// File: contracts/LiquidityMining.sol



// SPDX-License-Identifier: Apache-2.0

pragma solidity >=0.8.0;

import "@openzeppelin/contracts/utils/math/Math.sol";
import "@openzeppelin/contracts/utils/math/SafeCast.sol";
import "@openzeppelin/contracts-upgradeable/proxy/utils/UUPSUpgradeable.sol";
import "@openzeppelin/contracts-upgradeable/proxy/utils/Initializable.sol";
import "@openzeppelin/contracts-upgradeable/security/ReentrancyGuardUpgradeable.sol";
import "@openzeppelin/contracts-upgradeable/access/OwnableUpgradeable.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import "@openzeppelin/contracts/token/ERC20/extensions/draft-IERC20Permit.sol";
import "./interfaces/IEmission.sol";
import "./interfaces/ILiquidityMining.sol";

error InvalidArguments();
error InvalidOrder();
error ForbiddenZeroArgument();
error ReferrerMismatch();
error ReferrerUnqualified();
error LockTimeExpired();
error InsufficientLockTime();
error TierQualificationFailed();
error UnstakeOrderCannotBeFilled();

contract LiquidityMiningV2 is ILiquidityMining, Initializable, UUPSUpgradeable, ReentrancyGuardUpgradeable, OwnableUpgradeable {
    using SafeERC20 for IERC20;
    using SafeCast for uint;
 
    /// a library for handling binary fixed point numbers https://en.wikipedia.org/wiki/Q_(number_format)
    uint private constant Q64 = 2**64;
    uint16 private constant REFERRAL_LINK_REWARD_IN_BP = 100; // 1% * BP
    uint16 private constant REFERRER_REWARD_IN_BP = 500; // 5% * BP
    uint16 private constant BP = 10_000;

    uint64 public constant override MIN_VESTING_TIME_IN_SECONDS = 7 days;
    address public override PHTR;
    address public override LP;
    address public override emission;
    uint16 public override minTierReferrerBooster;

    uint public override totalBoostedStake;
    mapping(address => mapping(uint8 => uint)) public _vestingOptionStake;
    
    uint private accumulatedPHTRInTotalSharesInQ;
    uint private exitFeesInPHTR;
    uint private lastPHTRBalance;

    Tier[] private tiers;
    uint[] private vestingLockDateInSeconds;
    uint16[] private vestingTimeBoostersInBP;
    mapping(address => AccountDetails) private accountOf;
    
    function initialize(
        address _PHTR, 
        address _LP, 
        address _emission,
        uint8 _minTierReferrerBoosterIndex,
        Tier[] memory _tiers, 
        uint[] memory _vestingLockDateInSeconds, 
        uint16[] memory _vestingTimeBoostersInBP
    ) initializer public {
        __Ownable_init();
        __ReentrancyGuard_init();

        if (_PHTR == address(0) || _LP == address(0)) {
            revert ForbiddenZeroArgument();
        }
        if (
            _tiers.length < 2 // zero tier + 1 other tier
            || _tiers[0].boosterInBP != 0
            || _minTierReferrerBoosterIndex == 0
            || _tiers.length > type(uint8).max
            || _vestingLockDateInSeconds.length == 0
            || _vestingLockDateInSeconds.length > type(uint8).max
            || _vestingLockDateInSeconds.length != _vestingTimeBoostersInBP.length
        ) {
            revert InvalidArguments();
        }
        PHTR = _PHTR;
        LP = _LP;
        emission = _emission;
        minTierReferrerBooster = _tiers[_minTierReferrerBoosterIndex].boosterInBP;

        for (uint i; i < _tiers.length; ++i) {
            if (i > 0) {
                if (_tiers[i - 1].boosterInBP > _tiers[i].boosterInBP || _tiers[i - 1].thresholdInBP > _tiers[i].thresholdInBP) {
                    revert InvalidOrder();
                }
                if (_tiers[i].boosterInBP == 0) {
                    revert InvalidArguments();
                }
            }
            tiers.push(_tiers[i]);
        }

        for (uint i; i < _vestingLockDateInSeconds.length; ++i) {
            if (i > 0 && (
                _vestingLockDateInSeconds[i - 1] > _vestingLockDateInSeconds[i]
                || _vestingTimeBoostersInBP[i - 1] > _vestingTimeBoostersInBP[i]
            )) {
                revert InvalidOrder();
            }
            vestingLockDateInSeconds.push(_vestingLockDateInSeconds[i]);
            vestingTimeBoostersInBP.push(_vestingTimeBoostersInBP[i]);
        }
    } 

    function setEmission(address _emission) external onlyOwner {
        emission = _emission;
        emit SetEmission(msg.sender, _emission);
    }

    function stakeWithPermit(StakeWithPermitParams calldata _params) 
        external 
        override  
        nonReentrant 
        accumulateRewards(_params.referrer)
    {
        IERC20Permit(LP).permit(
            msg.sender, 
            address(this), 
            _params.approveMax ? type(uint).max : _params.amount, 
            _params.deadline, 
            _params.v, 
            _params.r, 
            _params.s
        );    
        _stake(_params.referrer, _params.amount, _params.minTierIndex, _params.vestingRange);
    }

    function stake(
        address _referrer, 
        uint _amount, 
        uint8 _minTierIndex, 
        VestingRange calldata _vestingRange
    )  
        external 
        override 
        nonReentrant 
        accumulateRewards(_referrer)
    {
        _stake(_referrer, _amount, _minTierIndex, _vestingRange);
    }
    
    function _stake(
        address _referrer, 
        uint _amount, 
        uint8 _minTierIndex, 
        VestingRange memory _vestingRange
    ) private {
        if (_vestingRange.startIndex > _vestingRange.endIndex) {
            revert InvalidArguments();
        }
        if (_amount == 0) {
            revert ForbiddenZeroArgument();
        }
        AccountDetails storage account = accountOf[msg.sender];

        if ((account.referrer != address(0) && account.referrer != _referrer) || _referrer == msg.sender) {
            revert ReferrerMismatch();
        }
        if (block.timestamp > vestingLockDateInSeconds[_vestingRange.startIndex] || block.timestamp > vestingLockDateInSeconds[_vestingRange.endIndex]) {
            revert LockTimeExpired();
        }
        if (vestingLockDateInSeconds[_vestingRange.startIndex] - block.timestamp < MIN_VESTING_TIME_IN_SECONDS) {
            revert InsufficientLockTime();
        }

        IERC20(LP).safeTransferFrom(msg.sender, address(this), _amount);
           
        // vesting booster = max achieved vesting option
        uint16 lastTierBoosterInBP = account.tierBoosterInBP;
        uint16 tierBoosterInBP_ = _tierBoosterInBP(account.totalStake + _amount, _minTierIndex);
        uint16 vestingBoosterInBP = vestingTimeBoostersInBP[_vestingRange.endIndex - _vestingRange.startIndex];
    
        _vestingOptionStake[msg.sender][_vestingRangeKey(_vestingRange)] += _amount;
        // tier booster is not reduceable during (re)staking
        account.tierBoosterInBP = uint16(Math.max(tierBoosterInBP_, lastTierBoosterInBP));
        account.vestedBoostedStake += (_amount * (BP + vestingBoosterInBP) / BP).toUint128();
        account.totalStake += _amount.toUint128();

        if (_referrer != address(0) && account.referrer == address(0)) {
            if (accountOf[_referrer].tierBoosterInBP < minTierReferrerBooster) {
                revert ReferrerUnqualified();
            }
            account.referrer = _referrer;
        }

        emit Stake(msg.sender, _amount, _vestingRange.startIndex, _vestingRange.endIndex);
    }

    function unstake(
        VestingRange[] calldata _vestingRanges, 
        uint _amount
    ) 
        external 
        override 
        nonReentrant 
        accumulateRewards(accountOf[msg.sender].referrer)
    {
        if (_amount == 0) {
            revert ForbiddenZeroArgument();
        }
        if (_vestingRanges.length == 0) {
            revert InvalidArguments();
        }
        
        AccountDetails storage account = accountOf[msg.sender];
        uint vestedBoostedStake;
        uint earlyUnstakedAmount;
        uint unstakedAmount;
        for (uint i; i < _vestingRanges.length; ++i) {
            VestingRange calldata vestingRange = _vestingRanges[i];
            if (vestingRange.startIndex > vestingRange.endIndex) {
                revert InvalidArguments();
            }
            uint vestingOptionStake_ = _vestingOptionStake[msg.sender][_vestingRangeKey(vestingRange)];
            uint16 vestingBoosterInBP = vestingTimeBoostersInBP[vestingRange.endIndex - vestingRange.startIndex];
            uint unstaked = unstakedAmount + vestingOptionStake_ > _amount ? _amount - unstakedAmount : vestingOptionStake_;
            if (unstaked == 0) {
                break;
            }
            if (block.timestamp < vestingLockDateInSeconds[vestingRange.endIndex]) {
                // early unstake
                earlyUnstakedAmount += unstaked;
            }
            unstakedAmount += unstaked;
            _vestingOptionStake[msg.sender][_vestingRangeKey(vestingRange)] -= unstaked;            
            vestedBoostedStake += unstaked * (BP + vestingBoosterInBP) / BP;

            emit UnstakeRange(msg.sender, unstaked, vestingRange.startIndex, vestingRange.endIndex);
        }
        if (unstakedAmount != _amount) {
            revert UnstakeOrderCannotBeFilled();
        }

        IERC20(LP).safeTransfer(msg.sender, _amount);
        
        uint totalAmountInPHTR = _amount * account.rewardInPHTR / account.totalStake;
        uint exitFeeInPHTR = earlyUnstakedAmount * account.rewardInPHTR / account.totalStake;
        if (exitFeeInPHTR > 0) {
           exitFeesInPHTR += exitFeeInPHTR;
        }
        uint rewardInPHTR = totalAmountInPHTR - exitFeeInPHTR;
        if (rewardInPHTR > 0) {
            IERC20(PHTR).safeTransfer(msg.sender, rewardInPHTR);
        }
        
        account.vestedBoostedStake -= Math.min(vestedBoostedStake, account.vestedBoostedStake).toUint128();
        account.tierBoosterInBP = _tierBoosterInBP(account.totalStake - _amount, 0);
        account.totalStake -= _amount.toUint128();
        account.rewardInPHTR -= totalAmountInPHTR;

        emit Unstake(msg.sender, _amount, totalAmountInPHTR, exitFeeInPHTR);
    }

    function programDetails() 
        external 
        view 
        override
        returns (
            uint _totalBoostedStake,
            uint _accumulatedPHTRInTotalSharesInQ,
            Tier[] memory _tiers,
            uint[] memory _vestingDatesInSeconds, 
            uint[] memory _vestingTimeBoostersInBP
        ) 
    {
        _totalBoostedStake = totalBoostedStake;
        _accumulatedPHTRInTotalSharesInQ = accumulatedPHTRInTotalSharesInQ;
        _tiers = tiers;
        _vestingDatesInSeconds = new uint[](vestingLockDateInSeconds.length);
        _vestingTimeBoostersInBP = new uint[](vestingTimeBoostersInBP.length);
        
        for (uint i; i < vestingLockDateInSeconds.length; ++i) {
            _vestingDatesInSeconds[i] = vestingLockDateInSeconds[i];
            _vestingTimeBoostersInBP[i] = vestingTimeBoostersInBP[i];
        }
    }

    function accountDetails(address _account) 
        external 
        view 
        override
        returns (
            uint _boostedStake,
            uint _totalReward,
            AccountDetails memory _accountDetails
        ) 
    {
        _boostedStake = _boostedStakeOf(_account);
        _accountDetails = accountOf[_account];
        uint PHTRIncrease = exitFeesInPHTR + IEmission(emission).withdrawable() + IERC20(PHTR).balanceOf(address(this)) - lastPHTRBalance;
        uint _accumulatedPHTRInTotalSharesInQ = accumulatedPHTRInTotalSharesInQ;
        if (PHTRIncrease > 0 && totalBoostedStake > 0) {
            unchecked { // overflow is desired
                _accumulatedPHTRInTotalSharesInQ += PHTRIncrease * Q64 / totalBoostedStake;    
            }  
        }
        uint last = accountOf[_account].totalStake == 0 ? _accumulatedPHTRInTotalSharesInQ : accountOf[_account].lastAccumulatedPHTRInTotalBoostedStakeInQ;
        uint accumulatedPHTRInTotalSharesIncreaseInQ;
        unchecked { // overflow is desired
            accumulatedPHTRInTotalSharesIncreaseInQ = _accumulatedPHTRInTotalSharesInQ - last;
        }
        uint rewardInPHTR = _boostedStake * accumulatedPHTRInTotalSharesIncreaseInQ / Q64;
        _totalReward = rewardInPHTR + _accountDetails.rewardInPHTR;
    }

    function tierBoosterInBP(uint _amount, uint8 _minTierIndex) external view override returns (uint16) {
        return _tierBoosterInBP(_amount, _minTierIndex);
    }

    function vestingOptionStake(
        address _account, 
        VestingRange calldata _vestingRange
    ) 
        external 
        view 
        override 
        returns (uint) 
    {
        return _vestingOptionStake[_account][_vestingRangeKey(_vestingRange)];
    }

    function _updateReferralBooster(address _referrer, uint _newReferralBoosterInBP, uint _lastReferralBoosterInBP) private {
        // let lastStake == 0 without referrer
        // lastStake == 0 && stake != 0 = mint referral booster
        // lastStake != 0 && stake == 0 = burn referral booster
        // lastStake != 0 && stake != 0 = update referral booster
        // lastStake == 0 && stake == 0 = referral booster stays zero
        if (_referrer == address(0) || accountOf[msg.sender].tierBoosterInBP < minTierReferrerBooster) {
            return;
        }
        
        if (_lastReferralBoosterInBP == type(uint).max) {
            uint newReferralBoosterInBP = accountOf[_referrer].referralBoosterInBP + _newReferralBoosterInBP;
            accountOf[_referrer].referralBoosterInBP += uint16(Math.min(type(uint16).max, newReferralBoosterInBP));
        } else {
            // TODO: handle subtraction lower bound
            if (accountOf[_referrer].referralBoosterInBP + _newReferralBoosterInBP < _lastReferralBoosterInBP) {
                accountOf[_referrer].referralBoosterInBP = 0;
            } else {
                uint newReferralBoosterInBP = accountOf[_referrer].referralBoosterInBP + _newReferralBoosterInBP - _lastReferralBoosterInBP;
                accountOf[_referrer].referralBoosterInBP = uint16(Math.min(type(uint16).max, newReferralBoosterInBP));
            }
        }
    }

    function _updateAccountReward(address _account, uint _boostedStake) private {
        if (_account == address(0)) {
            return;
        }
        
        // TODO: check if this works together with referrer
        uint last = accountOf[_account].totalStake == 0 ? accumulatedPHTRInTotalSharesInQ : accountOf[_account].lastAccumulatedPHTRInTotalBoostedStakeInQ;
        uint accumulatedPHTRInTotalSharesIncreaseInQ;
        unchecked { // overflow is desired
            accumulatedPHTRInTotalSharesIncreaseInQ = accumulatedPHTRInTotalSharesInQ - last;
        }
        uint rewardInPHTR = _boostedStake * accumulatedPHTRInTotalSharesIncreaseInQ / Q64;
        if (rewardInPHTR > 0) {
            accountOf[_account].rewardInPHTR += rewardInPHTR;
        }
        
        accountOf[_account].lastAccumulatedPHTRInTotalBoostedStakeInQ = accumulatedPHTRInTotalSharesInQ;
    }

    function _referralBoosterInBP(address _account, uint _boostedStake) private view returns (uint) {
        if (accountOf[_account].referrer == address(0)) {
            return type(uint).max; // 'unset' booster state
        }
        uint stake_ = accountOf[_account].totalStake;
        if (stake_ == 0) {
            return 0;
        }
        uint referralBoosterInBP = accountOf[_account].referralBoosterInBP;
        uint allBoosters = _boostedStake * BP / stake_ - BP;
        uint allBoostersWithoutReferral = allBoosters < referralBoosterInBP ? 0 : allBoosters - referralBoosterInBP;
        return REFERRER_REWARD_IN_BP * allBoostersWithoutReferral / BP;
    }
    
    function _boostedStakeOf(address _account) private view returns (uint) {
        if (_account == address(0)) {
            return 0;
        }
        AccountDetails storage account = accountOf[_account];
        uint16 referralLinkBoosterInBP = account.referrer == address(0) ? 0 : REFERRAL_LINK_REWARD_IN_BP; 
        uint vestedBoosterInBP;
        if (account.totalStake > 0) {
           vestedBoosterInBP = (account.vestedBoostedStake * BP / account.totalStake) - BP;
        }
        return (BP + account.tierBoosterInBP + account.referralBoosterInBP + referralLinkBoosterInBP + vestedBoosterInBP) * account.totalStake / BP;
    }

    function _tierBoosterInBP(uint _amount, uint8 _minTierIndex) private view returns (uint16 tierBoosterInBP_) {
        // LP.totalSupply cannot be zero on UNI-V2 (https://github.com/Uniswap/uniswap-v2-core/blob/master/contracts/UniswapV2Pair.sol#L121)
        uint accountTotalStakeInBP = _amount * BP / IERC20(LP).totalSupply();
        for (uint i = tiers.length; i > 0; --i) {
            // tier booster = totalStake as a percentage of total LP
            if (accountTotalStakeInBP >= tiers[i - 1].thresholdInBP) {
                if (_minTierIndex > i - 1) {
                    revert TierQualificationFailed();
                }
                tierBoosterInBP_ = tiers[i - 1].boosterInBP;
                break;
            } 
        }  
    }

    /// @dev Encodes _vestingRange with unique key combination
    function _vestingRangeKey(VestingRange memory _vestingRange) private view returns (uint8) {
        return (_vestingRange.startIndex * vestingLockDateInSeconds.length + _vestingRange.endIndex).toUint8();
    }

    function _authorizeUpgrade(address) internal override onlyOwner {}

    /// @dev Accumulates unclaimed PHTR reward for account and it's referrer
    modifier accumulateRewards(address _referrer) {
        uint lastBoostedStake = _boostedStakeOf(msg.sender);
        uint lastBoostedStakeOfReferrer = _boostedStakeOf(_referrer);
        uint lastReferralBoosterInBP = _referralBoosterInBP(msg.sender, lastBoostedStake);

        if (totalBoostedStake > 0) {
            IEmission(emission).withdraw();
            uint PHTRIncrease = IERC20(PHTR).balanceOf(address(this)) - lastPHTRBalance + exitFeesInPHTR;
            if (PHTRIncrease > 0) {
                unchecked { // overflow is desired
                    accumulatedPHTRInTotalSharesInQ += PHTRIncrease * Q64 / totalBoostedStake;    
                }   
                exitFeesInPHTR = 0; // unset exit fee carry
            }
            _updateAccountReward(msg.sender, lastBoostedStake);
            _updateAccountReward(_referrer, lastBoostedStakeOfReferrer);
        }

        _;
        
        uint boostedStake = _boostedStakeOf(msg.sender);
        _updateReferralBooster(_referrer, _referralBoosterInBP(msg.sender, boostedStake), lastReferralBoosterInBP);
        // lastBoostedStakeOfReferrer must be accounted somewhere for last value to be subtracted even if referrer is not present
        uint lastBoostedStakeWithReferrer = lastBoostedStake + lastBoostedStakeOfReferrer;
        uint boostedStakeWithReferrer = boostedStake + _boostedStakeOf(_referrer);
        if (boostedStakeWithReferrer > lastBoostedStakeWithReferrer) {
            totalBoostedStake += boostedStakeWithReferrer - lastBoostedStakeWithReferrer;
        } else if (lastBoostedStakeWithReferrer > boostedStakeWithReferrer) {
            totalBoostedStake -= lastBoostedStakeWithReferrer - boostedStakeWithReferrer;
        }
        if (totalBoostedStake + lastBoostedStakeWithReferrer > 0) { // don't account for last PHTR when previous total stake was zero
            // TODO: log state here
            lastPHTRBalance = IERC20(PHTR).balanceOf(address(this));
        }
    }
}
// File: @openzeppelin/contracts/utils/math/Math.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/math/Math.sol)

pragma solidity ^0.8.0;

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

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

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

    /**
     * @dev Returns the ceiling of the division of two numbers.
     *
     * This differs from standard division with `/` in that it rounds up instead
     * of rounding down.
     */
    function ceilDiv(uint256 a, uint256 b) internal pure returns (uint256) {
        // (a + b - 1) / b can overflow on addition, so we distribute.
        return a / b + (a % b == 0 ? 0 : 1);
    }
}

// File: @openzeppelin/contracts/utils/math/SafeCast.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/math/SafeCast.sol)

pragma solidity ^0.8.0;

/**
 * @dev Wrappers over Solidity's uintXX/intXX casting operators with added overflow
 * checks.
 *
 * Downcasting from uint256/int256 in Solidity does not revert on overflow. This can
 * easily result in undesired exploitation or bugs, since developers usually
 * assume that overflows raise errors. `SafeCast` restores this intuition by
 * reverting the transaction when such 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.
 *
 * Can be combined with {SafeMath} and {SignedSafeMath} to extend it to smaller types, by performing
 * all math on `uint256` and `int256` and then downcasting.
 */
library SafeCast {
    /**
     * @dev Returns the downcasted uint224 from uint256, reverting on
     * overflow (when the input is greater than largest uint224).
     *
     * Counterpart to Solidity's `uint224` operator.
     *
     * Requirements:
     *
     * - input must fit into 224 bits
     */
    function toUint224(uint256 value) internal pure returns (uint224) {
        require(value <= type(uint224).max, "SafeCast: value doesn't fit in 224 bits");
        return uint224(value);
    }

    /**
     * @dev Returns the downcasted uint128 from uint256, reverting on
     * overflow (when the input is greater than largest uint128).
     *
     * Counterpart to Solidity's `uint128` operator.
     *
     * Requirements:
     *
     * - input must fit into 128 bits
     */
    function toUint128(uint256 value) internal pure returns (uint128) {
        require(value <= type(uint128).max, "SafeCast: value doesn't fit in 128 bits");
        return uint128(value);
    }

    /**
     * @dev Returns the downcasted uint96 from uint256, reverting on
     * overflow (when the input is greater than largest uint96).
     *
     * Counterpart to Solidity's `uint96` operator.
     *
     * Requirements:
     *
     * - input must fit into 96 bits
     */
    function toUint96(uint256 value) internal pure returns (uint96) {
        require(value <= type(uint96).max, "SafeCast: value doesn't fit in 96 bits");
        return uint96(value);
    }

    /**
     * @dev Returns the downcasted uint64 from uint256, reverting on
     * overflow (when the input is greater than largest uint64).
     *
     * Counterpart to Solidity's `uint64` operator.
     *
     * Requirements:
     *
     * - input must fit into 64 bits
     */
    function toUint64(uint256 value) internal pure returns (uint64) {
        require(value <= type(uint64).max, "SafeCast: value doesn't fit in 64 bits");
        return uint64(value);
    }

    /**
     * @dev Returns the downcasted uint32 from uint256, reverting on
     * overflow (when the input is greater than largest uint32).
     *
     * Counterpart to Solidity's `uint32` operator.
     *
     * Requirements:
     *
     * - input must fit into 32 bits
     */
    function toUint32(uint256 value) internal pure returns (uint32) {
        require(value <= type(uint32).max, "SafeCast: value doesn't fit in 32 bits");
        return uint32(value);
    }

    /**
     * @dev Returns the downcasted uint16 from uint256, reverting on
     * overflow (when the input is greater than largest uint16).
     *
     * Counterpart to Solidity's `uint16` operator.
     *
     * Requirements:
     *
     * - input must fit into 16 bits
     */
    function toUint16(uint256 value) internal pure returns (uint16) {
        require(value <= type(uint16).max, "SafeCast: value doesn't fit in 16 bits");
        return uint16(value);
    }

    /**
     * @dev Returns the downcasted uint8 from uint256, reverting on
     * overflow (when the input is greater than largest uint8).
     *
     * Counterpart to Solidity's `uint8` operator.
     *
     * Requirements:
     *
     * - input must fit into 8 bits.
     */
    function toUint8(uint256 value) internal pure returns (uint8) {
        require(value <= type(uint8).max, "SafeCast: value doesn't fit in 8 bits");
        return uint8(value);
    }

    /**
     * @dev Converts a signed int256 into an unsigned uint256.
     *
     * Requirements:
     *
     * - input must be greater than or equal to 0.
     */
    function toUint256(int256 value) internal pure returns (uint256) {
        require(value >= 0, "SafeCast: value must be positive");
        return uint256(value);
    }

    /**
     * @dev Returns the downcasted int128 from int256, reverting on
     * overflow (when the input is less than smallest int128 or
     * greater than largest int128).
     *
     * Counterpart to Solidity's `int128` operator.
     *
     * Requirements:
     *
     * - input must fit into 128 bits
     *
     * _Available since v3.1._
     */
    function toInt128(int256 value) internal pure returns (int128) {
        require(value >= type(int128).min && value <= type(int128).max, "SafeCast: value doesn't fit in 128 bits");
        return int128(value);
    }

    /**
     * @dev Returns the downcasted int64 from int256, reverting on
     * overflow (when the input is less than smallest int64 or
     * greater than largest int64).
     *
     * Counterpart to Solidity's `int64` operator.
     *
     * Requirements:
     *
     * - input must fit into 64 bits
     *
     * _Available since v3.1._
     */
    function toInt64(int256 value) internal pure returns (int64) {
        require(value >= type(int64).min && value <= type(int64).max, "SafeCast: value doesn't fit in 64 bits");
        return int64(value);
    }

    /**
     * @dev Returns the downcasted int32 from int256, reverting on
     * overflow (when the input is less than smallest int32 or
     * greater than largest int32).
     *
     * Counterpart to Solidity's `int32` operator.
     *
     * Requirements:
     *
     * - input must fit into 32 bits
     *
     * _Available since v3.1._
     */
    function toInt32(int256 value) internal pure returns (int32) {
        require(value >= type(int32).min && value <= type(int32).max, "SafeCast: value doesn't fit in 32 bits");
        return int32(value);
    }

    /**
     * @dev Returns the downcasted int16 from int256, reverting on
     * overflow (when the input is less than smallest int16 or
     * greater than largest int16).
     *
     * Counterpart to Solidity's `int16` operator.
     *
     * Requirements:
     *
     * - input must fit into 16 bits
     *
     * _Available since v3.1._
     */
    function toInt16(int256 value) internal pure returns (int16) {
        require(value >= type(int16).min && value <= type(int16).max, "SafeCast: value doesn't fit in 16 bits");
        return int16(value);
    }

    /**
     * @dev Returns the downcasted int8 from int256, reverting on
     * overflow (when the input is less than smallest int8 or
     * greater than largest int8).
     *
     * Counterpart to Solidity's `int8` operator.
     *
     * Requirements:
     *
     * - input must fit into 8 bits.
     *
     * _Available since v3.1._
     */
    function toInt8(int256 value) internal pure returns (int8) {
        require(value >= type(int8).min && value <= type(int8).max, "SafeCast: value doesn't fit in 8 bits");
        return int8(value);
    }

    /**
     * @dev Converts an unsigned uint256 into a signed int256.
     *
     * Requirements:
     *
     * - input must be less than or equal to maxInt256.
     */
    function toInt256(uint256 value) internal pure returns (int256) {
        // Note: Unsafe cast below is okay because `type(int256).max` is guaranteed to be positive
        require(value <= uint256(type(int256).max), "SafeCast: value doesn't fit in an int256");
        return int256(value);
    }
}

// File: @openzeppelin/contracts-upgradeable/proxy/utils/UUPSUpgradeable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (proxy/utils/UUPSUpgradeable.sol)

pragma solidity ^0.8.0;

import "../ERC1967/ERC1967UpgradeUpgradeable.sol";
import "./Initializable.sol";

/**
 * @dev An upgradeability mechanism designed for UUPS proxies. The functions included here can perform an upgrade of an
 * {ERC1967Proxy}, when this contract is set as the implementation behind such a proxy.
 *
 * A security mechanism ensures that an upgrade does not turn off upgradeability accidentally, although this risk is
 * reinstated if the upgrade retains upgradeability but removes the security mechanism, e.g. by replacing
 * `UUPSUpgradeable` with a custom implementation of upgrades.
 *
 * The {_authorizeUpgrade} function must be overridden to include access restriction to the upgrade mechanism.
 *
 * _Available since v4.1._
 */
abstract contract UUPSUpgradeable is Initializable, ERC1967UpgradeUpgradeable {
    function __UUPSUpgradeable_init() internal onlyInitializing {
        __ERC1967Upgrade_init_unchained();
        __UUPSUpgradeable_init_unchained();
    }

    function __UUPSUpgradeable_init_unchained() internal onlyInitializing {
    }
    /// @custom:oz-upgrades-unsafe-allow state-variable-immutable state-variable-assignment
    address private immutable __self = address(this);

    /**
     * @dev Check that the execution is being performed through a delegatecall call and that the execution context is
     * a proxy contract with an implementation (as defined in ERC1967) pointing to self. This should only be the case
     * for UUPS and transparent proxies that are using the current contract as their implementation. Execution of a
     * function through ERC1167 minimal proxies (clones) would not normally pass this test, but is not guaranteed to
     * fail.
     */
    modifier onlyProxy() {
        require(address(this) != __self, "Function must be called through delegatecall");
        require(_getImplementation() == __self, "Function must be called through active proxy");
        _;
    }

    /**
     * @dev Upgrade the implementation of the proxy to `newImplementation`.
     *
     * Calls {_authorizeUpgrade}.
     *
     * Emits an {Upgraded} event.
     */
    function upgradeTo(address newImplementation) external virtual onlyProxy {
        _authorizeUpgrade(newImplementation);
        _upgradeToAndCallSecure(newImplementation, new bytes(0), false);
    }

    /**
     * @dev Upgrade the implementation of the proxy to `newImplementation`, and subsequently execute the function call
     * encoded in `data`.
     *
     * Calls {_authorizeUpgrade}.
     *
     * Emits an {Upgraded} event.
     */
    function upgradeToAndCall(address newImplementation, bytes memory data) external payable virtual onlyProxy {
        _authorizeUpgrade(newImplementation);
        _upgradeToAndCallSecure(newImplementation, data, true);
    }

    /**
     * @dev Function that should revert when `msg.sender` is not authorized to upgrade the contract. Called by
     * {upgradeTo} and {upgradeToAndCall}.
     *
     * Normally, this function will use an xref:access.adoc[access control] modifier such as {Ownable-onlyOwner}.
     *
     * ```solidity
     * function _authorizeUpgrade(address) internal override onlyOwner {}
     * ```
     */
    function _authorizeUpgrade(address newImplementation) internal virtual;
    uint256[50] private __gap;
}

// File: @openzeppelin/contracts-upgradeable/proxy/utils/Initializable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (proxy/utils/Initializable.sol)

pragma solidity ^0.8.0;

import "../../utils/AddressUpgradeable.sol";

/**
 * @dev This is a base contract to aid in writing upgradeable contracts, or any kind of contract that will be deployed
 * behind a proxy. Since a proxied contract can't have a constructor, it's common to move constructor logic to an
 * external initializer function, usually called `initialize`. It then becomes necessary to protect this initializer
 * function so it can only be called once. The {initializer} modifier provided by this contract will have this effect.
 *
 * TIP: To avoid leaving the proxy in an uninitialized state, the initializer function should be called as early as
 * possible by providing the encoded function call as the `_data` argument to {ERC1967Proxy-constructor}.
 *
 * CAUTION: When used with inheritance, manual care must be taken to not invoke a parent initializer twice, or to ensure
 * that all initializers are idempotent. This is not verified automatically as constructors are by Solidity.
 *
 * [CAUTION]
 * ====
 * Avoid leaving a contract uninitialized.
 *
 * An uninitialized contract can be taken over by an attacker. This applies to both a proxy and its implementation
 * contract, which may impact the proxy. To initialize the implementation contract, you can either invoke the
 * initializer manually, or you can include a constructor to automatically mark it as initialized when it is deployed:
 *
 * [.hljs-theme-light.nopadding]
 * ```
 * /// @custom:oz-upgrades-unsafe-allow constructor
 * constructor() initializer {}
 * ```
 * ====
 */
abstract contract Initializable {
    /**
     * @dev Indicates that the contract has been initialized.
     */
    bool private _initialized;

    /**
     * @dev Indicates that the contract is in the process of being initialized.
     */
    bool private _initializing;

    /**
     * @dev Modifier to protect an initializer function from being invoked twice.
     */
    modifier initializer() {
        // If the contract is initializing we ignore whether _initialized is set in order to support multiple
        // inheritance patterns, but we only do this in the context of a constructor, because in other contexts the
        // contract may have been reentered.
        require(_initializing ? _isConstructor() : !_initialized, "Initializable: contract is already initialized");

        bool isTopLevelCall = !_initializing;
        if (isTopLevelCall) {
            _initializing = true;
            _initialized = true;
        }

        _;

        if (isTopLevelCall) {
            _initializing = false;
        }
    }

    /**
     * @dev Modifier to protect an initialization function so that it can only be invoked by functions with the
     * {initializer} modifier, directly or indirectly.
     */
    modifier onlyInitializing() {
        require(_initializing, "Initializable: contract is not initializing");
        _;
    }

    function _isConstructor() private view returns (bool) {
        return !AddressUpgradeable.isContract(address(this));
    }
}

// File: @openzeppelin/contracts-upgradeable/security/ReentrancyGuardUpgradeable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (security/ReentrancyGuard.sol)

pragma solidity ^0.8.0;
import "../proxy/utils/Initializable.sol";

/**
 * @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 ReentrancyGuardUpgradeable is Initializable {
    // 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;

    function __ReentrancyGuard_init() internal onlyInitializing {
        __ReentrancyGuard_init_unchained();
    }

    function __ReentrancyGuard_init_unchained() internal onlyInitializing {
        _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 making 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;
    }
    uint256[49] private __gap;
}

// File: @openzeppelin/contracts-upgradeable/access/OwnableUpgradeable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (access/Ownable.sol)

pragma solidity ^0.8.0;

import "../utils/ContextUpgradeable.sol";
import "../proxy/utils/Initializable.sol";

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract OwnableUpgradeable is Initializable, ContextUpgradeable {
    address private _owner;

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

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    function __Ownable_init() internal onlyInitializing {
        __Context_init_unchained();
        __Ownable_init_unchained();
    }

    function __Ownable_init_unchained() internal onlyInitializing {
        _transferOwnership(_msgSender());
    }

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

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

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

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
    uint256[49] private __gap;
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/IERC20.sol)

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: @openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/utils/SafeERC20.sol)

pragma solidity ^0.8.0;

import "../IERC20.sol";
import "../../../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.
 */
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 Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    function safeApprove(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        require(
            (value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    function safeIncreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        uint256 newAllowance = token.allowance(address(this), spender) + value;
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        unchecked {
            uint256 oldAllowance = token.allowance(address(this), spender);
            require(oldAllowance >= value, "SafeERC20: decreased allowance below zero");
            uint256 newAllowance = oldAllowance - value;
            _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
        }
    }

    /**
     * @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: @openzeppelin/contracts/token/ERC20/extensions/draft-IERC20Permit.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/draft-IERC20Permit.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 Permit extension allowing approvals to be made via signatures, as defined in
 * https://eips.ethereum.org/EIPS/eip-2612[EIP-2612].
 *
 * Adds the {permit} method, which can be used to change an account's ERC20 allowance (see {IERC20-allowance}) by
 * presenting a message signed by the account. By not relying on {IERC20-approve}, the token holder account doesn't
 * need to send a transaction, and thus is not required to hold Ether at all.
 */
interface IERC20Permit {
    /**
     * @dev Sets `value` as the allowance of `spender` over ``owner``'s tokens,
     * given ``owner``'s signed approval.
     *
     * IMPORTANT: The same issues {IERC20-approve} has related to transaction
     * ordering also apply here.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `deadline` must be a timestamp in the future.
     * - `v`, `r` and `s` must be a valid `secp256k1` signature from `owner`
     * over the EIP712-formatted function arguments.
     * - the signature must use ``owner``'s current nonce (see {nonces}).
     *
     * For more information on the signature format, see the
     * https://eips.ethereum.org/EIPS/eip-2612#specification[relevant EIP
     * section].
     */
    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external;

    /**
     * @dev Returns the current nonce for `owner`. This value must be
     * included whenever a signature is generated for {permit}.
     *
     * Every successful call to {permit} increases ``owner``'s nonce by one. This
     * prevents a signature from being used multiple times.
     */
    function nonces(address owner) external view returns (uint256);

    /**
     * @dev Returns the domain separator used in the encoding of the signature for {permit}, as defined by {EIP712}.
     */
    // solhint-disable-next-line func-name-mixedcase
    function DOMAIN_SEPARATOR() external view returns (bytes32);
}

// File: contracts/interfaces/IEmission.sol



// SPDX-License-Identifier: Apache-2.0

pragma solidity >=0.8.0;

interface IEmission {
    event SetDistribution(uint distributionInterval, uint distributedPerInterval);

    function setDistribution(uint _distributionInterval, uint _distributedPerInterval) external;
    function withdraw() external;
    function withdrawable() external view returns (uint);
    function distributionInterval() external view returns (uint);
    function distributedPerInterval() external view returns (uint);
}
// File: contracts/interfaces/ILiquidityMining.sol



// SPDX-License-Identifier: Apache-2.0

pragma solidity >=0.8.0;

interface ILiquidityMining {

    event Stake(address indexed account, uint amount, uint8 indexed rangeStartIndex, uint8 indexed rangeEndIndex);
    event UnstakeRange(address indexed account, uint unstakedAmount, uint8 indexed rangeStartIndex, uint8 indexed rangeEndIndex);
    event Unstake(address indexed account, uint amount, uint rewardInPHTR, uint exitFeeInPHTR);
    event SetEmission(address indexed account, address indexed emission);

    struct Tier {
        /// % booster for tier qualification
        uint16 boosterInBP;
        /// % of totalSupply, required to qualify for this tier
        uint16 thresholdInBP;
    }

    struct VestingRange {
        uint8 startIndex;
        uint8 endIndex;
    }

    struct AccountDetails {
        uint128 vestedBoostedStake; // 128
        uint128 totalStake; // 128 + 128 = 256
        address referrer; // 160
        uint16 tierBoosterInBP; // 160 + 16 = 176
        uint16 referralBoosterInBP; // 160 + 16 + 16 = 192
        uint lastAccumulatedPHTRInTotalBoostedStakeInQ;
        uint rewardInPHTR;
    }

    struct StakeWithPermitParams {
        address referrer;
        uint amount;
        uint8 minTierIndex; 
        VestingRange vestingRange;
        uint deadline;
        bool approveMax;
        uint8 v; 
        bytes32 r; 
        bytes32 s;
    }

    function MIN_VESTING_TIME_IN_SECONDS() external view returns (uint64);
    function PHTR() external view returns (address);
    function LP() external view returns (address);
    function emission() external view returns (address);
    function minTierReferrerBooster() external view returns (uint16);
    function totalBoostedStake() external view returns (uint);
    function tierBoosterInBP(uint _amount, uint8 _minTierIndex) external view returns (uint16);
    function programDetails() 
        external 
        view 
        returns (
            uint _totalBoostedStake,
            uint _accumulatedPHTRInTotalSharesInQ,
            Tier[] memory _tiers,
            uint[] memory _vestingDatesInSeconds, 
            uint[] memory _vestingTimeBoostersInBP
        );
     function accountDetails(address _account) 
        external 
        view 
        returns (
            uint _boostedStake,
            uint _totalReward,
            AccountDetails memory _accountDetails
        );

    function vestingOptionStake(address _account, VestingRange calldata _vestingRange) external view returns (uint);

    function stake(
        address _referrer, 
        uint _amount, 
        uint8 _minTierIndex, 
        VestingRange calldata _vestingRange
    ) external;

    function stakeWithPermit(StakeWithPermitParams calldata _params) external;

    function unstake(VestingRange[] calldata _vestingRanges, uint _amount) external;
}
// File: @openzeppelin/contracts-upgradeable/proxy/ERC1967/ERC1967UpgradeUpgradeable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (proxy/ERC1967/ERC1967Upgrade.sol)

pragma solidity ^0.8.2;

import "../beacon/IBeaconUpgradeable.sol";
import "../../utils/AddressUpgradeable.sol";
import "../../utils/StorageSlotUpgradeable.sol";
import "../utils/Initializable.sol";

/**
 * @dev This abstract contract provides getters and event emitting update functions for
 * https://eips.ethereum.org/EIPS/eip-1967[EIP1967] slots.
 *
 * _Available since v4.1._
 *
 * @custom:oz-upgrades-unsafe-allow delegatecall
 */
abstract contract ERC1967UpgradeUpgradeable is Initializable {
    function __ERC1967Upgrade_init() internal onlyInitializing {
        __ERC1967Upgrade_init_unchained();
    }

    function __ERC1967Upgrade_init_unchained() internal onlyInitializing {
    }
    // This is the keccak-256 hash of "eip1967.proxy.rollback" subtracted by 1
    bytes32 private constant _ROLLBACK_SLOT = 0x4910fdfa16fed3260ed0e7147f7cc6da11a60208b5b9406d12a635614ffd9143;

    /**
     * @dev Storage slot with the address of the current implementation.
     * This is the keccak-256 hash of "eip1967.proxy.implementation" subtracted by 1, and is
     * validated in the constructor.
     */
    bytes32 internal constant _IMPLEMENTATION_SLOT = 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc;

    /**
     * @dev Emitted when the implementation is upgraded.
     */
    event Upgraded(address indexed implementation);

    /**
     * @dev Returns the current implementation address.
     */
    function _getImplementation() internal view returns (address) {
        return StorageSlotUpgradeable.getAddressSlot(_IMPLEMENTATION_SLOT).value;
    }

    /**
     * @dev Stores a new address in the EIP1967 implementation slot.
     */
    function _setImplementation(address newImplementation) private {
        require(AddressUpgradeable.isContract(newImplementation), "ERC1967: new implementation is not a contract");
        StorageSlotUpgradeable.getAddressSlot(_IMPLEMENTATION_SLOT).value = newImplementation;
    }

    /**
     * @dev Perform implementation upgrade
     *
     * Emits an {Upgraded} event.
     */
    function _upgradeTo(address newImplementation) internal {
        _setImplementation(newImplementation);
        emit Upgraded(newImplementation);
    }

    /**
     * @dev Perform implementation upgrade with additional setup call.
     *
     * Emits an {Upgraded} event.
     */
    function _upgradeToAndCall(
        address newImplementation,
        bytes memory data,
        bool forceCall
    ) internal {
        _upgradeTo(newImplementation);
        if (data.length > 0 || forceCall) {
            _functionDelegateCall(newImplementation, data);
        }
    }

    /**
     * @dev Perform implementation upgrade with security checks for UUPS proxies, and additional setup call.
     *
     * Emits an {Upgraded} event.
     */
    function _upgradeToAndCallSecure(
        address newImplementation,
        bytes memory data,
        bool forceCall
    ) internal {
        address oldImplementation = _getImplementation();

        // Initial upgrade and setup call
        _setImplementation(newImplementation);
        if (data.length > 0 || forceCall) {
            _functionDelegateCall(newImplementation, data);
        }

        // Perform rollback test if not already in progress
        StorageSlotUpgradeable.BooleanSlot storage rollbackTesting = StorageSlotUpgradeable.getBooleanSlot(_ROLLBACK_SLOT);
        if (!rollbackTesting.value) {
            // Trigger rollback using upgradeTo from the new implementation
            rollbackTesting.value = true;
            _functionDelegateCall(
                newImplementation,
                abi.encodeWithSignature("upgradeTo(address)", oldImplementation)
            );
            rollbackTesting.value = false;
            // Check rollback was effective
            require(oldImplementation == _getImplementation(), "ERC1967Upgrade: upgrade breaks further upgrades");
            // Finally reset to the new implementation and log the upgrade
            _upgradeTo(newImplementation);
        }
    }

    /**
     * @dev Storage slot with the admin of the contract.
     * This is the keccak-256 hash of "eip1967.proxy.admin" subtracted by 1, and is
     * validated in the constructor.
     */
    bytes32 internal constant _ADMIN_SLOT = 0xb53127684a568b3173ae13b9f8a6016e243e63b6e8ee1178d6a717850b5d6103;

    /**
     * @dev Emitted when the admin account has changed.
     */
    event AdminChanged(address previousAdmin, address newAdmin);

    /**
     * @dev Returns the current admin.
     */
    function _getAdmin() internal view returns (address) {
        return StorageSlotUpgradeable.getAddressSlot(_ADMIN_SLOT).value;
    }

    /**
     * @dev Stores a new address in the EIP1967 admin slot.
     */
    function _setAdmin(address newAdmin) private {
        require(newAdmin != address(0), "ERC1967: new admin is the zero address");
        StorageSlotUpgradeable.getAddressSlot(_ADMIN_SLOT).value = newAdmin;
    }

    /**
     * @dev Changes the admin of the proxy.
     *
     * Emits an {AdminChanged} event.
     */
    function _changeAdmin(address newAdmin) internal {
        emit AdminChanged(_getAdmin(), newAdmin);
        _setAdmin(newAdmin);
    }

    /**
     * @dev The storage slot of the UpgradeableBeacon contract which defines the implementation for this proxy.
     * This is bytes32(uint256(keccak256('eip1967.proxy.beacon')) - 1)) and is validated in the constructor.
     */
    bytes32 internal constant _BEACON_SLOT = 0xa3f0ad74e5423aebfd80d3ef4346578335a9a72aeaee59ff6cb3582b35133d50;

    /**
     * @dev Emitted when the beacon is upgraded.
     */
    event BeaconUpgraded(address indexed beacon);

    /**
     * @dev Returns the current beacon.
     */
    function _getBeacon() internal view returns (address) {
        return StorageSlotUpgradeable.getAddressSlot(_BEACON_SLOT).value;
    }

    /**
     * @dev Stores a new beacon in the EIP1967 beacon slot.
     */
    function _setBeacon(address newBeacon) private {
        require(AddressUpgradeable.isContract(newBeacon), "ERC1967: new beacon is not a contract");
        require(
            AddressUpgradeable.isContract(IBeaconUpgradeable(newBeacon).implementation()),
            "ERC1967: beacon implementation is not a contract"
        );
        StorageSlotUpgradeable.getAddressSlot(_BEACON_SLOT).value = newBeacon;
    }

    /**
     * @dev Perform beacon upgrade with additional setup call. Note: This upgrades the address of the beacon, it does
     * not upgrade the implementation contained in the beacon (see {UpgradeableBeacon-_setImplementation} for that).
     *
     * Emits a {BeaconUpgraded} event.
     */
    function _upgradeBeaconToAndCall(
        address newBeacon,
        bytes memory data,
        bool forceCall
    ) internal {
        _setBeacon(newBeacon);
        emit BeaconUpgraded(newBeacon);
        if (data.length > 0 || forceCall) {
            _functionDelegateCall(IBeaconUpgradeable(newBeacon).implementation(), data);
        }
    }

    /**
     * @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) private returns (bytes memory) {
        require(AddressUpgradeable.isContract(target), "Address: delegate call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return AddressUpgradeable.verifyCallResult(success, returndata, "Address: low-level delegate call failed");
    }
    uint256[50] private __gap;
}

// File: @openzeppelin/contracts-upgradeable/proxy/beacon/IBeaconUpgradeable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (proxy/beacon/IBeacon.sol)

pragma solidity ^0.8.0;

/**
 * @dev This is the interface that {BeaconProxy} expects of its beacon.
 */
interface IBeaconUpgradeable {
    /**
     * @dev Must return an address that can be used as a delegate call target.
     *
     * {BeaconProxy} will check that this address is a contract.
     */
    function implementation() external view returns (address);
}

// File: @openzeppelin/contracts-upgradeable/utils/AddressUpgradeable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Address.sol)

pragma solidity ^0.8.0;

/**
 * @dev Collection of functions related to the address type
 */
library AddressUpgradeable {
    /**
     * @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 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);
            }
        }
    }
}

// File: @openzeppelin/contracts-upgradeable/utils/StorageSlotUpgradeable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/StorageSlot.sol)

pragma solidity ^0.8.0;

/**
 * @dev Library for reading and writing primitive types to specific storage slots.
 *
 * Storage slots are often used to avoid storage conflict when dealing with upgradeable contracts.
 * This library helps with reading and writing to such slots without the need for inline assembly.
 *
 * The functions in this library return Slot structs that contain a `value` member that can be used to read or write.
 *
 * Example usage to set ERC1967 implementation slot:
 * ```
 * contract ERC1967 {
 *     bytes32 internal constant _IMPLEMENTATION_SLOT = 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc;
 *
 *     function _getImplementation() internal view returns (address) {
 *         return StorageSlot.getAddressSlot(_IMPLEMENTATION_SLOT).value;
 *     }
 *
 *     function _setImplementation(address newImplementation) internal {
 *         require(Address.isContract(newImplementation), "ERC1967: new implementation is not a contract");
 *         StorageSlot.getAddressSlot(_IMPLEMENTATION_SLOT).value = newImplementation;
 *     }
 * }
 * ```
 *
 * _Available since v4.1 for `address`, `bool`, `bytes32`, and `uint256`._
 */
library StorageSlotUpgradeable {
    struct AddressSlot {
        address value;
    }

    struct BooleanSlot {
        bool value;
    }

    struct Bytes32Slot {
        bytes32 value;
    }

    struct Uint256Slot {
        uint256 value;
    }

    /**
     * @dev Returns an `AddressSlot` with member `value` located at `slot`.
     */
    function getAddressSlot(bytes32 slot) internal pure returns (AddressSlot storage r) {
        assembly {
            r.slot := slot
        }
    }

    /**
     * @dev Returns an `BooleanSlot` with member `value` located at `slot`.
     */
    function getBooleanSlot(bytes32 slot) internal pure returns (BooleanSlot storage r) {
        assembly {
            r.slot := slot
        }
    }

    /**
     * @dev Returns an `Bytes32Slot` with member `value` located at `slot`.
     */
    function getBytes32Slot(bytes32 slot) internal pure returns (Bytes32Slot storage r) {
        assembly {
            r.slot := slot
        }
    }

    /**
     * @dev Returns an `Uint256Slot` with member `value` located at `slot`.
     */
    function getUint256Slot(bytes32 slot) internal pure returns (Uint256Slot storage r) {
        assembly {
            r.slot := slot
        }
    }
}

// File: @openzeppelin/contracts-upgradeable/utils/ContextUpgradeable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)

pragma solidity ^0.8.0;
import "../proxy/utils/Initializable.sol";

/**
 * @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 ContextUpgradeable is Initializable {
    function __Context_init() internal onlyInitializing {
        __Context_init_unchained();
    }

    function __Context_init_unchained() internal onlyInitializing {
    }
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
    uint256[50] private __gap;
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Address.sol)

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);
            }
        }
    }
}