# @version 0.2.4
"""
@title Curve DAO Token
@author Curve Finance
@license MIT
@notice ERC20 with piecewise-linear mining supply.
@dev Based on the ERC-20 token standard as defined at
     https://eips.ethereum.org/EIPS/eip-20
"""

from vyper.interfaces import ERC20

implements: ERC20


event Transfer:
    _from: indexed(address)
    _to: indexed(address)
    _value: uint256

event Approval:
    _owner: indexed(address)
    _spender: indexed(address)
    _value: uint256

event UpdateMiningParameters:
    time: uint256
    rate: uint256
    supply: uint256

event SetMinter:
    minter: address

event SetAdmin:
    admin: address


name: public(String[64])
symbol: public(String[32])
decimals: public(uint256)

balanceOf: public(HashMap[address, uint256])
allowances: HashMap[address, HashMap[address, uint256]]
total_supply: uint256

minter: public(address)
admin: public(address)

# General constants
YEAR: constant(uint256) = 86400 * 365

# Allocation:
# =========
# * shareholders - 30%
# * emplyees - 3%
# * DAO-controlled reserve - 5%
# * Early users - 5%
# == 43% ==
# left for inflation: 57%

# Supply parameters
INITIAL_SUPPLY: constant(uint256) = 1_303_030_303
INITIAL_RATE: constant(uint256) = 274_815_283 * 10 ** 18 / YEAR  # leading to 43% premine
RATE_REDUCTION_TIME: constant(uint256) = YEAR
RATE_REDUCTION_COEFFICIENT: constant(uint256) = 1189207115002721024  # 2 ** (1/4) * 1e18
RATE_DENOMINATOR: constant(uint256) = 10 ** 18
INFLATION_DELAY: constant(uint256) = 86400

# Supply variables
mining_epoch: public(int128)
start_epoch_time: public(uint256)
rate: public(uint256)

start_epoch_supply: uint256


@external
def __init__(_name: String[64], _symbol: String[32], _decimals: uint256):
    """
    @notice Contract constructor
    @param _name Token full name
    @param _symbol Token symbol
    @param _decimals Number of decimals for token
    """
    init_supply: uint256 = INITIAL_SUPPLY * 10 ** _decimals
    self.name = _name
    self.symbol = _symbol
    self.decimals = _decimals
    self.balanceOf[msg.sender] = init_supply
    self.total_supply = init_supply
    self.admin = msg.sender
    log Transfer(ZERO_ADDRESS, msg.sender, init_supply)

    self.start_epoch_time = block.timestamp + INFLATION_DELAY - RATE_REDUCTION_TIME
    self.mining_epoch = -1
    self.rate = 0
    self.start_epoch_supply = init_supply


@internal
def _update_mining_parameters():
    """
    @dev Update mining rate and supply at the start of the epoch
         Any modifying mining call must also call this
    """
    _rate: uint256 = self.rate
    _start_epoch_supply: uint256 = self.start_epoch_supply

    self.start_epoch_time += RATE_REDUCTION_TIME
    self.mining_epoch += 1

    if _rate == 0:
        _rate = INITIAL_RATE
    else:
        _start_epoch_supply += _rate * RATE_REDUCTION_TIME
        self.start_epoch_supply = _start_epoch_supply
        _rate = _rate * RATE_DENOMINATOR / RATE_REDUCTION_COEFFICIENT

    self.rate = _rate

    log UpdateMiningParameters(block.timestamp, _rate, _start_epoch_supply)


@external
def update_mining_parameters():
    """
    @notice Update mining rate and supply at the start of the epoch
    @dev Callable by any address, but only once per epoch
         Total supply becomes slightly larger if this function is called late
    """
    assert block.timestamp >= self.start_epoch_time + RATE_REDUCTION_TIME  # dev: too soon!
    self._update_mining_parameters()


@external
def start_epoch_time_write() -> uint256:
    """
    @notice Get timestamp of the current mining epoch start
            while simultaneously updating mining parameters
    @return Timestamp of the epoch
    """
    _start_epoch_time: uint256 = self.start_epoch_time
    if block.timestamp >= _start_epoch_time + RATE_REDUCTION_TIME:
        self._update_mining_parameters()
        return self.start_epoch_time
    else:
        return _start_epoch_time


@external
def future_epoch_time_write() -> uint256:
    """
    @notice Get timestamp of the next mining epoch start
            while simultaneously updating mining parameters
    @return Timestamp of the next epoch
    """
    _start_epoch_time: uint256 = self.start_epoch_time
    if block.timestamp >= _start_epoch_time + RATE_REDUCTION_TIME:
        self._update_mining_parameters()
        return self.start_epoch_time + RATE_REDUCTION_TIME
    else:
        return _start_epoch_time + RATE_REDUCTION_TIME


@internal
@view
def _available_supply() -> uint256:
    return self.start_epoch_supply + (block.timestamp - self.start_epoch_time) * self.rate


@external
@view
def available_supply() -> uint256:
    """
    @notice Current number of tokens in existence (claimed or unclaimed)
    """
    return self._available_supply()


@external
@view
def mintable_in_timeframe(start: uint256, end: uint256) -> uint256:
    """
    @notice How much supply is mintable from start timestamp till end timestamp
    @param start Start of the time interval (timestamp)
    @param end End of the time interval (timestamp)
    @return Tokens mintable from `start` till `end`
    """
    assert start <= end  # dev: start > end
    to_mint: uint256 = 0
    current_epoch_time: uint256 = self.start_epoch_time
    current_rate: uint256 = self.rate

    # Special case if end is in future (not yet minted) epoch
    if end > current_epoch_time + RATE_REDUCTION_TIME:
        current_epoch_time += RATE_REDUCTION_TIME
        current_rate = current_rate * RATE_DENOMINATOR / RATE_REDUCTION_COEFFICIENT

    assert end <= current_epoch_time + RATE_REDUCTION_TIME  # dev: too far in future

    for i in range(999):  # Curve will not work in 1000 years. Darn!
        if end >= current_epoch_time:
            current_end: uint256 = end
            if current_end > current_epoch_time + RATE_REDUCTION_TIME:
                current_end = current_epoch_time + RATE_REDUCTION_TIME

            current_start: uint256 = start
            if current_start >= current_epoch_time + RATE_REDUCTION_TIME:
                break  # We should never get here but what if...
            elif current_start < current_epoch_time:
                current_start = current_epoch_time

            to_mint += current_rate * (current_end - current_start)

            if start >= current_epoch_time:
                break

        current_epoch_time -= RATE_REDUCTION_TIME
        current_rate = current_rate * RATE_REDUCTION_COEFFICIENT / RATE_DENOMINATOR  # double-division with rounding made rate a bit less => good
        assert current_rate <= INITIAL_RATE  # This should never happen

    return to_mint


@external
def set_minter(_minter: address):
    """
    @notice Set the minter address
    @dev Only callable once, when minter has not yet been set
    @param _minter Address of the minter
    """
    assert msg.sender == self.admin  # dev: admin only
    assert self.minter == ZERO_ADDRESS  # dev: can set the minter only once, at creation
    self.minter = _minter
    log SetMinter(_minter)


@external
def set_admin(_admin: address):
    """
    @notice Set the new admin.
    @dev After all is set up, admin only can change the token name
    @param _admin New admin address
    """
    assert msg.sender == self.admin  # dev: admin only
    self.admin = _admin
    log SetAdmin(_admin)


@external
@view
def totalSupply() -> uint256:
    """
    @notice Total number of tokens in existence.
    """
    return self.total_supply


@external
@view
def allowance(_owner : address, _spender : address) -> uint256:
    """
    @notice Check the amount of tokens that an owner allowed to a spender
    @param _owner The address which owns the funds
    @param _spender The address which will spend the funds
    @return uint256 specifying the amount of tokens still available for the spender
    """
    return self.allowances[_owner][_spender]


@external
def transfer(_to : address, _value : uint256) -> bool:
    """
    @notice Transfer `_value` tokens from `msg.sender` to `_to`
    @dev Vyper does not allow underflows, so the subtraction in
         this function will revert on an insufficient balance
    @param _to The address to transfer to
    @param _value The amount to be transferred
    @return bool success
    """
    assert _to != ZERO_ADDRESS  # dev: transfers to 0x0 are not allowed
    self.balanceOf[msg.sender] -= _value
    self.balanceOf[_to] += _value
    log Transfer(msg.sender, _to, _value)
    return True


@external
def transferFrom(_from : address, _to : address, _value : uint256) -> bool:
    """
     @notice Transfer `_value` tokens from `_from` to `_to`
     @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
     @return bool success
    """
    assert _to != ZERO_ADDRESS  # dev: transfers to 0x0 are not allowed
    # NOTE: vyper does not allow underflows
    #       so the following subtraction would revert on insufficient balance
    self.balanceOf[_from] -= _value
    self.balanceOf[_to] += _value
    self.allowances[_from][msg.sender] -= _value
    log Transfer(_from, _to, _value)
    return True


@external
def approve(_spender : address, _value : uint256) -> bool:
    """
    @notice Approve `_spender` to transfer `_value` tokens on behalf of `msg.sender`
    @dev Approval may only be from zero -> nonzero or from nonzero -> zero in order
        to mitigate the potential race condition described here:
        https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
    @param _spender The address which will spend the funds
    @param _value The amount of tokens to be spent
    @return bool success
    """
    assert _value == 0 or self.allowances[msg.sender][_spender] == 0
    self.allowances[msg.sender][_spender] = _value
    log Approval(msg.sender, _spender, _value)
    return True


@external
def mint(_to: address, _value: uint256) -> bool:
    """
    @notice Mint `_value` tokens and assign them to `_to`
    @dev Emits a Transfer event originating from 0x00
    @param _to The account that will receive the created tokens
    @param _value The amount that will be created
    @return bool success
    """
    assert msg.sender == self.minter  # dev: minter only
    assert _to != ZERO_ADDRESS  # dev: zero address

    if block.timestamp >= self.start_epoch_time + RATE_REDUCTION_TIME:
        self._update_mining_parameters()

    _total_supply: uint256 = self.total_supply + _value
    assert _total_supply <= self._available_supply()  # dev: exceeds allowable mint amount
    self.total_supply = _total_supply

    self.balanceOf[_to] += _value
    log Transfer(ZERO_ADDRESS, _to, _value)

    return True


@external
def burn(_value: uint256) -> bool:
    """
    @notice Burn `_value` tokens belonging to `msg.sender`
    @dev Emits a Transfer event with a destination of 0x00
    @param _value The amount that will be burned
    @return bool success
    """
    self.balanceOf[msg.sender] -= _value
    self.total_supply -= _value

    log Transfer(msg.sender, ZERO_ADDRESS, _value)
    return True


@external
def set_name(_name: String[64], _symbol: String[32]):
    """
    @notice Change the token name and symbol to `_name` and `_symbol`
    @dev Only callable by the admin account
    @param _name New token name
    @param _symbol New token symbol
    """
    assert msg.sender == self.admin, "Only admin is allowed to change name"
    self.name = _name
    self.symbol = _symbol

# @version 0.2.4

"""
@title Gauge Controller
@author Curve Finance
@license MIT
@notice Controls liquidity gauges and the issuance of coins through the gauges
"""

# 7 * 86400 seconds - all future times are rounded by week
WEEK: constant(uint256) = 604800

# Cannot change weight votes more often than once in 10 days
WEIGHT_VOTE_DELAY: constant(uint256) = 10 * 86400


struct Point:
    bias: uint256
    slope: uint256

struct VotedSlope:
    slope: uint256
    power: uint256
    end: uint256


interface VotingEscrow:
    def get_last_user_slope(addr: address) -> int128: view
    def locked__end(addr: address) -> uint256: view


event CommitOwnership:
    admin: address

event ApplyOwnership:
    admin: address

event AddType:
    name: String[64]
    type_id: int128

event NewTypeWeight:
    type_id: int128
    time: uint256
    weight: uint256
    total_weight: uint256

event NewGaugeWeight:
    gauge_address: address
    time: uint256
    weight: uint256
    total_weight: uint256

event VoteForGauge:
    time: uint256
    user: address
    gauge_addr: address
    weight: uint256

event NewGauge:
    addr: address
    gauge_type: int128
    weight: uint256


MULTIPLIER: constant(uint256) = 10 ** 18

admin: public(address)  # Can and will be a smart contract
future_admin: public(address)  # Can and will be a smart contract

token: public(address)  # CRV token
voting_escrow: public(address)  # Voting escrow

# Gauge parameters
# All numbers are "fixed point" on the basis of 1e18
n_gauge_types: public(int128)
n_gauges: public(int128)
gauge_type_names: public(HashMap[int128, String[64]])

# Needed for enumeration
gauges: public(address[1000000000])

# we increment values by 1 prior to storing them here so we can rely on a value
# of zero as meaning the gauge has not been set
gauge_types_: HashMap[address, int128]

vote_user_slopes: public(HashMap[address, HashMap[address, VotedSlope]])  # user -> gauge_addr -> VotedSlope
vote_user_power: public(HashMap[address, uint256])  # Total vote power used by user
last_user_vote: public(HashMap[address, HashMap[address, uint256]])  # Last user vote's timestamp for each gauge address

# Past and scheduled points for gauge weight, sum of weights per type, total weight
# Point is for bias+slope
# changes_* are for changes in slope
# time_* are for the last change timestamp
# timestamps are rounded to whole weeks

points_weight: public(HashMap[address, HashMap[uint256, Point]])  # gauge_addr -> time -> Point
changes_weight: HashMap[address, HashMap[uint256, uint256]]  # gauge_addr -> time -> slope
time_weight: public(HashMap[address, uint256])  # gauge_addr -> last scheduled time (next week)

points_sum: public(HashMap[int128, HashMap[uint256, Point]])  # type_id -> time -> Point
changes_sum: HashMap[int128, HashMap[uint256, uint256]]  # type_id -> time -> slope
time_sum: public(uint256[1000000000])  # type_id -> last scheduled time (next week)

points_total: public(HashMap[uint256, uint256])  # time -> total weight
time_total: public(uint256)  # last scheduled time

points_type_weight: public(HashMap[int128, HashMap[uint256, uint256]])  # type_id -> time -> type weight
time_type_weight: public(uint256[1000000000])  # type_id -> last scheduled time (next week)


@external
def __init__(_token: address, _voting_escrow: address):
    """
    @notice Contract constructor
    @param _token `ERC20CRV` contract address
    @param _voting_escrow `VotingEscrow` contract address
    """
    assert _token != ZERO_ADDRESS
    assert _voting_escrow != ZERO_ADDRESS

    self.admin = msg.sender
    self.token = _token
    self.voting_escrow = _voting_escrow
    self.time_total = block.timestamp / WEEK * WEEK


@external
def commit_transfer_ownership(addr: address):
    """
    @notice Transfer ownership of GaugeController to `addr`
    @param addr Address to have ownership transferred to
    """
    assert msg.sender == self.admin  # dev: admin only
    self.future_admin = addr
    log CommitOwnership(addr)


@external
def apply_transfer_ownership():
    """
    @notice Apply pending ownership transfer
    """
    assert msg.sender == self.admin  # dev: admin only
    _admin: address = self.future_admin
    assert _admin != ZERO_ADDRESS  # dev: admin not set
    self.admin = _admin
    log ApplyOwnership(_admin)


@external
@view
def gauge_types(_addr: address) -> int128:
    """
    @notice Get gauge type for address
    @param _addr Gauge address
    @return Gauge type id
    """
    gauge_type: int128 = self.gauge_types_[_addr]
    assert gauge_type != 0

    return gauge_type - 1


@internal
def _get_type_weight(gauge_type: int128) -> uint256:
    """
    @notice Fill historic type weights week-over-week for missed checkins
            and return the type weight for the future week
    @param gauge_type Gauge type id
    @return Type weight
    """
    t: uint256 = self.time_type_weight[gauge_type]
    if t > 0:
        w: uint256 = self.points_type_weight[gauge_type][t]
        for i in range(500):
            if t > block.timestamp:
                break
            t += WEEK
            self.points_type_weight[gauge_type][t] = w
            if t > block.timestamp:
                self.time_type_weight[gauge_type] = t
        return w
    else:
        return 0


@internal
def _get_sum(gauge_type: int128) -> uint256:
    """
    @notice Fill sum of gauge weights for the same type week-over-week for
            missed checkins and return the sum for the future week
    @param gauge_type Gauge type id
    @return Sum of weights
    """
    t: uint256 = self.time_sum[gauge_type]
    if t > 0:
        pt: Point = self.points_sum[gauge_type][t]
        for i in range(500):
            if t > block.timestamp:
                break
            t += WEEK
            d_bias: uint256 = pt.slope * WEEK
            if pt.bias > d_bias:
                pt.bias -= d_bias
                d_slope: uint256 = self.changes_sum[gauge_type][t]
                pt.slope -= d_slope
            else:
                pt.bias = 0
                pt.slope = 0
            self.points_sum[gauge_type][t] = pt
            if t > block.timestamp:
                self.time_sum[gauge_type] = t
        return pt.bias
    else:
        return 0


@internal
def _get_total() -> uint256:
    """
    @notice Fill historic total weights week-over-week for missed checkins
            and return the total for the future week
    @return Total weight
    """
    t: uint256 = self.time_total
    _n_gauge_types: int128 = self.n_gauge_types
    if t > block.timestamp:
        # If we have already checkpointed - still need to change the value
        t -= WEEK
    pt: uint256 = self.points_total[t]

    for gauge_type in range(100):
        if gauge_type == _n_gauge_types:
            break
        self._get_sum(gauge_type)
        self._get_type_weight(gauge_type)

    for i in range(500):
        if t > block.timestamp:
            break
        t += WEEK
        pt = 0
        # Scales as n_types * n_unchecked_weeks (hopefully 1 at most)
        for gauge_type in range(100):
            if gauge_type == _n_gauge_types:
                break
            type_sum: uint256 = self.points_sum[gauge_type][t].bias
            type_weight: uint256 = self.points_type_weight[gauge_type][t]
            pt += type_sum * type_weight
        self.points_total[t] = pt

        if t > block.timestamp:
            self.time_total = t
    return pt


@internal
def _get_weight(gauge_addr: address) -> uint256:
    """
    @notice Fill historic gauge weights week-over-week for missed checkins
            and return the total for the future week
    @param gauge_addr Address of the gauge
    @return Gauge weight
    """
    t: uint256 = self.time_weight[gauge_addr]
    if t > 0:
        pt: Point = self.points_weight[gauge_addr][t]
        for i in range(500):
            if t > block.timestamp:
                break
            t += WEEK
            d_bias: uint256 = pt.slope * WEEK
            if pt.bias > d_bias:
                pt.bias -= d_bias
                d_slope: uint256 = self.changes_weight[gauge_addr][t]
                pt.slope -= d_slope
            else:
                pt.bias = 0
                pt.slope = 0
            self.points_weight[gauge_addr][t] = pt
            if t > block.timestamp:
                self.time_weight[gauge_addr] = t
        return pt.bias
    else:
        return 0


@external
def add_gauge(addr: address, gauge_type: int128, weight: uint256 = 0):
    """
    @notice Add gauge `addr` of type `gauge_type` with weight `weight`
    @param addr Gauge address
    @param gauge_type Gauge type
    @param weight Gauge weight
    """
    assert msg.sender == self.admin
    assert (gauge_type >= 0) and (gauge_type < self.n_gauge_types)
    assert self.gauge_types_[addr] == 0  # dev: cannot add the same gauge twice

    n: int128 = self.n_gauges
    self.n_gauges = n + 1
    self.gauges[n] = addr

    self.gauge_types_[addr] = gauge_type + 1
    next_time: uint256 = (block.timestamp + WEEK) / WEEK * WEEK

    if weight > 0:
        _type_weight: uint256 = self._get_type_weight(gauge_type)
        _old_sum: uint256 = self._get_sum(gauge_type)
        _old_total: uint256 = self._get_total()

        self.points_sum[gauge_type][next_time].bias = weight + _old_sum
        self.time_sum[gauge_type] = next_time
        self.points_total[next_time] = _old_total + _type_weight * weight
        self.time_total = next_time

        self.points_weight[addr][next_time].bias = weight

    if self.time_sum[gauge_type] == 0:
        self.time_sum[gauge_type] = next_time
    self.time_weight[addr] = next_time

    log NewGauge(addr, gauge_type, weight)


@external
def checkpoint():
    """
    @notice Checkpoint to fill data common for all gauges
    """
    self._get_total()


@external
def checkpoint_gauge(addr: address):
    """
    @notice Checkpoint to fill data for both a specific gauge and common for all gauges
    @param addr Gauge address
    """
    self._get_weight(addr)
    self._get_total()


@internal
@view
def _gauge_relative_weight(addr: address, time: uint256) -> uint256:
    """
    @notice Get Gauge relative weight (not more than 1.0) normalized to 1e18
            (e.g. 1.0 == 1e18). Inflation which will be received by it is
            inflation_rate * relative_weight / 1e18
    @param addr Gauge address
    @param time Relative weight at the specified timestamp in the past or present
    @return Value of relative weight normalized to 1e18
    """
    t: uint256 = time / WEEK * WEEK
    _total_weight: uint256 = self.points_total[t]

    if _total_weight > 0:
        gauge_type: int128 = self.gauge_types_[addr] - 1
        _type_weight: uint256 = self.points_type_weight[gauge_type][t]
        _gauge_weight: uint256 = self.points_weight[addr][t].bias
        return MULTIPLIER * _type_weight * _gauge_weight / _total_weight

    else:
        return 0


@external
@view
def gauge_relative_weight(addr: address, time: uint256 = block.timestamp) -> uint256:
    """
    @notice Get Gauge relative weight (not more than 1.0) normalized to 1e18
            (e.g. 1.0 == 1e18). Inflation which will be received by it is
            inflation_rate * relative_weight / 1e18
    @param addr Gauge address
    @param time Relative weight at the specified timestamp in the past or present
    @return Value of relative weight normalized to 1e18
    """
    return self._gauge_relative_weight(addr, time)


@external
def gauge_relative_weight_write(addr: address, time: uint256 = block.timestamp) -> uint256:
    """
    @notice Get gauge weight normalized to 1e18 and also fill all the unfilled
            values for type and gauge records
    @dev Any address can call, however nothing is recorded if the values are filled already
    @param addr Gauge address
    @param time Relative weight at the specified timestamp in the past or present
    @return Value of relative weight normalized to 1e18
    """
    self._get_weight(addr)
    self._get_total()  # Also calculates get_sum
    return self._gauge_relative_weight(addr, time)




@internal
def _change_type_weight(type_id: int128, weight: uint256):
    """
    @notice Change type weight
    @param type_id Type id
    @param weight New type weight
    """
    old_weight: uint256 = self._get_type_weight(type_id)
    old_sum: uint256 = self._get_sum(type_id)
    _total_weight: uint256 = self._get_total()
    next_time: uint256 = (block.timestamp + WEEK) / WEEK * WEEK

    _total_weight = _total_weight + old_sum * weight - old_sum * old_weight
    self.points_total[next_time] = _total_weight
    self.points_type_weight[type_id][next_time] = weight
    self.time_total = next_time
    self.time_type_weight[type_id] = next_time

    log NewTypeWeight(type_id, next_time, weight, _total_weight)


@external
def add_type(_name: String[64], weight: uint256 = 0):
    """
    @notice Add gauge type with name `_name` and weight `weight`
    @param _name Name of gauge type
    @param weight Weight of gauge type
    """
    assert msg.sender == self.admin
    type_id: int128 = self.n_gauge_types
    self.gauge_type_names[type_id] = _name
    self.n_gauge_types = type_id + 1
    if weight != 0:
        self._change_type_weight(type_id, weight)
        log AddType(_name, type_id)


@external
def change_type_weight(type_id: int128, weight: uint256):
    """
    @notice Change gauge type `type_id` weight to `weight`
    @param type_id Gauge type id
    @param weight New Gauge weight
    """
    assert msg.sender == self.admin
    self._change_type_weight(type_id, weight)


@internal
def _change_gauge_weight(addr: address, weight: uint256):
    # Change gauge weight
    # Only needed when testing in reality
    gauge_type: int128 = self.gauge_types_[addr] - 1
    old_gauge_weight: uint256 = self._get_weight(addr)
    type_weight: uint256 = self._get_type_weight(gauge_type)
    old_sum: uint256 = self._get_sum(gauge_type)
    _total_weight: uint256 = self._get_total()
    next_time: uint256 = (block.timestamp + WEEK) / WEEK * WEEK

    self.points_weight[addr][next_time].bias = weight
    self.time_weight[addr] = next_time

    new_sum: uint256 = old_sum + weight - old_gauge_weight
    self.points_sum[gauge_type][next_time].bias = new_sum
    self.time_sum[gauge_type] = next_time

    _total_weight = _total_weight + new_sum * type_weight - old_sum * type_weight
    self.points_total[next_time] = _total_weight
    self.time_total = next_time

    log NewGaugeWeight(addr, block.timestamp, weight, _total_weight)


@external
def change_gauge_weight(addr: address, weight: uint256):
    """
    @notice Change weight of gauge `addr` to `weight`
    @param addr `GaugeController` contract address
    @param weight New Gauge weight
    """
    assert msg.sender == self.admin
    self._change_gauge_weight(addr, weight)


@external
def vote_for_gauge_weights(_gauge_addr: address, _user_weight: uint256):
    """
    @notice Allocate voting power for changing pool weights
    @param _gauge_addr Gauge which `msg.sender` votes for
    @param _user_weight Weight for a gauge in bps (units of 0.01%). Minimal is 0.01%. Ignored if 0
    """
    escrow: address = self.voting_escrow
    slope: uint256 = convert(VotingEscrow(escrow).get_last_user_slope(msg.sender), uint256)
    lock_end: uint256 = VotingEscrow(escrow).locked__end(msg.sender)
    _n_gauges: int128 = self.n_gauges
    next_time: uint256 = (block.timestamp + WEEK) / WEEK * WEEK
    assert lock_end > next_time, "Your token lock expires too soon"
    assert (_user_weight >= 0) and (_user_weight <= 10000), "You used all your voting power"
    assert block.timestamp >= self.last_user_vote[msg.sender][_gauge_addr] + WEIGHT_VOTE_DELAY, "Cannot vote so often"

    gauge_type: int128 = self.gauge_types_[_gauge_addr] - 1
    assert gauge_type >= 0, "Gauge not added"
    # Prepare slopes and biases in memory
    old_slope: VotedSlope = self.vote_user_slopes[msg.sender][_gauge_addr]
    old_dt: uint256 = 0
    if old_slope.end > next_time:
        old_dt = old_slope.end - next_time
    old_bias: uint256 = old_slope.slope * old_dt
    new_slope: VotedSlope = VotedSlope({
        slope: slope * _user_weight / 10000,
        end: lock_end,
        power: _user_weight
    })
    new_dt: uint256 = lock_end - next_time  # dev: raises when expired
    new_bias: uint256 = new_slope.slope * new_dt

    # Check and update powers (weights) used
    power_used: uint256 = self.vote_user_power[msg.sender]
    power_used = power_used + new_slope.power - old_slope.power
    self.vote_user_power[msg.sender] = power_used
    assert (power_used >= 0) and (power_used <= 10000), 'Used too much power'

    ## Remove old and schedule new slope changes
    # Remove slope changes for old slopes
    # Schedule recording of initial slope for next_time
    old_weight_bias: uint256 = self._get_weight(_gauge_addr)
    old_weight_slope: uint256 = self.points_weight[_gauge_addr][next_time].slope
    old_sum_bias: uint256 = self._get_sum(gauge_type)
    old_sum_slope: uint256 = self.points_sum[gauge_type][next_time].slope

    self.points_weight[_gauge_addr][next_time].bias = max(old_weight_bias + new_bias, old_bias) - old_bias
    self.points_sum[gauge_type][next_time].bias = max(old_sum_bias + new_bias, old_bias) - old_bias
    if old_slope.end > next_time:
        self.points_weight[_gauge_addr][next_time].slope = max(old_weight_slope + new_slope.slope, old_slope.slope) - old_slope.slope
        self.points_sum[gauge_type][next_time].slope = max(old_sum_slope + new_slope.slope, old_slope.slope) - old_slope.slope
    else:
        self.points_weight[_gauge_addr][next_time].slope += new_slope.slope
        self.points_sum[gauge_type][next_time].slope += new_slope.slope
    if old_slope.end > block.timestamp:
        # Cancel old slope changes if they still didn't happen
        self.changes_weight[_gauge_addr][old_slope.end] -= old_slope.slope
        self.changes_sum[gauge_type][old_slope.end] -= old_slope.slope
    # Add slope changes for new slopes
    self.changes_weight[_gauge_addr][new_slope.end] += new_slope.slope
    self.changes_sum[gauge_type][new_slope.end] += new_slope.slope

    self._get_total()

    self.vote_user_slopes[msg.sender][_gauge_addr] = new_slope

    # Record last action time
    self.last_user_vote[msg.sender][_gauge_addr] = block.timestamp

    log VoteForGauge(block.timestamp, msg.sender, _gauge_addr, _user_weight)


@external
@view
def get_gauge_weight(addr: address) -> uint256:
    """
    @notice Get current gauge weight
    @param addr Gauge address
    @return Gauge weight
    """
    return self.points_weight[addr][self.time_weight[addr]].bias


@external
@view
def get_type_weight(type_id: int128) -> uint256:
    """
    @notice Get current type weight
    @param type_id Type id
    @return Type weight
    """
    return self.points_type_weight[type_id][self.time_type_weight[type_id]]


@external
@view
def get_total_weight() -> uint256:
    """
    @notice Get current total (type-weighted) weight
    @return Total weight
    """
    return self.points_total[self.time_total]


@external
@view
def get_weights_sum_per_type(type_id: int128) -> uint256:
    """
    @notice Get sum of gauge weights per type
    @param type_id Type id
    @return Sum of gauge weights
    """
    return self.points_sum[type_id][self.time_sum[type_id]].bias

# @version 0.2.15
"""
@title Voting Escrow Delegation Proxy
@author Curve Finance
@license MIT
"""

from vyper.interfaces import ERC20


interface VeDelegation:
    def adjusted_balance_of(_account: address) -> uint256: view


event CommitAdmins:
    ownership_admin: address
    emergency_admin: address

event ApplyAdmins:
    ownership_admin: address
    emergency_admin: address

event DelegationSet:
    delegation: address


VOTING_ESCROW: constant(address) = 0x5f3b5DfEb7B28CDbD7FAba78963EE202a494e2A2


delegation: public(address)

emergency_admin: public(address)
ownership_admin: public(address)
future_emergency_admin: public(address)
future_ownership_admin: public(address)


@external
def __init__(_delegation: address, _o_admin: address, _e_admin: address):
    self.delegation = _delegation

    self.ownership_admin = _o_admin
    self.emergency_admin = _e_admin

    log DelegationSet(_delegation)


@view
@external
def adjusted_balance_of(_account: address) -> uint256:
    """
    @notice Get the adjusted veCRV balance from the active boost delegation contract
    @param _account The account to query the adjusted veCRV balance of
    @return veCRV balance
    """
    _delegation: address = self.delegation
    if _delegation == ZERO_ADDRESS:
        return ERC20(VOTING_ESCROW).balanceOf(_account)
    return VeDelegation(_delegation).adjusted_balance_of(_account)


@external
def kill_delegation():
    """
    @notice Set delegation contract to 0x00, disabling boost delegation
    @dev Callable by the emergency admin in case of an issue with the delegation logic
    """
    assert msg.sender in [self.ownership_admin, self.emergency_admin]

    self.delegation = ZERO_ADDRESS
    log DelegationSet(ZERO_ADDRESS)


@external
def set_delegation(_delegation: address):
    """
    @notice Set the delegation contract
    @dev Only callable by the ownership admin
    @param _delegation `VotingEscrowDelegation` deployment address
    """
    assert msg.sender == self.ownership_admin

    # call `adjusted_balance_of` to make sure it works
    VeDelegation(_delegation).adjusted_balance_of(msg.sender)

    self.delegation = _delegation
    log DelegationSet(_delegation)


@external
def commit_set_admins(_o_admin: address, _e_admin: address):
    """
    @notice Set ownership admin to `_o_admin` and emergency admin to `_e_admin`
    @param _o_admin Ownership admin
    @param _e_admin Emergency admin
    """
    assert msg.sender == self.ownership_admin, "Access denied"

    self.future_ownership_admin = _o_admin
    self.future_emergency_admin = _e_admin

    log CommitAdmins(_o_admin, _e_admin)


@external
def apply_set_admins():
    """
    @notice Apply the effects of `commit_set_admins`
    """
    assert msg.sender == self.ownership_admin, "Access denied"

    _o_admin: address = self.future_ownership_admin
    _e_admin: address = self.future_emergency_admin
    self.ownership_admin = _o_admin
    self.emergency_admin = _e_admin

    log ApplyAdmins(_o_admin, _e_admin)

# @version 0.2.4
"""
@title Voting Escrow
@author Curve Finance
@license MIT
@notice Votes have a weight depending on time, so that users are
        committed to the future of (whatever they are voting for)
@dev Vote weight decays linearly over time. Lock time cannot be
     more than `MAXTIME` (4 years).
"""

# Voting escrow to have time-weighted votes
# Votes have a weight depending on time, so that users are committed
# to the future of (whatever they are voting for).
# The weight in this implementation is linear, and lock cannot be more than maxtime:
# w ^
# 1 +        /
#   |      /
#   |    /
#   |  /
#   |/
# 0 +--------+------> time
#       maxtime (4 years?)

struct Point:
    bias: int128
    slope: int128  # - dweight / dt
    ts: uint256
    blk: uint256  # block
# We cannot really do block numbers per se b/c slope is per time, not per block
# and per block could be fairly bad b/c Ethereum changes blocktimes.
# What we can do is to extrapolate ***At functions

struct LockedBalance:
    amount: int128
    end: uint256


interface ERC20:
    def decimals() -> uint256: view
    def name() -> String[64]: view
    def symbol() -> String[32]: view
    def transfer(to: address, amount: uint256) -> bool: nonpayable
    def transferFrom(spender: address, to: address, amount: uint256) -> bool: nonpayable


# Interface for checking whether address belongs to a whitelisted
# type of a smart wallet.
# When new types are added - the whole contract is changed
# The check() method is modifying to be able to use caching
# for individual wallet addresses
interface SmartWalletChecker:
    def check(addr: address) -> bool: nonpayable

DEPOSIT_FOR_TYPE: constant(int128) = 0
CREATE_LOCK_TYPE: constant(int128) = 1
INCREASE_LOCK_AMOUNT: constant(int128) = 2
INCREASE_UNLOCK_TIME: constant(int128) = 3


event CommitOwnership:
    admin: address

event ApplyOwnership:
    admin: address

event Deposit:
    provider: indexed(address)
    value: uint256
    locktime: indexed(uint256)
    type: int128
    ts: uint256

event Withdraw:
    provider: indexed(address)
    value: uint256
    ts: uint256

event Supply:
    prevSupply: uint256
    supply: uint256


WEEK: constant(uint256) = 7 * 86400  # all future times are rounded by week
MAXTIME: constant(uint256) = 4 * 365 * 86400  # 4 years
MULTIPLIER: constant(uint256) = 10 ** 18

token: public(address)
supply: public(uint256)

locked: public(HashMap[address, LockedBalance])

epoch: public(uint256)
point_history: public(Point[100000000000000000000000000000])  # epoch -> unsigned point
user_point_history: public(HashMap[address, Point[1000000000]])  # user -> Point[user_epoch]
user_point_epoch: public(HashMap[address, uint256])
slope_changes: public(HashMap[uint256, int128])  # time -> signed slope change

# Aragon's view methods for compatibility
controller: public(address)
transfersEnabled: public(bool)

name: public(String[64])
symbol: public(String[32])
version: public(String[32])
decimals: public(uint256)

# Checker for whitelisted (smart contract) wallets which are allowed to deposit
# The goal is to prevent tokenizing the escrow
future_smart_wallet_checker: public(address)
smart_wallet_checker: public(address)

admin: public(address)  # Can and will be a smart contract
future_admin: public(address)


@external
def __init__(token_addr: address, _name: String[64], _symbol: String[32], _version: String[32]):
    """
    @notice Contract constructor
    @param token_addr `ERC20CRV` token address
    @param _name Token name
    @param _symbol Token symbol
    @param _version Contract version - required for Aragon compatibility
    """
    self.admin = msg.sender
    self.token = token_addr
    self.point_history[0].blk = block.number
    self.point_history[0].ts = block.timestamp
    self.controller = msg.sender
    self.transfersEnabled = True

    _decimals: uint256 = ERC20(token_addr).decimals()
    assert _decimals <= 255
    self.decimals = _decimals

    self.name = _name
    self.symbol = _symbol
    self.version = _version


@external
def commit_transfer_ownership(addr: address):
    """
    @notice Transfer ownership of VotingEscrow contract to `addr`
    @param addr Address to have ownership transferred to
    """
    assert msg.sender == self.admin  # dev: admin only
    self.future_admin = addr
    log CommitOwnership(addr)


@external
def apply_transfer_ownership():
    """
    @notice Apply ownership transfer
    """
    assert msg.sender == self.admin  # dev: admin only
    _admin: address = self.future_admin
    assert _admin != ZERO_ADDRESS  # dev: admin not set
    self.admin = _admin
    log ApplyOwnership(_admin)


@external
def commit_smart_wallet_checker(addr: address):
    """
    @notice Set an external contract to check for approved smart contract wallets
    @param addr Address of Smart contract checker
    """
    assert msg.sender == self.admin
    self.future_smart_wallet_checker = addr


@external
def apply_smart_wallet_checker():
    """
    @notice Apply setting external contract to check approved smart contract wallets
    """
    assert msg.sender == self.admin
    self.smart_wallet_checker = self.future_smart_wallet_checker


@internal
def assert_not_contract(addr: address):
    """
    @notice Check if the call is from a whitelisted smart contract, revert if not
    @param addr Address to be checked
    """
    if addr != tx.origin:
        checker: address = self.smart_wallet_checker
        if checker != ZERO_ADDRESS:
            if SmartWalletChecker(checker).check(addr):
                return
        raise "Smart contract depositors not allowed"


@external
@view
def get_last_user_slope(addr: address) -> int128:
    """
    @notice Get the most recently recorded rate of voting power decrease for `addr`
    @param addr Address of the user wallet
    @return Value of the slope
    """
    uepoch: uint256 = self.user_point_epoch[addr]
    return self.user_point_history[addr][uepoch].slope


@external
@view
def user_point_history__ts(_addr: address, _idx: uint256) -> uint256:
    """
    @notice Get the timestamp for checkpoint `_idx` for `_addr`
    @param _addr User wallet address
    @param _idx User epoch number
    @return Epoch time of the checkpoint
    """
    return self.user_point_history[_addr][_idx].ts


@external
@view
def locked__end(_addr: address) -> uint256:
    """
    @notice Get timestamp when `_addr`'s lock finishes
    @param _addr User wallet
    @return Epoch time of the lock end
    """
    return self.locked[_addr].end


@internal
def _checkpoint(addr: address, old_locked: LockedBalance, new_locked: LockedBalance):
    """
    @notice Record global and per-user data to checkpoint
    @param addr User's wallet address. No user checkpoint if 0x0
    @param old_locked Pevious locked amount / end lock time for the user
    @param new_locked New locked amount / end lock time for the user
    """
    u_old: Point = empty(Point)
    u_new: Point = empty(Point)
    old_dslope: int128 = 0
    new_dslope: int128 = 0
    _epoch: uint256 = self.epoch

    if addr != ZERO_ADDRESS:
        # Calculate slopes and biases
        # Kept at zero when they have to
        if old_locked.end > block.timestamp and old_locked.amount > 0:
            u_old.slope = old_locked.amount / MAXTIME
            u_old.bias = u_old.slope * convert(old_locked.end - block.timestamp, int128)
        if new_locked.end > block.timestamp and new_locked.amount > 0:
            u_new.slope = new_locked.amount / MAXTIME
            u_new.bias = u_new.slope * convert(new_locked.end - block.timestamp, int128)

        # Read values of scheduled changes in the slope
        # old_locked.end can be in the past and in the future
        # new_locked.end can ONLY by in the FUTURE unless everything expired: than zeros
        old_dslope = self.slope_changes[old_locked.end]
        if new_locked.end != 0:
            if new_locked.end == old_locked.end:
                new_dslope = old_dslope
            else:
                new_dslope = self.slope_changes[new_locked.end]

    last_point: Point = Point({bias: 0, slope: 0, ts: block.timestamp, blk: block.number})
    if _epoch > 0:
        last_point = self.point_history[_epoch]
    last_checkpoint: uint256 = last_point.ts
    # initial_last_point 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
    initial_last_point: Point = last_point
    block_slope: uint256 = 0  # dblock/dt
    if block.timestamp > last_point.ts:
        block_slope = MULTIPLIER * (block.number - last_point.blk) / (block.timestamp - last_point.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
    t_i: uint256 = (last_checkpoint / WEEK) * WEEK
    for i in range(255):
        # 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
        t_i += WEEK
        d_slope: int128 = 0
        if t_i > block.timestamp:
            t_i = block.timestamp
        else:
            d_slope = self.slope_changes[t_i]
        last_point.bias -= last_point.slope * convert(t_i - last_checkpoint, int128)
        last_point.slope += d_slope
        if last_point.bias < 0:  # This can happen
            last_point.bias = 0
        if last_point.slope < 0:  # This cannot happen - just in case
            last_point.slope = 0
        last_checkpoint = t_i
        last_point.ts = t_i
        last_point.blk = initial_last_point.blk + block_slope * (t_i - initial_last_point.ts) / MULTIPLIER
        _epoch += 1
        if t_i == block.timestamp:
            last_point.blk = block.number
            break
        else:
            self.point_history[_epoch] = last_point

    self.epoch = _epoch
    # Now point_history is filled until t=now

    if addr != ZERO_ADDRESS:
        # If last point was in this block, the slope change has been applied already
        # But in such case we have 0 slope(s)
        last_point.slope += (u_new.slope - u_old.slope)
        last_point.bias += (u_new.bias - u_old.bias)
        if last_point.slope < 0:
            last_point.slope = 0
        if last_point.bias < 0:
            last_point.bias = 0

    # Record the changed point into history
    self.point_history[_epoch] = last_point

    if addr != ZERO_ADDRESS:
        # 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 old_locked.end > block.timestamp:
            # old_dslope was <something> - u_old.slope, so we cancel that
            old_dslope += u_old.slope
            if new_locked.end == old_locked.end:
                old_dslope -= u_new.slope  # It was a new deposit, not extension
            self.slope_changes[old_locked.end] = old_dslope

        if new_locked.end > block.timestamp:
            if new_locked.end > old_locked.end:
                new_dslope -= u_new.slope  # old slope disappeared at this point
                self.slope_changes[new_locked.end] = new_dslope
            # else: we recorded it already in old_dslope

        # Now handle user history
        user_epoch: uint256 = self.user_point_epoch[addr] + 1

        self.user_point_epoch[addr] = user_epoch
        u_new.ts = block.timestamp
        u_new.blk = block.number
        self.user_point_history[addr][user_epoch] = u_new


@internal
def _deposit_for(_addr: address, _value: uint256, unlock_time: uint256, locked_balance: LockedBalance, type: int128):
    """
    @notice Deposit and lock tokens for a user
    @param _addr User's wallet address
    @param _value Amount to deposit
    @param unlock_time New time when to unlock the tokens, or 0 if unchanged
    @param locked_balance Previous locked amount / timestamp
    """
    _locked: LockedBalance = locked_balance
    supply_before: uint256 = self.supply

    self.supply = supply_before + _value
    old_locked: LockedBalance = _locked
    # Adding to existing lock, or if a lock is expired - creating a new one
    _locked.amount += convert(_value, int128)
    if unlock_time != 0:
        _locked.end = unlock_time
    self.locked[_addr] = _locked

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

    if _value != 0:
        assert ERC20(self.token).transferFrom(_addr, self, _value)

    log Deposit(_addr, _value, _locked.end, type, block.timestamp)
    log Supply(supply_before, supply_before + _value)


@external
def checkpoint():
    """
    @notice Record global data to checkpoint
    """
    self._checkpoint(ZERO_ADDRESS, empty(LockedBalance), empty(LockedBalance))


@external
@nonreentrant('lock')
def deposit_for(_addr: address, _value: uint256):
    """
    @notice Deposit `_value` tokens for `_addr` and add to the lock
    @dev Anyone (even a smart contract) can deposit for someone else, but
         cannot extend their locktime and deposit for a brand new user
    @param _addr User's wallet address
    @param _value Amount to add to user's lock
    """
    _locked: LockedBalance = self.locked[_addr]

    assert _value > 0  # dev: need non-zero value
    assert _locked.amount > 0, "No existing lock found"
    assert _locked.end > block.timestamp, "Cannot add to expired lock. Withdraw"

    self._deposit_for(_addr, _value, 0, self.locked[_addr], DEPOSIT_FOR_TYPE)


@external
@nonreentrant('lock')
def create_lock(_value: uint256, _unlock_time: uint256):
    """
    @notice Deposit `_value` tokens for `msg.sender` and lock until `_unlock_time`
    @param _value Amount to deposit
    @param _unlock_time Epoch time when tokens unlock, rounded down to whole weeks
    """
    self.assert_not_contract(msg.sender)
    unlock_time: uint256 = (_unlock_time / WEEK) * WEEK  # Locktime is rounded down to weeks
    _locked: LockedBalance = self.locked[msg.sender]

    assert _value > 0  # dev: need non-zero value
    assert _locked.amount == 0, "Withdraw old tokens first"
    assert unlock_time > block.timestamp, "Can only lock until time in the future"
    assert unlock_time <= block.timestamp + MAXTIME, "Voting lock can be 4 years max"

    self._deposit_for(msg.sender, _value, unlock_time, _locked, CREATE_LOCK_TYPE)


@external
@nonreentrant('lock')
def increase_amount(_value: uint256):
    """
    @notice Deposit `_value` additional tokens for `msg.sender`
            without modifying the unlock time
    @param _value Amount of tokens to deposit and add to the lock
    """
    self.assert_not_contract(msg.sender)
    _locked: LockedBalance = self.locked[msg.sender]

    assert _value > 0  # dev: need non-zero value
    assert _locked.amount > 0, "No existing lock found"
    assert _locked.end > block.timestamp, "Cannot add to expired lock. Withdraw"

    self._deposit_for(msg.sender, _value, 0, _locked, INCREASE_LOCK_AMOUNT)


@external
@nonreentrant('lock')
def increase_unlock_time(_unlock_time: uint256):
    """
    @notice Extend the unlock time for `msg.sender` to `_unlock_time`
    @param _unlock_time New epoch time for unlocking
    """
    self.assert_not_contract(msg.sender)
    _locked: LockedBalance = self.locked[msg.sender]
    unlock_time: uint256 = (_unlock_time / WEEK) * WEEK  # Locktime is rounded down to weeks

    assert _locked.end > block.timestamp, "Lock expired"
    assert _locked.amount > 0, "Nothing is locked"
    assert unlock_time > _locked.end, "Can only increase lock duration"
    assert unlock_time <= block.timestamp + MAXTIME, "Voting lock can be 4 years max"

    self._deposit_for(msg.sender, 0, unlock_time, _locked, INCREASE_UNLOCK_TIME)


@external
@nonreentrant('lock')
def withdraw():
    """
    @notice Withdraw all tokens for `msg.sender`
    @dev Only possible if the lock has expired
    """
    _locked: LockedBalance = self.locked[msg.sender]
    assert block.timestamp >= _locked.end, "The lock didn't expire"
    value: uint256 = convert(_locked.amount, uint256)

    old_locked: LockedBalance = _locked
    _locked.end = 0
    _locked.amount = 0
    self.locked[msg.sender] = _locked
    supply_before: uint256 = self.supply
    self.supply = supply_before - value

    # old_locked can have either expired <= timestamp or zero end
    # _locked has only 0 end
    # Both can have >= 0 amount
    self._checkpoint(msg.sender, old_locked, _locked)

    assert ERC20(self.token).transfer(msg.sender, value)

    log Withdraw(msg.sender, value, block.timestamp)
    log Supply(supply_before, supply_before - value)


# The following ERC20/minime-compatible methods are not real balanceOf and supply!
# They measure the weights for the purpose of voting, so they don't represent
# real coins.

@internal
@view
def find_block_epoch(_block: uint256, max_epoch: uint256) -> uint256:
    """
    @notice Binary search to estimate timestamp for block number
    @param _block Block to find
    @param max_epoch Don't go beyond this epoch
    @return Approximate timestamp for block
    """
    # Binary search
    _min: uint256 = 0
    _max: uint256 = max_epoch
    for i in range(128):  # Will be always enough for 128-bit numbers
        if _min >= _max:
            break
        _mid: uint256 = (_min + _max + 1) / 2
        if self.point_history[_mid].blk <= _block:
            _min = _mid
        else:
            _max = _mid - 1
    return _min


@external
@view
def balanceOf(addr: address, _t: uint256 = block.timestamp) -> uint256:
    """
    @notice Get the current voting power for `msg.sender`
    @dev Adheres to the ERC20 `balanceOf` interface for Aragon compatibility
    @param addr User wallet address
    @param _t Epoch time to return voting power at
    @return User voting power
    """
    _epoch: uint256 = self.user_point_epoch[addr]
    if _epoch == 0:
        return 0
    else:
        last_point: Point = self.user_point_history[addr][_epoch]
        last_point.bias -= last_point.slope * convert(_t - last_point.ts, int128)
        if last_point.bias < 0:
            last_point.bias = 0
        return convert(last_point.bias, uint256)


@external
@view
def balanceOfAt(addr: address, _block: uint256) -> uint256:
    """
    @notice Measure voting power of `addr` at block height `_block`
    @dev Adheres to MiniMe `balanceOfAt` interface: https://github.com/Giveth/minime
    @param addr User's wallet address
    @param _block Block to calculate the voting power at
    @return Voting power
    """
    # Copying and pasting totalSupply code because Vyper cannot pass by
    # reference yet
    assert _block <= block.number

    # Binary search
    _min: uint256 = 0
    _max: uint256 = self.user_point_epoch[addr]
    for i in range(128):  # Will be always enough for 128-bit numbers
        if _min >= _max:
            break
        _mid: uint256 = (_min + _max + 1) / 2
        if self.user_point_history[addr][_mid].blk <= _block:
            _min = _mid
        else:
            _max = _mid - 1

    upoint: Point = self.user_point_history[addr][_min]

    max_epoch: uint256 = self.epoch
    _epoch: uint256 = self.find_block_epoch(_block, max_epoch)
    point_0: Point = self.point_history[_epoch]
    d_block: uint256 = 0
    d_t: uint256 = 0
    if _epoch < max_epoch:
        point_1: Point = self.point_history[_epoch + 1]
        d_block = point_1.blk - point_0.blk
        d_t = point_1.ts - point_0.ts
    else:
        d_block = block.number - point_0.blk
        d_t = block.timestamp - point_0.ts
    block_time: uint256 = point_0.ts
    if d_block != 0:
        block_time += d_t * (_block - point_0.blk) / d_block

    upoint.bias -= upoint.slope * convert(block_time - upoint.ts, int128)
    if upoint.bias >= 0:
        return convert(upoint.bias, uint256)
    else:
        return 0


@internal
@view
def supply_at(point: Point, t: uint256) -> uint256:
    """
    @notice Calculate total voting power at some point in the past
    @param point The point (bias/slope) to start search from
    @param t Time to calculate the total voting power at
    @return Total voting power at that time
    """
    last_point: Point = point
    t_i: uint256 = (last_point.ts / WEEK) * WEEK
    for i in range(255):
        t_i += WEEK
        d_slope: int128 = 0
        if t_i > t:
            t_i = t
        else:
            d_slope = self.slope_changes[t_i]
        last_point.bias -= last_point.slope * convert(t_i - last_point.ts, int128)
        if t_i == t:
            break
        last_point.slope += d_slope
        last_point.ts = t_i

    if last_point.bias < 0:
        last_point.bias = 0
    return convert(last_point.bias, uint256)


@external
@view
def totalSupply(t: uint256 = block.timestamp) -> uint256:
    """
    @notice Calculate total voting power
    @dev Adheres to the ERC20 `totalSupply` interface for Aragon compatibility
    @return Total voting power
    """
    _epoch: uint256 = self.epoch
    last_point: Point = self.point_history[_epoch]
    return self.supply_at(last_point, t)


@external
@view
def totalSupplyAt(_block: uint256) -> uint256:
    """
    @notice Calculate total voting power at some point in the past
    @param _block Block to calculate the total voting power at
    @return Total voting power at `_block`
    """
    assert _block <= block.number
    _epoch: uint256 = self.epoch
    target_epoch: uint256 = self.find_block_epoch(_block, _epoch)

    point: Point = self.point_history[target_epoch]
    dt: uint256 = 0
    if target_epoch < _epoch:
        point_next: Point = self.point_history[target_epoch + 1]
        if point.blk != point_next.blk:
            dt = (_block - point.blk) * (point_next.ts - point.ts) / (point_next.blk - point.blk)
    else:
        if point.blk != block.number:
            dt = (_block - point.blk) * (block.timestamp - point.ts) / (block.number - point.blk)
    # Now dt contains info on how far are we beyond point

    return self.supply_at(point, point.ts + dt)


# Dummy methods for compatibility with Aragon

@external
def changeController(_newController: address):
    """
    @dev Dummy method required for Aragon compatibility
    """
    assert msg.sender == self.controller
    self.controller = _newController

# @version 0.3.10
"""
@title Vault
@notice ERC4626+ Vault for lending with crvUSD using LLAMMA algorithm
@author Curve.Fi
@license Copyright (c) Curve.Fi, 2020-2024 - all rights reserved
"""
from vyper.interfaces import ERC20 as ERC20Spec
from vyper.interfaces import ERC20Detailed


implements: ERC20Spec
implements: ERC20Detailed


interface ERC20:
    def transferFrom(_from: address, _to: address, _value: uint256) -> bool: nonpayable
    def transfer(_to: address, _value: uint256) -> bool: nonpayable
    def decimals() -> uint256: view
    def balanceOf(_from: address) -> uint256: view
    def symbol() -> String[32]: view
    def name() -> String[64]: view

interface AMM:
    def set_admin(_admin: address): nonpayable
    def rate() -> uint256: view

interface Controller:
    def total_debt() -> uint256: view
    def minted() -> uint256: view
    def redeemed() -> uint256: view
    def monetary_policy() -> address: view
    def check_lock() -> bool: view
    def save_rate(): nonpayable

interface PriceOracle:
    def price() -> uint256: view
    def price_w() -> uint256: nonpayable

interface Factory:
    def admin() -> address: view


# ERC20 events

event Approval:
    owner: indexed(address)
    spender: indexed(address)
    value: uint256

event Transfer:
    sender: indexed(address)
    receiver: indexed(address)
    value: uint256

# ERC4626 events

event Deposit:
    sender: indexed(address)
    owner: indexed(address)
    assets: uint256
    shares: uint256

event Withdraw:
    sender: indexed(address)
    receiver: indexed(address)
    owner: indexed(address)
    assets: uint256
    shares: uint256


# Limits
MIN_A: constant(uint256) = 2
MAX_A: constant(uint256) = 10000
MIN_FEE: constant(uint256) = 10**6  # 1e-12, still needs to be above 0
MAX_FEE: constant(uint256) = 10**17  # 10%
MAX_LOAN_DISCOUNT: constant(uint256) = 5 * 10**17
MIN_LIQUIDATION_DISCOUNT: constant(uint256) = 10**16
ADMIN_FEE: constant(uint256) = 0

# These are virtual shares from method proposed by OpenZeppelin
# see: https://blog.openzeppelin.com/a-novel-defense-against-erc4626-inflation-attacks
# and
# https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC20/extensions/ERC4626.sol
DEAD_SHARES: constant(uint256) = 1000
MIN_ASSETS: constant(uint256) = 10000

borrowed_token: public(ERC20)
collateral_token: public(ERC20)

price_oracle: public(PriceOracle)
amm: public(AMM)
controller: public(Controller)
factory: public(Factory)


# ERC20 publics

decimals: public(constant(uint8)) = 18
name: public(String[64])
symbol: public(String[34])

NAME_PREFIX: constant(String[16]) = 'Curve Vault for '
SYMBOL_PREFIX: constant(String[2]) = 'cv'

allowance: public(HashMap[address, HashMap[address, uint256]])
balanceOf: public(HashMap[address, uint256])
totalSupply: public(uint256)

precision: uint256


@external
def __init__():
    """
    @notice Template for Vault implementation
    """
    # The contract is made a "normal" template (not blueprint) so that we can get contract address before init
    # This is needed if we want to create a rehypothecation dual-market with two vaults
    # where vaults are collaterals of each other
    self.borrowed_token = ERC20(0x0000000000000000000000000000000000000001)


@internal
@pure
def ln_int(_x: uint256) -> int256:
    """
    @notice Logarithm ln() function based on log2. Not very gas-efficient but brief
    """
    # adapted from: https://medium.com/coinmonks/9aef8515136e
    # and vyper log implementation
    # This can be much more optimal but that's not important here
    x: uint256 = _x
    res: uint256 = 0
    for i in range(8):
        t: uint256 = 2**(7 - i)
        p: uint256 = 2**t
        if x >= p * 10**18:
            x /= p
            res += t * 10**18
    d: uint256 = 10**18
    for i in range(59):  # 18 decimals: math.log2(10**10) == 59.7
        if (x >= 2 * 10**18):
            res += d
            x /= 2
        x = x * x / 10**18
        d /= 2
    # Now res = log2(x)
    # ln(x) = log2(x) / log2(e)
    return convert(res * 10**18 / 1442695040888963328, int256)


@external
def initialize(
        amm_impl: address,
        controller_impl: address,
        borrowed_token: ERC20,
        collateral_token: ERC20,
        A: uint256,
        fee: uint256,
        price_oracle: PriceOracle,  # Factory makes from template if needed, deploying with a from_pool()
        monetary_policy: address,  # Standard monetary policy set in factory
        loan_discount: uint256,
        liquidation_discount: uint256
    ) -> (address, address):
    """
    @notice Initializer for vaults
    @param amm_impl AMM implementation (blueprint)
    @param controller_impl Controller implementation (blueprint)
    @param borrowed_token Token which is being borrowed
    @param collateral_token Token used for collateral
    @param A Amplification coefficient: band size is ~1/A
    @param fee Fee for swaps in AMM (for ETH markets found to be 0.6%)
    @param price_oracle Already initialized price oracle
    @param monetary_policy Already initialized monetary policy
    @param loan_discount Maximum discount. LTV = sqrt(((A - 1) / A) ** 4) - loan_discount
    @param liquidation_discount Liquidation discount. LT = sqrt(((A - 1) / A) ** 4) - liquidation_discount
    """
    assert self.borrowed_token.address == empty(address)

    self.borrowed_token = borrowed_token
    self.collateral_token = collateral_token
    self.price_oracle = price_oracle

    assert A >= MIN_A and A <= MAX_A, "Wrong A"
    assert fee <= MAX_FEE, "Fee too high"
    assert fee >= MIN_FEE, "Fee too low"
    assert liquidation_discount >= MIN_LIQUIDATION_DISCOUNT, "Liquidation discount too low"
    assert loan_discount <= MAX_LOAN_DISCOUNT, "Loan discount too high"
    assert loan_discount > liquidation_discount, "need loan_discount>liquidation_discount"

    p: uint256 = price_oracle.price()  # This also validates price oracle ABI
    assert p > 0
    assert price_oracle.price_w() == p
    A_ratio: uint256 = 10**18 * A / (A - 1)

    borrowed_precision: uint256 = 10**(18 - borrowed_token.decimals())

    amm: address = create_from_blueprint(
        amm_impl,
        borrowed_token.address, borrowed_precision,
        collateral_token.address, 10**(18 - collateral_token.decimals()),
        A, isqrt(A_ratio * 10**18), self.ln_int(A_ratio),
        p, fee, ADMIN_FEE, price_oracle.address,
        code_offset=3)
    controller: address = create_from_blueprint(
        controller_impl,
        empty(address), monetary_policy, loan_discount, liquidation_discount, amm,
        code_offset=3)
    AMM(amm).set_admin(controller)

    self.amm = AMM(amm)
    self.controller = Controller(controller)
    self.factory = Factory(msg.sender)

    # ERC20 set up
    self.precision = borrowed_precision
    borrowed_symbol: String[32] = borrowed_token.symbol()
    self.name = concat(NAME_PREFIX, borrowed_symbol)
    # Symbol must be String[32], but we do String[34]. It doesn't affect contracts which read it (they will truncate)
    # However this will be changed as soon as Vyper can *properly* manipulate strings
    self.symbol = concat(SYMBOL_PREFIX, borrowed_symbol)

    # No events because it's the only market we would ever create in this contract

    return controller, amm


@external
@view
@nonreentrant('lock')
def borrow_apr() -> uint256:
    """
    @notice Borrow APR (annualized and 1e18-based)
    """
    return self.amm.rate() * (365 * 86400)


@external
@view
@nonreentrant('lock')
def lend_apr() -> uint256:
    """
    @notice Lending APR (annualized and 1e18-based)
    """
    debt: uint256 = self.controller.total_debt()
    if debt == 0:
        return 0
    else:
        return self.amm.rate() * (365 * 86400) * debt / self._total_assets()


@external
@view
def asset() -> ERC20:
    """
    @notice Asset which is the same as borrowed_token
    """
    return self.borrowed_token


@internal
@view
def _total_assets() -> uint256:
    # admin fee should be accounted for here when enabled
    self.controller.check_lock()
    return self.borrowed_token.balanceOf(self.controller.address) + self.controller.total_debt()


@external
@view
@nonreentrant('lock')
def totalAssets() -> uint256:
    """
    @notice Total assets which can be lent out or be in reserve
    """
    return self._total_assets()


@internal
@view
def _convert_to_shares(assets: uint256, is_floor: bool = True,
                       _total_assets: uint256 = max_value(uint256)) -> uint256:
    total_assets: uint256 = _total_assets
    if total_assets == max_value(uint256):
        total_assets = self._total_assets()
    precision: uint256 = self.precision
    numerator: uint256 = (self.totalSupply + DEAD_SHARES) * assets * precision
    denominator: uint256 = (total_assets * precision + 1)
    if is_floor:
        return numerator / denominator
    else:
        return (numerator + denominator - 1) / denominator


@internal
@view
def _convert_to_assets(shares: uint256, is_floor: bool = True,
                       _total_assets: uint256 = max_value(uint256)) -> uint256:
    total_assets: uint256 = _total_assets
    if total_assets == max_value(uint256):
        total_assets = self._total_assets()
    precision: uint256 = self.precision
    numerator: uint256 = shares * (total_assets * precision + 1)
    denominator: uint256 = (self.totalSupply + DEAD_SHARES) * precision
    if is_floor:
        return numerator / denominator
    else:
        return (numerator + denominator - 1) / denominator


@external
@view
@nonreentrant('lock')
def pricePerShare(is_floor: bool = True) -> uint256:
    """
    @notice Method which shows how much one pool share costs in asset tokens if they are normalized to 18 decimals
    """
    supply: uint256 = self.totalSupply
    if supply == 0:
        return 10**18 / DEAD_SHARES
    else:
        precision: uint256 = self.precision
        numerator: uint256 = 10**18 * (self._total_assets() * precision + 1)
        denominator: uint256 = (supply + DEAD_SHARES)
        pps: uint256 = 0
        if is_floor:
            pps = numerator / denominator
        else:
            pps = (numerator + denominator - 1) / denominator
        assert pps > 0
        return pps


@external
@view
@nonreentrant('lock')
def convertToShares(assets: uint256) -> uint256:
    """
    @notice Returns the amount of shares which the Vault would exchange for the given amount of shares provided
    """
    return self._convert_to_shares(assets)


@external
@view
@nonreentrant('lock')
def convertToAssets(shares: uint256) -> uint256:
    """
    @notice Returns the amount of assets that the Vault would exchange for the amount of shares provided
    """
    return self._convert_to_assets(shares)


@external
@view
def maxDeposit(receiver: address) -> uint256:
    """
    @notice Maximum amount of assets which a given user can deposit (inf)
    """
    return max_value(uint256)


@external
@view
@nonreentrant('lock')
def previewDeposit(assets: uint256) -> uint256:
    """
    @notice Returns the amount of shares which can be obtained upon depositing assets
    """
    return self._convert_to_shares(assets)


@external
@nonreentrant('lock')
def deposit(assets: uint256, receiver: address = msg.sender) -> uint256:
    """
    @notice Deposit assets in return for whatever number of shares corresponds to the current conditions
    @param assets Amount of assets to deposit
    @param receiver Receiver of the shares who is optional. If not specified - receiver is the sender
    """
    controller: Controller = self.controller
    total_assets: uint256 = self._total_assets()
    assert total_assets + assets >= MIN_ASSETS, "Need more assets"
    to_mint: uint256 = self._convert_to_shares(assets, True, total_assets)
    assert self.borrowed_token.transferFrom(msg.sender, controller.address, assets, default_return_value=True)
    self._mint(receiver, to_mint)
    controller.save_rate()
    log Deposit(msg.sender, receiver, assets, to_mint)
    return to_mint


@external
@view
def maxMint(receiver: address) -> uint256:
    """
    @notice Return maximum amount of shares which a given user can mint (inf)
    """
    return max_value(uint256)


@external
@view
@nonreentrant('lock')
def previewMint(shares: uint256) -> uint256:
    """
    @notice Calculate the amount of assets which is needed to exactly mint the given amount of shares
    """
    return self._convert_to_assets(shares, False)


@external
@nonreentrant('lock')
def mint(shares: uint256, receiver: address = msg.sender) -> uint256:
    """
    @notice Mint given amount of shares taking whatever number of assets it requires
    @param shares Number of sharess to mint
    @param receiver Optional receiver for the shares. If not specified - it's the sender
    """
    controller: Controller = self.controller
    total_assets: uint256 = self._total_assets()
    assets: uint256 = self._convert_to_assets(shares, False, total_assets)
    assert total_assets + assets >= MIN_ASSETS, "Need more assets"
    assert self.borrowed_token.transferFrom(msg.sender, controller.address, assets, default_return_value=True)
    self._mint(receiver, shares)
    controller.save_rate()
    log Deposit(msg.sender, receiver, assets, shares)
    return assets


@external
@view
@nonreentrant('lock')
def maxWithdraw(owner: address) -> uint256:
    """
    @notice Maximum amount of assets which a given user can withdraw. Aware of both user's balance and available liquidity
    """
    return min(
        self._convert_to_assets(self.balanceOf[owner]),
        self.borrowed_token.balanceOf(self.controller.address))


@external
@view
@nonreentrant('lock')
def previewWithdraw(assets: uint256) -> uint256:
    """
    @notice Calculate number of shares which gets burned when withdrawing given amount of asset
    """
    assert assets <= self.borrowed_token.balanceOf(self.controller.address)
    return self._convert_to_shares(assets, False)


@external
@nonreentrant('lock')
def withdraw(assets: uint256, receiver: address = msg.sender, owner: address = msg.sender) -> uint256:
    """
    @notice Withdraw given amount of asset and burn the corresponding amount of vault shares
    @param assets Amount of assets to withdraw
    @param receiver Receiver of the assets (optional, sender if not specified)
    @param owner Owner who's shares the caller takes. Only can take those if owner gave the approval to the sender. Optional
    """
    total_assets: uint256 = self._total_assets()
    assert total_assets - assets >= MIN_ASSETS or total_assets == assets, "Need more assets"
    shares: uint256 = self._convert_to_shares(assets, False, total_assets)
    if owner != msg.sender:
        allowance: uint256 = self.allowance[owner][msg.sender]
        if allowance != max_value(uint256):
            self._approve(owner, msg.sender, allowance - shares)

    controller: Controller = self.controller
    self._burn(owner, shares)
    assert self.borrowed_token.transferFrom(controller.address, receiver, assets, default_return_value=True)
    controller.save_rate()
    log Withdraw(msg.sender, receiver, owner, assets, shares)
    return shares


@external
@view
@nonreentrant('lock')
def maxRedeem(owner: address) -> uint256:
    """
    @notice Calculate maximum amount of shares which a given user can redeem
    """
    return min(
        self._convert_to_shares(self.borrowed_token.balanceOf(self.controller.address), False),
        self.balanceOf[owner])


@external
@view
@nonreentrant('lock')
def previewRedeem(shares: uint256) -> uint256:
    """
    @notice Calculate the amount of assets which can be obtained by redeeming the given amount of shares
    """
    if self.totalSupply == 0:
        assert shares == 0
        return 0

    else:
        assets_to_redeem: uint256 = self._convert_to_assets(shares)
        assert assets_to_redeem <= self.borrowed_token.balanceOf(self.controller.address)
        return assets_to_redeem


@external
@nonreentrant('lock')
def redeem(shares: uint256, receiver: address = msg.sender, owner: address = msg.sender) -> uint256:
    """
    @notice Burn given amount of shares and give corresponding assets to the user
    @param shares Amount of shares to burn
    @param receiver Optional receiver of the assets
    @param owner Optional owner of the shares. Can only redeem if owner gave approval to the sender
    """
    if owner != msg.sender:
        allowance: uint256 = self.allowance[owner][msg.sender]
        if allowance != max_value(uint256):
            self._approve(owner, msg.sender, allowance - shares)

    total_assets: uint256 = self._total_assets()
    assets_to_redeem: uint256 = self._convert_to_assets(shares, True, total_assets)
    if total_assets - assets_to_redeem < MIN_ASSETS:
        if shares == self.totalSupply:
            # This is the last withdrawal, so we can take everything
            assets_to_redeem = total_assets
        else:
            raise "Need more assets"
    self._burn(owner, shares)
    controller: Controller = self.controller
    assert self.borrowed_token.transferFrom(controller.address, receiver, assets_to_redeem, default_return_value=True)
    controller.save_rate()
    log Withdraw(msg.sender, receiver, owner, assets_to_redeem, shares)
    return assets_to_redeem


# ERC20 methods

@internal
def _approve(_owner: address, _spender: address, _value: uint256):
    self.allowance[_owner][_spender] = _value

    log Approval(_owner, _spender, _value)


@internal
def _burn(_from: address, _value: uint256):
    self.balanceOf[_from] -= _value
    self.totalSupply -= _value

    log Transfer(_from, empty(address), _value)


@internal
def _mint(_to: address, _value: uint256):
    self.balanceOf[_to] += _value
    self.totalSupply += _value

    log Transfer(empty(address), _to, _value)


@internal
def _transfer(_from: address, _to: address, _value: uint256):
    assert _to not in [self, empty(address)]

    self.balanceOf[_from] -= _value
    self.balanceOf[_to] += _value

    log Transfer(_from, _to, _value)


@external
def transferFrom(_from: address, _to: address, _value: uint256) -> bool:
    """
    @notice Transfer tokens from one account to another.
    @dev The caller needs to have an allowance from account `_from` greater than or
        equal to the value being transferred. An allowance equal to the uint256 type's
        maximum, is considered infinite and does not decrease.
    @param _from The account which tokens will be spent from.
    @param _to The account which tokens will be sent to.
    @param _value The amount of tokens to be transferred.
    """
    allowance: uint256 = self.allowance[_from][msg.sender]
    if allowance != max_value(uint256):
        self._approve(_from, msg.sender, allowance - _value)

    self._transfer(_from, _to, _value)
    return True


@external
def transfer(_to: address, _value: uint256) -> bool:
    """
    @notice Transfer tokens to `_to`.
    @param _to The account to transfer tokens to.
    @param _value The amount of tokens to transfer.
    """
    self._transfer(msg.sender, _to, _value)
    return True


@external
def approve(_spender: address, _value: uint256) -> bool:
    """
    @notice Allow `_spender` to transfer up to `_value` amount of tokens from the caller's account.
    @dev Non-zero to non-zero approvals are allowed, but should be used cautiously. The methods
        increaseAllowance + decreaseAllowance are available to prevent any front-running that
        may occur.
    @param _spender The account permitted to spend up to `_value` amount of caller's funds.
    @param _value The amount of tokens `_spender` is allowed to spend.
    """
    self._approve(msg.sender, _spender, _value)
    return True


@external
def increaseAllowance(_spender: address, _add_value: uint256) -> bool:
    """
    @notice Increase the allowance granted to `_spender`.
    @dev This function will never overflow, and instead will bound
        allowance to MAX_UINT256. This has the potential to grant an
        infinite approval.
    @param _spender The account to increase the allowance of.
    @param _add_value The amount to increase the allowance by.
    """
    cached_allowance: uint256 = self.allowance[msg.sender][_spender]
    allowance: uint256 = unsafe_add(cached_allowance, _add_value)

    # check for an overflow
    if allowance < cached_allowance:
        allowance = max_value(uint256)

    if allowance != cached_allowance:
        self._approve(msg.sender, _spender, allowance)

    return True


@external
def decreaseAllowance(_spender: address, _sub_value: uint256) -> bool:
    """
    @notice Decrease the allowance granted to `_spender`.
    @dev This function will never underflow, and instead will bound
        allowance to 0.
    @param _spender The account to decrease the allowance of.
    @param _sub_value The amount to decrease the allowance by.
    """
    cached_allowance: uint256 = self.allowance[msg.sender][_spender]
    allowance: uint256 = unsafe_sub(cached_allowance, _sub_value)

    # check for an underflow
    if cached_allowance < allowance:
        allowance = 0

    if allowance != cached_allowance:
        self._approve(msg.sender, _spender, allowance)

    return True


@external
@view
def admin() -> address:
    return self.factory.admin()