// File: contracts/PLBTStaking.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.4;

import "@openzeppelin/contracts/access/AccessControl.sol";
import "@openzeppelin/contracts/security/ReentrancyGuard.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "./utils/SafeERC20.sol";
import "./interfaces/PLBTStaking/IPLBTStaking.sol";
import "./interfaces/DAO/IDAO.sol";

///@title Staking contract
contract PLBTStaking is IPLBTStaking, AccessControl, ReentrancyGuard {
    using SafeERC20 for IERC20;

    // Staker storage instance
    struct Staker {
        uint256 amount; // amount of tokens currently staked to the contract
        uint256 rewardGained; // increases every time staker unstakes their tokens. used to keep track of how much user earned before unstaking
        uint256 rewardMissed; // increases every time staker stakes more tokens. used to keep track of how much user missed before staking
        uint256 distributed; // total amount of reward tokens earned by the staker
    }
    
    // Staking information
    struct StakingInfo {
        uint256 _startTime; // staking start time
        uint256 _distributionTime; // period, over which _rewardTotal should be distributed
        uint256 _rewardTotalWBTC;
        uint256 _rewardTotalWETH;
        uint256 _totalStaked; // total amount of tokens currently staked on the contract
        uint256 _producedWETH; // total amount of produced wETH rewards
        uint256 _producedWBTC; // total amount of produced wBTC rewards
        address _PLBTAddress; // address of staking token
        address _wETHAddress; // address of reward token
        address _wBTCAddress; // address of reward token
    }


    // Map<address, staker> maps staker's information by their address
    mapping(address => Staker) private stakers;

    /// role of treasury holder
    bytes32 public TREASURY_ROLE = keccak256("TREASURY_ROLE");

    // address of the treasury
    address treasury;

    // Staking token
    IERC20 private PLBT;

    // Reward tokens
    IERC20 private wBTC;
    IERC20 private wETH;

    // Staking configuration variables
    uint256 public rewardTotal; // total reward over distribution time
    uint256 public allProduced; // variable used to store value of produced rewards before changing rewardTotal
    uint256 public totalStaked; // total amount of currently staked tokens
    uint256 public totalDistributed; // total amount of tokens earned by stakers
    uint256 public totalWBTC; // total rewards in wBTC distributed over distibutionTime
    uint256 public totalWETH; // total rewards in wETH distributed over distributionTime
    uint256 public totalProducedWETH; // total produced rewards in wETH
    uint256 public totalProducedWBTC; // total produced rewards in wBTC

    uint256 private producedTime; // variable used  to store time when rewardTotal is changed
    uint256 private startTime; // staking's start time
    uint256 private immutable distributionTime; // period, over which rewardTotal is distributed
    uint256 private tokensPerStake; // reward token per staked token
    uint256 private rewardProduced; // total amount of produced reward tokens
    bool private initialized; //shows if staking is initialized
    
    //DAO address
    IDAO private DAO; // DAO contract

     ///@dev Emitted when user stake tokens 
    ///@param amount amount of staked tokens
    ///@param time current block.timestamp
    ///@param sender msg.sender addresss
    event Staked(uint256 amount, uint256 time, address indexed sender);

    ///@dev Emitted when user claims reward tokens
    ///@param amountWETH amount of claimed  wETH tokens
    ///@param amountWBTC amount of claimed wBTC  tokens
    ///@param time current block.timestamp
    ///@param sender msg.sender addresss
    event Claimed(uint256 amountWETH, uint amountWBTC, uint256 time, address indexed sender);

    ///@dev Emitted when user unstakes token
    ///@param amount amount of unstaked tokens
    ///@param time current block.timestamp
    ///@param sender msg.sender address
    event Unstaked(uint256 amount, uint256 time, address indexed sender);

   
    ///@param _distributionTime period, over which `_rewardTotal` is distributed
    constructor(uint256 _distributionTime  ){
        _setupRole(DEFAULT_ADMIN_ROLE, msg.sender);
        _setRoleAdmin(TREASURY_ROLE, DEFAULT_ADMIN_ROLE);
        distributionTime = _distributionTime;
    }

     ///@dev Initializes Staking contract with tokens
    ///@param _startTime time when staking becomes active
     ///@param _wETH Wrapped Ethereum token address
     ///@param _wBTC Wrapped Bitcoin token address
     ///@param _PLBT PLBT Token address
     ///@param _addressDAO DAO address
    function initialize(uint256 _startTime, address _wETH, address _wBTC, address _PLBT, address _addressDAO, address _treasury) external  onlyRole(DEFAULT_ADMIN_ROLE){
        require(
            !initialized,
            "Staking: contract already initialized"
        );
        require(
            _startTime >= block.timestamp, 
            "Staking: current time greater than startTime"
        );
        startTime = _startTime;
        producedTime = _startTime;
        wETH = IERC20(_wETH);
        wBTC = IERC20(_wBTC);
        PLBT = IERC20(_PLBT);
        DAO = IDAO(_addressDAO);
        treasury = _treasury;
        _setupRole(TREASURY_ROLE, treasury);
        _setupRole(DEFAULT_ADMIN_ROLE, _addressDAO);
        renounceRole(DEFAULT_ADMIN_ROLE, msg.sender);
        initialized = true;
    }

    ///@dev retrieve reward leftovers
    function sweep() external onlyRole(TREASURY_ROLE){
        uint256 amountWETH = wETH.balanceOf(address(this));
        uint256 amountWBTC = wBTC.balanceOf(address(this));
        wETH.safeTransfer(treasury, amountWETH);
        wBTC.safeTransfer(treasury, amountWBTC);
    }

    ///@dev changes treasury address
    ///@param _treasury address of the treasury
    function changeTreasury(address _treasury) external override onlyRole(DEFAULT_ADMIN_ROLE){
        revokeRole(TREASURY_ROLE, treasury);
        treasury = _treasury;
        grantRole(TREASURY_ROLE, treasury);
    }

    ///@dev Sets amount of reward during `distributionTime`
    ///@param _amountWETH amount of rewards in wETH
    ///@param _amountWBTC amount of rewards in wBTC
    function setReward(uint256 _amountWETH, uint256 _amountWBTC) external  override onlyRole(DEFAULT_ADMIN_ROLE) {
        allProduced = produced();
        producedTime = block.timestamp;
        totalWBTC = _amountWBTC;
        totalWETH = _amountWETH;
        rewardTotal = _amountWETH + _amountWBTC;
    }

    ///@dev calculates available reward
    ///@param _staker address of the staker
    ///@param _tps reward tokens per staked tokens
    function calcReward(address _staker, uint256 _tps) private view returns (uint256 reward)
    {
        Staker storage staker = stakers[_staker];
        reward = staker.amount*_tps/1e20 + staker.rewardGained - staker.distributed - staker.rewardMissed;
        return reward;
    }

    ///@dev Calculates the total amount of currently produced reward
    ///@return current produced amount of reward tokens
    function produced() private view returns (uint256) {
        return allProduced + rewardTotal*(block.timestamp - producedTime)/distributionTime;
    }
    
    ///@dev updates produced reward. called  inside stake, unstake and claim functions
    function update() private {
        uint256 rewardProducedAtNow = produced();
        if (rewardProducedAtNow > rewardProduced) {
            uint256 producedNew = rewardProducedAtNow - rewardProduced;
            if (totalStaked > 0) {
                tokensPerStake = tokensPerStake+producedNew*1e20/totalStaked;
            }
            rewardProduced += producedNew;
        }
    }

    ///@notice transfers `_amount` staking tokens from staker to staking contract
    ///@param _amount amount of tokens to unstaket
    function stake(uint256 _amount) external {
        require(
            block.timestamp > startTime,
            "Staking: staking time has not come yet"
        );
        require(
            _amount > 0,
            "Staking: stake amount should be greater than 0"
        );
        Staker storage staker = stakers[msg.sender];
        PLBT.safeTransferFrom(
            msg.sender,
            address(this),
            _amount
        );
        staker.rewardMissed += _amount*tokensPerStake/1e20;
        totalStaked += _amount;
        staker.amount += _amount;
        update();
        emit Staked(_amount, block.timestamp, msg.sender);
    }

    ///@notice transfers `_amount` of staking tokens back to the staker
    ///@param _amount amount of tokens to unstake
    function unstake(uint256 _amount) external  nonReentrant {
        require(
            _amount > 0,
            "Staking: unstake amount should be greater than 0"
        );
        Staker storage staker = stakers[msg.sender];
        uint256 locked = DAO.getLockedTokens(msg.sender);
        uint256 unstakable = staker.amount - locked;
        require(
             _amount <= unstakable, //staker can't unstake tokens used for voting
            "Staking: Not enough tokens to unstake"
        );
        update();

        staker.rewardGained += _amount*tokensPerStake/1e20;
        staker.amount  -= _amount;
        totalStaked -= _amount;

        PLBT.safeTransfer(msg.sender, _amount);

        emit Unstaked(_amount, block.timestamp, msg.sender);
    }

    ///@dev transfers reward tokens to the staker
    ///@return wETHReward  amount of claimed wETH
    ///@return wBTCReward amount of claimed wBTC
    function claim() external  nonReentrant returns (uint256 wETHReward, uint256 wBTCReward) {
        if (totalStaked > 0) {
            update();
        }
        uint256 reward = calcReward(msg.sender, tokensPerStake);
        require(reward > 0, "Staking: Nothing to claim");
        
        Staker storage staker = stakers[msg.sender];
        staker.distributed += reward;
        totalDistributed += reward;

        wETHReward  = (reward*totalWETH)/(rewardTotal);
        wBTCReward = (reward*totalWBTC)/(rewardTotal);
        wETH.safeTransfer(msg.sender, wETHReward);
        wBTC.safeTransfer(msg.sender, wBTCReward);
        emit Claimed(wETHReward, wBTCReward, block.timestamp, msg.sender);
        return  (wETHReward, wBTCReward);
    }

    ///@dev returns information about the stake
    ///@return info_ struct containing staking information
    function getStakingInfo() external view returns (StakingInfo memory info_) {
        uint256 producedAtNow = produced();
        uint256 producedWETH = (producedAtNow*totalWETH)/rewardTotal;
        uint256 producedWBTC = (producedAtNow*totalWBTC)/rewardTotal;
        info_ = StakingInfo({
            _startTime: startTime,
            _distributionTime: distributionTime,
            _rewardTotalWBTC: totalWBTC,
            _rewardTotalWETH: totalWETH,
            _totalStaked: totalStaked,
            _producedWETH: producedWETH,
            _producedWBTC: producedWBTC,
            _PLBTAddress: address(PLBT),
            _wETHAddress: address(wETH),
            _wBTCAddress: address(wBTC)
        });
        return info_;
    }

    ///@notice return staker's information by their `_address`
    ///@param _address address of the staker
    ///@return staked_ amount of tokens staked by the staker
    ///@return claimWETH_ awailable to claim amount of rewards in wETH
    ///@return claimWBTC_ awailable to claim amount of rewards in wBTC
    function getInfoByAddress(address _address) external view returns (
        uint256 staked_,
        uint256 claimWETH_,
        uint256 claimWBTC_
    ){
        Staker storage staker = stakers[_address];
        staked_ = staker.amount;
        uint256 _tps = tokensPerStake;
        if (totalStaked > 0) {
            uint256 rewardProducedAtNow = produced();
            if (rewardProducedAtNow > rewardProduced) {
                uint256 producedNew = rewardProducedAtNow - rewardProduced;
                _tps = _tps + producedNew*1e20/totalStaked;
            }
        }
        uint256 reward = calcReward(_address, _tps);
        claimWETH_  = (reward*totalWETH)/rewardTotal;
        claimWBTC_ = (reward*totalWBTC)/rewardTotal;
        return (staked_, claimWETH_, claimWBTC_);
    }

    function getStakedTokens(address _address) external view override returns (uint256){
        return stakers[_address].amount;
    }
}
// File: @openzeppelin/contracts/access/AccessControl.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "./IAccessControl.sol";
import "../utils/Context.sol";
import "../utils/Strings.sol";
import "../utils/introspection/ERC165.sol";

/**
 * @dev Contract module that allows children to implement role-based access
 * control mechanisms. This is a lightweight version that doesn't allow enumerating role
 * members except through off-chain means by accessing the contract event logs. Some
 * applications may benefit from on-chain enumerability, for those cases see
 * {AccessControlEnumerable}.
 *
 * Roles are referred to by their `bytes32` identifier. These should be exposed
 * in the external API and be unique. The best way to achieve this is by
 * using `public constant` hash digests:
 *
 * ```
 * bytes32 public constant MY_ROLE = keccak256("MY_ROLE");
 * ```
 *
 * Roles can be used to represent a set of permissions. To restrict access to a
 * function call, use {hasRole}:
 *
 * ```
 * function foo() public {
 *     require(hasRole(MY_ROLE, msg.sender));
 *     ...
 * }
 * ```
 *
 * Roles can be granted and revoked dynamically via the {grantRole} and
 * {revokeRole} functions. Each role has an associated admin role, and only
 * accounts that have a role's admin role can call {grantRole} and {revokeRole}.
 *
 * By default, the admin role for all roles is `DEFAULT_ADMIN_ROLE`, which means
 * that only accounts with this role will be able to grant or revoke other
 * roles. More complex role relationships can be created by using
 * {_setRoleAdmin}.
 *
 * WARNING: The `DEFAULT_ADMIN_ROLE` is also its own admin: it has permission to
 * grant and revoke this role. Extra precautions should be taken to secure
 * accounts that have been granted it.
 */
abstract contract AccessControl is Context, IAccessControl, ERC165 {
    struct RoleData {
        mapping(address => bool) members;
        bytes32 adminRole;
    }

    mapping(bytes32 => RoleData) private _roles;

    bytes32 public constant DEFAULT_ADMIN_ROLE = 0x00;

    /**
     * @dev Modifier that checks that an account has a specific role. Reverts
     * with a standardized message including the required role.
     *
     * The format of the revert reason is given by the following regular expression:
     *
     *  /^AccessControl: account (0x[0-9a-f]{40}) is missing role (0x[0-9a-f]{64})$/
     *
     * _Available since v4.1._
     */
    modifier onlyRole(bytes32 role) {
        _checkRole(role, _msgSender());
        _;
    }

    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
        return interfaceId == type(IAccessControl).interfaceId || super.supportsInterface(interfaceId);
    }

    /**
     * @dev Returns `true` if `account` has been granted `role`.
     */
    function hasRole(bytes32 role, address account) public view override returns (bool) {
        return _roles[role].members[account];
    }

    /**
     * @dev Revert with a standard message if `account` is missing `role`.
     *
     * The format of the revert reason is given by the following regular expression:
     *
     *  /^AccessControl: account (0x[0-9a-f]{40}) is missing role (0x[0-9a-f]{64})$/
     */
    function _checkRole(bytes32 role, address account) internal view {
        if (!hasRole(role, account)) {
            revert(
                string(
                    abi.encodePacked(
                        "AccessControl: account ",
                        Strings.toHexString(uint160(account), 20),
                        " is missing role ",
                        Strings.toHexString(uint256(role), 32)
                    )
                )
            );
        }
    }

    /**
     * @dev Returns the admin role that controls `role`. See {grantRole} and
     * {revokeRole}.
     *
     * To change a role's admin, use {_setRoleAdmin}.
     */
    function getRoleAdmin(bytes32 role) public view override returns (bytes32) {
        return _roles[role].adminRole;
    }

    /**
     * @dev Grants `role` to `account`.
     *
     * If `account` had not been already granted `role`, emits a {RoleGranted}
     * event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     */
    function grantRole(bytes32 role, address account) public virtual override onlyRole(getRoleAdmin(role)) {
        _grantRole(role, account);
    }

    /**
     * @dev Revokes `role` from `account`.
     *
     * If `account` had been granted `role`, emits a {RoleRevoked} event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     */
    function revokeRole(bytes32 role, address account) public virtual override onlyRole(getRoleAdmin(role)) {
        _revokeRole(role, account);
    }

    /**
     * @dev Revokes `role` from the calling account.
     *
     * Roles are often managed via {grantRole} and {revokeRole}: this function's
     * purpose is to provide a mechanism for accounts to lose their privileges
     * if they are compromised (such as when a trusted device is misplaced).
     *
     * If the calling account had been granted `role`, emits a {RoleRevoked}
     * event.
     *
     * Requirements:
     *
     * - the caller must be `account`.
     */
    function renounceRole(bytes32 role, address account) public virtual override {
        require(account == _msgSender(), "AccessControl: can only renounce roles for self");

        _revokeRole(role, account);
    }

    /**
     * @dev Grants `role` to `account`.
     *
     * If `account` had not been already granted `role`, emits a {RoleGranted}
     * event. Note that unlike {grantRole}, this function doesn't perform any
     * checks on the calling account.
     *
     * [WARNING]
     * ====
     * This function should only be called from the constructor when setting
     * up the initial roles for the system.
     *
     * Using this function in any other way is effectively circumventing the admin
     * system imposed by {AccessControl}.
     * ====
     */
    function _setupRole(bytes32 role, address account) internal virtual {
        _grantRole(role, account);
    }

    /**
     * @dev Sets `adminRole` as ``role``'s admin role.
     *
     * Emits a {RoleAdminChanged} event.
     */
    function _setRoleAdmin(bytes32 role, bytes32 adminRole) internal virtual {
        bytes32 previousAdminRole = getRoleAdmin(role);
        _roles[role].adminRole = adminRole;
        emit RoleAdminChanged(role, previousAdminRole, adminRole);
    }

    function _grantRole(bytes32 role, address account) private {
        if (!hasRole(role, account)) {
            _roles[role].members[account] = true;
            emit RoleGranted(role, account, _msgSender());
        }
    }

    function _revokeRole(bytes32 role, address account) private {
        if (hasRole(role, account)) {
            _roles[role].members[account] = false;
            emit RoleRevoked(role, account, _msgSender());
        }
    }
}

// File: @openzeppelin/contracts/security/ReentrancyGuard.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Contract module that helps prevent reentrant calls to a function.
 *
 * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
 * available, which can be applied to functions to make sure there are no nested
 * (reentrant) calls to them.
 *
 * Note that because there is a single `nonReentrant` guard, functions marked as
 * `nonReentrant` may not call one another. This can be worked around by making
 * those functions `private`, and then adding `external` `nonReentrant` entry
 * points to them.
 *
 * TIP: If you would like to learn more about reentrancy and alternative ways
 * to protect against it, check out our blog post
 * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
 */
abstract contract ReentrancyGuard {
    // Booleans are more expensive than uint256 or any type that takes up a full
    // word because each write operation emits an extra SLOAD to first read the
    // slot's contents, replace the bits taken up by the boolean, and then write
    // back. This is the compiler's defense against contract upgrades and
    // pointer aliasing, and it cannot be disabled.

    // The values being non-zero value makes deployment a bit more expensive,
    // but in exchange the refund on every call to nonReentrant will be lower in
    // amount. Since refunds are capped to a percentage of the total
    // transaction's gas, it is best to keep them low in cases like this one, to
    // increase the likelihood of the full refund coming into effect.
    uint256 private constant _NOT_ENTERED = 1;
    uint256 private constant _ENTERED = 2;

    uint256 private _status;

    constructor() {
        _status = _NOT_ENTERED;
    }

    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and make it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        // On the first call to nonReentrant, _notEntered will be true
        require(_status != _ENTERED, "ReentrancyGuard: reentrant call");

        // Any calls to nonReentrant after this point will fail
        _status = _ENTERED;

        _;

        // By storing the original value once again, a refund is triggered (see
        // https://eips.ethereum.org/EIPS/eip-2200)
        _status = _NOT_ENTERED;
    }
}

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

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

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

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

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

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

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

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

// File: contracts/utils/SafeERC20.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/utils/Address.sol";

/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 * This contract is a stripped down version of openzeppelin's  SafeERC20
 */
library SafeERC20 {
    using Address for address;

    function safeTransfer(
        IERC20 token,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(
        IERC20 token,
        address from,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
        if (returndata.length > 0) {
            // Return data is optional
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

// File: contracts/interfaces/PLBTStaking/IPLBTStaking.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.4;


///@title Interface for PLBTSTaking contract for DAO interactions
interface IPLBTStaking {

    ///@dev returns amount of staked tokens by user `_address`
    ///@param _address address of the user
    ///@return amount of tokens
    function getStakedTokens(address _address) external view returns (uint256);

    ///@dev sets reward for next distribution time
    ///@param _amountWETH amount of wETH tokens
    ///@param _amountWBTC amount of wBTC tokens
    function setReward(uint256 _amountWETH, uint256 _amountWBTC) external;

    ///@dev changes treasury address
    ///@param _treasury address of the treasury
    function changeTreasury(address _treasury) external;
}
// File: contracts/interfaces/DAO/IDAO.sol



//SPDX-License-Identifier: Unlicense
pragma solidity ^0.8.4;

interface IDAO {
 
    function getLockedTokens(address staker) external view returns(uint256 locked);
    
    function getAvailableTokens(address staker) external view returns(uint256 locked);

}

// File: @openzeppelin/contracts/access/IAccessControl.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev External interface of AccessControl declared to support ERC165 detection.
 */
interface IAccessControl {
    /**
     * @dev Emitted when `newAdminRole` is set as ``role``'s admin role, replacing `previousAdminRole`
     *
     * `DEFAULT_ADMIN_ROLE` is the starting admin for all roles, despite
     * {RoleAdminChanged} not being emitted signaling this.
     *
     * _Available since v3.1._
     */
    event RoleAdminChanged(bytes32 indexed role, bytes32 indexed previousAdminRole, bytes32 indexed newAdminRole);

    /**
     * @dev Emitted when `account` is granted `role`.
     *
     * `sender` is the account that originated the contract call, an admin role
     * bearer except when using {AccessControl-_setupRole}.
     */
    event RoleGranted(bytes32 indexed role, address indexed account, address indexed sender);

    /**
     * @dev Emitted when `account` is revoked `role`.
     *
     * `sender` is the account that originated the contract call:
     *   - if using `revokeRole`, it is the admin role bearer
     *   - if using `renounceRole`, it is the role bearer (i.e. `account`)
     */
    event RoleRevoked(bytes32 indexed role, address indexed account, address indexed sender);

    /**
     * @dev Returns `true` if `account` has been granted `role`.
     */
    function hasRole(bytes32 role, address account) external view returns (bool);

    /**
     * @dev Returns the admin role that controls `role`. See {grantRole} and
     * {revokeRole}.
     *
     * To change a role's admin, use {AccessControl-_setRoleAdmin}.
     */
    function getRoleAdmin(bytes32 role) external view returns (bytes32);

    /**
     * @dev Grants `role` to `account`.
     *
     * If `account` had not been already granted `role`, emits a {RoleGranted}
     * event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     */
    function grantRole(bytes32 role, address account) external;

    /**
     * @dev Revokes `role` from `account`.
     *
     * If `account` had been granted `role`, emits a {RoleRevoked} event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     */
    function revokeRole(bytes32 role, address account) external;

    /**
     * @dev Revokes `role` from the calling account.
     *
     * Roles are often managed via {grantRole} and {revokeRole}: this function's
     * purpose is to provide a mechanism for accounts to lose their privileges
     * if they are compromised (such as when a trusted device is misplaced).
     *
     * If the calling account had been granted `role`, emits a {RoleRevoked}
     * event.
     *
     * Requirements:
     *
     * - the caller must be `account`.
     */
    function renounceRole(bytes32 role, address account) external;
}

// File: @openzeppelin/contracts/utils/Context.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}

// File: @openzeppelin/contracts/utils/Strings.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev String operations.
 */
library Strings {
    bytes16 private constant _HEX_SYMBOLS = "0123456789abcdef";

    /**
     * @dev Converts a `uint256` to its ASCII `string` decimal representation.
     */
    function toString(uint256 value) internal pure returns (string memory) {
        // Inspired by OraclizeAPI's implementation - MIT licence
        // https://github.com/oraclize/ethereum-api/blob/b42146b063c7d6ee1358846c198246239e9360e8/oraclizeAPI_0.4.25.sol

        if (value == 0) {
            return "0";
        }
        uint256 temp = value;
        uint256 digits;
        while (temp != 0) {
            digits++;
            temp /= 10;
        }
        bytes memory buffer = new bytes(digits);
        while (value != 0) {
            digits -= 1;
            buffer[digits] = bytes1(uint8(48 + uint256(value % 10)));
            value /= 10;
        }
        return string(buffer);
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
     */
    function toHexString(uint256 value) internal pure returns (string memory) {
        if (value == 0) {
            return "0x00";
        }
        uint256 temp = value;
        uint256 length = 0;
        while (temp != 0) {
            length++;
            temp >>= 8;
        }
        return toHexString(value, length);
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.
     */
    function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {
        bytes memory buffer = new bytes(2 * length + 2);
        buffer[0] = "0";
        buffer[1] = "x";
        for (uint256 i = 2 * length + 1; i > 1; --i) {
            buffer[i] = _HEX_SYMBOLS[value & 0xf];
            value >>= 4;
        }
        require(value == 0, "Strings: hex length insufficient");
        return string(buffer);
    }
}

// File: @openzeppelin/contracts/utils/introspection/ERC165.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "./IERC165.sol";

/**
 * @dev Implementation of the {IERC165} interface.
 *
 * Contracts that want to implement ERC165 should inherit from this contract and override {supportsInterface} to check
 * for the additional interface id that will be supported. For example:
 *
 * ```solidity
 * function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
 *     return interfaceId == type(MyInterface).interfaceId || super.supportsInterface(interfaceId);
 * }
 * ```
 *
 * Alternatively, {ERC165Storage} provides an easier to use but more expensive implementation.
 */
abstract contract ERC165 is IERC165 {
    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
        return interfaceId == type(IERC165).interfaceId;
    }
}

// File: @openzeppelin/contracts/utils/introspection/IERC165.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC165 standard, as defined in the
 * https://eips.ethereum.org/EIPS/eip-165[EIP].
 *
 * Implementers can declare support of contract interfaces, which can then be
 * queried by others ({ERC165Checker}).
 *
 * For an implementation, see {ERC165}.
 */
interface IERC165 {
    /**
     * @dev Returns true if this contract implements the interface defined by
     * `interfaceId`. See the corresponding
     * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
     * to learn more about how these ids are created.
     *
     * This function call must use less than 30 000 gas.
     */
    function supportsInterface(bytes4 interfaceId) external view returns (bool);
}

// File: @openzeppelin/contracts/utils/Address.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

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

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

        (bool success, ) = recipient.call{value: amount}("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain `call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");

        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");

        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason using the provided one.
     *
     * _Available since v4.3._
     */
    function verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal pure returns (bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}