creation_sourcecode: # pragma version 0.3.10
  # pragma optimize gas
  # pragma evm-version shanghai
  """
  @title LiquidityGaugeV6
  @author Curve.Fi
  @license Copyright (c) Curve.Fi, 2020-2023 - all rights reserved
  @notice Implementation contract for use with Curve Factory
  @dev Differs from v5.0.0 in that it uses create_from_blueprint to deploy Gauges
  """
  from vyper.interfaces import ERC20
  
  implements: ERC20
  
  
  interface CRV20:
      def future_epoch_time_write() -> uint256: nonpayable
      def rate() -> uint256: view
  
  interface Controller:
      def checkpoint_gauge(addr: address): nonpayable
      def gauge_relative_weight(addr: address, time: uint256) -> uint256: view
  
  interface ERC20Extended:
      def symbol() -> String[32]: view
  
  interface ERC1271:
      def isValidSignature(_hash: bytes32, _signature: Bytes[65]) -> bytes32: view
  
  interface Factory:
      def admin() -> address: view
  
  interface Minter:
      def minted(user: address, gauge: address) -> uint256: view
  
  interface VotingEscrow:
      def user_point_epoch(addr: address) -> uint256: view
      def user_point_history__ts(addr: address, epoch: uint256) -> uint256: view
  
  interface VotingEscrowBoost:
      def adjusted_balance_of(_account: address) -> uint256: view
  
  
  event Deposit:
      provider: indexed(address)
      value: uint256
  
  event Withdraw:
      provider: indexed(address)
      value: uint256
  
  event UpdateLiquidityLimit:
      user: indexed(address)
      original_balance: uint256
      original_supply: uint256
      working_balance: uint256
      working_supply: uint256
  
  event CommitOwnership:
      admin: address
  
  event ApplyOwnership:
      admin: address
  
  event SetGaugeManager:
      _gauge_manager: address
  
  
  event Transfer:
      _from: indexed(address)
      _to: indexed(address)
      _value: uint256
  
  event Approval:
      _owner: indexed(address)
      _spender: indexed(address)
      _value: uint256
  
  
  struct Reward:
      token: address
      distributor: address
      period_finish: uint256
      rate: uint256
      last_update: uint256
      integral: uint256
  
  
  MAX_REWARDS: constant(uint256) = 8
  TOKENLESS_PRODUCTION: constant(uint256) = 40
  WEEK: constant(uint256) = 604800
  
  VERSION: constant(String[8]) = "v6.1.0"  # <- updated from v6.0.0 (makes rewards semi-permissionless)
  
  EIP712_TYPEHASH: constant(bytes32) = keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)")
  EIP2612_TYPEHASH: constant(bytes32) = keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)")
  
  VERSION_HASH: constant(bytes32) = keccak256(VERSION)
  NAME_HASH: immutable(bytes32)
  CACHED_CHAIN_ID: immutable(uint256)
  salt: public(immutable(bytes32))
  CACHED_DOMAIN_SEPARATOR: immutable(bytes32)
  
  CRV: constant(address) = 0xD533a949740bb3306d119CC777fa900bA034cd52
  GAUGE_CONTROLLER: constant(address) = 0x2F50D538606Fa9EDD2B11E2446BEb18C9D5846bB
  MINTER: constant(address) = 0xd061D61a4d941c39E5453435B6345Dc261C2fcE0
  VEBOOST_PROXY: constant(address) = 0x8E0c00ed546602fD9927DF742bbAbF726D5B0d16
  VOTING_ESCROW: constant(address) = 0x5f3b5DfEb7B28CDbD7FAba78963EE202a494e2A2
  
  
  # ERC20
  balanceOf: public(HashMap[address, uint256])
  totalSupply: public(uint256)
  allowance: public(HashMap[address, HashMap[address, uint256]])
  
  name: public(String[64])
  symbol: public(String[40])
  
  # ERC2612
  nonces: public(HashMap[address, uint256])
  
  # Gauge
  factory: public(address)
  manager: public(address)
  lp_token: public(address)
  
  is_killed: public(bool)
  
  # [future_epoch_time uint40][inflation_rate uint216]
  inflation_params: uint256
  
  # For tracking external rewards
  reward_count: public(uint256)
  reward_data: public(HashMap[address, Reward])
  
  # claimant -> default reward receiver
  rewards_receiver: public(HashMap[address, address])
  
  # reward token -> claiming address -> integral
  reward_integral_for: public(HashMap[address, HashMap[address, uint256]])
  
  # user -> [uint128 claimable amount][uint128 claimed amount]
  claim_data: HashMap[address, HashMap[address, uint256]]
  
  working_balances: public(HashMap[address, uint256])
  working_supply: public(uint256)
  
  # 1e18 * ∫(rate(t) / totalSupply(t) dt) from (last_action) till checkpoint
  integrate_inv_supply_of: public(HashMap[address, uint256])
  integrate_checkpoint_of: public(HashMap[address, uint256])
  
  # ∫(balance * rate(t) / totalSupply(t) dt) from 0 till checkpoint
  # Units: rate * t = already number of coins per address to issue
  integrate_fraction: public(HashMap[address, uint256])
  
  # The goal is to be able to calculate ∫(rate * balance / totalSupply dt) from 0 till checkpoint
  # All values are kept in units of being multiplied by 1e18
  period: public(int128)
  
  # array of reward tokens
  reward_tokens: public(address[MAX_REWARDS])
  
  period_timestamp: public(uint256[100000000000000000000000000000])
  # 1e18 * ∫(rate(t) / totalSupply(t) dt) from 0 till checkpoint
  integrate_inv_supply: public(uint256[100000000000000000000000000000])  # bump epoch when rate() changes
  
  
  @external
  def __init__(_lp_token: address):
      """
      @notice Contract constructor
      @param _lp_token Liquidity Pool contract address
      """
      self.lp_token = _lp_token
      self.factory = msg.sender
      self.manager = tx.origin
  
      symbol: String[32] = ERC20Extended(_lp_token).symbol()
      name: String[64] = concat("Curve.fi ", symbol, " Gauge Deposit")
  
      self.name = name
      self.symbol = concat(symbol, "-gauge")
  
      self.period_timestamp[0] = block.timestamp
      self.inflation_params = (
          (CRV20(CRV).future_epoch_time_write() << 216)
          + CRV20(CRV).rate()
      )
  
      NAME_HASH = keccak256(name)
      salt = block.prevhash
      CACHED_CHAIN_ID = chain.id
      CACHED_DOMAIN_SEPARATOR = keccak256(
          _abi_encode(
              EIP712_TYPEHASH,
              NAME_HASH,
              VERSION_HASH,
              chain.id,
              self,
              salt,
          )
      )
  
  
  # Internal Functions
  
  @view
  @internal
  def _domain_separator() -> bytes32:
      if chain.id != CACHED_CHAIN_ID:
          return keccak256(
              _abi_encode(
                  EIP712_TYPEHASH,
                  NAME_HASH,
                  VERSION_HASH,
                  chain.id,
                  self,
                  salt,
              )
          )
      return CACHED_DOMAIN_SEPARATOR
  
  
  @internal
  def _checkpoint(addr: address):
      """
      @notice Checkpoint for a user
      @dev Updates the CRV emissions a user is entitled to receive
      @param addr User address
      """
      _period: int128 = self.period
      _period_time: uint256 = self.period_timestamp[_period]
      _integrate_inv_supply: uint256 = self.integrate_inv_supply[_period]
  
      inflation_params: uint256 = self.inflation_params
      prev_future_epoch: uint256 = inflation_params >> 216
      gauge_is_killed: bool = self.is_killed
  
      rate: uint256 = inflation_params % 2 ** 216
      new_rate: uint256 = rate
      if gauge_is_killed:
          rate = 0
          new_rate = 0
  
      if prev_future_epoch >= _period_time:
          future_epoch_time_write: uint256 = CRV20(CRV).future_epoch_time_write()
          if not gauge_is_killed:
              new_rate = CRV20(CRV).rate()
          self.inflation_params = (future_epoch_time_write << 216) + new_rate
  
      # Update integral of 1/supply
      if block.timestamp > _period_time:
          _working_supply: uint256 = self.working_supply
          Controller(GAUGE_CONTROLLER).checkpoint_gauge(self)
          prev_week_time: uint256 = _period_time
          week_time: uint256 = min((_period_time + WEEK) / WEEK * WEEK, block.timestamp)
  
          for i in range(500):
              dt: uint256 = week_time - prev_week_time
              w: uint256 = Controller(GAUGE_CONTROLLER).gauge_relative_weight(self, prev_week_time)
  
              if _working_supply > 0:
                  if prev_future_epoch >= prev_week_time and prev_future_epoch < week_time:
                      # If we went across one or multiple epochs, apply the rate
                      # of the first epoch until it ends, and then the rate of
                      # the last epoch.
                      # If more than one epoch is crossed - the gauge gets less,
                      # but that'd meen it wasn't called for more than 1 year
                      _integrate_inv_supply += rate * w * (prev_future_epoch - prev_week_time) / _working_supply
                      rate = new_rate
                      _integrate_inv_supply += rate * w * (week_time - prev_future_epoch) / _working_supply
                  else:
                      _integrate_inv_supply += rate * w * dt / _working_supply
                  # On precisions of the calculation
                  # rate ~= 10e18
                  # last_weight > 0.01 * 1e18 = 1e16 (if pool weight is 1%)
                  # _working_supply ~= TVL * 1e18 ~= 1e26 ($100M for example)
                  # The largest loss is at dt = 1
                  # Loss is 1e-9 - acceptable
  
              if week_time == block.timestamp:
                  break
              prev_week_time = week_time
              week_time = min(week_time + WEEK, block.timestamp)
  
      _period += 1
      self.period = _period
      self.period_timestamp[_period] = block.timestamp
      self.integrate_inv_supply[_period] = _integrate_inv_supply
  
      # Update user-specific integrals
      _working_balance: uint256 = self.working_balances[addr]
      self.integrate_fraction[addr] += _working_balance * (_integrate_inv_supply - self.integrate_inv_supply_of[addr]) / 10 ** 18
      self.integrate_inv_supply_of[addr] = _integrate_inv_supply
      self.integrate_checkpoint_of[addr] = block.timestamp
  
  
  @internal
  def _checkpoint_rewards(_user: address, _total_supply: uint256, _claim: bool, _receiver: address):
      """
      @notice Claim pending rewards and checkpoint rewards for a user
      """
  
      user_balance: uint256 = 0
      receiver: address = _receiver
      if _user != empty(address):
          user_balance = self.balanceOf[_user]
          if _claim and _receiver == empty(address):
              # if receiver is not explicitly declared, check if a default receiver is set
              receiver = self.rewards_receiver[_user]
              if receiver == empty(address):
                  # if no default receiver is set, direct claims to the user
                  receiver = _user
  
      reward_count: uint256 = self.reward_count
      for i in range(MAX_REWARDS):
          if i == reward_count:
              break
          token: address = self.reward_tokens[i]
  
          integral: uint256 = self.reward_data[token].integral
          last_update: uint256 = min(block.timestamp, self.reward_data[token].period_finish)
          duration: uint256 = last_update - self.reward_data[token].last_update
  
          if duration != 0 and _total_supply != 0:
              self.reward_data[token].last_update = last_update
              integral += duration * self.reward_data[token].rate * 10**18 / _total_supply
              self.reward_data[token].integral = integral
  
          if _user != empty(address):
              integral_for: uint256 = self.reward_integral_for[token][_user]
              new_claimable: uint256 = 0
  
              if integral_for < integral:
                  self.reward_integral_for[token][_user] = integral
                  new_claimable = user_balance * (integral - integral_for) / 10**18
  
              claim_data: uint256 = self.claim_data[_user][token]
              total_claimable: uint256 = (claim_data >> 128) + new_claimable
              if total_claimable > 0:
                  total_claimed: uint256 = claim_data % 2**128
                  if _claim:
                      assert ERC20(token).transfer(receiver, total_claimable, default_return_value=True)
                      self.claim_data[_user][token] = total_claimed + total_claimable
                  elif new_claimable > 0:
                      self.claim_data[_user][token] = total_claimed + (total_claimable << 128)
  
  
  @internal
  def _update_liquidity_limit(addr: address, l: uint256, L: uint256):
      """
      @notice Calculate limits which depend on the amount of CRV token per-user.
              Effectively it calculates working balances to apply amplification
              of CRV production by CRV
      @param addr User address
      @param l User's amount of liquidity (LP tokens)
      @param L Total amount of liquidity (LP tokens)
      """
      # To be called after totalSupply is updated
      voting_balance: uint256 = VotingEscrowBoost(VEBOOST_PROXY).adjusted_balance_of(addr)
      voting_total: uint256 = ERC20(VOTING_ESCROW).totalSupply()
  
      lim: uint256 = l * TOKENLESS_PRODUCTION / 100
      if voting_total > 0:
          lim += L * voting_balance / voting_total * (100 - TOKENLESS_PRODUCTION) / 100
  
      lim = min(l, lim)
      old_bal: uint256 = self.working_balances[addr]
      self.working_balances[addr] = lim
      _working_supply: uint256 = self.working_supply + lim - old_bal
      self.working_supply = _working_supply
  
      log UpdateLiquidityLimit(addr, l, L, lim, _working_supply)
  
  
  @internal
  def _transfer(_from: address, _to: address, _value: uint256):
      """
      @notice Transfer tokens as well as checkpoint users
      """
      self._checkpoint(_from)
      self._checkpoint(_to)
  
      if _value != 0:
          total_supply: uint256 = self.totalSupply
          is_rewards: bool = self.reward_count != 0
          if is_rewards:
              self._checkpoint_rewards(_from, total_supply, False, empty(address))
          new_balance: uint256 = self.balanceOf[_from] - _value
          self.balanceOf[_from] = new_balance
          self._update_liquidity_limit(_from, new_balance, total_supply)
  
          if is_rewards:
              self._checkpoint_rewards(_to, total_supply, False, empty(address))
          new_balance = self.balanceOf[_to] + _value
          self.balanceOf[_to] = new_balance
          self._update_liquidity_limit(_to, new_balance, total_supply)
  
      log Transfer(_from, _to, _value)
  
  
  # External User Facing Functions
  
  
  @external
  @nonreentrant('lock')
  def deposit(_value: uint256, _addr: address = msg.sender, _claim_rewards: bool = False):
      """
      @notice Deposit `_value` LP tokens
      @dev Depositting also claims pending reward tokens
      @param _value Number of tokens to deposit
      @param _addr Address to deposit for
      """
      assert _addr != empty(address)  # dev: cannot deposit for zero address
      self._checkpoint(_addr)
  
      if _value != 0:
          is_rewards: bool = self.reward_count != 0
          total_supply: uint256 = self.totalSupply
          if is_rewards:
              self._checkpoint_rewards(_addr, total_supply, _claim_rewards, empty(address))
  
          total_supply += _value
          new_balance: uint256 = self.balanceOf[_addr] + _value
          self.balanceOf[_addr] = new_balance
          self.totalSupply = total_supply
  
          self._update_liquidity_limit(_addr, new_balance, total_supply)
  
          ERC20(self.lp_token).transferFrom(msg.sender, self, _value)
  
          log Deposit(_addr, _value)
          log Transfer(empty(address), _addr, _value)
  
  
  @external
  @nonreentrant('lock')
  def withdraw(_value: uint256, _claim_rewards: bool = False):
      """
      @notice Withdraw `_value` LP tokens
      @dev Withdrawing also claims pending reward tokens
      @param _value Number of tokens to withdraw
      """
      self._checkpoint(msg.sender)
  
      if _value != 0:
          is_rewards: bool = self.reward_count != 0
          total_supply: uint256 = self.totalSupply
          if is_rewards:
              self._checkpoint_rewards(msg.sender, total_supply, _claim_rewards, empty(address))
  
          total_supply -= _value
          new_balance: uint256 = self.balanceOf[msg.sender] - _value
          self.balanceOf[msg.sender] = new_balance
          self.totalSupply = total_supply
  
          self._update_liquidity_limit(msg.sender, new_balance, total_supply)
  
          ERC20(self.lp_token).transfer(msg.sender, _value)
  
      log Withdraw(msg.sender, _value)
      log Transfer(msg.sender, empty(address), _value)
  
  
  @external
  @nonreentrant('lock')
  def claim_rewards(_addr: address = msg.sender, _receiver: address = empty(address)):
      """
      @notice Claim available reward tokens for `_addr`
      @param _addr Address to claim for
      @param _receiver Address to transfer rewards to - if set to
                       empty(address), uses the default reward receiver
                       for the caller
      """
      if _receiver != empty(address):
          assert _addr == msg.sender  # dev: cannot redirect when claiming for another user
      self._checkpoint_rewards(_addr, self.totalSupply, True, _receiver)
  
  
  @external
  @nonreentrant('lock')
  def transferFrom(_from: address, _to :address, _value: uint256) -> bool:
      """
       @notice Transfer tokens from one address to another.
       @dev Transferring claims pending reward tokens for the sender and receiver
       @param _from address The address which you want to send tokens from
       @param _to address The address which you want to transfer to
       @param _value uint256 the amount of tokens to be transferred
      """
      _allowance: uint256 = self.allowance[_from][msg.sender]
      if _allowance != max_value(uint256):
          self.allowance[_from][msg.sender] = _allowance - _value
  
      self._transfer(_from, _to, _value)
  
      return True
  
  
  @external
  @nonreentrant('lock')
  def transfer(_to: address, _value: uint256) -> bool:
      """
      @notice Transfer token for a specified address
      @dev Transferring claims pending reward tokens for the sender and receiver
      @param _to The address to transfer to.
      @param _value The amount to be transferred.
      """
      self._transfer(msg.sender, _to, _value)
  
      return True
  
  
  @external
  def approve(_spender : address, _value : uint256) -> bool:
      """
      @notice Approve the passed address to transfer the specified amount of
              tokens on behalf of msg.sender
      @dev Beware that changing an allowance via this method brings the risk
           that someone may use both the old and new allowance by unfortunate
           transaction ordering. This may be mitigated with the use of
           {incraseAllowance} and {decreaseAllowance}.
           https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
      @param _spender The address which will transfer the funds
      @param _value The amount of tokens that may be transferred
      @return bool success
      """
      self.allowance[msg.sender][_spender] = _value
      log Approval(msg.sender, _spender, _value)
  
      return True
  
  
  @external
  def permit(
      _owner: address,
      _spender: address,
      _value: uint256,
      _deadline: uint256,
      _v: uint8,
      _r: bytes32,
      _s: bytes32
  ) -> bool:
      """
      @notice Approves spender by owner's signature to expend owner's tokens.
          See https://eips.ethereum.org/EIPS/eip-2612.
      @dev Inspired by https://github.com/yearn/yearn-vaults/blob/main/contracts/Vault.vy#L753-L793
      @dev Supports smart contract wallets which implement ERC1271
          https://eips.ethereum.org/EIPS/eip-1271
      @param _owner The address which is a source of funds and has signed the Permit.
      @param _spender The address which is allowed to spend the funds.
      @param _value The amount of tokens to be spent.
      @param _deadline The timestamp after which the Permit is no longer valid.
      @param _v The bytes[64] of the valid secp256k1 signature of permit by owner
      @param _r The bytes[0:32] of the valid secp256k1 signature of permit by owner
      @param _s The bytes[32:64] of the valid secp256k1 signature of permit by owner
      @return True, if transaction completes successfully
      """
      assert _owner != empty(address)  # dev: invalid owner
      assert block.timestamp <= _deadline  # dev: permit expired
  
      nonce: uint256 = self.nonces[_owner]
      digest: bytes32 = keccak256(
          concat(
              b"\x19\x01",
              self._domain_separator(),
              keccak256(
                  _abi_encode(
                      EIP2612_TYPEHASH, _owner, _spender, _value, nonce, _deadline
                  )
              ),
          )
      )
      assert ecrecover(digest, _v, _r, _s) == _owner  # dev: invalid signature
  
      self.allowance[_owner][_spender] = _value
      self.nonces[_owner] = unsafe_add(nonce, 1)
  
      log Approval(_owner, _spender, _value)
      return True
  
  
  @external
  def increaseAllowance(_spender: address, _added_value: uint256) -> bool:
      """
      @notice Increase the allowance granted to `_spender` by the caller
      @dev This is alternative to {approve} that can be used as a mitigation for
           the potential race condition
      @param _spender The address which will transfer the funds
      @param _added_value The amount of to increase the allowance
      @return bool success
      """
      allowance: uint256 = self.allowance[msg.sender][_spender] + _added_value
      self.allowance[msg.sender][_spender] = allowance
  
      log Approval(msg.sender, _spender, allowance)
  
      return True
  
  
  @external
  def decreaseAllowance(_spender: address, _subtracted_value: uint256) -> bool:
      """
      @notice Decrease the allowance granted to `_spender` by the caller
      @dev This is alternative to {approve} that can be used as a mitigation for
           the potential race condition
      @param _spender The address which will transfer the funds
      @param _subtracted_value The amount of to decrease the allowance
      @return bool success
      """
      allowance: uint256 = self.allowance[msg.sender][_spender] - _subtracted_value
      self.allowance[msg.sender][_spender] = allowance
  
      log Approval(msg.sender, _spender, allowance)
  
      return True
  
  
  @external
  def user_checkpoint(addr: address) -> bool:
      """
      @notice Record a checkpoint for `addr`
      @param addr User address
      @return bool success
      """
      assert msg.sender in [addr, MINTER]  # dev: unauthorized
      self._checkpoint(addr)
      self._update_liquidity_limit(addr, self.balanceOf[addr], self.totalSupply)
      return True
  
  
  @external
  def set_rewards_receiver(_receiver: address):
      """
      @notice Set the default reward receiver for the caller.
      @dev When set to empty(address), rewards are sent to the caller
      @param _receiver Receiver address for any rewards claimed via `claim_rewards`
      """
      self.rewards_receiver[msg.sender] = _receiver
  
  
  @external
  def kick(addr: address):
      """
      @notice Kick `addr` for abusing their boost
      @dev Only if either they had another voting event, or their voting escrow lock expired
      @param addr Address to kick
      """
      t_last: uint256 = self.integrate_checkpoint_of[addr]
      t_ve: uint256 = VotingEscrow(VOTING_ESCROW).user_point_history__ts(
          addr, VotingEscrow(VOTING_ESCROW).user_point_epoch(addr)
      )
      _balance: uint256 = self.balanceOf[addr]
  
      assert ERC20(VOTING_ESCROW).balanceOf(addr) == 0 or t_ve > t_last # dev: kick not allowed
      assert self.working_balances[addr] > _balance * TOKENLESS_PRODUCTION / 100  # dev: kick not needed
  
      self._checkpoint(addr)
      self._update_liquidity_limit(addr, self.balanceOf[addr], self.totalSupply)
  
  
  # Administrative Functions
  
  
  @external
  def set_gauge_manager(_gauge_manager: address):
      """
      @notice Change the gauge manager for a gauge
      @dev The manager of this contract, or the ownership admin can outright modify gauge
          managership. A gauge manager can also transfer managership to a new manager via this
          method, but only for the gauge which they are the manager of.
      @param _gauge_manager The account to set as the new manager of the gauge.
      """
      assert msg.sender in [self.manager, Factory(self.factory).admin()]  # dev: only manager or factory admin
  
      self.manager = _gauge_manager
      log SetGaugeManager(_gauge_manager)
  
  
  @external
  @nonreentrant("lock")
  def deposit_reward_token(_reward_token: address, _amount: uint256, _epoch: uint256 = WEEK):
      """
      @notice Deposit a reward token for distribution
      @param _reward_token The reward token being deposited
      @param _amount The amount of `_reward_token` being deposited
      @param _epoch The duration the rewards are distributed across.
      """
      assert msg.sender == self.reward_data[_reward_token].distributor
  
      self._checkpoint_rewards(empty(address), self.totalSupply, False, empty(address))
  
      # transferFrom reward token and use transferred amount henceforth:
      amount_received: uint256 = ERC20(_reward_token).balanceOf(self)
      assert ERC20(_reward_token).transferFrom(
          msg.sender,
          self,
          _amount,
          default_return_value=True
      )
      amount_received = ERC20(_reward_token).balanceOf(self) - amount_received
  
      period_finish: uint256 = self.reward_data[_reward_token].period_finish
      assert amount_received > _epoch  # dev: rate will tend to zero!
  
      if block.timestamp >= period_finish:
          self.reward_data[_reward_token].rate = amount_received / _epoch
      else:
          remaining: uint256 = period_finish - block.timestamp
          leftover: uint256 = remaining * self.reward_data[_reward_token].rate
          self.reward_data[_reward_token].rate = (amount_received + leftover) / _epoch
  
      self.reward_data[_reward_token].last_update = block.timestamp
      self.reward_data[_reward_token].period_finish = block.timestamp + _epoch
  
  
  @external
  def add_reward(_reward_token: address, _distributor: address):
      """
      @notice Add additional rewards to be distributed to stakers
      @param _reward_token The token to add as an additional reward
      @param _distributor Address permitted to fund this contract with the reward token
      """
      assert msg.sender in [self.manager, Factory(self.factory).admin()]  # dev: only manager or factory admin
      assert _distributor != empty(address)  # dev: distributor cannot be zero address
  
      reward_count: uint256 = self.reward_count
      assert reward_count < MAX_REWARDS
      assert self.reward_data[_reward_token].distributor == empty(address)
  
      self.reward_data[_reward_token].distributor = _distributor
      self.reward_tokens[reward_count] = _reward_token
      self.reward_count = reward_count + 1
  
  
  @external
  def set_reward_distributor(_reward_token: address, _distributor: address):
      """
      @notice Reassign the reward distributor for a reward token
      @param _reward_token The reward token to reassign distribution rights to
      @param _distributor The address of the new distributor
      """
      current_distributor: address = self.reward_data[_reward_token].distributor
  
      assert msg.sender in [current_distributor, Factory(self.factory).admin(), self.manager]
      assert current_distributor != empty(address)
      assert _distributor != empty(address)
  
      self.reward_data[_reward_token].distributor = _distributor
  
  
  @external
  def set_killed(_is_killed: bool):
      """
      @notice Set the killed status for this contract
      @dev When killed, the gauge always yields a rate of 0 and so cannot mint CRV
      @param _is_killed Killed status to set
      """
      assert msg.sender == Factory(self.factory).admin()  # dev: only owner
  
      self.is_killed = _is_killed
  
  
  # View Methods
  
  
  @view
  @external
  def claimed_reward(_addr: address, _token: address) -> uint256:
      """
      @notice Get the number of already-claimed reward tokens for a user
      @param _addr Account to get reward amount for
      @param _token Token to get reward amount for
      @return uint256 Total amount of `_token` already claimed by `_addr`
      """
      return self.claim_data[_addr][_token] % 2**128
  
  
  @view
  @external
  def claimable_reward(_user: address, _reward_token: address) -> uint256:
      """
      @notice Get the number of claimable reward tokens for a user
      @param _user Account to get reward amount for
      @param _reward_token Token to get reward amount for
      @return uint256 Claimable reward token amount
      """
      integral: uint256 = self.reward_data[_reward_token].integral
      total_supply: uint256 = self.totalSupply
      if total_supply != 0:
          last_update: uint256 = min(block.timestamp, self.reward_data[_reward_token].period_finish)
          duration: uint256 = last_update - self.reward_data[_reward_token].last_update
          integral += (duration * self.reward_data[_reward_token].rate * 10**18 / total_supply)
  
      integral_for: uint256 = self.reward_integral_for[_reward_token][_user]
      new_claimable: uint256 = self.balanceOf[_user] * (integral - integral_for) / 10**18
  
      return (self.claim_data[_user][_reward_token] >> 128) + new_claimable
  
  
  @external
  def claimable_tokens(addr: address) -> uint256:
      """
      @notice Get the number of claimable tokens per user
      @dev This function should be manually changed to "view" in the ABI
      @return uint256 number of claimable tokens per user
      """
      self._checkpoint(addr)
      return self.integrate_fraction[addr] - Minter(MINTER).minted(addr, self)
  
  
  @view
  @external
  def integrate_checkpoint() -> uint256:
      """
      @notice Get the timestamp of the last checkpoint
      """
      return self.period_timestamp[self.period]
  
  
  @view
  @external
  def future_epoch_time() -> uint256:
      """
      @notice Get the locally stored CRV future epoch start time
      """
      return self.inflation_params >> 216
  
  
  @view
  @external
  def inflation_rate() -> uint256:
      """
      @notice Get the locally stored CRV inflation rate
      """
      return self.inflation_params % 2 ** 216
  
  
  @view
  @external
  def decimals() -> uint256:
      """
      @notice Get the number of decimals for this token
      @dev Implemented as a view method to reduce gas costs
      @return uint256 decimal places
      """
      return 18
  
  
  @view
  @external
  def version() -> String[8]:
      """
      @notice Get the version of this gauge contract
      """
      return VERSION
  
  
  @view
  @external
  def DOMAIN_SEPARATOR() -> bytes32:
      """
      @notice EIP712 domain separator.
      """
      return self._domain_separator()