# @version 0.3.7
"""
@title Curve Fee Distribution
@author Curve Finance
@license MIT
"""

from vyper.interfaces import ERC20


interface VotingEscrow:
    def user_point_epoch(addr: address) -> uint256: view
    def epoch() -> uint256: view
    def user_point_history(addr: address, loc: uint256) -> Point: view
    def point_history(loc: uint256) -> Point: view
    def checkpoint(): nonpayable


event CommitAdmin:
    admin: address

event ApplyAdmin:
    admin: address

event ToggleAllowCheckpointToken:
    toggle_flag: bool

event CheckpointToken:
    time: uint256
    tokens: uint256

event Claimed:
    recipient: indexed(address)
    amount: uint256
    claim_epoch: uint256
    max_epoch: uint256


struct Point:
    bias: int128
    slope: int128  # - dweight / dt
    ts: uint256
    blk: uint256  # block


WEEK: constant(uint256) = 7 * 86400
TOKEN_CHECKPOINT_DEADLINE: constant(uint256) = 86400

start_time: public(uint256)
time_cursor: public(uint256)
time_cursor_of: public(HashMap[address, uint256])
user_epoch_of: public(HashMap[address, uint256])

last_token_time: public(uint256)
tokens_per_week: public(uint256[1000000000000000])

voting_escrow: public(address)
token: public(address)
total_received: public(uint256)
token_last_balance: public(uint256)

ve_supply: public(uint256[1000000000000000])  # VE total supply at week bounds

admin: public(address)
future_admin: public(address)
can_checkpoint_token: public(bool)
emergency_return: public(address)
is_killed: public(bool)


@external
def __init__(
    _voting_escrow: address,
    _start_time: uint256,
    _token: address,
    _admin: address,
    _emergency_return: address
):
    """
    @notice Contract constructor
    @param _voting_escrow VotingEscrow contract address
    @param _start_time Epoch time for fee distribution to start
    @param _token Fee token address (crvUSD)
    @param _admin Admin address
    @param _emergency_return Address to transfer `_token` balance to
                             if this contract is killed
    """
    t: uint256 = _start_time / WEEK * WEEK
    self.start_time = t
    self.last_token_time = t
    self.time_cursor = t
    self.token = _token
    self.voting_escrow = _voting_escrow
    self.admin = _admin
    self.emergency_return = _emergency_return


@internal
def _checkpoint_token():
    token_balance: uint256 = ERC20(self.token).balanceOf(self)
    to_distribute: uint256 = token_balance - self.token_last_balance
    self.token_last_balance = token_balance

    t: uint256 = self.last_token_time
    since_last: uint256 = block.timestamp - t
    self.last_token_time = block.timestamp
    this_week: uint256 = t / WEEK * WEEK
    next_week: uint256 = 0

    for i in range(20):
        next_week = this_week + WEEK
        if block.timestamp < next_week:
            if since_last == 0 and block.timestamp == t:
                self.tokens_per_week[this_week] += to_distribute
            else:
                self.tokens_per_week[this_week] += to_distribute * (block.timestamp - t) / since_last
            break
        else:
            if since_last == 0 and next_week == t:
                self.tokens_per_week[this_week] += to_distribute
            else:
                self.tokens_per_week[this_week] += to_distribute * (next_week - t) / since_last
        t = next_week
        this_week = next_week

    log CheckpointToken(block.timestamp, to_distribute)


@external
def checkpoint_token():
    """
    @notice Update the token checkpoint
    @dev Calculates the total number of tokens to be distributed in a given week.
         During setup for the initial distribution this function is only callable
         by the contract owner. Beyond initial distro, it can be enabled for anyone
         to call.
    """
    assert (msg.sender == self.admin) or\
           (self.can_checkpoint_token and (block.timestamp > self.last_token_time + TOKEN_CHECKPOINT_DEADLINE))
    self._checkpoint_token()


@internal
def _find_timestamp_epoch(ve: address, _timestamp: uint256) -> uint256:
    _min: uint256 = 0
    _max: uint256 = VotingEscrow(ve).epoch()
    for i in range(128):
        if _min >= _max:
            break
        _mid: uint256 = (_min + _max + 2) / 2
        pt: Point = VotingEscrow(ve).point_history(_mid)
        if pt.ts <= _timestamp:
            _min = _mid
        else:
            _max = _mid - 1
    return _min


@view
@internal
def _find_timestamp_user_epoch(ve: address, user: address, _timestamp: uint256, max_user_epoch: uint256) -> uint256:
    _min: uint256 = 0
    _max: uint256 = max_user_epoch
    for i in range(128):
        if _min >= _max:
            break
        _mid: uint256 = (_min + _max + 2) / 2
        pt: Point = VotingEscrow(ve).user_point_history(user, _mid)
        if pt.ts <= _timestamp:
            _min = _mid
        else:
            _max = _mid - 1
    return _min


@view
@external
def ve_for_at(_user: address, _timestamp: uint256) -> uint256:
    """
    @notice Get the veCRV balance for `_user` at `_timestamp`
    @param _user Address to query balance for
    @param _timestamp Epoch time
    @return uint256 veCRV balance
    """
    ve: address = self.voting_escrow
    max_user_epoch: uint256 = VotingEscrow(ve).user_point_epoch(_user)
    epoch: uint256 = self._find_timestamp_user_epoch(ve, _user, _timestamp, max_user_epoch)
    pt: Point = VotingEscrow(ve).user_point_history(_user, epoch)
    return convert(max(pt.bias - pt.slope * convert(_timestamp - pt.ts, int128), 0), uint256)


@internal
def _checkpoint_total_supply():
    ve: address = self.voting_escrow
    t: uint256 = self.time_cursor
    rounded_timestamp: uint256 = (block.timestamp - 1) / WEEK * WEEK
    VotingEscrow(ve).checkpoint()

    for i in range(20):
        if t > rounded_timestamp:
            break
        else:
            epoch: uint256 = self._find_timestamp_epoch(ve, t)
            pt: Point = VotingEscrow(ve).point_history(epoch)
            dt: int128 = 0
            if t > pt.ts:
                # If the point is at 0 epoch, it can actually be earlier than the first deposit
                # Then make dt 0
                dt = convert(t - pt.ts, int128)
            self.ve_supply[t] = convert(max(pt.bias - pt.slope * dt, 0), uint256)
        t += WEEK

    self.time_cursor = t


@external
def checkpoint_total_supply():
    """
    @notice Update the veCRV total supply checkpoint
    @dev The checkpoint is also updated by the first claimant each
         new epoch week. This function may be called independently
         of a claim, to reduce claiming gas costs.
    """
    self._checkpoint_total_supply()


@internal
def _claim(addr: address, ve: address, _last_token_time: uint256) -> uint256:
    # Minimal user_epoch is 0 (if user had no point)
    user_epoch: uint256 = 0
    to_distribute: uint256 = 0

    max_user_epoch: uint256 = VotingEscrow(ve).user_point_epoch(addr)
    _start_time: uint256 = self.start_time

    if max_user_epoch == 0:
        # No lock = no fees
        return 0

    week_cursor: uint256 = self.time_cursor_of[addr]
    if week_cursor == 0:
        # Need to do the initial binary search
        user_epoch = self._find_timestamp_user_epoch(ve, addr, _start_time, max_user_epoch)
    else:
        user_epoch = self.user_epoch_of[addr]

    if user_epoch == 0:
        user_epoch = 1

    user_point: Point = VotingEscrow(ve).user_point_history(addr, user_epoch)

    if week_cursor == 0:
        week_cursor = (user_point.ts + WEEK - 1) / WEEK * WEEK

    if week_cursor >= _last_token_time:
        return 0

    if week_cursor < _start_time:
        week_cursor = _start_time
    old_user_point: Point = empty(Point)

    # Iterate over weeks
    for i in range(50):
        if week_cursor >= _last_token_time:
            break

        if week_cursor >= user_point.ts and user_epoch <= max_user_epoch:
            user_epoch += 1
            old_user_point = user_point
            if user_epoch > max_user_epoch:
                user_point = empty(Point)
            else:
                user_point = VotingEscrow(ve).user_point_history(addr, user_epoch)

        else:
            # Calc
            # + i * 2 is for rounding errors
            dt: int128 = convert(week_cursor - old_user_point.ts, int128)
            balance_of: uint256 = convert(max(old_user_point.bias - dt * old_user_point.slope, 0), uint256)
            if balance_of == 0 and user_epoch > max_user_epoch:
                break
            if balance_of > 0:
                to_distribute += balance_of * self.tokens_per_week[week_cursor] / self.ve_supply[week_cursor]

            week_cursor += WEEK

    user_epoch = min(max_user_epoch, user_epoch - 1)
    self.user_epoch_of[addr] = user_epoch
    self.time_cursor_of[addr] = week_cursor

    log Claimed(addr, to_distribute, user_epoch, max_user_epoch)

    return to_distribute


@external
@nonreentrant('lock')
def claim(_addr: address = msg.sender) -> uint256:
    """
    @notice Claim fees for `_addr`
    @dev Each call to claim look at a maximum of 50 user veCRV points.
         For accounts with many veCRV related actions, this function
         may need to be called more than once to claim all available
         fees. In the `Claimed` event that fires, if `claim_epoch` is
         less than `max_epoch`, the account may claim again.
    @param _addr Address to claim fees for
    @return uint256 Amount of fees claimed in the call
    """
    assert not self.is_killed

    if block.timestamp >= self.time_cursor:
        self._checkpoint_total_supply()

    last_token_time: uint256 = self.last_token_time

    if self.can_checkpoint_token and (block.timestamp > last_token_time + TOKEN_CHECKPOINT_DEADLINE):
        self._checkpoint_token()
        last_token_time = block.timestamp

    last_token_time = last_token_time / WEEK * WEEK

    amount: uint256 = self._claim(_addr, self.voting_escrow, last_token_time)
    if amount != 0:
        token: address = self.token
        assert ERC20(token).transfer(_addr, amount)
        self.token_last_balance -= amount

    return amount


@external
@nonreentrant('lock')
def claim_many(_receivers: address[20]) -> bool:
    """
    @notice Make multiple fee claims in a single call
    @dev Used to claim for many accounts at once, or to make
         multiple claims for the same address when that address
         has significant veCRV history
    @param _receivers List of addresses to claim for. Claiming
                      terminates at the first `ZERO_ADDRESS`.
    @return bool success
    """
    assert not self.is_killed

    if block.timestamp >= self.time_cursor:
        self._checkpoint_total_supply()

    last_token_time: uint256 = self.last_token_time

    if self.can_checkpoint_token and (block.timestamp > last_token_time + TOKEN_CHECKPOINT_DEADLINE):
        self._checkpoint_token()
        last_token_time = block.timestamp

    last_token_time = last_token_time / WEEK * WEEK
    voting_escrow: address = self.voting_escrow
    token: address = self.token
    total: uint256 = 0

    for addr in _receivers:
        if addr == ZERO_ADDRESS:
            break

        amount: uint256 = self._claim(addr, voting_escrow, last_token_time)
        if amount != 0:
            assert ERC20(token).transfer(addr, amount)
            total += amount

    if total != 0:
        self.token_last_balance -= total

    return True


@external
def burn(_coin: address) -> bool:
    """
    @notice Receive crvUSD into the contract and trigger a token checkpoint
    @param _coin Address of the coin being received (must be crvUSD)
    @return bool success
    """
    assert _coin == self.token
    assert not self.is_killed

    amount: uint256 = ERC20(_coin).balanceOf(msg.sender)
    if amount != 0:
        ERC20(_coin).transferFrom(msg.sender, self, amount)
        if self.can_checkpoint_token and (block.timestamp > self.last_token_time + TOKEN_CHECKPOINT_DEADLINE):
            self._checkpoint_token()

    return True


@external
def commit_admin(_addr: address):
    """
    @notice Commit transfer of ownership
    @param _addr New admin address
    """
    assert msg.sender == self.admin  # dev: access denied
    self.future_admin = _addr
    log CommitAdmin(_addr)


@external
def apply_admin():
    """
    @notice Apply transfer of ownership
    """
    assert msg.sender == self.admin
    assert self.future_admin != ZERO_ADDRESS
    future_admin: address = self.future_admin
    self.admin = future_admin
    log ApplyAdmin(future_admin)


@external
def toggle_allow_checkpoint_token():
    """
    @notice Toggle permission for checkpointing by any account
    """
    assert msg.sender == self.admin
    flag: bool = not self.can_checkpoint_token
    self.can_checkpoint_token = flag
    log ToggleAllowCheckpointToken(flag)


@external
def kill_me():
    """
    @notice Kill the contract
    @dev Killing transfers the entire crvUSD balance to the emergency return address
         and blocks the ability to claim or burn. The contract cannot be unkilled.
    """
    assert msg.sender == self.admin

    self.is_killed = True

    token: address = self.token
    assert ERC20(token).transfer(self.emergency_return, ERC20(token).balanceOf(self))


@external
def recover_balance(_coin: address) -> bool:
    """
    @notice Recover ERC20 tokens from this contract
    @dev Tokens are sent to the emergency return address.
    @param _coin Token address
    @return bool success
    """
    assert msg.sender == self.admin
    assert _coin != self.token

    amount: uint256 = ERC20(_coin).balanceOf(self)
    response: Bytes[32] = raw_call(
        _coin,
        concat(
            method_id("transfer(address,uint256)"),
            convert(self.emergency_return, bytes32),
            convert(amount, bytes32),
        ),
        max_outsize=32,
    )
    if len(response) != 0:
        assert convert(response, bool)

    return True

# @version 0.3.7
"""
@title crvUSD Stablecoin
@author Curve.Fi
@license Copyright (c) Curve.Fi, 2020-2023 - all rights reserved
"""
from vyper.interfaces import ERC20

implements: ERC20


interface ERC1271:
    def isValidSignature(_hash: bytes32, _signature: Bytes[65]) -> bytes4: view


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

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

event SetMinter:
    minter: indexed(address)


decimals: public(constant(uint8)) = 18
version: public(constant(String[8])) = "v1.0.0"

ERC1271_MAGIC_VAL: constant(bytes4) = 0x1626ba7e
EIP712_TYPEHASH: constant(bytes32) = keccak256(
    "EIP712Domain(string name,string version,uint256 chainId,address verifyingContract,bytes32 salt)"
)
EIP2612_TYPEHASH: constant(bytes32) = keccak256(
    "Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)"
)
VERSION_HASH: constant(bytes32) = keccak256(version)


name: public(immutable(String[64]))
symbol: public(immutable(String[32]))
salt: public(immutable(bytes32))

NAME_HASH: immutable(bytes32)
CACHED_CHAIN_ID: immutable(uint256)
CACHED_DOMAIN_SEPARATOR: immutable(bytes32)


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

nonces: public(HashMap[address, uint256])
minter: public(address)


@external
def __init__(_name: String[64], _symbol: String[32]):
    name = _name
    symbol = _symbol

    NAME_HASH = keccak256(_name)
    CACHED_CHAIN_ID = chain.id
    salt = block.prevhash
    CACHED_DOMAIN_SEPARATOR = keccak256(
        _abi_encode(
            EIP712_TYPEHASH,
            keccak256(_name),
            VERSION_HASH,
            chain.id,
            self,
            block.prevhash,
        )
    )

    self.minter = msg.sender
    log SetMinter(msg.sender)


@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 _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)


@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


@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 permit(
    _owner: address,
    _spender: address,
    _value: uint256,
    _deadline: uint256,
    _v: uint8,
    _r: bytes32,
    _s: bytes32,
) -> bool:
    """
    @notice Permit `_spender` to spend up to `_value` amount of `_owner`'s tokens via a signature.
    @dev In the event of a chain fork, replay attacks are prevented as domain separator is recalculated.
        However, this is only if the resulting chains update their chainId.
    @param _owner The account which generated the signature and is granting an allowance.
    @param _spender The account which will be granted an allowance.
    @param _value The approval amount.
    @param _deadline The deadline by which the signature must be submitted.
    @param _v The last byte of the ECDSA signature.
    @param _r The first 32 bytes of the ECDSA signature.
    @param _s The second 32 bytes of the ECDSA signature.
    """
    assert _owner != empty(address) and block.timestamp <= _deadline

    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)),
        )
    )

    if _owner.is_contract:
        sig: Bytes[65] = concat(_abi_encode(_r, _s), slice(convert(_v, bytes32), 31, 1))
        assert ERC1271(_owner).isValidSignature(digest, sig) == ERC1271_MAGIC_VAL
    else:
        assert ecrecover(digest, _v, _r, _s) == _owner

    self.nonces[_owner] = nonce + 1
    self._approve(_owner, _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
def burnFrom(_from: address, _value: uint256) -> bool:
    """
    @notice Burn `_value` amount of tokens from `_from`.
    @dev The caller must have previously been given an allowance by `_from`.
    @param _from The account to burn the tokens from.
    @param _value The amount of tokens to burn.
    """
    allowance: uint256 = self.allowance[_from][msg.sender]
    if allowance != max_value(uint256):
        self._approve(_from, msg.sender, allowance - _value)

    self._burn(_from, _value)
    return True


@external
def burn(_value: uint256) -> bool:
    """
    @notice Burn `_value` amount of tokens.
    @param _value The amount of tokens to burn.
    """
    self._burn(msg.sender, _value)
    return True


@external
def mint(_to: address, _value: uint256) -> bool:
    """
    @notice Mint `_value` amount of tokens to `_to`.
    @dev Only callable by an account with minter privileges.
    @param _to The account newly minted tokens are credited to.
    @param _value The amount of tokens to mint.
    """
    assert msg.sender == self.minter
    assert _to not in [self, empty(address)]

    self.balanceOf[_to] += _value
    self.totalSupply += _value

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


@external
def set_minter(_minter: address):
    assert msg.sender == self.minter

    self.minter = _minter
    log SetMinter(_minter)


@view
@external
def DOMAIN_SEPARATOR() -> bytes32:
    """
    @notice EIP712 domain separator.
    """
    return self._domain_separator()

# @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