// File: contracts/node/StafiSuperNode.sol



pragma solidity 0.7.6;
pragma abicoder v2;

// SPDX-License-Identifier: GPL-3.0-only

import "../StafiBase.sol";
import "../interfaces/node/IStafiSuperNode.sol";
import "../interfaces/node/IStafiNodeManager.sol";
import "../interfaces/deposit/IStafiUserDeposit.sol";
import "../interfaces/eth/IDepositContract.sol";
import "../interfaces/settings/IStafiNetworkSettings.sol";
import "../interfaces/storage/IPubkeySetStorage.sol";
import "@openzeppelin/contracts/math/SafeMath.sol";

contract StafiSuperNode is StafiBase, IStafiSuperNode {
    // Libs
    using SafeMath for uint256;

    event EtherDeposited(address indexed from, uint256 amount, uint256 time);
    event Staked(address node, bytes pubkey);
    event Deposited(address node, bytes pubkey, bytes validatorSignature);
    event SetPubkeyStatus(bytes pubkey, uint256 status);

    uint256 public constant PUBKEY_STATUS_UNINITIAL = 0;
    uint256 public constant PUBKEY_STATUS_INITIAL = 1;
    uint256 public constant PUBKEY_STATUS_MATCH = 2;
    uint256 public constant PUBKEY_STATUS_STAKING = 3;
    uint256 public constant PUBKEY_STATUS_UNMATCH = 4;
    // Construct
    constructor(address _stafiStorageAddress) StafiBase(_stafiStorageAddress) {
        version = 1;
    }

    // Deposit ETH from deposit pool
    // Only accepts calls from the StafiUserDeposit contract
    function depositEth() override external payable onlyLatestContract("stafiUserDeposit", msg.sender) {
        // Emit ether deposited event
        emit EtherDeposited(msg.sender, msg.value, block.timestamp);
    }

    function EthDeposit() private view returns (IDepositContract) {
        return IDepositContract(getContractAddress("ethDeposit"));
    }

    function StafiNetworkSettings() private view returns (IStafiNetworkSettings) {
        return IStafiNetworkSettings(getContractAddress("stafiNetworkSettings"));
    }

    function PubkeySetStorage() public view returns (IPubkeySetStorage) {
        return IPubkeySetStorage(getContractAddress("pubkeySetStorage"));
    }

    // Get the number of pubkeys owned by a super node
    function getSuperNodePubkeyCount(address _nodeAddress) override public view returns (uint256) {
        return PubkeySetStorage().getCount(keccak256(abi.encodePacked("superNode.pubkeys.index", _nodeAddress)));
    }

    // Get a super node pubkey by index
    function getSuperNodePubkeyAt(address _nodeAddress, uint256 _index) override public view returns (bytes memory) {
        return PubkeySetStorage().getItem(keccak256(abi.encodePacked("superNode.pubkeys.index", _nodeAddress)), _index);
    }
    
    // Get a super node pubkey status
    function getSuperNodePubkeyStatus(bytes calldata _validatorPubkey) override public view returns (uint256) {
        return getUint(keccak256(abi.encodePacked("superNode.pubkey.status", _validatorPubkey)));
    }

    // Set a super node pubkey status
    function _setSuperNodePubkeyStatus(bytes calldata _validatorPubkey, uint256 _status) private {
        setUint(keccak256(abi.encodePacked("superNode.pubkey.status", _validatorPubkey)), _status);

        emit SetPubkeyStatus(_validatorPubkey, _status);
    }

    function setSuperNodePubkeyStatus(bytes calldata _validatorPubkey, uint256 _status) public onlySuperUser {
        _setSuperNodePubkeyStatus(_validatorPubkey, _status);
    }

    function getSuperNodeDepositEnabled() public view returns (bool) {
        return getBoolS("settings.superNode.deposit.enabled");
    }

    function getPubkeyVoted(bytes calldata _validatorPubkey, address user) public view returns (bool) {
        return getBool(keccak256(abi.encodePacked("superNode.memberVotes.", _validatorPubkey, user)));
    }

    function setSuperNodeDepositEnabled(bool _value) public onlySuperUser {
        setBoolS("settings.superNode.deposit.enabled", _value);
    }

    function deposit(bytes[] calldata _validatorPubkeys, bytes[] calldata _validatorSignatures, bytes32[] calldata _depositDataRoots) override external onlyLatestContract("stafiSuperNode", address(this)) onlySuperNode(msg.sender) {
        require(getSuperNodeDepositEnabled(), "super node deposits are currently disabled");
        uint256 len = _validatorPubkeys.length;
        require(len == _validatorSignatures.length && len == _depositDataRoots.length, "params len err");
        require(getSuperNodePubkeyCount(msg.sender).add(len) <= StafiNetworkSettings().getSuperNodePubkeyLimit(), "pubkey amount over limit");
        // Load contracts
        IStafiUserDeposit stafiUserDeposit = IStafiUserDeposit(getContractAddress("stafiUserDeposit"));
        stafiUserDeposit.withdrawExcessBalanceForSuperNode(len.mul(1 ether));

        for (uint256 i = 0; i < len; i++) {
            _deposit(_validatorPubkeys[i], _validatorSignatures[i], _depositDataRoots[i]);
        }
    }

    function stake(bytes[] calldata _validatorPubkeys, bytes[] calldata _validatorSignatures, bytes32[] calldata _depositDataRoots) override external onlyLatestContract("stafiSuperNode", address(this)) onlySuperNode(msg.sender) {
        uint256 len = _validatorPubkeys.length;
        require(len == _validatorSignatures.length && len == _depositDataRoots.length, "params len err");
        // Load contracts
        IStafiUserDeposit stafiUserDeposit = IStafiUserDeposit(getContractAddress("stafiUserDeposit"));
        stafiUserDeposit.withdrawExcessBalanceForSuperNode(len.mul(31 ether));
        
        for (uint256 i = 0; i < len; i++) {
            _stake(_validatorPubkeys[i], _validatorSignatures[i], _depositDataRoots[i]);
        }
    }

    function _deposit(bytes calldata _validatorPubkey, bytes calldata _validatorSignature, bytes32 _depositDataRoot) private {
        setAndCheckNodePubkeyInDeposit(_validatorPubkey);
        // Send staking deposit to casper
        EthDeposit().deposit{value: 1 ether}(_validatorPubkey, StafiNetworkSettings().getWithdrawalCredentials(), _validatorSignature, _depositDataRoot);

        emit Deposited(msg.sender, _validatorPubkey, _validatorSignature);
    }


    function _stake(bytes calldata _validatorPubkey, bytes calldata _validatorSignature, bytes32 _depositDataRoot) private {
        setAndCheckNodePubkeyInStake(_validatorPubkey);
        // Send staking deposit to casper
        EthDeposit().deposit{value: 31 ether}(_validatorPubkey, StafiNetworkSettings().getWithdrawalCredentials(), _validatorSignature, _depositDataRoot);

        emit Staked(msg.sender, _validatorPubkey);
    }

    
    // Set and check a node's validator pubkey
    function setAndCheckNodePubkeyInDeposit(bytes calldata _pubkey) private {
        // check pubkey of stakingpools
        require(getAddress(keccak256(abi.encodePacked("validator.stakingpool", _pubkey))) == address(0x0), "stakingpool pubkey exists");
        // check pubkey of lightNodes
        require(getUint(keccak256(abi.encodePacked("lightNode.pubkey.status", _pubkey))) == PUBKEY_STATUS_UNINITIAL, "light Node pubkey exists");

        // check status
        require(getSuperNodePubkeyStatus(_pubkey) == PUBKEY_STATUS_UNINITIAL, "pubkey status unmatch");
        // set pubkey status
        _setSuperNodePubkeyStatus(_pubkey, PUBKEY_STATUS_INITIAL);
        // add pubkey to set
        PubkeySetStorage().addItem(keccak256(abi.encodePacked("superNode.pubkeys.index", msg.sender)), _pubkey);
    }
    
    // Set and check a node's validator pubkey
    function setAndCheckNodePubkeyInStake(bytes calldata _pubkey) private {
        // check status
        require(getSuperNodePubkeyStatus(_pubkey) == PUBKEY_STATUS_MATCH, "pubkey status unmatch");
        // set pubkey status
        _setSuperNodePubkeyStatus(_pubkey, PUBKEY_STATUS_STAKING);
    }

    function voteWithdrawCredentials(bytes[] calldata _pubkeys, bool[] calldata _matchs) override external onlyLatestContract("stafiSuperNode", address(this)) onlyTrustedNode(msg.sender) {
        require(_pubkeys.length == _matchs.length, "params len err");
        for ( uint256 i = 0; i < _pubkeys.length; i++) {
            _voteWithdrawCredentials(_pubkeys[i], _matchs[i]);
        }
    }

    // Only accepts calls from trusted (oracle) nodes
    function _voteWithdrawCredentials(bytes calldata _pubkey, bool _match) private {
        // Check & update node vote status
        require(!getBool(keccak256(abi.encodePacked("superNode.memberVotes.", _pubkey, msg.sender))), "Member has already voted to withdrawCredentials");
        setBool(keccak256(abi.encodePacked("superNode.memberVotes.", _pubkey, msg.sender)), true);
       
        // Increment votes count
        uint256 totalVotes = getUint(keccak256(abi.encodePacked("superNode.totalVotes", _pubkey, _match)));
        totalVotes = totalVotes.add(1);
        setUint(keccak256(abi.encodePacked("superNode.totalVotes", _pubkey, _match)), totalVotes);

        // Check count and set status
        uint256 calcBase = 1 ether;
        IStafiNodeManager stafiNodeManager = IStafiNodeManager(getContractAddress("stafiNodeManager"));
        if (getSuperNodePubkeyStatus(_pubkey) == PUBKEY_STATUS_INITIAL &&  calcBase.mul(totalVotes) >= stafiNodeManager.getTrustedNodeCount().mul(StafiNetworkSettings().getNodeConsensusThreshold())) {
            _setSuperNodePubkeyStatus(_pubkey, _match ? PUBKEY_STATUS_MATCH : PUBKEY_STATUS_UNMATCH);
        }
    }
}

// File: contracts/StafiBase.sol



pragma solidity 0.7.6;

// SPDX-License-Identifier: GPL-3.0-only

import "./interfaces/storage/IStafiStorage.sol";

abstract contract StafiBase {

    // Version of the contract
    uint8 public version;

    // The main storage contract where primary persistant storage is maintained
    IStafiStorage stafiStorage = IStafiStorage(0);


    /**
    * @dev Throws if called by any sender that doesn't match a network contract
    */
    modifier onlyLatestNetworkContract() {
        require(getBool(keccak256(abi.encodePacked("contract.exists", msg.sender))), "Invalid or outdated network contract");
        _;
    }


    /**
    * @dev Throws if called by any sender that doesn't match one of the supplied contract or is the latest version of that contract
    */
    modifier onlyLatestContract(string memory _contractName, address _contractAddress) {
        require(_contractAddress == getAddress(keccak256(abi.encodePacked("contract.address", _contractName))), "Invalid or outdated contract");
        _;
    }


    /**
    * @dev Throws if called by any sender that isn't a trusted node
    */
    modifier onlyTrustedNode(address _nodeAddress) {
        require(getBool(keccak256(abi.encodePacked("node.trusted", _nodeAddress))), "Invalid trusted node");
        _;
    }
    
    /**
    * @dev Throws if called by any sender that isn't a super node
    */
    modifier onlySuperNode(address _nodeAddress) {
        require(getBool(keccak256(abi.encodePacked("node.super", _nodeAddress))), "Invalid super node");
        _;
    }


    /**
    * @dev Throws if called by any sender that isn't a registered staking pool
    */
    modifier onlyRegisteredStakingPool(address _stakingPoolAddress) {
        require(getBool(keccak256(abi.encodePacked("stakingpool.exists", _stakingPoolAddress))), "Invalid staking pool");
        _;
    }


    /**
    * @dev Throws if called by any account other than the owner.
    */
    modifier onlyOwner() {
        require(roleHas("owner", msg.sender), "Account is not the owner");
        _;
    }


    /**
    * @dev Modifier to scope access to admins
    */
    modifier onlyAdmin() {
        require(roleHas("admin", msg.sender), "Account is not an admin");
        _;
    }


    /**
    * @dev Modifier to scope access to admins
    */
    modifier onlySuperUser() {
        require(roleHas("owner", msg.sender) || roleHas("admin", msg.sender), "Account is not a super user");
        _;
    }


    /**
    * @dev Reverts if the address doesn't have this role
    */
    modifier onlyRole(string memory _role) {
        require(roleHas(_role, msg.sender), "Account does not match the specified role");
        _;
    }


    /// @dev Set the main Storage address
    constructor(address _stafiStorageAddress) {
        // Update the contract address
        stafiStorage = IStafiStorage(_stafiStorageAddress);
    }


    /// @dev Get the address of a network contract by name
    function getContractAddress(string memory _contractName) internal view returns (address) {
        // Get the current contract address
        address contractAddress = getAddress(keccak256(abi.encodePacked("contract.address", _contractName)));
        // Check it
        require(contractAddress != address(0x0), "Contract not found");
        // Return
        return contractAddress;
    }


    /// @dev Get the name of a network contract by address
    function getContractName(address _contractAddress) internal view returns (string memory) {
        // Get the contract name
        string memory contractName = getString(keccak256(abi.encodePacked("contract.name", _contractAddress)));
        // Check it
        require(keccak256(abi.encodePacked(contractName)) != keccak256(abi.encodePacked("")), "Contract not found");
        // Return
        return contractName;
    }


    /// @dev Storage get methods
    function getAddress(bytes32 _key) internal view returns (address) { return stafiStorage.getAddress(_key); }
    function getUint(bytes32 _key) internal view returns (uint256) { return stafiStorage.getUint(_key); }
    function getString(bytes32 _key) internal view returns (string memory) { return stafiStorage.getString(_key); }
    function getBytes(bytes32 _key) internal view returns (bytes memory) { return stafiStorage.getBytes(_key); }
    function getBool(bytes32 _key) internal view returns (bool) { return stafiStorage.getBool(_key); }
    function getInt(bytes32 _key) internal view returns (int256) { return stafiStorage.getInt(_key); }
    function getBytes32(bytes32 _key) internal view returns (bytes32) { return stafiStorage.getBytes32(_key); }
    function getAddressS(string memory _key) internal view returns (address) { return stafiStorage.getAddress(keccak256(abi.encodePacked(_key))); }
    function getUintS(string memory _key) internal view returns (uint256) { return stafiStorage.getUint(keccak256(abi.encodePacked(_key))); }
    function getStringS(string memory _key) internal view returns (string memory) { return stafiStorage.getString(keccak256(abi.encodePacked(_key))); }
    function getBytesS(string memory _key) internal view returns (bytes memory) { return stafiStorage.getBytes(keccak256(abi.encodePacked(_key))); }
    function getBoolS(string memory _key) internal view returns (bool) { return stafiStorage.getBool(keccak256(abi.encodePacked(_key))); }
    function getIntS(string memory _key) internal view returns (int256) { return stafiStorage.getInt(keccak256(abi.encodePacked(_key))); }
    function getBytes32S(string memory _key) internal view returns (bytes32) { return stafiStorage.getBytes32(keccak256(abi.encodePacked(_key))); }

    /// @dev Storage set methods
    function setAddress(bytes32 _key, address _value) internal { stafiStorage.setAddress(_key, _value); }
    function setUint(bytes32 _key, uint256 _value) internal { stafiStorage.setUint(_key, _value); }
    function setString(bytes32 _key, string memory _value) internal { stafiStorage.setString(_key, _value); }
    function setBytes(bytes32 _key, bytes memory _value) internal { stafiStorage.setBytes(_key, _value); }
    function setBool(bytes32 _key, bool _value) internal { stafiStorage.setBool(_key, _value); }
    function setInt(bytes32 _key, int256 _value) internal { stafiStorage.setInt(_key, _value); }
    function setBytes32(bytes32 _key, bytes32 _value) internal { stafiStorage.setBytes32(_key, _value); }
    function setAddressS(string memory _key, address _value) internal { stafiStorage.setAddress(keccak256(abi.encodePacked(_key)), _value); }
    function setUintS(string memory _key, uint256 _value) internal { stafiStorage.setUint(keccak256(abi.encodePacked(_key)), _value); }
    function setStringS(string memory _key, string memory _value) internal { stafiStorage.setString(keccak256(abi.encodePacked(_key)), _value); }
    function setBytesS(string memory _key, bytes memory _value) internal { stafiStorage.setBytes(keccak256(abi.encodePacked(_key)), _value); }
    function setBoolS(string memory _key, bool _value) internal { stafiStorage.setBool(keccak256(abi.encodePacked(_key)), _value); }
    function setIntS(string memory _key, int256 _value) internal { stafiStorage.setInt(keccak256(abi.encodePacked(_key)), _value); }
    function setBytes32S(string memory _key, bytes32 _value) internal { stafiStorage.setBytes32(keccak256(abi.encodePacked(_key)), _value); }

    /// @dev Storage delete methods
    function deleteAddress(bytes32 _key) internal { stafiStorage.deleteAddress(_key); }
    function deleteUint(bytes32 _key) internal { stafiStorage.deleteUint(_key); }
    function deleteString(bytes32 _key) internal { stafiStorage.deleteString(_key); }
    function deleteBytes(bytes32 _key) internal { stafiStorage.deleteBytes(_key); }
    function deleteBool(bytes32 _key) internal { stafiStorage.deleteBool(_key); }
    function deleteInt(bytes32 _key) internal { stafiStorage.deleteInt(_key); }
    function deleteBytes32(bytes32 _key) internal { stafiStorage.deleteBytes32(_key); }
    function deleteAddressS(string memory _key) internal { stafiStorage.deleteAddress(keccak256(abi.encodePacked(_key))); }
    function deleteUintS(string memory _key) internal { stafiStorage.deleteUint(keccak256(abi.encodePacked(_key))); }
    function deleteStringS(string memory _key) internal { stafiStorage.deleteString(keccak256(abi.encodePacked(_key))); }
    function deleteBytesS(string memory _key) internal { stafiStorage.deleteBytes(keccak256(abi.encodePacked(_key))); }
    function deleteBoolS(string memory _key) internal { stafiStorage.deleteBool(keccak256(abi.encodePacked(_key))); }
    function deleteIntS(string memory _key) internal { stafiStorage.deleteInt(keccak256(abi.encodePacked(_key))); }
    function deleteBytes32S(string memory _key) internal { stafiStorage.deleteBytes32(keccak256(abi.encodePacked(_key))); }


    /**
    * @dev Check if an address has this role
    */
    function roleHas(string memory _role, address _address) internal view returns (bool) {
        return getBool(keccak256(abi.encodePacked("access.role", _role, _address)));
    }

}

// File: contracts/interfaces/node/IStafiSuperNode.sol



pragma solidity 0.7.6;
pragma abicoder v2;
// SPDX-License-Identifier: GPL-3.0-only

interface IStafiSuperNode {
    function depositEth() external payable;
    function deposit(bytes[] calldata _validatorPubkeys, bytes[] calldata _validatorSignatures, bytes32[] calldata _depositDataRoots) external;
    function stake(bytes[] calldata _validatorPubkeys, bytes[] calldata _validatorSignatures, bytes32[] calldata _depositDataRoots) external;
    function getSuperNodePubkeyCount(address _nodeAddress) external view returns (uint256);
    function getSuperNodePubkeyAt(address _nodeAddress, uint256 _index) external view returns (bytes memory);
    function getSuperNodePubkeyStatus(bytes calldata _validatorPubkey) external view returns (uint256);
    function voteWithdrawCredentials(bytes[] calldata _pubkey, bool[] calldata _match) external;
}

// File: contracts/interfaces/node/IStafiNodeManager.sol



pragma solidity 0.7.6;

// SPDX-License-Identifier: GPL-3.0-only

interface IStafiNodeManager {
    function getNodeCount() external view returns (uint256);
    function getNodeAt(uint256 _index) external view returns (address);
    function getTrustedNodeCount() external view returns (uint256);
    function getTrustedNodeAt(uint256 _index) external view returns (address);
    function getSuperNodeCount() external view returns (uint256);
    function getSuperNodeAt(uint256 _index) external view returns (address);
    function getNodeExists(address _nodeAddress) external view returns (bool);
    function getNodeTrusted(address _nodeAddress) external view returns (bool);
    function getSuperNodeExists(address _nodeAddress) external view returns (bool);
    function registerNode(address _nodeAddress) external;
    function setNodeTrusted(address _nodeAddress, bool _trusted) external;
    function setNodeSuper(address _nodeAddress, bool _super) external;
}

// File: contracts/interfaces/deposit/IStafiUserDeposit.sol



pragma solidity 0.7.6;

// SPDX-License-Identifier: GPL-3.0-only

interface IStafiUserDeposit {
    function getBalance() external view returns (uint256);
    function getExcessBalance() external view returns (uint256);
    function deposit() external payable;
    function recycleDissolvedDeposit() external payable;
    function recycleWithdrawnDeposit() external payable;
    function recycleDistributorDeposit() external payable;
    function assignDeposits() external;
    function withdrawExcessBalance(uint256 _amount) external;
    function withdrawExcessBalanceForSuperNode(uint256 _amount) external;
    function withdrawExcessBalanceForLightNode(uint256 _amount) external;
}

// File: contracts/interfaces/eth/IDepositContract.sol



pragma solidity 0.7.6;

// SPDX-License-Identifier: GPL-3.0-only

interface IDepositContract {
    function deposit(bytes calldata _pubkey, bytes calldata _withdrawalCredentials, bytes calldata _signature, bytes32 _depositDataRoot) external payable;
}

// File: contracts/interfaces/settings/IStafiNetworkSettings.sol



pragma solidity 0.7.6;

// SPDX-License-Identifier: GPL-3.0-only

interface IStafiNetworkSettings {
    function getNodeConsensusThreshold() external view returns (uint256);
    function getSubmitBalancesEnabled() external view returns (bool);
    function getProcessWithdrawalsEnabled() external view returns (bool);
    function getNodeFee() external view returns (uint256);
    function getPlatformFee() external view returns (uint256);
    function getNodeRefundRatio() external view returns (uint256);
    function getNodeTrustedRefundRatio() external view returns (uint256);
    function getWithdrawalCredentials() external view returns (bytes memory);
    function getSuperNodePubkeyLimit() external view returns (uint256);
}

// File: contracts/interfaces/storage/IPubkeySetStorage.sol



pragma solidity 0.7.6;

// SPDX-License-Identifier: GPL-3.0-only

interface IPubkeySetStorage {
    function getCount(bytes32 _key) external view returns (uint256);
    function getItem(bytes32 _key, uint256 _index) external view returns (bytes memory);
    function getIndexOf(bytes32 _key, bytes calldata _value) external view returns (int256);
    function addItem(bytes32 _key, bytes memory _value) external;
    function removeItem(bytes32 _key, bytes calldata _value) external;
}

// File: @openzeppelin/contracts/math/SafeMath.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.7.0;

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

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

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

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

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

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

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

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

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

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

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

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

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

// File: contracts/interfaces/storage/IStafiStorage.sol



pragma solidity 0.7.6;

// SPDX-License-Identifier: GPL-3.0-only

interface IStafiStorage {

    // Getters
    function getAddress(bytes32 _key) external view returns (address);
    function getUint(bytes32 _key) external view returns (uint);
    function getString(bytes32 _key) external view returns (string memory);
    function getBytes(bytes32 _key) external view returns (bytes memory);
    function getBool(bytes32 _key) external view returns (bool);
    function getInt(bytes32 _key) external view returns (int);
    function getBytes32(bytes32 _key) external view returns (bytes32);

    // Setters
    function setAddress(bytes32 _key, address _value) external;
    function setUint(bytes32 _key, uint _value) external;
    function setString(bytes32 _key, string calldata _value) external;
    function setBytes(bytes32 _key, bytes calldata _value) external;
    function setBool(bytes32 _key, bool _value) external;
    function setInt(bytes32 _key, int _value) external;
    function setBytes32(bytes32 _key, bytes32 _value) external;

    // Deleters
    function deleteAddress(bytes32 _key) external;
    function deleteUint(bytes32 _key) external;
    function deleteString(bytes32 _key) external;
    function deleteBytes(bytes32 _key) external;
    function deleteBool(bytes32 _key) external;
    function deleteInt(bytes32 _key) external;
    function deleteBytes32(bytes32 _key) external;

}