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VotingEscrow

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// SPDX-License-Identifier: AGPL-3.0-or-later

pragma solidity 0.8.6;

pragma solidity ^0.8.3;

import { IBasicToken } from "../shared/IBasicToken.sol";

import { IIncentivisedVotingLockup } from "../interfaces/IIncentivisedVotingLockup.sol";

import { ReentrancyGuard } from "@openzeppelin/contracts/security/ReentrancyGuard.sol";

import { RewardsDistributionRecipient } from "../rewards/RewardsDistributionRecipient.sol";

import { IERC20 } from "@openzeppelin/contracts/token/ERC20/IERC20.sol";

import { SafeERC20 } from "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";

import { SafeCast } from "@openzeppelin/contracts/utils/math/SafeCast.sol";

import { StableMath } from "../shared/StableMath.sol";

import { Root } from "../shared/Root.sol";

/**

import {

* @title IncentivisedVotingLockup

ReentrancyGuard

* @author Voting Weight tracking & Decay

} from "@openzeppelin/contracts/security/ReentrancyGuard.sol";

* -> Curve Finance (MIT) - forked & ported to Solidity

import { IERC20 } from "./interfaces/IERC20.sol";

* -> https://github.com/curvefi/curve-dao-contracts/blob/master/contracts/VotingEscrow.vy

import { IVotingEscrow } from "./interfaces/IVotingEscrow.sol";

* osolmaz - Research & Reward distributions

import { IBlocklist } from "./interfaces/IBlocklist.sol";

* alsco77 - Solidity implementation

* @notice Lockup MTA, receive vMTA (voting weight that decays over time), and earn

* rewards based on staticWeight

* @dev Supports:

* 1) Tracking MTA Locked up (LockedBalance)

* 2) Pull Based Reward allocations based on Lockup (Static Balance)

* 3) Decaying voting weight lookup through CheckpointedERC20 (balanceOf)

* 4) Ejecting fully decayed participants from reward allocation (eject)

* 5) Migration of points to v2 (used as multiplier in future) ***** (rewardsPaid)

* 6) Closure of contract (expire)

contract IncentivisedVotingLockup is

IIncentivisedVotingLockup,

ReentrancyGuard,

RewardsDistributionRecipient

{

using StableMath for uint256;

using SafeERC20 for IERC20;

/** Shared Events */

/// @title VotingEscrow

/// @author Curve Finance (MIT) - original concept and implementation in Vyper

/// (see https://github.com/curvefi/curve-dao-contracts/blob/master/contracts/VotingEscrow.vy)

/// mStable (AGPL) - forking Curve's Vyper contract and porting to Solidity

/// (see https://github.com/mstable/mStable-contracts/blob/master/contracts/governance/IncentivisedVotingLockup.sol)

/// FIAT DAO (AGPL) - this version

/// @notice Plain Curve VotingEscrow mechanics with following adjustments:

/// 1) Delegation of lock and voting power

/// 2) Quit an existing lock and pay a penalty

/// 3) Whitelisting of SmartWallets outside the VotingEscrow

/// 4) Reduced pointHistory array size and, as a result, lifetime of the contract

/// 5) Removed public deposit_for and Aragon compatibility (no use case)

contract VotingEscrow is IVotingEscrow, ReentrancyGuard {

// Shared Events

event Deposit(

address indexed provider,

uint256 value,

uint256 locktime,

LockAction indexed action,

uint256 ts

);

event Withdraw(address indexed provider, uint256 value, uint256 ts);

event Withdraw(

event Ejected(address indexed ejected, address ejector, uint256 ts);

address indexed provider,

event Expired();

uint256 value,

event RewardAdded(uint256 reward);

LockAction indexed action,

event RewardPaid(address indexed user, uint256 reward);

uint256 ts

);

event TransferOwnership(address owner);

event UpdateBlocklist(address blocklist);

event UpdatePenaltyRecipient(address recipient);

event CollectPenalty(uint256 amount, address recipient);

event Unlock();

/** Shared Globals */

// Shared global state

IERC20 public stakingToken;

IERC20 public token;

uint256 private constant WEEK = 7 days;

uint256 public constant WEEK = 7 days;

uint256 public constant MAXTIME = 365 days;

uint256 public END;

uint256 public constant MULTIPLIER = 10**18;

bool public expired = false;

address public owner;

address public penaltyRecipient; // receives collected penalty payments

uint256 public maxPenalty = 10**18; // penalty for quitters with MAXTIME remaining lock

uint256 public penaltyAccumulated; // accumulated and unwithdrawn penalty payments

address public blocklist;

/** Lockup */

// Lock state

uint256 public globalEpoch;

Point[] public pointHistory;

Point[1000000000000000000] public pointHistory; // 1e9 * userPointHistory-length, so sufficient for 1e9 users

mapping(address => Point[]) public userPointHistory;

mapping(address => Point[1000000000]) public userPointHistory;

mapping(address => uint256) public userPointEpoch;

mapping(uint256 => int128) public slopeChanges;

mapping(address => LockedBalance) public locked;

// Voting token - Checkpointed view only ERC20

// Voting token

string public name;

string public symbol;

uint256 public decimals = 18;

/** Rewards */

// Structs

// Updated upon admin deposit

uint256 public periodFinish = 0;

uint256 public rewardRate = 0;

// Globals updated per stake/deposit/withdrawal

uint256 public totalStaticWeight = 0;

uint256 public lastUpdateTime = 0;

uint256 public rewardPerTokenStored = 0;

// Per user storage updated per stake/deposit/withdrawal

mapping(address => uint256) public userRewardPerTokenPaid;

mapping(address => uint256) public rewards;

mapping(address => uint256) public rewardsPaid;

/** Structs */

struct Point {

int128 bias;

int128 slope;

uint256 ts;

uint256 blk;

}

struct LockedBalance {

int128 amount;

uint256 end;

int128 delegated;

address delegatee;

}

// Miscellaneous

enum LockAction {

CREATE_LOCK,

CREATE,

INCREASE_LOCK_AMOUNT,

INCREASE_AMOUNT,

INCREASE_LOCK_TIME

INCREASE_AMOUNT_AND_DELEGATION,

INCREASE_TIME,

WITHDRAW,

QUIT,

DELEGATE,

UNDELEGATE

}

/// @notice Initializes state

/// @param _owner The owner is able to update `owner`, `penaltyRecipient` and `penaltyRate`

/// @param _penaltyRecipient The recipient of penalty paid by lock quitters

/// @param _token The token locked in order to obtain voting power

/// @param _name The name of the voting token

/// @param _symbol The symbol of the voting token

constructor(

address _stakingToken,

address _owner,

address _penaltyRecipient,

address _token,

string memory _name,

string memory _symbol,

string memory _symbol

address _nexus,

) {

address _rewardsDistributor

token = IERC20(_token);

) RewardsDistributionRecipient(_nexus, _rewardsDistributor) {

pointHistory[0] = Point({

stakingToken = IERC20(_stakingToken);

Point memory init = Point({

bias: int128(0),

slope: int128(0),

ts: block.timestamp,

blk: block.number

});

pointHistory.push(init);

decimals = IBasicToken(_stakingToken).decimals();

decimals = IERC20(_token).decimals();

require(decimals <= 18, "Cannot have more than 18 decimals");

require(decimals <= 18, "Exceeds max decimals");

name = _name;

symbol = _symbol;

owner = _owner;

END = block.timestamp + MAXTIME;

penaltyRecipient = _penaltyRecipient;

}

/** @dev Modifier to ensure contract has not yet expired */

modifier checkBlocklist() {

modifier contractNotExpired() {

require(

require(!expired, "Contract is expired");

!IBlocklist(blocklist).isBlocked(msg.sender),

"Blocked contract"

);

}

/**

/// ~~~~~~~~~~~~~~~~~~~~~~~~~~~ ///

* @dev Validates that the user has an expired lock && they still have capacity to earn

/// Owner Functions ///

* @param _addr User address to check

/// ~~~~~~~~~~~~~~~~~~~~~~~~~~~ ///

modifier lockupIsOver(address _addr) {

/// @notice Transfers ownership to a new owner

LockedBalance memory userLock = locked[_addr];

/// @param _addr The new owner

require(userLock.amount > 0 && block.timestamp >= userLock.end, "Users lock didn't expire");

/// @dev Owner should always be a timelock contract

require(staticBalanceOf(_addr) > 0, "User must have existing bias");

function transferOwnership(address _addr) external {

require(msg.sender == owner, "Only owner");

owner = _addr;

emit TransferOwnership(_addr);

}

/***************************************

/// @notice Updates the blocklist contract

LOCKUP - GETTERS

function updateBlocklist(address _addr) external {

****************************************/

require(msg.sender == owner, "Only owner");

blocklist = _addr;

emit UpdateBlocklist(_addr);

}

/**

/// @notice Updates the recipient of the accumulated penalty paid by quitters

* @dev Gets the last available user point

function updatePenaltyRecipient(address _addr) external {

* @param _addr User address

require(msg.sender == owner, "Only owner");

* @return bias i.e. y

penaltyRecipient = _addr;

* @return slope i.e. linear gradient

emit UpdatePenaltyRecipient(_addr);

* @return ts i.e. time point was logged

}

/// @notice Removes quitlock penalty by setting it to zero

/// @dev This is an irreversible action

function unlock() external {

require(msg.sender == owner, "Only owner");

maxPenalty = 0;

emit Unlock();

}

/// @notice Forces an undelegation of virtual balance for a blocked locker

/// @dev Can only be called by the Blocklist contract (as part of a block)

/// @dev This is an irreversible action

function forceUndelegate(address _addr) external override {

require(msg.sender == blocklist, "Only Blocklist");

LockedBalance memory locked_ = locked[_addr];

address delegatee = locked_.delegatee;

int128 value = locked_.amount;

if (delegatee != _addr && value > 0) {

LockedBalance memory fromLocked;

locked_.delegatee = _addr;

fromLocked = locked[delegatee];

_delegate(delegatee, fromLocked, value, LockAction.UNDELEGATE);

_delegate(_addr, locked_, value, LockAction.DELEGATE);

}

/// ~~~~~~~~~~~~~~~~~~~~~~~~~~~ ///

/// LOCK MANAGEMENT ///

/// ~~~~~~~~~~~~~~~~~~~~~~~~~~~ ///

/// @notice Returns a user's lock expiration

/// @param _addr The address of the user

/// @return Expiration of the user's lock

function lockEnd(address _addr) external view returns (uint256) {

return locked[_addr].end;

}

/// @notice Returns the last available user point for a user

/// @param _addr User address

/// @return bias i.e. y

/// @return slope i.e. linear gradient

/// @return ts i.e. time point was logged

function getLastUserPoint(address _addr)

external

view

override

returns (

int128 bias,

int128 slope,

uint256 ts

)

{

uint256 uepoch = userPointEpoch[_addr];

if (uepoch == 0) {

return (0, 0, 0);

}

Point memory point = userPointHistory[_addr][uepoch];

return (point.bias, point.slope, point.ts);

}

/***************************************

/// @notice Records a checkpoint of both individual and global slope

LOCKUP

/// @param _addr User address, or address(0) for only global

****************************************/

/// @param _oldLocked Old amount that user had locked, or null for global

/// @param _newLocked new amount that user has locked, or null for global

/**

* @dev Records a checkpoint of both individual and global slope

* @param _addr User address, or address(0) for only global

* @param _oldLocked Old amount that user had locked, or null for global

* @param _newLocked new amount that user has locked, or null for global

function _checkpoint(

address _addr,

LockedBalance memory _oldLocked,

LockedBalance memory _newLocked

) internal {

Point memory userOldPoint;

Point memory userNewPoint;

int128 oldSlopeDelta = 0;

int128 newSlopeDelta = 0;

uint256 epoch = globalEpoch;

if (_addr != address(0)) {

// Calculate slopes and biases

// Kept at zero when they have to

if (_oldLocked.end > block.timestamp && _oldLocked.amount > 0) {

if (_oldLocked.end > block.timestamp && _oldLocked.delegated > 0) {

userOldPoint.slope = _oldLocked.amount / SafeCast.toInt128(int256(MAXTIME));

userOldPoint.slope =

_oldLocked.delegated /

int128(int256(MAXTIME));

userOldPoint.bias =

userOldPoint.slope *

SafeCast.toInt128(int256(_oldLocked.end - block.timestamp));

int128(int256(_oldLocked.end - block.timestamp));

}

if (_newLocked.end > block.timestamp && _newLocked.amount > 0) {

if (_newLocked.end > block.timestamp && _newLocked.delegated > 0) {

userNewPoint.slope = _newLocked.amount / SafeCast.toInt128(int256(MAXTIME));

userNewPoint.slope =

_newLocked.delegated /

int128(int256(MAXTIME));

userNewPoint.bias =

userNewPoint.slope *

SafeCast.toInt128(int256(_newLocked.end - block.timestamp));

int128(int256(_newLocked.end - block.timestamp));

}

// Moved from bottom final if statement to resolve stack too deep err

// start {

// Now handle user history

uint256 uEpoch = userPointEpoch[_addr];

if (uEpoch == 0) {

userPointHistory[_addr].push(userOldPoint);

userPointHistory[_addr][uEpoch + 1] = userOldPoint;

}

// track the total static weight

uint256 newStatic = _staticBalance(userNewPoint.slope, block.timestamp, _newLocked.end);

uint256 additiveStaticWeight = totalStaticWeight + newStatic;

if (uEpoch > 0) {

uint256 oldStatic = _staticBalance(

userPointHistory[_addr][uEpoch].slope,

userPointHistory[_addr][uEpoch].ts,

_oldLocked.end

);

additiveStaticWeight = additiveStaticWeight - oldStatic;

}

totalStaticWeight = additiveStaticWeight;

userPointEpoch[_addr] = uEpoch + 1;

userNewPoint.ts = block.timestamp;

userNewPoint.blk = block.number;

userPointHistory[_addr].push(userNewPoint);

userPointHistory[_addr][uEpoch + 1] = userNewPoint;

// } end

// Read values of scheduled changes in the slope

// oldLocked.end can be in the past and in the future

// newLocked.end can ONLY by in the FUTURE unless everything expired: than zeros

oldSlopeDelta = slopeChanges[_oldLocked.end];

if (_newLocked.end != 0) {

if (_newLocked.end == _oldLocked.end) {

newSlopeDelta = oldSlopeDelta;

} else {

newSlopeDelta = slopeChanges[_newLocked.end];

}

Point memory lastPoint = Point({

Point memory lastPoint =

bias: 0,

Point({

slope: 0,

bias: 0,

ts: block.timestamp,

slope: 0,

blk: block.number

ts: block.timestamp,

});

blk: block.number

});

if (epoch > 0) {

lastPoint = pointHistory[epoch];

}

uint256 lastCheckpoint = lastPoint.ts;

// initialLastPoint is used for extrapolation to calculate block number

// (approximately, for *At methods) and save them

// as we cannot figure that out exactly from inside the contract

Point memory initialLastPoint = Point({

Point memory initialLastPoint =

bias: 0,

Point({ bias: 0, slope: 0, ts: lastPoint.ts, blk: lastPoint.blk });

slope: 0,

ts: lastPoint.ts,

blk: lastPoint.blk

});

uint256 blockSlope = 0; // dblock/dt

if (block.timestamp > lastPoint.ts) {

blockSlope =

StableMath.scaleInteger(block.number - lastPoint.blk) /

(MULTIPLIER * (block.number - lastPoint.blk)) /

(block.timestamp - lastPoint.ts);

}

// If last point is already recorded in this block, slope=0

// But that's ok b/c we know the block in such case

// Go over weeks to fill history and calculate what the current point is

uint256 iterativeTime = _floorToWeek(lastCheckpoint);

for (uint256 i = 0; i < 255; i++) {

// Hopefully it won't happen that this won't get used in 5 years!

// If it does, users will be able to withdraw but vote weight will be broken

iterativeTime = iterativeTime + WEEK;

int128 dSlope = 0;

if (iterativeTime > block.timestamp) {

iterativeTime = block.timestamp;

} else {

dSlope = slopeChanges[iterativeTime];

}

int128 biasDelta = lastPoint.slope *

int128 biasDelta =

SafeCast.toInt128(int256((iterativeTime - lastCheckpoint)));

lastPoint.slope *

int128(int256((iterativeTime - lastCheckpoint)));

lastPoint.bias = lastPoint.bias - biasDelta;

lastPoint.slope = lastPoint.slope + dSlope;

// This can happen

if (lastPoint.bias < 0) {

lastPoint.bias = 0;

}

// This cannot happen - just in case

if (lastPoint.slope < 0) {

lastPoint.slope = 0;

}

lastCheckpoint = iterativeTime;

lastPoint.ts = iterativeTime;

lastPoint.blk =

initialLastPoint.blk +

blockSlope.mulTruncate(iterativeTime - initialLastPoint.ts);

(blockSlope * (iterativeTime - initialLastPoint.ts)) /

MULTIPLIER;

// when epoch is incremented, we either push here or after slopes updated below

epoch = epoch + 1;

if (iterativeTime == block.timestamp) {

lastPoint.blk = block.number;

break;

} else {

// pointHistory[epoch] = lastPoint;

pointHistory[epoch] = lastPoint;

pointHistory.push(lastPoint);

}

globalEpoch = epoch;

// Now pointHistory is filled until t=now

if (_addr != address(0)) {

// If last point was in this block, the slope change has been applied already

// But in such case we have 0 slope(s)

lastPoint.slope = lastPoint.slope + userNewPoint.slope - userOldPoint.slope;

lastPoint.slope =

lastPoint.bias = lastPoint.bias + userNewPoint.bias - userOldPoint.bias;

lastPoint.slope +

userNewPoint.slope -

userOldPoint.slope;

lastPoint.bias =

lastPoint.bias +

userNewPoint.bias -

userOldPoint.bias;

if (lastPoint.slope < 0) {

lastPoint.slope = 0;

}

if (lastPoint.bias < 0) {

lastPoint.bias = 0;

}

// Record the changed point into history

// pointHistory[epoch] = lastPoint;

pointHistory[epoch] = lastPoint;

pointHistory.push(lastPoint);

if (_addr != address(0)) {

// Schedule the slope changes (slope is going down)

// We subtract new_user_slope from [new_locked.end]

// and add old_user_slope to [old_locked.end]

if (_oldLocked.end > block.timestamp) {

// oldSlopeDelta was <something> - userOldPoint.slope, so we cancel that

oldSlopeDelta = oldSlopeDelta + userOldPoint.slope;

if (_newLocked.end == _oldLocked.end) {

oldSlopeDelta = oldSlopeDelta - userNewPoint.slope; // It was a new deposit, not extension

}

slopeChanges[_oldLocked.end] = oldSlopeDelta;

}

if (_newLocked.end > block.timestamp) {

if (_newLocked.end > _oldLocked.end) {

newSlopeDelta = newSlopeDelta - userNewPoint.slope; // old slope disappeared at this point

slopeChanges[_newLocked.end] = newSlopeDelta;

}

// else: we recorded it already in oldSlopeDelta

}

/**

/// @notice Public function to trigger global checkpoint

* @dev Deposits or creates a stake for a given address

* @param _addr User address to assign the stake

* @param _value Total units of StakingToken to lockup

* @param _unlockTime Time at which the stake should unlock

* @param _oldLocked Previous amount staked by this user

* @param _action See LockAction enum

function _depositFor(

address _addr,

uint256 _value,

uint256 _unlockTime,

LockedBalance memory _oldLocked,

LockAction _action

) internal {

LockedBalance memory newLocked = LockedBalance({

amount: _oldLocked.amount,

end: _oldLocked.end

});

// Adding to existing lock, or if a lock is expired - creating a new one

newLocked.amount = newLocked.amount + SafeCast.toInt128(int256(_value));

if (_unlockTime != 0) {

newLocked.end = _unlockTime;

}

locked[_addr] = newLocked;

// Possibilities:

// Both _oldLocked.end could be current or expired (>/< block.timestamp)

// value == 0 (extend lock) or value > 0 (add to lock or extend lock)

// newLocked.end > block.timestamp (always)

_checkpoint(_addr, _oldLocked, newLocked);

if (_value != 0) {

stakingToken.safeTransferFrom(_addr, address(this), _value);

}

emit Deposit(_addr, _value, newLocked.end, _action, block.timestamp);

}

/**

* @dev Public function to trigger global checkpoint

function checkpoint() external {

LockedBalance memory empty;

_checkpoint(address(0), empty, empty);

}

/**

// See IVotingEscrow for documentation

* @dev Creates a new lock

* @param _value Total units of StakingToken to lockup

* @param _unlockTime Time at which the stake should unlock

function createLock(uint256 _value, uint256 _unlockTime)

external

override

nonReentrant

contractNotExpired

checkBlocklist

updateReward(msg.sender)

{

uint256 unlock_time = _floorToWeek(_unlockTime); // Locktime is rounded down to weeks

LockedBalance memory locked_ = LockedBalance({

LockedBalance memory locked_ = locked[msg.sender];

amount: locked[msg.sender].amount,

// Validate inputs

end: locked[msg.sender].end

require(_value > 0, "Only non zero amount");

});

require(locked_.amount == 0, "Lock exists");

require(unlock_time >= locked_.end, "Only increase lock end"); // from using quitLock, user should increaseAmount instead

require(_value > 0, "Must stake non zero amount");

require(unlock_time > block.timestamp, "Only future lock end");

require(locked_.amount == 0, "Withdraw old tokens first");

require(unlock_time <= block.timestamp + MAXTIME, "Exceeds maxtime");

// Update lock and voting power (checkpoint)

require(unlock_time > block.timestamp, "Can only lock until time in the future");

locked_.amount += int128(int256(_value));

require(unlock_time <= END, "Voting lock can be 1 year max (until recol)");

locked_.end = unlock_time;

locked_.delegated += int128(int256(_value));

_depositFor(msg.sender, _value, unlock_time, locked_, LockAction.CREATE_LOCK);

locked_.delegatee = msg.sender;

locked[msg.sender] = locked_;

_checkpoint(msg.sender, LockedBalance(0, 0, 0, address(0)), locked_);

// Deposit locked tokens

require(

token.transferFrom(msg.sender, address(this), _value),

"Transfer failed"

);

emit Deposit(

msg.sender,

_value,

unlock_time,

LockAction.CREATE,

block.timestamp

);

}

/**

// See IVotingEscrow for documentation

* @dev Increases amount of stake thats locked up & resets decay

// @dev A lock is active until both lock.amount==0 and lock.end<=block.timestamp

* @param _value Additional units of StakingToken to add to exiting stake

function increaseAmount(uint256 _value)

function increaseLockAmount(uint256 _value)

external

override

nonReentrant

contractNotExpired

checkBlocklist

updateReward(msg.sender)

{

LockedBalance memory locked_ = LockedBalance({

LockedBalance memory locked_ = locked[msg.sender];

amount: locked[msg.sender].amount,

// Validate inputs

end: locked[msg.sender].end

require(_value > 0, "Only non zero amount");

});

require(locked_.amount > 0, "No lock");

require(locked_.end > block.timestamp, "Lock expired");

require(_value > 0, "Must stake non zero amount");

// Update lock

require(locked_.amount > 0, "No existing lock found");

address delegatee = locked_.delegatee;

require(locked_.end > block.timestamp, "Cannot add to expired lock. Withdraw");

uint256 unlockTime = locked_.end;

LockAction action = LockAction.INCREASE_AMOUNT;

_depositFor(msg.sender, _value, 0, locked_, LockAction.INCREASE_LOCK_AMOUNT);

LockedBalance memory newLocked;

if (delegatee == msg.sender) {

// Undelegated lock

action = LockAction.INCREASE_AMOUNT_AND_DELEGATION;

newLocked = _copyLock(locked_);

newLocked.amount += int128(int256(_value));

newLocked.delegated += int128(int256(_value));

locked[msg.sender] = newLocked;

} else {

// Delegated lock, update sender's lock first

locked_.amount += int128(int256(_value));

locked[msg.sender] = locked_;

// Then, update delegatee's lock and voting power (checkpoint)

locked_ = locked[delegatee];

require(locked_.amount > 0, "Delegatee has no lock");

require(locked_.end > block.timestamp, "Delegatee lock expired");

newLocked = _copyLock(locked_);

newLocked.delegated += int128(int256(_value));

locked[delegatee] = newLocked;

emit Deposit(

delegatee,

_value,

newLocked.end,

LockAction.DELEGATE,

block.timestamp

);

}

// Checkpoint only for delegatee

_checkpoint(delegatee, locked_, newLocked);

// Deposit locked tokens

require(

token.transferFrom(msg.sender, address(this), _value),

"Transfer failed"

);

emit Deposit(msg.sender, _value, unlockTime, action, block.timestamp);

}

/**

// See IVotingEscrow for documentation

* @dev Increases length of lockup & resets decay

function increaseUnlockTime(uint256 _unlockTime)

* @param _unlockTime New unlocktime for lockup

function increaseLockLength(uint256 _unlockTime)

external

override

nonReentrant

contractNotExpired

checkBlocklist

updateReward(msg.sender)

{

LockedBalance memory locked_ = LockedBalance({

LockedBalance memory locked_ = locked[msg.sender];

amount: locked[msg.sender].amount,

end: locked[msg.sender].end

});

uint256 unlock_time = _floorToWeek(_unlockTime); // Locktime is rounded down to weeks

// Validate inputs

require(locked_.amount > 0, "Nothing is locked");

require(locked_.amount > 0, "No lock");

require(locked_.end > block.timestamp, "Lock expired");

require(unlock_time > locked_.end, "Only increase lock end");

require(unlock_time > locked_.end, "Can only increase lock WEEK");

require(unlock_time <= block.timestamp + MAXTIME, "Exceeds maxtime");

require(unlock_time <= END, "Voting lock can be 1 year max (until recol)");

// Update lock

uint256 oldUnlockTime = locked_.end;

_depositFor(msg.sender, 0, unlock_time, locked_, LockAction.INCREASE_LOCK_TIME);

locked_.end = unlock_time;

}

locked[msg.sender] = locked_;

if (locked_.delegatee == msg.sender) {

/**

// Undelegated lock

* @dev Withdraws all the senders stake, providing lockup is over

require(oldUnlockTime > block.timestamp, "Lock expired");

LockedBalance memory oldLocked = _copyLock(locked_);

function withdraw() external override {

oldLocked.end = unlock_time;

_withdraw(msg.sender);

_checkpoint(msg.sender, oldLocked, locked_);

}

emit Deposit(

msg.sender,

unlock_time,

LockAction.INCREASE_TIME,

block.timestamp

);

}

/**

// See IVotingEscrow for documentation

* @dev Withdraws a given users stake, providing the lockup has finished

function withdraw() external override nonReentrant {

* @param _addr User for which to withdraw

LockedBalance memory locked_ = locked[msg.sender];

// Validate inputs

function _withdraw(address _addr) internal nonReentrant updateReward(_addr) {

require(locked_.amount > 0, "No lock");

LockedBalance memory oldLock = LockedBalance({

require(locked_.end <= block.timestamp, "Lock not expired");

end: locked[_addr].end,

require(locked_.delegatee == msg.sender, "Lock delegated");

amount: locked[_addr].amount

// Update lock

});

uint256 value = uint256(uint128(locked_.amount));

require(block.timestamp >= oldLock.end || expired, "The lock didn't expire");

LockedBalance memory newLocked = _copyLock(locked_);

require(oldLock.amount > 0, "Must have something to withdraw");

newLocked.amount = 0;

newLocked.end = 0;

uint256 value = SafeCast.toUint256(oldLock.amount);

newLocked.delegated -= int128(int256(value));

newLocked.delegatee = address(0);

LockedBalance memory currentLock = LockedBalance({ end: 0, amount: 0 });

locked[msg.sender] = newLocked;

locked[_addr] = currentLock;

newLocked.delegated = 0;

// oldLocked can have either expired <= timestamp or zero end

// currentLock has only 0 end

// Both can have >= 0 amount

if (!expired) {

_checkpoint(msg.sender, locked_, newLocked);

_checkpoint(_addr, oldLock, currentLock);

// Send back deposited tokens

}

require(token.transfer(msg.sender, value), "Transfer failed");

stakingToken.safeTransfer(_addr, value);

emit Withdraw(msg.sender, value, LockAction.WITHDRAW, block.timestamp);

emit Withdraw(_addr, value, block.timestamp);

}

/**

* @dev Withdraws and consequently claims rewards for the sender

function exit() external override {

_withdraw(msg.sender);

claimReward();

}

/**

/// ~~~~~~~~~~~~~~~~~~~~~~~~~~ ///

* @dev Ejects a user from the reward allocation, given their lock has freshly expired.

/// DELEGATION ///

* Leave it to the user to withdraw and claim their rewards.

/// ~~~~~~~~~~~~~~~~~~~~~~~~~~ ///

* @param _addr Address of the user

function eject(address _addr) external override contractNotExpired lockupIsOver(_addr) {

_withdraw(_addr);

// solium-disable-next-line security/no-tx-origin

emit Ejected(_addr, tx.origin, block.timestamp);

}

/**

// See IVotingEscrow for documentation

* @dev Ends the contract, unlocking all stakes.

function delegate(address _addr)

* No more staking can happen. Only withdraw and Claim.

function expireContract()

external

override

onlyGovernor

nonReentrant

contractNotExpired

checkBlocklist

updateReward(address(0))

{

require(block.timestamp > periodFinish, "Period must be over");

LockedBalance memory locked_ = locked[msg.sender];

// Validate inputs

expired = true;

require(!IBlocklist(blocklist).isBlocked(_addr), "Blocked contract");

require(locked_.amount > 0, "No lock");

emit Expired();

require(locked_.delegatee != _addr, "Already delegated");

}

// Update locks

int128 value = locked_.amount;

/***************************************

address delegatee = locked_.delegatee;

GETTERS

LockedBalance memory fromLocked;

****************************************/

LockedBalance memory toLocked;

locked_.delegatee = _addr;

/** @dev Floors a timestamp to the nearest weekly increment */

if (delegatee == msg.sender) {

function _floorToWeek(uint256 _t) internal pure returns (uint256) {

// Delegate

return (_t / WEEK) * WEEK;

fromLocked = locked_;

}

toLocked = locked[_addr];

} else if (_addr == msg.sender) {

/**

// Undelegate

* @dev Uses binarysearch to find the most recent point history preceeding block

fromLocked = locked[delegatee];

* @param _block Find the most recent point history before this block

toLocked = locked_;

* @param _maxEpoch Do not search pointHistories past this index

} else {

// Re-delegate

function _findBlockEpoch(uint256 _block, uint256 _maxEpoch) internal view returns (uint256) {

fromLocked = locked[delegatee];

// Binary search

toLocked = locked[_addr];

uint256 min = 0;

// Update owner lock if not involved in delegation

uint256 max = _maxEpoch;

locked[msg.sender] = locked_;

// Will be always enough for 128-bit numbers

for (uint256 i = 0; i < 128; i++) {

if (min >= max) break;

uint256 mid = (min + max + 1) / 2;

if (pointHistory[mid].blk <= _block) {

min = mid;

} else {

max = mid - 1;

}

return min;

}

/**

* @dev Uses binarysearch to find the most recent user point history preceeding block

* @param _addr User for which to search

* @param _block Find the most recent point history before this block

function _findUserBlockEpoch(address _addr, uint256 _block) internal view returns (uint256) {

uint256 min = 0;

uint256 max = userPointEpoch[_addr];

for (uint256 i = 0; i < 128; i++) {

if (min >= max) {

break;

}

uint256 mid = (min + max + 1) / 2;

if (userPointHistory[_addr][mid].blk <= _block) {

min = mid;

} else {

max = mid - 1;

}

return min;

require(toLocked.amount > 0, "Delegatee has no lock");

require(toLocked.end > block.timestamp, "Delegatee lock expired");

require(toLocked.end >= fromLocked.end, "Only delegate to longer lock");

_delegate(delegatee, fromLocked, value, LockAction.UNDELEGATE);

_delegate(_addr, toLocked, value, LockAction.DELEGATE);

}

/**

// Delegates from/to lock and voting power

* @dev Gets curent user voting weight (aka effectiveStake)

function _delegate(

* @param _owner User for which to return the balance

address addr,

* @return uint256 Balance of user

LockedBalance memory _locked,

int128 value,

function balanceOf(address _owner) public view override returns (uint256) {

LockAction action

uint256 epoch = userPointEpoch[_owner];

) internal {

if (epoch == 0) {

LockedBalance memory newLocked = _copyLock(_locked);

return 0;

if (action == LockAction.DELEGATE) {

newLocked.delegated += value;

emit Deposit(

addr,

uint256(int256(value)),

newLocked.end,

action,

block.timestamp

);

} else {

newLocked.delegated -= value;

emit Withdraw(

addr,

uint256(int256(value)),

action,

block.timestamp

);

}

Point memory lastPoint = userPointHistory[_owner][epoch];

locked[addr] = newLocked;

lastPoint.bias =

if (newLocked.amount > 0) {

lastPoint.bias -

// Only if lock (from lock) hasn't been withdrawn/quitted

(lastPoint.slope * SafeCast.toInt128(int256(block.timestamp - lastPoint.ts)));

_checkpoint(addr, _locked, newLocked);

if (lastPoint.bias < 0) {

lastPoint.bias = 0;

}

return SafeCast.toUint256(lastPoint.bias);

}

/**

/// ~~~~~~~~~~~~~~~~~~~~~~~~~~ ///

* @dev Gets a users votingWeight at a given blockNumber

/// QUIT LOCK ///

* @param _owner User for which to return the balance

/// ~~~~~~~~~~~~~~~~~~~~~~~~~~ ///

* @param _blockNumber Block at which to calculate balance

* @return uint256 Balance of user

function balanceOfAt(address _owner, uint256 _blockNumber)

public

view

override

returns (uint256)

{

require(_blockNumber <= block.number, "Must pass block number in the past");

// Get most recent user Point to block

uint256 userEpoch = _findUserBlockEpoch(_owner, _blockNumber);

if (userEpoch == 0) {

return 0;

}

Point memory upoint = userPointHistory[_owner][userEpoch];

// Get most recent global Point to block

uint256 maxEpoch = globalEpoch;

uint256 epoch = _findBlockEpoch(_blockNumber, maxEpoch);

Point memory point0 = pointHistory[epoch];

// Calculate delta (block & time) between user Point and target block

// See IVotingEscrow for documentation

// Allowing us to calculate the average seconds per block between

function quitLock() external override nonReentrant {

// the two points

LockedBalance memory locked_ = locked[msg.sender];

uint256 dBlock = 0;

// Validate inputs

uint256 dTime = 0;

require(locked_.amount > 0, "No lock");

if (epoch < maxEpoch) {

require(locked_.end > block.timestamp, "Lock expired");

Point memory point1 = pointHistory[epoch + 1];

require(locked_.delegatee == msg.sender, "Lock delegated");

dBlock = point1.blk - point0.blk;

// Update lock

dTime = point1.ts - point0.ts;

uint256 value = uint256(uint128(locked_.amount));

} else {

LockedBalance memory newLocked = _copyLock(locked_);

dBlock = block.number - point0.blk;

newLocked.amount = 0;

dTime = block.timestamp - point0.ts;

newLocked.delegated -= int128(int256(value));

}

newLocked.delegatee = address(0);

// (Deterministically) Estimate the time at which block _blockNumber was mined

locked[msg.sender] = newLocked;

uint256 blockTime = point0.ts;

newLocked.end = 0;

if (dBlock != 0) {

newLocked.delegated = 0;

blockTime = blockTime + ((dTime * (_blockNumber - point0.blk)) / dBlock);

// oldLocked can have either expired <= timestamp or zero end

}

// currentLock has only 0 end

// Current Bias = most recent bias - (slope * time since update)

// Both can have >= 0 amount

upoint.bias =

_checkpoint(msg.sender, locked_, newLocked);

upoint.bias -

// apply penalty

(upoint.slope * SafeCast.toInt128(int256(blockTime - upoint.ts)));

uint256 penaltyRate = _calculatePenaltyRate(locked_.end);

if (upoint.bias >= 0) {

uint256 penaltyAmount = (value * penaltyRate) / 10**18; // quitlock_penalty is in 18 decimals precision

return SafeCast.toUint256(upoint.bias);

penaltyAccumulated += penaltyAmount;

} else {

uint256 remainingAmount = value - penaltyAmount;

return 0;

// Send back remaining tokens

}

require(token.transfer(msg.sender, remainingAmount), "Transfer failed");

emit Withdraw(msg.sender, value, LockAction.QUIT, block.timestamp);

}

/**

// Calculate penalty

* @dev Calcula

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// SPDX-License-Identifier: AGPL-3.0-or-later
pragma solidity 0.8.6;

import { IBasicToken } from "../shared/IBasicToken.sol";
import { IIncentivisedVotingLockup } from "../interfaces/IIncentivisedVotingLockup.sol";
import { ReentrancyGuard } from "@openzeppelin/contracts/security/ReentrancyGuard.sol";
import { RewardsDistributionRecipient } from "../rewards/RewardsDistributionRecipient.sol";
import { IERC20 } from "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import { SafeERC20 } from "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import { SafeCast } from "@openzeppelin/contracts/utils/math/SafeCast.sol";
import { StableMath } from "../shared/StableMath.sol";
import { Root } from "../shared/Root.sol";

/**
 * @title  IncentivisedVotingLockup
 * @author Voting Weight tracking & Decay
 *             -> Curve Finance (MIT) - forked & ported to Solidity
 *             -> https://github.com/curvefi/curve-dao-contracts/blob/master/contracts/VotingEscrow.vy
 *         osolmaz - Research & Reward distributions
 *         alsco77 - Solidity implementation
 * @notice Lockup MTA, receive vMTA (voting weight that decays over time), and earn
 *         rewards based on staticWeight
 * @dev    Supports:
 *            1) Tracking MTA Locked up (LockedBalance)
 *            2) Pull Based Reward allocations based on Lockup (Static Balance)
 *            3) Decaying voting weight lookup through CheckpointedERC20 (balanceOf)
 *            4) Ejecting fully decayed participants from reward allocation (eject)
 *            5) Migration of points to v2 (used as multiplier in future) ***** (rewardsPaid)
 *            6) Closure of contract (expire)
 */
contract IncentivisedVotingLockup is
    IIncentivisedVotingLockup,
    ReentrancyGuard,
    RewardsDistributionRecipient
{
    using StableMath for uint256;
    using SafeERC20 for IERC20;

/** Shared Events */
    event Deposit(
        address indexed provider,
        uint256 value,
        uint256 locktime,
        LockAction indexed action,
        uint256 ts
    );
    event Withdraw(address indexed provider, uint256 value, uint256 ts);
    event Ejected(address indexed ejected, address ejector, uint256 ts);
    event Expired();
    event RewardAdded(uint256 reward);
    event RewardPaid(address indexed user, uint256 reward);

/** Shared Globals */
    IERC20 public stakingToken;
    uint256 private constant WEEK = 7 days;
    uint256 public constant MAXTIME = 365 days;
    uint256 public END;
    bool public expired = false;

/** Lockup */
    uint256 public globalEpoch;
    Point[] public pointHistory;
    mapping(address => Point[]) public userPointHistory;
    mapping(address => uint256) public userPointEpoch;
    mapping(uint256 => int128) public slopeChanges;
    mapping(address => LockedBalance) public locked;

// Voting token - Checkpointed view only ERC20
    string public name;
    string public symbol;
    uint256 public decimals = 18;

/** Rewards */
    // Updated upon admin deposit
    uint256 public periodFinish = 0;
    uint256 public rewardRate = 0;

// Globals updated per stake/deposit/withdrawal
    uint256 public totalStaticWeight = 0;
    uint256 public lastUpdateTime = 0;
    uint256 public rewardPerTokenStored = 0;

// Per user storage updated per stake/deposit/withdrawal
    mapping(address => uint256) public userRewardPerTokenPaid;
    mapping(address => uint256) public rewards;
    mapping(address => uint256) public rewardsPaid;

/** Structs */
    struct Point {
        int128 bias;
        int128 slope;
        uint256 ts;
        uint256 blk;
    }

struct LockedBalance {
        int128 amount;
        uint256 end;
    }

enum LockAction {
        CREATE_LOCK,
        INCREASE_LOCK_AMOUNT,
        INCREASE_LOCK_TIME
    }

constructor(
        address _stakingToken,
        string memory _name,
        string memory _symbol,
        address _nexus,
        address _rewardsDistributor
    ) RewardsDistributionRecipient(_nexus, _rewardsDistributor) {
        stakingToken = IERC20(_stakingToken);
        Point memory init = Point({
            bias: int128(0),
            slope: int128(0),
            ts: block.timestamp,
            blk: block.number
        });
        pointHistory.push(init);

decimals = IBasicToken(_stakingToken).decimals();
        require(decimals <= 18, "Cannot have more than 18 decimals");

name = _name;
        symbol = _symbol;

END = block.timestamp + MAXTIME;
    }

/** @dev Modifier to ensure contract has not yet expired */
    modifier contractNotExpired() {
        require(!expired, "Contract is expired");
        _;
    }

/**
     * @dev Validates that the user has an expired lock && they still have capacity to earn
     * @param _addr User address to check
     */
    modifier lockupIsOver(address _addr) {
        LockedBalance memory userLock = locked[_addr];
        require(userLock.amount > 0 && block.timestamp >= userLock.end, "Users lock didn't expire");
        require(staticBalanceOf(_addr) > 0, "User must have existing bias");
        _;
    }

/***************************************
                LOCKUP - GETTERS
    ****************************************/

/**
     * @dev Gets the last available user point
     * @param _addr User address
     * @return bias i.e. y
     * @return slope i.e. linear gradient
     * @return ts i.e. time point was logged
     */
    function getLastUserPoint(address _addr)
        external
        view
        override
        returns (
            int128 bias,
            int128 slope,
            uint256 ts
        )
    {
        uint256 uepoch = userPointEpoch[_addr];
        if (uepoch == 0) {
            return (0, 0, 0);
        }
        Point memory point = userPointHistory[_addr][uepoch];
        return (point.bias, point.slope, point.ts);
    }

/***************************************
                    LOCKUP
    ****************************************/

/**
     * @dev Records a checkpoint of both individual and global slope
     * @param _addr User address, or address(0) for only global
     * @param _oldLocked Old amount that user had locked, or null for global
     * @param _newLocked new amount that user has locked, or null for global
     */
    function _checkpoint(
        address _addr,
        LockedBalance memory _oldLocked,
        LockedBalance memory _newLocked
    ) internal {
        Point memory userOldPoint;
        Point memory userNewPoint;
        int128 oldSlopeDelta = 0;
        int128 newSlopeDelta = 0;
        uint256 epoch = globalEpoch;

if (_addr != address(0)) {
            // Calculate slopes and biases
            // Kept at zero when they have to
            if (_oldLocked.end > block.timestamp && _oldLocked.amount > 0) {
                userOldPoint.slope = _oldLocked.amount / SafeCast.toInt128(int256(MAXTIME));
                userOldPoint.bias =
                    userOldPoint.slope *
                    SafeCast.toInt128(int256(_oldLocked.end - block.timestamp));
            }
            if (_newLocked.end > block.timestamp && _newLocked.amount > 0) {
                userNewPoint.slope = _newLocked.amount / SafeCast.toInt128(int256(MAXTIME));
                userNewPoint.bias =
                    userNewPoint.slope *
                    SafeCast.toInt128(int256(_newLocked.end - block.timestamp));
            }

// Moved from bottom final if statement to resolve stack too deep err
            // start {
            // Now handle user history
            uint256 uEpoch = userPointEpoch[_addr];
            if (uEpoch == 0) {
                userPointHistory[_addr].push(userOldPoint);
            }
            // track the total static weight
            uint256 newStatic = _staticBalance(userNewPoint.slope, block.timestamp, _newLocked.end);
            uint256 additiveStaticWeight = totalStaticWeight + newStatic;
            if (uEpoch > 0) {
                uint256 oldStatic = _staticBalance(
                    userPointHistory[_addr][uEpoch].slope,
                    userPointHistory[_addr][uEpoch].ts,
                    _oldLocked.end
                );
                additiveStaticWeight = additiveStaticWeight - oldStatic;
            }
            totalStaticWeight = additiveStaticWeight;

userPointEpoch[_addr] = uEpoch + 1;
            userNewPoint.ts = block.timestamp;
            userNewPoint.blk = block.number;
            userPointHistory[_addr].push(userNewPoint);

// } end

// Read values of scheduled changes in the slope
            // oldLocked.end can be in the past and in the future
            // newLocked.end can ONLY by in the FUTURE unless everything expired: than zeros
            oldSlopeDelta = slopeChanges[_oldLocked.end];
            if (_newLocked.end != 0) {
                if (_newLocked.end == _oldLocked.end) {
                    newSlopeDelta = oldSlopeDelta;
                } else {
                    newSlopeDelta = slopeChanges[_newLocked.end];
                }
            }
        }

Point memory lastPoint = Point({
            bias: 0,
            slope: 0,
            ts: block.timestamp,
            blk: block.number
        });
        if (epoch > 0) {
            lastPoint = pointHistory[epoch];
        }
        uint256 lastCheckpoint = lastPoint.ts;

// initialLastPoint is used for extrapolation to calculate block number
        // (approximately, for *At methods) and save them
        // as we cannot figure that out exactly from inside the contract
        Point memory initialLastPoint = Point({
            bias: 0,
            slope: 0,
            ts: lastPoint.ts,
            blk: lastPoint.blk
        });
        uint256 blockSlope = 0; // dblock/dt
        if (block.timestamp > lastPoint.ts) {
            blockSlope =
                StableMath.scaleInteger(block.number - lastPoint.blk) /
                (block.timestamp - lastPoint.ts);
        }
        // If last point is already recorded in this block, slope=0
        // But that's ok b/c we know the block in such case

// Go over weeks to fill history and calculate what the current point is
        uint256 iterativeTime = _floorToWeek(lastCheckpoint);
        for (uint256 i = 0; i < 255; i++) {
            // Hopefully it won't happen that this won't get used in 5 years!
            // If it does, users will be able to withdraw but vote weight will be broken
            iterativeTime = iterativeTime + WEEK;
            int128 dSlope = 0;
            if (iterativeTime > block.timestamp) {
                iterativeTime = block.timestamp;
            } else {
                dSlope = slopeChanges[iterativeTime];
            }
            int128 biasDelta = lastPoint.slope *
                SafeCast.toInt128(int256((iterativeTime - lastCheckpoint)));
            lastPoint.bias = lastPoint.bias - biasDelta;
            lastPoint.slope = lastPoint.slope + dSlope;
            // This can happen
            if (lastPoint.bias < 0) {
                lastPoint.bias = 0;
            }
            // This cannot happen - just in case
            if (lastPoint.slope < 0) {
                lastPoint.slope = 0;
            }
            lastCheckpoint = iterativeTime;
            lastPoint.ts = iterativeTime;
            lastPoint.blk =
                initialLastPoint.blk +
                blockSlope.mulTruncate(iterativeTime - initialLastPoint.ts);

// when epoch is incremented, we either push here or after slopes updated below
            epoch = epoch + 1;
            if (iterativeTime == block.timestamp) {
                lastPoint.blk = block.number;
                break;
            } else {
                // pointHistory[epoch] = lastPoint;
                pointHistory.push(lastPoint);
            }
        }

globalEpoch = epoch;
        // Now pointHistory is filled until t=now

if (_addr != address(0)) {
            // If last point was in this block, the slope change has been applied already
            // But in such case we have 0 slope(s)
            lastPoint.slope = lastPoint.slope + userNewPoint.slope - userOldPoint.slope;
            lastPoint.bias = lastPoint.bias + userNewPoint.bias - userOldPoint.bias;
            if (lastPoint.slope < 0) {
                lastPoint.slope = 0;
            }
            if (lastPoint.bias < 0) {
                lastPoint.bias = 0;
            }
        }

// Record the changed point into history
        // pointHistory[epoch] = lastPoint;
        pointHistory.push(lastPoint);

if (_addr != address(0)) {
            // Schedule the slope changes (slope is going down)
            // We subtract new_user_slope from [new_locked.end]
            // and add old_user_slope to [old_locked.end]
            if (_oldLocked.end > block.timestamp) {
                // oldSlopeDelta was <something> - userOldPoint.slope, so we cancel that
                oldSlopeDelta = oldSlopeDelta + userOldPoint.slope;
                if (_newLocked.end == _oldLocked.end) {
                    oldSlopeDelta = oldSlopeDelta - userNewPoint.slope; // It was a new deposit, not extension
                }
                slopeChanges[_oldLocked.end] = oldSlopeDelta;
            }
            if (_newLocked.end > block.timestamp) {
                if (_newLocked.end > _oldLocked.end) {
                    newSlopeDelta = newSlopeDelta - userNewPoint.slope; // old slope disappeared at this point
                    slopeChanges[_newLocked.end] = newSlopeDelta;
                }
                // else: we recorded it already in oldSlopeDelta
            }
        }
    }

/**
     * @dev Deposits or creates a stake for a given address
     * @param _addr User address to assign the stake
     * @param _value Total units of StakingToken to lockup
     * @param _unlockTime Time at which the stake should unlock
     * @param _oldLocked Previous amount staked by this user
     * @param _action See LockAction enum
     */
    function _depositFor(
        address _addr,
        uint256 _value,
        uint256 _unlockTime,
        LockedBalance memory _oldLocked,
        LockAction _action
    ) internal {
        LockedBalance memory newLocked = LockedBalance({
            amount: _oldLocked.amount,
            end: _oldLocked.end
        });

// Adding to existing lock, or if a lock is expired - creating a new one
        newLocked.amount = newLocked.amount + SafeCast.toInt128(int256(_value));
        if (_unlockTime != 0) {
            newLocked.end = _unlockTime;
        }
        locked[_addr] = newLocked;

// Possibilities:
        // Both _oldLocked.end could be current or expired (>/< block.timestamp)
        // value == 0 (extend lock) or value > 0 (add to lock or extend lock)
        // newLocked.end > block.timestamp (always)
        _checkpoint(_addr, _oldLocked, newLocked);

if (_value != 0) {
            stakingToken.safeTransferFrom(_addr, address(this), _value);
        }
        emit Deposit(_addr, _value, newLocked.end, _action, block.timestamp);
    }

/**
     * @dev Public function to trigger global checkpoint
     */
    function checkpoint() external {
        LockedBalance memory empty;
        _checkpoint(address(0), empty, empty);
    }

/**
     * @dev Creates a new lock
     * @param _value Total units of StakingToken to lockup
     * @param _unlockTime Time at which the stake should unlock
     */
    function createLock(uint256 _value, uint256 _unlockTime)
        external
        override
        nonReentrant
        contractNotExpired
        updateReward(msg.sender)
    {
        uint256 unlock_time = _floorToWeek(_unlockTime); // Locktime is rounded down to weeks
        LockedBalance memory locked_ = LockedBalance({
            amount: locked[msg.sender].amount,
            end: locked[msg.sender].end
        });

require(_value > 0, "Must stake non zero amount");
        require(locked_.amount == 0, "Withdraw old tokens first");

require(unlock_time > block.timestamp, "Can only lock until time in the future");
        require(unlock_time <= END, "Voting lock can be 1 year max (until recol)");

_depositFor(msg.sender, _value, unlock_time, locked_, LockAction.CREATE_LOCK);
    }

/**
     * @dev Increases amount of stake thats locked up & resets decay
     * @param _value Additional units of StakingToken to add to exiting stake
     */
    function increaseLockAmount(uint256 _value)
        external
        override
        nonReentrant
        contractNotExpired
        updateReward(msg.sender)
    {
        LockedBalance memory locked_ = LockedBalance({
            amount: locked[msg.sender].amount,
            end: locked[msg.sender].end
        });

require(_value > 0, "Must stake non zero amount");
        require(locked_.amount > 0, "No existing lock found");
        require(locked_.end > block.timestamp, "Cannot add to expired lock. Withdraw");

_depositFor(msg.sender, _value, 0, locked_, LockAction.INCREASE_LOCK_AMOUNT);
    }

/**
     * @dev Increases length of lockup & resets decay
     * @param _unlockTime New unlocktime for lockup
     */
    function increaseLockLength(uint256 _unlockTime)
        external
        override
        nonReentrant
        contractNotExpired
        updateReward(msg.sender)
    {
        LockedBalance memory locked_ = LockedBalance({
            amount: locked[msg.sender].amount,
            end: locked[msg.sender].end
        });
        uint256 unlock_time = _floorToWeek(_unlockTime); // Locktime is rounded down to weeks

require(locked_.amount > 0, "Nothing is locked");
        require(locked_.end > block.timestamp, "Lock expired");
        require(unlock_time > locked_.end, "Can only increase lock WEEK");
        require(unlock_time <= END, "Voting lock can be 1 year max (until recol)");

_depositFor(msg.sender, 0, unlock_time, locked_, LockAction.INCREASE_LOCK_TIME);
    }

/**
     * @dev Withdraws all the senders stake, providing lockup is over
     */
    function withdraw() external override {
        _withdraw(msg.sender);
    }

/**
     * @dev Withdraws a given users stake, providing the lockup has finished
     * @param _addr User for which to withdraw
     */
    function _withdraw(address _addr) internal nonReentrant updateReward(_addr) {
        LockedBalance memory oldLock = LockedBalance({
            end: locked[_addr].end,
            amount: locked[_addr].amount
        });
        require(block.timestamp >= oldLock.end || expired, "The lock didn't expire");
        require(oldLock.amount > 0, "Must have something to withdraw");

uint256 value = SafeCast.toUint256(oldLock.amount);

LockedBalance memory currentLock = LockedBalance({ end: 0, amount: 0 });
        locked[_addr] = currentLock;

// oldLocked can have either expired <= timestamp or zero end
        // currentLock has only 0 end
        // Both can have >= 0 amount
        if (!expired) {
            _checkpoint(_addr, oldLock, currentLock);
        }
        stakingToken.safeTransfer(_addr, value);

emit Withdraw(_addr, value, block.timestamp);
    }

/**
     * @dev Withdraws and consequently claims rewards for the sender
     */
    function exit() external override {
        _withdraw(msg.sender);
        claimReward();
    }

/**
     * @dev Ejects a user from the reward allocation, given their lock has freshly expired.
     * Leave it to the user to withdraw and claim their rewards.
     * @param _addr Address of the user
     */
    function eject(address _addr) external override contractNotExpired lockupIsOver(_addr) {
        _withdraw(_addr);

// solium-disable-next-line security/no-tx-origin
        emit Ejected(_addr, tx.origin, block.timestamp);
    }

/**
     * @dev Ends the contract, unlocking all stakes.
     * No more staking can happen. Only withdraw and Claim.
     */
    function expireContract()
        external
        override
        onlyGovernor
        contractNotExpired
        updateReward(address(0))
    {
        require(block.timestamp > periodFinish, "Period must be over");

expired = true;

emit Expired();
    }

/***************************************
                    GETTERS
    ****************************************/

/** @dev Floors a timestamp to the nearest weekly increment */
    function _floorToWeek(uint256 _t) internal pure returns (uint256) {
        return (_t / WEEK) * WEEK;
    }

/**
     * @dev Uses binarysearch to find the most recent point history preceeding block
     * @param _block Find the most recent point history before this block
     * @param _maxEpoch Do not search pointHistories past this index
     */
    function _findBlockEpoch(uint256 _block, uint256 _maxEpoch) internal view returns (uint256) {
        // Binary search
        uint256 min = 0;
        uint256 max = _maxEpoch;
        // Will be always enough for 128-bit numbers
        for (uint256 i = 0; i < 128; i++) {
            if (min >= max) break;
            uint256 mid = (min + max + 1) / 2;
            if (pointHistory[mid].blk <= _block) {
                min = mid;
            } else {
                max = mid - 1;
            }
        }
        return min;
    }

/**
     * @dev Uses binarysearch to find the most recent user point history preceeding block
     * @param _addr User for which to search
     * @param _block Find the most recent point history before this block
     */
    function _findUserBlockEpoch(address _addr, uint256 _block) internal view returns (uint256) {
        uint256 min = 0;
        uint256 max = userPointEpoch[_addr];
        for (uint256 i = 0; i < 128; i++) {
            if (min >= max) {
                break;
            }
            uint256 mid = (min + max + 1) / 2;
            if (userPointHistory[_addr][mid].blk <= _block) {
                min = mid;
            } else {
                max = mid - 1;
            }
        }
        return min;
    }

/**
     * @dev Gets curent user voting weight (aka effectiveStake)
     * @param _owner User for which to return the balance
     * @return uint256 Balance of user
     */
    function balanceOf(address _owner) public view override returns (uint256) {
        uint256 epoch = userPointEpoch[_owner];
        if (epoch == 0) {
            return 0;
        }
        Point memory lastPoint = userPointHistory[_owner][epoch];
        lastPoint.bias =
            lastPoint.bias -
            (lastPoint.slope * SafeCast.toInt128(int256(block.timestamp - lastPoint.ts)));
        if (lastPoint.bias < 0) {
            lastPoint.bias = 0;
        }
        return SafeCast.toUint256(lastPoint.bias);
    }

/**
     * @dev Gets a users votingWeight at a given blockNumber
     * @param _owner User for which to return the balance
     * @param _blockNumber Block at which to calculate balance
     * @return uint256 Balance of user
     */
    function balanceOfAt(address _owner, uint256 _blockNumber)
        public
        view
        override
        returns (uint256)
    {
        require(_blockNumber <= block.number, "Must pass block number in the past");

// Get most recent user Point to block
        uint256 userEpoch = _findUserBlockEpoch(_owner, _blockNumber);
        if (userEpoch == 0) {
            return 0;
        }
        Point memory upoint = userPointHistory[_owner][userEpoch];

// Get most recent global Point to block
        uint256 maxEpoch = globalEpoch;
        uint256 epoch = _findBlockEpoch(_blockNumber, maxEpoch);
        Point memory point0 = pointHistory[epoch];

// Calculate delta (block & time) between user Point and target block
        // Allowing us to calculate the average seconds per block between
        // the two points
        uint256 dBlock = 0;
        uint256 dTime = 0;
        if (epoch < maxEpoch) {
            Point memory point1 = pointHistory[epoch + 1];
            dBlock = point1.blk - point0.blk;
            dTime = point1.ts - point0.ts;
        } else {
            dBlock = block.number - point0.blk;
            dTime = block.timestamp - point0.ts;
        }
        // (Deterministically) Estimate the time at which block _blockNumber was mined
        uint256 blockTime = point0.ts;
        if (dBlock != 0) {
            blockTime = blockTime + ((dTime * (_blockNumber - point0.blk)) / dBlock);
        }
        // Current Bias = most recent bias - (slope * time since update)
        upoint.bias =
            upoint.bias -
            (upoint.slope * SafeCast.toInt128(int256(blockTime - upoint.ts)));
        if (upoint.bias >= 0) {
            return SafeCast.toUint256(upoint.bias);
        } else {
            return 0;
        }
    }

/**
     * @dev Calculates total supply of votingWeight at a given time _t
     * @param _point Most recent point before time _t
     * @param _t Time at which to calculate supply
     * @return totalSupply at given point in time
     */
    function _supplyAt(Point memory _point, uint256 _t) internal view returns (uint256) {
        Point memory lastPoint = _point;
        // Floor the timestamp to weekly interval
        uint256 iterativeTime = _floorToWeek(lastPoint.ts);
        // Iterate through all weeks between _point & _t to account for slope changes
        for (uint256 i = 0; i < 255; i++) {
            iterativeTime = iterativeTime + WEEK;
            int128 dSlope = 0;
            // If week end is after timestamp, then truncate & leave dSlope to 0
            if (iterativeTime > _t) {
                iterativeTime = _t;
            }
            // else get most recent slope change
            else {
                dSlope = slopeChanges[iterativeTime];
            }

lastPoint.bias =
                lastPoint.bias -
                (lastPoint.slope * SafeCast.toInt128(int256(iterativeTime - lastPoint.ts)));
            if (iterativeTime == _t) {
                break;
            }
            lastPoint.slope = lastPoint.slope + dSlope;
            lastPoint.ts = iterativeTime;
        }

if (lastPoint.bias < 0) {
            lastPoint.bias = 0;
        }
        return SafeCast.toUint256(lastPoint.bias);
    }

/**
     * @dev Calculates current total supply of votingWeight
     * @return totalSupply of voting token weight
     */
    function totalSupply() public view override returns (uint256) {
        uint256 epoch_ = globalEpoch;
        Point memory lastPoint = pointHistory[epoch_];
        return _supplyAt(lastPoint, block.timestamp);
    }

/**
     * @dev Calculates total supply of votingWeight at a given blockNumber
     * @param _blockNumber Block number at which to calculate total supply
     * @return totalSupply of voting token weight at the given blockNumber
     */
    function totalSupplyAt(uint256 _blockNumber) public view override returns (uint256) {
        require(_blockNumber <= block.number, "Must pass block number in the past");

uint256 epoch = globalEpoch;
        uint256 targetEpoch = _findBlockEpoch(_blockNumber, epoch);

Point memory point = pointHistory[targetEpoch];

// If point.blk > _blockNumber that means we got the initial epoch & contract did not yet exist
        if (point.blk > _blockNumber) {
            return 0;
        }

uint256 dTime = 0;
        if (targetEpoch < epoch) {
            Point memory pointNext = pointHistory[targetEpoch + 1];
            if (point.blk != pointNext.blk) {
                dTime =
                    ((_blockNumber - point.blk) * (pointNext.ts - point.ts)) /
                    (pointNext.blk - point.blk);
            }
        } else if (point.blk != block.number) {
            dTime =
                ((_blockNumber - point.blk) * (block.timestamp - point.ts)) /
                (block.number - point.blk);
        }
        // Now dTime contains info on how far are we beyond point

return _supplyAt(point, point.ts + dTime);
    }

/***************************************
                    REWARDS
    ****************************************/

/** @dev Updates the reward for a given address, before executing function */
    modifier updateReward(address _account) {
        // Setting of global vars
        uint256 newRewardPerToken = rewardPerToken();
        // If statement protects against loss in initialisation case
        if (newRewardPerToken > 0) {
            rewardPerTokenStored = newRewardPerToken;
            lastUpdateTime = lastTimeRewardApplicable();
            // Setting of personal vars based on new globals
            if (_account != address(0)) {
                rewards[_account] = earned(_account);
                userRewardPerTokenPaid[_account] = newRewardPerToken;
            }
        }
        _;
    }

/**
     * @dev Claims outstanding rewards for the sender.
     * First updates outstanding reward allocation and then transfers.
     */
    function claimReward() public override updateReward(msg.sender) {
        uint256 reward = rewards[msg.sender];
        if (reward > 0) {
            rewards[msg.sender] = 0;
            stakingToken.safeTransfer(msg.sender, reward);
            rewardsPaid[msg.sender] = rewardsPaid[msg.sender] + reward;

emit RewardPaid(msg.sender, reward);
        }
    }

/***************************************
                REWARDS - GETTERS
    ****************************************/

/**
     * @dev Gets the most recent Static Balance (bias) for a user
     * @param _addr User for which to retrieve static balance
     * @return uint256 balance
     */
    function staticBalanceOf(address _addr) public view returns (uint256) {
        uint256 uepoch = userPointEpoch[_addr];
        if (uepoch == 0 || userPointHistory[_addr][uepoch].bias == 0) {
            return 0;
        }
        return
            _staticBalance(
                userPointHistory[_addr][uepoch].slope,
                userPointHistory[_addr][uepoch].ts,
                locked[_addr].end
            );
    }

function _staticBalance(
        int128 _slope,
        uint256 _startTime,
        uint256 _endTime
    ) internal pure returns (uint256) {
        if (_startTime > _endTime) return 0;
        // get lockup length (end - point.ts)
        uint256 lockupLength = _endTime - _startTime;
        // s = amount * sqrt(length)
        uint256 s = SafeCast.toUint256(_slope * 10000) * Root.sqrt(lockupLength);
        return s;
    }

/**
     * @dev Gets the RewardsToken
     */
    function getRewardToken() external view override returns (IERC20) {
        return stakingToken;
    }

/**
     * @dev Gets the duration of the rewards period
     */
    function getDuration() external pure returns (uint256) {
        return WEEK;
    }

/**
     * @dev Gets the last applicable timestamp for this reward period
     */
    function lastTimeRewardApplicable() public view returns (uint256) {
        return StableMath.min(block.timestamp, periodFinish);
    }

/**
     * @dev Calculates the amount of unclaimed rewards per token since last update,
     * and sums with stored to give the new cumulative reward per token
     * @return 'Reward' per staked token
     */
    function rewardPerToken() public view returns (uint256) {
        // If there is no StakingToken liquidity, avoid div(0)
        uint256 totalStatic = totalStaticWeight;
        if (totalStatic == 0) {
            return rewardPerTokenStored;
        }
        // new reward units to distribute = rewardRate * timeSinceLastUpdate
        uint256 rewardUnitsToDistribute = rewardRate *
            (lastTimeRewardApplicable() - lastUpdateTime);
        // new reward units per token = (rewardUnitsToDistribute * 1e18) / totalTokens
        uint256 unitsToDistributePerToken = rewardUnitsToDistribute.divPrecisely(totalStatic);
        // return summed rate
        return rewardPerTokenStored + unitsToDistributePerToken;
    }

/**
     * @dev Calculates the amount of unclaimed rewards a user has earned
     * @param _addr User address
     * @return Total reward amount earned
     */
    function earned(address _addr) public view override returns (uint256) {
        // current rate per token - rate user previously received
        uint256 userRewardDelta = rewardPerToken() - userRewardPerTokenPaid[_addr];
        // new reward = staked tokens * difference in rate
        uint256 userNewReward = staticBalanceOf(_addr).mulTruncate(userRewardDelta);
        // add to previous rewards
        return rewards[_addr] + userNewReward;
    }

/***************************************
                REWARDS - ADMIN
    ****************************************/

/**
     * @dev Notifies the contract that new rewards have been added.
     * Calculates an updated rewardRate based on the rewards in period.
     * @param _reward Units of RewardToken that have been added to the pool
     */
    function notifyRewardAmount(uint256 _reward)
        external
        override
        onlyRewardsDistributor
        contractNotExpired
        updateReward(address(0))
    {
        uint256 currentTime = block.timestamp;
        // If previous period over, reset rewardRate
        if (currentTime >= periodFinish) {
            rewardRate = _reward / WEEK;
        }
        // If additional reward to existing period, calc sum
        else {
            uint256 remaining = periodFinish - currentTime;
            uint256 leftover = remaining * rewardRate;
            rewardRate = (_reward + leftover) / WEEK;
        }

lastUpdateTime = currentTime;
        periodFinish = currentTime + WEEK;

emit RewardAdded(_reward);
    }
}

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// SPDX-License-Identifier: AGPL-3.0-or-later
pragma solidity ^0.8.3;

import {
    ReentrancyGuard
} from "@openzeppelin/contracts/security/ReentrancyGuard.sol";
import { IERC20 } from "./interfaces/IERC20.sol";
import { IVotingEscrow } from "./interfaces/IVotingEscrow.sol";
import { IBlocklist } from "./interfaces/IBlocklist.sol";

/// @title  VotingEscrow
/// @author Curve Finance (MIT) - original concept and implementation in Vyper
///           (see https://github.com/curvefi/curve-dao-contracts/blob/master/contracts/VotingEscrow.vy)
///         mStable (AGPL) - forking Curve's Vyper contract and porting to Solidity
///           (see https://github.com/mstable/mStable-contracts/blob/master/contracts/governance/IncentivisedVotingLockup.sol)
///         FIAT DAO (AGPL) - this version
/// @notice Plain Curve VotingEscrow mechanics with following adjustments:
///            1) Delegation of lock and voting power
///            2) Quit an existing lock and pay a penalty
///            3) Whitelisting of SmartWallets outside the VotingEscrow
///            4) Reduced pointHistory array size and, as a result, lifetime of the contract
///            5) Removed public deposit_for and Aragon compatibility (no use case)
contract VotingEscrow is IVotingEscrow, ReentrancyGuard {
    // Shared Events
    event Deposit(
        address indexed provider,
        uint256 value,
        uint256 locktime,
        LockAction indexed action,
        uint256 ts
    );
    event Withdraw(
        address indexed provider,
        uint256 value,
        LockAction indexed action,
        uint256 ts
    );
    event TransferOwnership(address owner);
    event UpdateBlocklist(address blocklist);
    event UpdatePenaltyRecipient(address recipient);
    event CollectPenalty(uint256 amount, address recipient);
    event Unlock();

// Shared global state
    IERC20 public token;
    uint256 public constant WEEK = 7 days;
    uint256 public constant MAXTIME = 365 days;
    uint256 public constant MULTIPLIER = 10**18;
    address public owner;
    address public penaltyRecipient; // receives collected penalty payments
    uint256 public maxPenalty = 10**18; // penalty for quitters with MAXTIME remaining lock
    uint256 public penaltyAccumulated; // accumulated and unwithdrawn penalty payments
    address public blocklist;

// Lock state
    uint256 public globalEpoch;
    Point[1000000000000000000] public pointHistory; // 1e9 * userPointHistory-length, so sufficient for 1e9 users
    mapping(address => Point[1000000000]) public userPointHistory;
    mapping(address => uint256) public userPointEpoch;
    mapping(uint256 => int128) public slopeChanges;
    mapping(address => LockedBalance) public locked;

// Voting token
    string public name;
    string public symbol;
    uint256 public decimals = 18;

// Structs
    struct Point {
        int128 bias;
        int128 slope;
        uint256 ts;
        uint256 blk;
    }
    struct LockedBalance {
        int128 amount;
        uint256 end;
        int128 delegated;
        address delegatee;
    }

// Miscellaneous
    enum LockAction {
        CREATE,
        INCREASE_AMOUNT,
        INCREASE_AMOUNT_AND_DELEGATION,
        INCREASE_TIME,
        WITHDRAW,
        QUIT,
        DELEGATE,
        UNDELEGATE
    }

/// @notice Initializes state
    /// @param _owner The owner is able to update `owner`, `penaltyRecipient` and `penaltyRate`
    /// @param _penaltyRecipient The recipient of penalty paid by lock quitters
    /// @param _token The token locked in order to obtain voting power
    /// @param _name The name of the voting token
    /// @param _symbol The symbol of the voting token
    constructor(
        address _owner,
        address _penaltyRecipient,
        address _token,
        string memory _name,
        string memory _symbol
    ) {
        token = IERC20(_token);
        pointHistory[0] = Point({
            bias: int128(0),
            slope: int128(0),
            ts: block.timestamp,
            blk: block.number
        });

decimals = IERC20(_token).decimals();
        require(decimals <= 18, "Exceeds max decimals");

name = _name;
        symbol = _symbol;
        owner = _owner;
        penaltyRecipient = _penaltyRecipient;
    }

modifier checkBlocklist() {
        require(
            !IBlocklist(blocklist).isBlocked(msg.sender),
            "Blocked contract"
        );
        _;
    }

/// ~~~~~~~~~~~~~~~~~~~~~~~~~~~ ///
    ///       Owner Functions       ///
    /// ~~~~~~~~~~~~~~~~~~~~~~~~~~~ ///

/// @notice Transfers ownership to a new owner
    /// @param _addr The new owner
    /// @dev Owner should always be a timelock contract
    function transferOwnership(address _addr) external {
        require(msg.sender == owner, "Only owner");
        owner = _addr;
        emit TransferOwnership(_addr);
    }

/// @notice Updates the blocklist contract
    function updateBlocklist(address _addr) external {
        require(msg.sender == owner, "Only owner");
        blocklist = _addr;
        emit UpdateBlocklist(_addr);
    }

/// @notice Updates the recipient of the accumulated penalty paid by quitters
    function updatePenaltyRecipient(address _addr) external {
        require(msg.sender == owner, "Only owner");
        penaltyRecipient = _addr;
        emit UpdatePenaltyRecipient(_addr);
    }

/// @notice Removes quitlock penalty by setting it to zero
    /// @dev This is an irreversible action
    function unlock() external {
        require(msg.sender == owner, "Only owner");
        maxPenalty = 0;
        emit Unlock();
    }

/// @notice Forces an undelegation of virtual balance for a blocked locker
    /// @dev Can only be called by the Blocklist contract (as part of a block)
    /// @dev This is an irreversible action
    function forceUndelegate(address _addr) external override {
        require(msg.sender == blocklist, "Only Blocklist");
        LockedBalance memory locked_ = locked[_addr];
        address delegatee = locked_.delegatee;
        int128 value = locked_.amount;

if (delegatee != _addr && value > 0) {
            LockedBalance memory fromLocked;
            locked_.delegatee = _addr;
            fromLocked = locked[delegatee];
            _delegate(delegatee, fromLocked, value, LockAction.UNDELEGATE);
            _delegate(_addr, locked_, value, LockAction.DELEGATE);
        }
    }

/// ~~~~~~~~~~~~~~~~~~~~~~~~~~~ ///
    ///       LOCK MANAGEMENT       ///
    /// ~~~~~~~~~~~~~~~~~~~~~~~~~~~ ///

/// @notice Returns a user's lock expiration
    /// @param _addr The address of the user
    /// @return Expiration of the user's lock
    function lockEnd(address _addr) external view returns (uint256) {
        return locked[_addr].end;
    }

/// @notice Returns the last available user point for a user
    /// @param _addr User address
    /// @return bias i.e. y
    /// @return slope i.e. linear gradient
    /// @return ts i.e. time point was logged
    function getLastUserPoint(address _addr)
        external
        view
        returns (
            int128 bias,
            int128 slope,
            uint256 ts
        )
    {
        uint256 uepoch = userPointEpoch[_addr];
        if (uepoch == 0) {
            return (0, 0, 0);
        }
        Point memory point = userPointHistory[_addr][uepoch];
        return (point.bias, point.slope, point.ts);
    }

/// @notice Records a checkpoint of both individual and global slope
    /// @param _addr User address, or address(0) for only global
    /// @param _oldLocked Old amount that user had locked, or null for global
    /// @param _newLocked new amount that user has locked, or null for global
    function _checkpoint(
        address _addr,
        LockedBalance memory _oldLocked,
        LockedBalance memory _newLocked
    ) internal {
        Point memory userOldPoint;
        Point memory userNewPoint;
        int128 oldSlopeDelta = 0;
        int128 newSlopeDelta = 0;
        uint256 epoch = globalEpoch;

if (_addr != address(0)) {
            // Calculate slopes and biases
            // Kept at zero when they have to
            if (_oldLocked.end > block.timestamp && _oldLocked.delegated > 0) {
                userOldPoint.slope =
                    _oldLocked.delegated /
                    int128(int256(MAXTIME));
                userOldPoint.bias =
                    userOldPoint.slope *
                    int128(int256(_oldLocked.end - block.timestamp));
            }
            if (_newLocked.end > block.timestamp && _newLocked.delegated > 0) {
                userNewPoint.slope =
                    _newLocked.delegated /
                    int128(int256(MAXTIME));
                userNewPoint.bias =
                    userNewPoint.slope *
                    int128(int256(_newLocked.end - block.timestamp));
            }

userPointEpoch[_addr] = uEpoch + 1;
            userNewPoint.ts = block.timestamp;
            userNewPoint.blk = block.number;
            userPointHistory[_addr][uEpoch + 1] = userNewPoint;

// } end

Point memory lastPoint =
            Point({
                bias: 0,
                slope: 0,
                ts: block.timestamp,
                blk: block.number
            });
        if (epoch > 0) {
            lastPoint = pointHistory[epoch];
        }
        uint256 lastCheckpoint = lastPoint.ts;

// initialLastPoint is used for extrapolation to calculate block number
        // (approximately, for *At methods) and save them
        // as we cannot figure that out exactly from inside the contract
        Point memory initialLastPoint =
            Point({ bias: 0, slope: 0, ts: lastPoint.ts, blk: lastPoint.blk });
        uint256 blockSlope = 0; // dblock/dt
        if (block.timestamp > lastPoint.ts) {
            blockSlope =
                (MULTIPLIER * (block.number - lastPoint.blk)) /
                (block.timestamp - lastPoint.ts);
        }
        // If last point is already recorded in this block, slope=0
        // But that's ok b/c we know the block in such case

// Go over weeks to fill history and calculate what the current point is
        uint256 iterativeTime = _floorToWeek(lastCheckpoint);
        for (uint256 i = 0; i < 255; i++) {
            // Hopefully it won't happen that this won't get used in 5 years!
            // If it does, users will be able to withdraw but vote weight will be broken
            iterativeTime = iterativeTime + WEEK;
            int128 dSlope = 0;
            if (iterativeTime > block.timestamp) {
                iterativeTime = block.timestamp;
            } else {
                dSlope = slopeChanges[iterativeTime];
            }
            int128 biasDelta =
                lastPoint.slope *
                    int128(int256((iterativeTime - lastCheckpoint)));
            lastPoint.bias = lastPoint.bias - biasDelta;
            lastPoint.slope = lastPoint.slope + dSlope;
            // This can happen
            if (lastPoint.bias < 0) {
                lastPoint.bias = 0;
            }
            // This cannot happen - just in case
            if (lastPoint.slope < 0) {
                lastPoint.slope = 0;
            }
            lastCheckpoint = iterativeTime;
            lastPoint.ts = iterativeTime;
            lastPoint.blk =
                initialLastPoint.blk +
                (blockSlope * (iterativeTime - initialLastPoint.ts)) /
                MULTIPLIER;

// when epoch is incremented, we either push here or after slopes updated below
            epoch = epoch + 1;
            if (iterativeTime == block.timestamp) {
                lastPoint.blk = block.number;
                break;
            } else {
                pointHistory[epoch] = lastPoint;
            }
        }

globalEpoch = epoch;
        // Now pointHistory is filled until t=now

if (_addr != address(0)) {
            // If last point was in this block, the slope change has been applied already
            // But in such case we have 0 slope(s)
            lastPoint.slope =
                lastPoint.slope +
                userNewPoint.slope -
                userOldPoint.slope;
            lastPoint.bias =
                lastPoint.bias +
                userNewPoint.bias -
                userOldPoint.bias;
            if (lastPoint.slope < 0) {
                lastPoint.slope = 0;
            }
            if (lastPoint.bias < 0) {
                lastPoint.bias = 0;
            }
        }

// Record the changed point into history
        pointHistory[epoch] = lastPoint;

/// @notice Public function to trigger global checkpoint
    function checkpoint() external {
        LockedBalance memory empty;
        _checkpoint(address(0), empty, empty);
    }

// See IVotingEscrow for documentation
    function createLock(uint256 _value, uint256 _unlockTime)
        external
        override
        nonReentrant
        checkBlocklist
    {
        uint256 unlock_time = _floorToWeek(_unlockTime); // Locktime is rounded down to weeks
        LockedBalance memory locked_ = locked[msg.sender];
        // Validate inputs
        require(_value > 0, "Only non zero amount");
        require(locked_.amount == 0, "Lock exists");
        require(unlock_time >= locked_.end, "Only increase lock end"); // from using quitLock, user should increaseAmount instead
        require(unlock_time > block.timestamp, "Only future lock end");
        require(unlock_time <= block.timestamp + MAXTIME, "Exceeds maxtime");
        // Update lock and voting power (checkpoint)
        locked_.amount += int128(int256(_value));
        locked_.end = unlock_time;
        locked_.delegated += int128(int256(_value));
        locked_.delegatee = msg.sender;
        locked[msg.sender] = locked_;
        _checkpoint(msg.sender, LockedBalance(0, 0, 0, address(0)), locked_);
        // Deposit locked tokens
        require(
            token.transferFrom(msg.sender, address(this), _value),
            "Transfer failed"
        );
        emit Deposit(
            msg.sender,
            _value,
            unlock_time,
            LockAction.CREATE,
            block.timestamp
        );
    }

// See IVotingEscrow for documentation
    // @dev A lock is active until both lock.amount==0 and lock.end<=block.timestamp
    function increaseAmount(uint256 _value)
        external
        override
        nonReentrant
        checkBlocklist
    {
        LockedBalance memory locked_ = locked[msg.sender];
        // Validate inputs
        require(_value > 0, "Only non zero amount");
        require(locked_.amount > 0, "No lock");
        require(locked_.end > block.timestamp, "Lock expired");
        // Update lock
        address delegatee = locked_.delegatee;
        uint256 unlockTime = locked_.end;
        LockAction action = LockAction.INCREASE_AMOUNT;
        LockedBalance memory newLocked;
        if (delegatee == msg.sender) {
            // Undelegated lock
            action = LockAction.INCREASE_AMOUNT_AND_DELEGATION;
            newLocked = _copyLock(locked_);
            newLocked.amount += int128(int256(_value));
            newLocked.delegated += int128(int256(_value));
            locked[msg.sender] = newLocked;
        } else {
            // Delegated lock, update sender's lock first
            locked_.amount += int128(int256(_value));
            locked[msg.sender] = locked_;
            // Then, update delegatee's lock and voting power (checkpoint)
            locked_ = locked[delegatee];
            require(locked_.amount > 0, "Delegatee has no lock");
            require(locked_.end > block.timestamp, "Delegatee lock expired");
            newLocked = _copyLock(locked_);
            newLocked.delegated += int128(int256(_value));
            locked[delegatee] = newLocked;
            emit Deposit(
                delegatee,
                _value,
                newLocked.end,
                LockAction.DELEGATE,
                block.timestamp
            );
        }
        // Checkpoint only for delegatee
        _checkpoint(delegatee, locked_, newLocked);
        // Deposit locked tokens
        require(
            token.transferFrom(msg.sender, address(this), _value),
            "Transfer failed"
        );
        emit Deposit(msg.sender, _value, unlockTime, action, block.timestamp);
    }

// See IVotingEscrow for documentation
    function increaseUnlockTime(uint256 _unlockTime)
        external
        override
        nonReentrant
        checkBlocklist
    {
        LockedBalance memory locked_ = locked[msg.sender];
        uint256 unlock_time = _floorToWeek(_unlockTime); // Locktime is rounded down to weeks
        // Validate inputs
        require(locked_.amount > 0, "No lock");
        require(unlock_time > locked_.end, "Only increase lock end");
        require(unlock_time <= block.timestamp + MAXTIME, "Exceeds maxtime");
        // Update lock
        uint256 oldUnlockTime = locked_.end;
        locked_.end = unlock_time;
        locked[msg.sender] = locked_;
        if (locked_.delegatee == msg.sender) {
            // Undelegated lock
            require(oldUnlockTime > block.timestamp, "Lock expired");
            LockedBalance memory oldLocked = _copyLock(locked_);
            oldLocked.end = unlock_time;
            _checkpoint(msg.sender, oldLocked, locked_);
        }
        emit Deposit(
            msg.sender,
            0,
            unlock_time,
            LockAction.INCREASE_TIME,
            block.timestamp
        );
    }

// See IVotingEscrow for documentation
    function withdraw() external override nonReentrant {
        LockedBalance memory locked_ = locked[msg.sender];
        // Validate inputs
        require(locked_.amount > 0, "No lock");
        require(locked_.end <= block.timestamp, "Lock not expired");
        require(locked_.delegatee == msg.sender, "Lock delegated");
        // Update lock
        uint256 value = uint256(uint128(locked_.amount));
        LockedBalance memory newLocked = _copyLock(locked_);
        newLocked.amount = 0;
        newLocked.end = 0;
        newLocked.delegated -= int128(int256(value));
        newLocked.delegatee = address(0);
        locked[msg.sender] = newLocked;
        newLocked.delegated = 0;
        // oldLocked can have either expired <= timestamp or zero end
        // currentLock has only 0 end
        // Both can have >= 0 amount
        _checkpoint(msg.sender, locked_, newLocked);
        // Send back deposited tokens
        require(token.transfer(msg.sender, value), "Transfer failed");
        emit Withdraw(msg.sender, value, LockAction.WITHDRAW, block.timestamp);
    }

/// ~~~~~~~~~~~~~~~~~~~~~~~~~~ ///
    ///         DELEGATION         ///
    /// ~~~~~~~~~~~~~~~~~~~~~~~~~~ ///

// See IVotingEscrow for documentation
    function delegate(address _addr)
        external
        override
        nonReentrant
        checkBlocklist
    {
        LockedBalance memory locked_ = locked[msg.sender];
        // Validate inputs
        require(!IBlocklist(blocklist).isBlocked(_addr), "Blocked contract");
        require(locked_.amount > 0, "No lock");
        require(locked_.delegatee != _addr, "Already delegated");
        // Update locks
        int128 value = locked_.amount;
        address delegatee = locked_.delegatee;
        LockedBalance memory fromLocked;
        LockedBalance memory toLocked;
        locked_.delegatee = _addr;
        if (delegatee == msg.sender) {
            // Delegate
            fromLocked = locked_;
            toLocked = locked[_addr];
        } else if (_addr == msg.sender) {
            // Undelegate
            fromLocked = locked[delegatee];
            toLocked = locked_;
        } else {
            // Re-delegate
            fromLocked = locked[delegatee];
            toLocked = locked[_addr];
            // Update owner lock if not involved in delegation
            locked[msg.sender] = locked_;
        }
        require(toLocked.amount > 0, "Delegatee has no lock");
        require(toLocked.end > block.timestamp, "Delegatee lock expired");
        require(toLocked.end >= fromLocked.end, "Only delegate to longer lock");
        _delegate(delegatee, fromLocked, value, LockAction.UNDELEGATE);
        _delegate(_addr, toLocked, value, LockAction.DELEGATE);
    }

// Delegates from/to lock and voting power
    function _delegate(
        address addr,
        LockedBalance memory _locked,
        int128 value,
        LockAction action
    ) internal {
        LockedBalance memory newLocked = _copyLock(_locked);
        if (action == LockAction.DELEGATE) {
            newLocked.delegated += value;
            emit Deposit(
                addr,
                uint256(int256(value)),
                newLocked.end,
                action,
                block.timestamp
            );
        } else {
            newLocked.delegated -= value;
            emit Withdraw(
                addr,
                uint256(int256(value)),
                action,
                block.timestamp
            );
        }
        locked[addr] = newLocked;
        if (newLocked.amount > 0) {
            // Only if lock (from lock) hasn't been withdrawn/quitted
            _checkpoint(addr, _locked, newLocked);
        }
    }

/// ~~~~~~~~~~~~~~~~~~~~~~~~~~ ///
    ///         QUIT LOCK          ///
    /// ~~~~~~~~~~~~~~~~~~~~~~~~~~ ///

// See IVotingEscrow for documentation
    function quitLock() external override nonReentrant {
        LockedBalance memory locked_ = locked[msg.sender];
        // Validate inputs
        require(locked_.amount > 0, "No lock");
        require(locked_.end > block.timestamp, "Lock expired");
        require(locked_.delegatee == msg.sender, "Lock delegated");
        // Update lock
        uint256 value = uint256(uint128(locked_.amount));
        LockedBalance memory newLocked = _copyLock(locked_);
        newLocked.amount = 0;
        newLocked.delegated -= int128(int256(value));
        newLocked.delegatee = address(0);
        locked[msg.sender] = newLocked;
        newLocked.end = 0;
        newLocked.delegated = 0;
        // oldLocked can have either expired <= timestamp or zero end
        // currentLock has only 0 end
        // Both can have >= 0 amount
        _checkpoint(msg.sender, locked_, newLocked);
        // apply penalty
        uint256 penaltyRate = _calculatePenaltyRate(locked_.end);
        uint256 penaltyAmount = (value * penaltyRate) / 10**18; // quitlock_penalty is in 18 decimals precision
        penaltyAccumulated += penaltyAmount;
        uint256 remainingAmount = value - penaltyAmount;
        // Send back remaining tokens
        require(token.transfer(msg.sender, remainingAmount), "Transfer failed");
        emit Withdraw(msg.sender, value, LockAction.QUIT, block.timestamp);
    }

// Calculate penalty rate (decreasing linearly)
    function _calculatePenaltyRate(uint256 end)
        internal
        view
        returns (uint256)
    {
        // We know that end > block.timestamp because expired locks cannot be quitted
        return ((end - block.timestamp) * maxPenalty) / MAXTIME;
    }

/// @notice Collect accumulated penalty from quitters
    /// @dev Everyone can collect but penalty is sent to `penaltyRecipient`
    function collectPenalty() external {
        uint256 amount = penaltyAccumulated;
        penaltyAccumulated = 0;
        require(token.transfer(penaltyRecipient, amount), "Transfer failed");
        emit CollectPenalty(amount, penaltyRecipient);
    }

/// ~~~~~~~~~~~~~~~~~~~~~~~~~~ ///
    ///            GETTERS         ///
    /// ~~~~~~~~~~~~~~~~~~~~~~~~~~ ///

// Creates a copy of a lock
    function _copyLock(LockedBalance memory _locked)
        internal
        pure
        returns (LockedBalance memory)
    {
        return
            LockedBalance({
                amount: _locked.amount,
                end: _locked.end,
                delegatee: _locked.delegatee,
                delegated: _locked.delegated
            });
    }

// @dev Floors a timestamp to the nearest weekly increment
    // @param _t Timestamp to floor
    function _floorToWeek(uint256 _t) internal pure returns (uint256) {
        return (_t / WEEK) * WEEK;
    }

// @dev Uses binarysearch to find the most recent point history preceeding block
    // @param _block Find the most recent point history before this block
    // @param _maxEpoch Do not search pointHistories past this index
    function _findBlockEpoch(uint256 _block, uint256 _maxEpoch)
        internal
        view
        returns (uint256)
    {
        // Binary search
        uint256 min = 0;
        uint256 max = _maxEpoch;
        // Will be always enough for 128-bit numbers
        for (uint256 i = 0; i < 128; i++) {
            if (min >= max) break;
            uint256 mid = (min + max + 1) / 2;
            if (pointHistory[mid].blk <= _block) {
                min = mid;
            } else {
                max = mid - 1;
            }
        }
        return min;
    }

// @dev Uses binarysearch to find the most recent user point history preceeding block
    // @param _addr User for which to search
    // @param _block Find the most recent point history before this block
    function _findUserBlockEpoch(address _addr, uint256 _block)
        internal
        view
        returns (uint256)
    {
        uint256 min = 0;
        uint256 max = userPointEpoch[_addr];
        for (uint256 i = 0; i < 128; i++) {
            if (min >= max) {
                break;
            }
            uint256 mid = (min + max + 1) / 2;
            if (userPointHistory[_addr][mid].blk <= _block) {
                min = mid;
            } else {
                max = mid - 1;
            }
        }
        return min;
    }

// See IVotingEscrow for documentation
    function balanceOf(address _owner) public view override returns (uint256) {
        uint256 epoch = userPointEpoch[_owner];
        if (epoch == 0) {
            return 0;
        }
        Point memory lastPoint = userPointHistory[_owner][epoch];
        lastPoint.bias =
            lastPoint.bias -
            (lastPoint.slope * int128(int256(block.timestamp - lastPoint.ts)));
        if (lastPoint.bias < 0) {
            lastPoint.bias = 0;
        }
        return uint256(uint128(lastPoint.bias));
    }

// See IVotingEscrow for documentation
    function balanceOfAt(address _owner, uint256 _blockNumber)
        public
        view
        override
        returns (uint256)
    {
        require(_blockNumber <= block.number, "Only past block number");

// Get most recent global Point to block
        uint256 maxEpoch = globalEpoch;
        uint256 epoch = _findBlockEpoch(_blockNumber, maxEpoch);
        Point memory point0 = pointHistory[epoch];

// Calculate delta (block & time) between user Point and target block
        // Allowing us to calculate the average seconds per block between
        // the two points
        uint256 dBlock = 0;
        uint256 dTime = 0;
        if (epoch < maxEpoch) {
            Point memory point1 = pointHistory[epoch + 1];
            dBlock = point1.blk - point0.blk;
            dTime = point1.ts - point0.ts;
        } else {
            dBlock = block.number - point0.blk;
            dTime = block.timestamp - point0.ts;
        }
        // (Deterministically) Estimate the time at which block _blockNumber was mined
        uint256 blockTime = point0.ts;
        if (dBlock != 0) {
            blockTime =
                blockTime +
                ((dTime * (_blockNumber - point0.blk)) / dBlock);
        }
        // Current Bias = most recent bias - (slope * time since update)
        upoint.bias =
            upoint.bias -
            (upoint.slope * int128(int256(blockTime - upoint.ts)));
        if (upoint.bias >= 0) {
            return uint256(uint128(upoint.bias));
        } else {
            return 0;
        }
    }

/// @notice Calculate total supply of voting power at a given time _t
    /// @param _point Most recent point before time _t
    /// @param _t Time at which to calculate supply
    /// @return totalSupply at given point in time
    function _supplyAt(Point memory _point, uint256 _t)
        internal
        view
        returns (uint256)
    {
        Point memory lastPoint = _point;
        // Floor the timestamp to weekly interval
        uint256 iterativeTime = _floorToWeek(lastPoint.ts);
        // Iterate through all weeks between _point & _t to account for slope changes
        for (uint256 i = 0; i < 255; i++) {
            iterativeTime = iterativeTime + WEEK;
            int128 dSlope = 0;
            // If week end is after timestamp, then truncate & leave dSlope to 0
            if (iterativeTime > _t) {
                iterativeTime = _t;
            }
            // else get most recent slope change
            else {
                dSlope = slopeChanges[iterativeTime];
            }

lastPoint.bias =
                lastPoint.bias -
                (lastPoint.slope *
                    int128(int256(iterativeTime - lastPoint.ts)));
            if (iterativeTime == _t) {
                break;
            }
            lastPoint.slope = lastPoint.slope + dSlope;
            lastPoint.ts = iterativeTime;
        }

if (lastPoint.bias < 0) {
            lastPoint.bias = 0;
        }
        return uint256(uint128(lastPoint.bias));
    }

// See IVotingEscrow for documentation
    function totalSupply() public view override returns (uint256) {
        uint256 epoch_ = globalEpoch;
        Point memory lastPoint = pointHistory[epoch_];
        return _supplyAt(lastPoint, block.timestamp);
    }

// See IVotingEscrow for documentation
    function totalSupplyAt(uint256 _blockNumber)
        public
        view
        override
        returns (uint256)
    {
        require(_blockNumber <= block.number, "Only past block number");

uint256 epoch = globalEpoch;
        uint256 targetEpoch = _findBlockEpoch(_blockNumber, epoch);

Point memory point = pointHistory[targetEpoch];

// If point.blk > _blockNumber that means we got the initial epoch & contract did not yet exist
        if (point.blk > _blockNumber) {
            return 0;
        }