if (liquidReward > amountRestaked) {
                // return change to the user
                require(
                    stakeManager.transferFunds(validatorId, liquidReward - amountRestaked, user),
                    "Insufficent rewards"
                );
                stakingLogger.logDelegatorClaimRewards(validatorId, user, liquidReward - amountRestaked);
            }

            (uint256 totalStaked, ) = getTotalStake(user);
            stakingLogger.logDelegatorRestaked(validatorId, user, totalStaked);
        }
        
        return (amountRestaked, liquidReward);
    }

    function sellVoucher(uint256 claimAmount, uint256 maximumSharesToBurn) public {
        (uint256 shares, uint256 _withdrawPoolShare) = _sellVoucher(claimAmount, maximumSharesToBurn);

        DelegatorUnbond memory unbond = unbonds[msg.sender];
        unbond.shares = unbond.shares.add(_withdrawPoolShare);
        // refresh undond period
        unbond.withdrawEpoch = stakeManager.epoch();
        unbonds[msg.sender] = unbond;

        StakingInfo logger = stakingLogger;
        logger.logShareBurned(validatorId, msg.sender, claimAmount, shares);
        logger.logStakeUpdate(validatorId);
    }

    function withdrawRewards() public {
        uint256 rewards = _withdrawAndTransferReward(msg.sender);
        require(rewards >= minAmount, "Too small rewards amount");
    }

    function migrateOut(address user, uint256 amount) external onlyOwner {
        _withdrawAndTransferReward(user);
        (uint256 totalStaked, uint256 rate) = getTotalStake(user);
        require(totalStaked >= amount, "Migrating too much");

        uint256 precision = _getRatePrecision();
        uint256 shares = amount.mul(precision).div(rate);
        _burn(user, shares);

        stakeManager.updateValidatorState(validatorId, -int256(amount));
        activeAmount = activeAmount.sub(amount);

        stakingLogger.logShareBurned(validatorId, user, amount, shares);
        stakingLogger.logStakeUpdate(validatorId);
        stakingLogger.logDelegatorUnstaked(validatorId, user, amount);
    }

    function migrateIn(address user, uint256 amount) external onlyOwner {
        _withdrawAndTransferReward(user);
        _buyShares(amount, 0, user);
    }

    function unstakeClaimTokens() public {
        DelegatorUnbond memory unbond = unbonds[msg.sender];
        uint256 amount = _unstakeClaimTokens(unbond);
        delete unbonds[msg.sender];
        stakingLogger.logDelegatorUnstaked(validatorId, msg.sender, amount);
    }

    function slash(
        uint256 validatorStake,
        uint256 delegatedAmount,
        uint256 totalAmountToSlash
    ) external onlyOwner returns (uint256) {
        uint256 _withdrawPool = withdrawPool;
        uint256 delegationAmount = delegatedAmount.add(_withdrawPool);
        if (delegationAmount == 0) {
            return 0;
        }
        // total amount to be slashed from delegation pool (active + inactive)
        uint256 _amountToSlash = delegationAmount.mul(totalAmountToSlash).div(validatorStake.add(delegationAmount));
        uint256 _amountToSlashWithdrawalPool = _withdrawPool.mul(_amountToSlash).div(delegationAmount);

        // slash inactive pool
        uint256 stakeSlashed = _amountToSlash.sub(_amountToSlashWithdrawalPool);
        stakeManager.decreaseValidatorDelegatedAmount(validatorId, stakeSlashed);
        activeAmount = activeAmount.sub(stakeSlashed);

        withdrawPool = withdrawPool.sub(_amountToSlashWithdrawalPool);
        return _amountToSlash;
    }

    function updateDelegation(bool _delegation) external onlyOwner {
        delegation = _delegation;
    }

    function drain(
        address token,
        address payable destination,
        uint256 amount
    ) external onlyOwner {
        if (token == address(0x0)) {
            destination.transfer(amount);
        } else {
            require(ERC20(token).transfer(destination, amount), "Drain failed");
        }
    }

    /**
        New shares exit API
     */

    function sellVoucher_new(uint256 claimAmount, uint256 maximumSharesToBurn) public {
        (uint256 shares, uint256 _withdrawPoolShare) = _sellVoucher(claimAmount, maximumSharesToBurn);

        uint256 unbondNonce = unbondNonces[msg.sender].add(1);

        DelegatorUnbond memory unbond = DelegatorUnbond({
            shares: _withdrawPoolShare,
            withdrawEpoch: stakeManager.epoch()
        });
        unbonds_new[msg.sender][unbondNonce] = unbond;
        unbondNonces[msg.sender] = unbondNonce;

        _getOrCacheEventsHub().logShareBurnedWithId(validatorId, msg.sender, claimAmount, shares, unbondNonce);
        stakingLogger.logStakeUpdate(validatorId);
    }

    function unstakeClaimTokens_new(uint256 unbondNonce) public {
        DelegatorUnbond memory unbond = unbonds_new[msg.sender][unbondNonce];
        uint256 amount = _unstakeClaimTokens(unbond);
        delete unbonds_new[msg.sender][unbondNonce];
        _getOrCacheEventsHub().logDelegatorUnstakedWithId(validatorId, msg.sender, amount, unbondNonce);
    }

    /**
        Private Methods
     */

    function _getOrCacheEventsHub() private returns(EventsHub) {
        EventsHub _eventsHub = eventsHub;
        if (_eventsHub == EventsHub(0x0)) {
            _eventsHub = EventsHub(Registry(stakeManager.getRegistry()).contractMap(keccak256("eventsHub")));
            eventsHub = _eventsHub;
        }
        return _eventsHub;
    }

    function _sellVoucher(uint256 claimAmount, uint256 maximumSharesToBurn) private returns(uint256, uint256) {
        // first get how much staked in total and compare to target unstake amount
        (uint256 totalStaked, uint256 rate) = getTotalStake(msg.sender);
        require(totalStaked != 0 && totalStaked >= claimAmount, "Too much requested");

        // convert requested amount back to shares
        uint256 precision = _getRatePrecision();
        uint256 shares = claimAmount.mul(precision).div(rate);
        require(shares <= maximumSharesToBurn, "too much slippage");

        _withdrawAndTransferReward(msg.sender);

        _burn(msg.sender, shares);
        stakeManager.updateValidatorState(validatorId, -int256(claimAmount));
        activeAmount = activeAmount.sub(claimAmount);

        uint256 _withdrawPoolShare = claimAmount.mul(precision).div(withdrawExchangeRate());
        withdrawPool = withdrawPool.add(claimAmount);
        withdrawShares = withdrawShares.add(_withdrawPoolShare);

        return (shares, _withdrawPoolShare);
    }

    function _unstakeClaimTokens(DelegatorUnbond memory unbond) private returns(uint256) {
        uint256 shares = unbond.shares;
        require(
            unbond.withdrawEpoch.add(stakeManager.withdrawalDelay()) <= stakeManager.epoch() && shares > 0,
            "Incomplete withdrawal period"
        );

        uint256 _amount = withdrawExchangeRate().mul(shares).div(_getRatePrecision());
        withdrawShares = withdrawShares.sub(shares);
        withdrawPool = withdrawPool.sub(_amount);

        require(stakeManager.transferFunds(validatorId, _amount, msg.sender), "Insufficent rewards");

        return _amount;
    }

    function _getRatePrecision() private view returns (uint256) {
        // if foundation validator, use old precision
        if (validatorId < 8) {
            return EXCHANGE_RATE_PRECISION;
        }

        return EXCHANGE_RATE_HIGH_PRECISION;
    }

    function _calculateRewardPerShareWithRewards(uint256 accumulatedReward) private view returns (uint256) {
        uint256 _rewardPerShare = rewardPerShare;
        if (accumulatedReward != 0) {
            uint256 totalShares = totalSupply();
            
            if (totalShares != 0) {
                _rewardPerShare = _rewardPerShare.add(accumulatedReward.mul(REWARD_PRECISION).div(totalShares));
            }
        }

        return _rewardPerShare;
    }

    function _calculateReward(address user, uint256 _rewardPerShare) private view returns (uint256) {
        uint256 shares = balanceOf(user);
        if (shares == 0) {
            return 0;
        }

        uint256 _initialRewardPerShare = initalRewardPerShare[user];

        if (_initialRewardPerShare == _rewardPerShare) {
            return 0;
        }

        return _rewardPerShare.sub(_initialRewardPerShare).mul(shares).div(REWARD_PRECISION);
    }

    function _withdrawReward(address user) private returns (uint256) {
        uint256 _rewardPerShare = _calculateRewardPerShareWithRewards(
            stakeManager.withdrawDelegatorsReward(validatorId)
        );
        uint256 liquidRewards = _calculateReward(user, _rewardPerShare);
        
        rewardPerShare = _rewardPerShare;
        initalRewardPerShare[user] = _rewardPerShare;
        return liquidRewards;
    }

    function _withdrawAndTransferReward(address user) private returns (uint256) {
        uint256 liquidRewards = _withdrawReward(user);
        if (liquidRewards != 0) {
            require(stakeManager.transferFunds(validatorId, liquidRewards, user), "Insufficent rewards");
            stakingLogger.logDelegatorClaimRewards(validatorId, user, liquidRewards);
        }
        return liquidRewards;
    }

    function _buyShares(
        uint256 _amount,
        uint256 _minSharesToMint,
        address user
    ) private onlyWhenUnlocked returns (uint256) {
        require(delegation, "Delegation is disabled");

        uint256 rate = exchangeRate();
        uint256 precision = _getRatePrecision();
        uint256 shares = _amount.mul(precision).div(rate);
        require(shares >= _minSharesToMint, "Too much slippage");
        require(unbonds[user].shares == 0, "Ongoing exit");

        _mint(user, shares);

        // clamp amount of tokens in case resulted shares requires less tokens than anticipated
        _amount = rate.mul(shares).div(precision);

        stakeManager.updateValidatorState(validatorId, int256(_amount));
        activeAmount = activeAmount.add(_amount);

        StakingInfo logger = stakingLogger;
        logger.logShareMinted(validatorId, user, _amount, shares);
        logger.logStakeUpdate(validatorId);

        return _amount;
    }

    function _transfer(
        address from,
        address to,
        uint256 value
    ) internal {
        // get rewards for recipient 
        _withdrawAndTransferReward(to);
        // convert rewards to shares
        _withdrawAndTransferReward(from);
        // move shares to recipient
        super._transfer(from, to, value);
        _getOrCacheEventsHub().logSharesTransfer(validatorId, from, to, value);
    }
}




contract ValidatorShareFactory {
    /**
    - factory to create new validatorShare contracts
   */
    function create(uint256 validatorId, address loggerAddress, address registry) public returns (address) {
        ValidatorShareProxy proxy = new ValidatorShareProxy(registry);

        proxy.transferOwnership(msg.sender);

        address proxyAddr = address(proxy);
        (bool success, bytes memory data) = proxyAddr.call.gas(gasleft())(
            abi.encodeWithSelector(
                ValidatorShare(proxyAddr).initialize.selector, 
                validatorId, 
                loggerAddress, 
                msg.sender
            )
        );
        require(success, string(data));

        return proxyAddr;
    }
}








contract StakeManagerStorage is GovernanceLockable, RootChainable {
    enum Status {Inactive, Active, Locked, Unstaked}

    struct Auction {
        uint256 amount;
        uint256 startEpoch;
        address user;
        bool acceptDelegation;
        bytes signerPubkey;
    }

    struct State {
        uint256 amount;
        uint256 stakerCount;
    }

    struct StateChange {
        int256 amount;
        int256 stakerCount;
    }

    struct Validator {
        uint256 amount;
        uint256 reward;
        uint256 activationEpoch;
        uint256 deactivationEpoch;
        uint256 jailTime;
        address signer;
        address contractAddress;
        Status status;
        uint256 commissionRate;
        uint256 lastCommissionUpdate;
        uint256 delegatorsReward;
        uint256 delegatedAmount;
        uint256 initialRewardPerStake;
    }

    uint256 constant MAX_COMMISION_RATE = 100;
    uint256 constant MAX_PROPOSER_BONUS = 100;
    uint256 constant REWARD_PRECISION = 10**25;
    uint256 internal constant INCORRECT_VALIDATOR_ID = 2**256 - 1;
    uint256 internal constant INITIALIZED_AMOUNT = 1;

    IERC20 public token;
    address public registry;
    StakingInfo public logger;
    StakingNFT public NFTContract;
    ValidatorShareFactory public validatorShareFactory;
    uint256 public WITHDRAWAL_DELAY; // unit: epoch
    uint256 public currentEpoch;

    // genesis/governance variables
    uint256 public dynasty; // unit: epoch 50 days
    uint256 public CHECKPOINT_REWARD; // update via governance
    uint256 public minDeposit; // in ERC20 token
    uint256 public minHeimdallFee; // in ERC20 token
    uint256 public checkPointBlockInterval;
    uint256 public signerUpdateLimit;

    uint256 public validatorThreshold; //128
    uint256 public totalStaked;
    uint256 public NFTCounter;
    uint256 public totalRewards;
    uint256 public totalRewardsLiquidated;
    uint256 public auctionPeriod; // 1 week in epochs
    uint256 public proposerBonus; // 10 % of total rewards
    bytes32 public accountStateRoot;
    // Stop validator auction for some time when updating dynasty value
    uint256 public replacementCoolDown;
    bool public delegationEnabled;

    mapping(uint256 => Validator) public validators;
    mapping(address => uint256) public signerToValidator;
    // current epoch stake power and stakers count
    State public validatorState;
    mapping(uint256 => StateChange) public validatorStateChanges;

    mapping(address => uint256) public userFeeExit;
    //Ongoing auctions for validatorId
    mapping(uint256 => Auction) public validatorAuction;
    // validatorId to last signer update epoch
    mapping(uint256 => uint256) public latestSignerUpdateEpoch;

    uint256 public totalHeimdallFee;
}



contract StakeManagerStorageExtension {
    address public eventsHub;
    uint256 public rewardPerStake;
    address public extensionCode;
    address[] public signers;

    uint256 constant CHK_REWARD_PRECISION = 100;
    uint256 public prevBlockInterval;
    // how much less reward per skipped checkpoint, 0 - 100%
    uint256 public rewardDecreasePerCheckpoint;
    // how many checkpoints to reward
    uint256 public maxRewardedCheckpoints;
    // increase / decrease value for faster or slower checkpoints, 0 - 100%
    uint256 public checkpointRewardDelta;
}



/**
 * @title Math
 * @dev Assorted math operations
 */
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 Calculates the average of two numbers. Since these are integers,
     * averages of an even and odd number cannot be represented, and will be
     * rounded down.
     */
    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);
    }
}



interface IValidatorRegistry {
    function validators(address _validator) external view returns (bool);
    function validatorWhitelistingEnable() external view returns (bool);
    function updateValidatorsPermission(address _validator, bool _isWhitelisted) external;
    function toggleWhitelisting(bool _validatorWhitelistingEnable) external;
}














contract StakeManagerExtension is StakeManagerStorage, Initializable, StakeManagerStorageExtension {
    using SafeMath for uint256;

    constructor() public GovernanceLockable(address(0x0)) {}

    IValidatorRegistry public validatorRegistry;

     function updateValidatorRegistry(address _newContract) public onlyOwner {
        require(_newContract != address(0), "address cannot be zero");
        validatorRegistry = IValidatorRegistry(_newContract);
    }

    //checks only when validator registry enabled
    function checkValidatorWhitelisting(address validator) public view returns(bool){
        if(validatorRegistry.validatorWhitelistingEnable()){
            return validatorRegistry.validators(validator);
        }
        else {
            return true;
        }
    }

    function startAuction(
        uint256 validatorId,
        uint256 amount,
        bool _acceptDelegation,
        bytes calldata _signerPubkey
    ) external {
        uint256 currentValidatorAmount = validators[validatorId].amount;

        require(
            validators[validatorId].deactivationEpoch == 0 && currentValidatorAmount != 0,
            "Invalid validator for an auction"
        );
        uint256 senderValidatorId = signerToValidator[msg.sender];
        // make sure that signer wasn't used already
        require(
            NFTContract.balanceOf(msg.sender) == 0 && // existing validators can't bid
                senderValidatorId != INCORRECT_VALIDATOR_ID,
            "Already used address"
        );

        uint256 _currentEpoch = currentEpoch;
        uint256 _replacementCoolDown = replacementCoolDown;
        // when dynasty period is updated validators are in cooldown period
        require(_replacementCoolDown == 0 || _replacementCoolDown <= _currentEpoch, "Cooldown period");
        // (auctionPeriod--dynasty)--(auctionPeriod--dynasty)--(auctionPeriod--dynasty)
        // if it's auctionPeriod then will get residue smaller then auctionPeriod
        // from (CurrentPeriod of validator )%(auctionPeriod--dynasty)
        // make sure that its `auctionPeriod` window
        // dynasty = 30, auctionPeriod = 7, activationEpoch = 1, currentEpoch = 39
        // residue 1 = (39-1)% (7+30), if residue <= auctionPeriod it's `auctionPeriod`

        require(
            (_currentEpoch.sub(validators[validatorId].activationEpoch) % dynasty.add(auctionPeriod)) < auctionPeriod,
            "Invalid auction period"
        );

        uint256 perceivedStake = currentValidatorAmount;
        perceivedStake = perceivedStake.add(validators[validatorId].delegatedAmount);

        Auction storage auction = validatorAuction[validatorId];
        uint256 currentAuctionAmount = auction.amount;

        perceivedStake = Math.max(perceivedStake, currentAuctionAmount);

        require(perceivedStake < amount, "Must bid higher");
        require(token.transferFrom(msg.sender, address(this), amount), "Transfer failed");

        //replace prev auction
        if (currentAuctionAmount != 0) {
            require(token.transfer(auction.user, currentAuctionAmount), "Bid return failed");
        }

        // create new auction
        auction.amount = amount;
        auction.user = msg.sender;
        auction.acceptDelegation = _acceptDelegation;
        auction.signerPubkey = _signerPubkey;

        logger.logStartAuction(validatorId, currentValidatorAmount, amount);
    }

    function confirmAuctionBid(
        uint256 validatorId,
        uint256 heimdallFee, /** for new validator */
        IStakeManager stakeManager
    ) external {
        Auction storage auction = validatorAuction[validatorId];
        address auctionUser = auction.user;

        require(
            msg.sender == auctionUser || NFTContract.tokenOfOwnerByIndex(msg.sender, 0) == validatorId,
            "Only bidder can confirm"
        );

        uint256 _currentEpoch = currentEpoch;
        require(
            _currentEpoch.sub(auction.startEpoch) % auctionPeriod.add(dynasty) >= auctionPeriod,
            "Not allowed before auctionPeriod"
        );
        require(auction.user != address(0x0), "Invalid auction");

        uint256 validatorAmount = validators[validatorId].amount;
        uint256 perceivedStake = validatorAmount;
        uint256 auctionAmount = auction.amount;

        perceivedStake = perceivedStake.add(validators[validatorId].delegatedAmount);

        // validator is last auctioner
        if (perceivedStake >= auctionAmount && validators[validatorId].deactivationEpoch == 0) {
            require(token.transfer(auctionUser, auctionAmount), "Bid return failed");
            //cleanup auction data
            auction.startEpoch = _currentEpoch;
            logger.logConfirmAuction(validatorId, validatorId, validatorAmount);
        } else {
            stakeManager.dethroneAndStake(
                auctionUser, 
                heimdallFee,
                validatorId,
                auctionAmount,
                auction.acceptDelegation,
                auction.signerPubkey
            );
        }
        uint256 startEpoch = auction.startEpoch;
        delete validatorAuction[validatorId];
        validatorAuction[validatorId].startEpoch = startEpoch;
    }

    function migrateValidatorsData(uint256 validatorIdFrom, uint256 validatorIdTo) external {       
        for (uint256 i = validatorIdFrom; i < validatorIdTo; ++i) {
            ValidatorShare contractAddress = ValidatorShare(validators[i].contractAddress);
            if (contractAddress != ValidatorShare(0)) {
                // move validator rewards out from ValidatorShare contract
                validators[i].reward = contractAddress.validatorRewards_deprecated().add(INITIALIZED_AMOUNT);
                validators[i].delegatedAmount = contractAddress.activeAmount();
                validators[i].commissionRate = contractAddress.commissionRate_deprecated();
            } else {
                validators[i].reward = validators[i].reward.add(INITIALIZED_AMOUNT);
            }

            validators[i].delegatorsReward = INITIALIZED_AMOUNT;
        }
    }

    function updateCheckpointRewardParams(
        uint256 _rewardDecreasePerCheckpoint,
        uint256 _maxRewardedCheckpoints,
        uint256 _checkpointRewardDelta
    ) external {
        require(_maxRewardedCheckpoints.mul(_rewardDecreasePerCheckpoint) <= CHK_REWARD_PRECISION);
        require(_checkpointRewardDelta <= CHK_REWARD_PRECISION);

        rewardDecreasePerCheckpoint = _rewardDecreasePerCheckpoint;
        maxRewardedCheckpoints = _maxRewardedCheckpoints;
        checkpointRewardDelta = _checkpointRewardDelta;

        _getOrCacheEventsHub().logRewardParams(_rewardDecreasePerCheckpoint, _maxRewardedCheckpoints, _checkpointRewardDelta);
    }

    function updateCommissionRate(uint256 validatorId, uint256 newCommissionRate) external {
        uint256 _epoch = currentEpoch;
        uint256 _lastCommissionUpdate = validators[validatorId].lastCommissionUpdate;

        require( // withdrawalDelay == dynasty
            (_lastCommissionUpdate.add(WITHDRAWAL_DELAY) <= _epoch) || _lastCommissionUpdate == 0, // For initial setting of commission rate
            "Cooldown"
        );

        require(newCommissionRate <= MAX_COMMISION_RATE, "Incorrect value");
        _getOrCacheEventsHub().logUpdateCommissionRate(validatorId, newCommissionRate, validators[validatorId].commissionRate);
        validators[validatorId].commissionRate = newCommissionRate;
        validators[validatorId].lastCommissionUpdate = _epoch;
    }

    function _getOrCacheEventsHub() private returns(EventsHub) {
        EventsHub _eventsHub = EventsHub(eventsHub);
        if (_eventsHub == EventsHub(0x0)) {
            _eventsHub = EventsHub(Registry(registry).contractMap(keccak256("eventsHub")));
            eventsHub = address(_eventsHub);
        }
        return _eventsHub;
    }
}