VaultV3.vy

# @version 0.3.7

"""
@title Yearn V3 Vault
@license GNU AGPLv3
@author yearn.finance
@notice
    The Yearn VaultV3 is designed as an non-opinionated system to distribute funds of 
    depositors for a specific `asset` into different opportunities (aka Strategies)
    and manage accounting in a robust way.

    Depositors receive shares (aka vaults tokens) proportional to their deposit amount. 
    Vault tokens are yield-bearing and can be redeemed at any time to get back deposit 
    plus any yield generated.

    Addresses that are given different permissioned roles by the `role_manager` 
    are then able to allocate funds as they best see fit to different strategies 
    and adjust the strategies and allocations as needed, as well as reporting realized
    profits or losses.

    Strategies are any ERC-4626 compliant contracts that use the same underlying `asset` 
    as the vault. The vault provides no assurances as to the safety of any strategy
    and it is the responsibility of those that hold the corresponding roles to choose
    and fund strategies that best fit their desired specifications.

    Those holding vault tokens are able to redeem the tokens for the corresponding
    amount of underlying asset based on any reported profits or losses since their
    initial deposit.

    The vault is built to be customized by the management to be able to fit their
    specific desired needs Including the customization of strategies, accountants, 
    ownership etc.
"""

from vyper.interfaces import ERC20
from vyper.interfaces import ERC20Detailed

# INTERFACES #
interface IStrategy:
    def asset() -> address: view
    def balanceOf(owner: address) -> uint256: view
    def maxDeposit(receiver: address) -> uint256: view
    def maxWithdraw(owner: address) -> uint256: view
    def withdraw(amount: uint256, receiver: address, owner: address) -> uint256: nonpayable
    def deposit(assets: uint256, receiver: address) -> uint256: nonpayable
    def totalAssets() -> (uint256): view
    def convertToAssets(shares: uint256) -> (uint256): view
    def convertToShares(assets: uint256) -> (uint256): view

interface IAccountant:
    def report(strategy: address, gain: uint256, loss: uint256) -> (uint256, uint256): nonpayable

interface IFactory:
    def protocol_fee_config() -> (uint16, address): view

# EVENTS #
# 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

# ERC20 EVENTS
event Transfer:
    sender: indexed(address)
    receiver: indexed(address)
    value: uint256

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

# STRATEGY EVENTS
event StrategyChanged:
    strategy: indexed(address)
    change_type: indexed(StrategyChangeType)
    
event StrategyReported:
    strategy: indexed(address)
    gain: uint256
    loss: uint256
    current_debt: uint256
    protocol_fees: uint256
    total_fees: uint256
    total_refunds: uint256

# DEBT MANAGEMENT EVENTS
event DebtUpdated:
    strategy: indexed(address)
    current_debt: uint256
    new_debt: uint256

# ROLE UPDATES
event RoleSet:
    account: indexed(address)
    role: indexed(Roles)

event RoleStatusChanged:
    role: indexed(Roles)
    status: indexed(RoleStatusChange)

# STORAGE MANAGEMENT EVENTS
event UpdateRoleManager:
    role_manager: indexed(address)

event UpdateAccountant:
    accountant: indexed(address)

event UpdateDefaultQueue:
    new_default_queue: DynArray[address, MAX_QUEUE]

event UpdatedMaxDebtForStrategy:
    sender: indexed(address)
    strategy: indexed(address)
    new_debt: uint256

event UpdateDepositLimit:
    deposit_limit: uint256

event UpdateMinimumTotalIdle:
    minimum_total_idle: uint256

event UpdateProfitMaxUnlockTime:
    profit_max_unlock_time: uint256

event DebtPurchased:
    strategy: indexed(address)
    amount: uint256

event Shutdown:
    pass

# STRUCTS #
struct StrategyParams:
    # Timestamp when the strategy was added.
    activation: uint256 
    # Timestamp of the strategies last report.
    last_report: uint256
    # The current assets the strategy holds.
    current_debt: uint256
    # The max assets the strategy can hold. 
    max_debt: uint256

# CONSTANTS #
# The max length the withdrawal queue can be.
MAX_QUEUE: constant(uint256) = 10
# 100% in Basis Points.
MAX_BPS: constant(uint256) = 10_000
# Extended for profit locking calculations.
MAX_BPS_EXTENDED: constant(uint256) = 1_000_000_000_000
# The version of this vault.
API_VERSION: constant(String[28]) = "3.0.1-beta"

# ENUMS #
# Each permissioned function has its own Role.
# Roles can be combined in any combination or all kept seperate.
# Follows python Enum patterns so the first Enum == 1 and doubles each time.
enum Roles:
    ADD_STRATEGY_MANAGER # Can add strategies to the vault.
    REVOKE_STRATEGY_MANAGER # Can remove strategies from the vault.
    FORCE_REVOKE_MANAGER # Can force remove a strategy causing a loss.
    ACCOUNTANT_MANAGER # Can set the accountant that assesss fees.
    QUEUE_MANAGER # Can set the default withdrawal queue.
    REPORTING_MANAGER # Calls report for strategies.
    DEBT_MANAGER # Adds and removes debt from strategies.
    MAX_DEBT_MANAGER # Can set the max debt for a strategy.
    DEPOSIT_LIMIT_MANAGER # Sets deposit limit for the vault.
    MINIMUM_IDLE_MANAGER # Sets the minimun total idle the vault should keep.
    PROFIT_UNLOCK_MANAGER # Sets the profit_max_unlock_time.
    DEBT_PURCHASER # Can purchase bad debt from the vault.
    EMERGENCY_MANAGER # Can shutdown vault in an emergency.

enum StrategyChangeType:
    ADDED
    REVOKED

enum Rounding:
    ROUND_DOWN
    ROUND_UP

enum RoleStatusChange:
    OPENED
    CLOSED

# IMMUTABLE #
# Underlying token used by the vault.
ASSET: immutable(ERC20)
# Based off the `asset` decimals.
DECIMALS: immutable(uint256)
# Deployer contract used to retreive the protocol fee config.
FACTORY: public(immutable(address))

# STORAGE #
# HashMap that records all the strategies that are allowed to receive assets from the vault.
strategies: public(HashMap[address, StrategyParams])
# The current default withdrawal queue.
default_queue: public(DynArray[address, MAX_QUEUE])

# ERC20 - amount of shares per account
balance_of: HashMap[address, uint256]
# ERC20 - owner -> (spender -> amount)
allowance: public(HashMap[address, HashMap[address, uint256]])
# Total amount of shares that are currently minted including those locked.
# NOTE: To get the ERC20 compliant version user totalSupply().
total_supply: public(uint256)

# Total amount of assets that has been deposited in strategies.
total_debt: uint256
# Current assets held in the vault contract. Replacing balanceOf(this) to avoid price_per_share manipulation.
total_idle: uint256
# Minimum amount of assets that should be kept in the vault contract to allow for fast, cheap redeems.
minimum_total_idle: public(uint256)
# Maximum amount of tokens that the vault can accept. If totalAssets > deposit_limit, deposits will revert.
deposit_limit: public(uint256)
# Contract that charges fees and can give refunds.
accountant: public(address)
# HashMap mapping addresses to their roles
roles: public(HashMap[address, Roles])
# HashMap mapping roles to their permissioned state. If false, the role is not open to the public.
open_roles: public(HashMap[Roles, bool])
# Address that can add and remove roles to addresses.
role_manager: public(address)
# Temporary variable to store the address of the next role_manager until the role is accepted.
future_role_manager: public(address)
# State of the vault - if set to true, only withdrawals will be available. It can't be reverted.
shutdown: public(bool)

# ERC20 - name of the vaults token.
name: public(String[64])
# ERC20 - symbol of the vaults token.
symbol: public(String[32])

# The amount of time profits will unlock over.
profit_max_unlock_time: uint256
# The timestamp of when the current unlocking period ends.
full_profit_unlock_date: uint256
# The per second rate at which profit will unlock.
profit_unlocking_rate: uint256
# Last timestamp of the most recent profitable report.
last_profit_update: uint256

# `nonces` track `permit` approvals with signature.
nonces: public(HashMap[address, uint256])
DOMAIN_TYPE_HASH: constant(bytes32) = keccak256('EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)')
PERMIT_TYPE_HASH: constant(bytes32) = keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)")

# Constructor
@external
def __init__(
    asset: ERC20, 
    name: String[64], 
    symbol: String[32], 
    role_manager: address, 
    profit_max_unlock_time: uint256
):
    """
    @notice
        The constructor for the vault. Sets the asset, name, symbol, and role manager.
    @param asset
        The address of the asset that the vault will accept.
    @param name
        The name of the vault token.
    @param symbol
        The symbol of the vault token.
    @param role_manager 
        The address that can add and remove roles to addresses
    @param profit_max_unlock_time
        The amount of time that the profit will be locked for
    """
    ASSET = asset
    DECIMALS = convert(ERC20Detailed(asset.address).decimals(), uint256)
    assert DECIMALS < 256 # dev: see VVE-2020-0001
    
    FACTORY = msg.sender

    # Must be > 0 so we can unlock shares
    assert profit_max_unlock_time > 0 # dev: profit unlock time too low
    # Must be less than one year for report cycles
    assert profit_max_unlock_time <= 31_556_952 # dev: profit unlock time too long
    self.profit_max_unlock_time = profit_max_unlock_time

    self.name = name
    self.symbol = symbol
    self.role_manager = role_manager
    self.shutdown = False

## SHARE MANAGEMENT ##
## ERC20 ##
@internal
def _spend_allowance(owner: address, spender: address, amount: uint256):
    # Unlimited approval does nothing (saves an SSTORE)
    current_allowance: uint256 = self.allowance[owner][spender]
    if (current_allowance < max_value(uint256)):
        assert current_allowance >= amount, "insufficient allowance"
        self._approve(owner, spender, current_allowance - amount)

@internal
def _transfer(sender: address, receiver: address, amount: uint256):
    assert self.balance_of[sender] >= amount, "insufficient funds"
    self.balance_of[sender] -= amount
    self.balance_of[receiver] += amount
    log Transfer(sender, receiver, amount)

@internal
def _transfer_from(sender: address, receiver: address, amount: uint256) -> bool:
    self._spend_allowance(sender, msg.sender, amount)
    self._transfer(sender, receiver, amount)
    return True

@internal
def _approve(owner: address, spender: address, amount: uint256) -> bool:
    self.allowance[owner][spender] = amount
    log Approval(owner, spender, amount)
    return True

@internal
def _increase_allowance(owner: address, spender: address, amount: uint256) -> bool:
    self.allowance[owner][spender] += amount
    log Approval(owner, spender, self.allowance[owner][spender])
    return True

@internal
def _decrease_allowance(owner: address, spender: address, amount: uint256) -> bool:
    self.allowance[owner][spender] -= amount
    log Approval(owner, spender, self.allowance[owner][spender])
    return True

@internal
def _permit(
    owner: address, 
    spender: address, 
    amount: uint256, 
    deadline: uint256, 
    v: uint8, 
    r: bytes32, 
    s: bytes32
) -> bool:
    assert owner != empty(address), "invalid owner"
    assert deadline >= block.timestamp, "permit expired"
    nonce: uint256 = self.nonces[owner]
    digest: bytes32 = keccak256(
        concat(
            b'\x19\x01',
            self.domain_separator(),
            keccak256(
                concat(
                    PERMIT_TYPE_HASH,
                    convert(owner, bytes32),
                    convert(spender, bytes32),
                    convert(amount, bytes32),
                    convert(nonce, bytes32),
                    convert(deadline, bytes32),
                )
            )
        )
    )
    assert ecrecover(
        digest, convert(v, uint256), convert(r, uint256), convert(s, uint256)
    ) == owner, "invalid signature"

    self.allowance[owner][spender] = amount
    self.nonces[owner] = nonce + 1
    log Approval(owner, spender, amount)
    return True

@internal
def _burn_shares(shares: uint256, owner: address):
    self.balance_of[owner] -= shares
    self.total_supply -= shares
    log Transfer(owner, empty(address), shares)

@view
@internal
def _unlocked_shares() -> uint256:
    """
    Returns the amount of shares that have been unlocked.
    To avoid sudden price_per_share spikes, profits must be processed 
    through an unlocking period. The mechanism involves shares to be 
    minted to the vault which are unlocked gradually over time. Shares 
    that have been locked are gradually unlocked over profit_max_unlock_time.
    """
    _full_profit_unlock_date: uint256 = self.full_profit_unlock_date
    unlocked_shares: uint256 = 0
    if _full_profit_unlock_date > block.timestamp:
        # If we have not fully unlocked, we need to calculate how much has been.
        unlocked_shares = self.profit_unlocking_rate * (block.timestamp - self.last_profit_update) / MAX_BPS_EXTENDED

    elif _full_profit_unlock_date != 0:
        # All shares have been unlocked
        unlocked_shares = self.balance_of[self]

    return unlocked_shares


@view
@internal
def _total_supply() -> uint256:
    # Need to account for the shares issued to the vault that have unlockded.
    return self.total_supply - self._unlocked_shares()

@internal
def _burn_unlocked_shares():
    """
    Burns shares that have been unlocked since last update. 
    In case the full unlocking period has passed, it stops the unlocking.
    """
    # Get the amount of shares that have unlocked
    unlocked_shares: uint256 = self._unlocked_shares()

    # IF 0 theres nothing to do.
    if unlocked_shares == 0:
        return

    # Only do an SSTORE if necessary
    if self.full_profit_unlock_date > block.timestamp:
        self.last_profit_update = block.timestamp

    # Burn the shares unlocked.
    self._burn_shares(unlocked_shares, self)

@view
@internal
def _total_assets() -> uint256:
    """
    Total amount of assets that are in the vault and in the strategies. 
    """
    return self.total_idle + self.total_debt

@view
@internal
def _convert_to_assets(shares: uint256, rounding: Rounding) -> uint256:
    """ 
    assets = shares * (total_assets / total_supply) --- (== price_per_share * shares)
    """
    total_supply: uint256 = self._total_supply()
    # if total_supply is 0, price_per_share is 1
    if total_supply == 0: 
        return shares

    numerator: uint256 = shares * self._total_assets()
    amount: uint256 = numerator / total_supply
    if rounding == Rounding.ROUND_UP and numerator % total_supply != 0:
        amount += 1

    return amount

@view
@internal
def _convert_to_shares(assets: uint256, rounding: Rounding) -> uint256:
    """
    shares = amount * (total_supply / total_assets) --- (== amount / price_per_share)
    """
    total_supply: uint256 = self._total_supply()
    total_assets: uint256 = self._total_assets()

    if total_assets == 0:
        # if total_assets and total_supply is 0, price_per_share is 1
        if total_supply == 0:
            return assets
        else:
            # Else if total_supply > 0 price_per_share is 0
            return 0

    numerator: uint256 = assets * total_supply
    shares: uint256 = numerator / total_assets
    if rounding == Rounding.ROUND_UP and numerator % total_assets != 0:
        shares += 1

    return shares


@internal
def _erc20_safe_approve(token: address, spender: address, amount: uint256):
    # Used only to send tokens that are not the type managed by this Vault.
    # HACK: Used to handle non-compliant tokens like USDT
    response: Bytes[32] = raw_call(
        token,
        concat(
            method_id("approve(address,uint256)"),
            convert(spender, bytes32),
            convert(amount, bytes32),
        ),
        max_outsize=32,
    )
    if len(response) > 0:
        assert convert(response, bool), "Transfer failed!"


@internal
def _erc20_safe_transfer_from(token: address, sender: address, receiver: address, amount: uint256):
    # Used only to send tokens that are not the type managed by this Vault.
    # HACK: Used to handle non-compliant tokens like USDT
    response: Bytes[32] = raw_call(
        token,
        concat(
            method_id("transferFrom(address,address,uint256)"),
            convert(sender, bytes32),
            convert(receiver, bytes32),
            convert(amount, bytes32),
        ),
        max_outsize=32,
    )
    if len(response) > 0:
        assert convert(response, bool), "Transfer failed!"

@internal
def _erc20_safe_transfer(token: address, receiver: address, amount: uint256):
    # Used only to send tokens that are not the type managed by this Vault.
    # HACK: Used to handle non-compliant tokens like USDT
    response: Bytes[32] = raw_call(
        token,
        concat(
            method_id("transfer(address,uint256)"),
            convert(receiver, bytes32),
            convert(amount, bytes32),
        ),
        max_outsize=32,
    )
    if len(response) > 0:
        assert convert(response, bool), "Transfer failed!"

@internal
def _issue_shares(shares: uint256, recipient: address):
    self.balance_of[recipient] += shares
    self.total_supply += shares

    log Transfer(empty(address), recipient, shares)

@internal
def _issue_shares_for_amount(amount: uint256, recipient: address) -> uint256:
    """
    Issues shares that are worth 'amount' in the underlying token (asset).
    WARNING: this takes into account that any new assets have been summed 
    to total_assets (otherwise pps will go down).
    """
    total_supply: uint256 = self._total_supply()
    total_assets: uint256 = self._total_assets()
    new_shares: uint256 = 0
    
    # If no supply PPS = 1.
    if total_supply == 0:
        new_shares = amount
    elif total_assets > amount:
        new_shares = amount * total_supply / (total_assets - amount)
    else:
        # If total_supply > 0 but amount = totalAssets we want to revert because
        # after first deposit, getting here would mean that the rest of the shares
        # would be diluted to a price_per_share of 0. Issuing shares would then mean
        # either the new depositer or the previous depositers will loose money.
        assert total_assets > amount, "amount too high"
  
    # We don't make the function revert
    if new_shares == 0:
       return 0

    self._issue_shares(new_shares, recipient)

    return new_shares

## ERC4626 ##
@view
@internal
def _max_deposit(receiver: address) -> uint256: 
    if receiver in [empty(address), self]:
        return 0

    _total_assets: uint256 = self._total_assets()
    _deposit_limit: uint256 = self.deposit_limit
    if (_total_assets >= _deposit_limit):
        return 0

    return _deposit_limit - _total_assets

@view
@internal
def _max_redeem(owner: address) -> uint256:
    return self.balance_of[owner]

@view
@internal
def _max_withdraw(owner: address) -> uint256:
    return self._convert_to_assets(self.balance_of[owner], Rounding.ROUND_DOWN)

@internal
def _deposit(sender: address, recipient: address, assets: uint256) -> uint256:
    """
    Used for `deposit` and `mint` calls to transfer the amoutn of `asset` to
    the vault, issue the corresponding shares to the `recipient` and update 
    all needed vault accounting.
    """
    assert self.shutdown == False # dev: shutdown
    assert recipient not in [self, empty(address)], "invalid recipient"
    assert self._total_assets() + assets <= self.deposit_limit, "exceed deposit limit"
 
    # Transfer the tokens to the vault first.
    self._erc20_safe_transfer_from(ASSET.address, msg.sender, self, assets)
    # Record the change in total assets.
    self.total_idle += assets
    
    # Issue the corresponding shares for assets.
    shares: uint256 = self._issue_shares_for_amount(assets, recipient)

    assert shares > 0, "cannot mint zero"

    log Deposit(sender, recipient, assets, shares)
    return shares

@view
@internal
def _assess_share_of_unrealised_losses(strategy: address, assets_needed: uint256) -> uint256:
    """
    Returns the share of losses that a user would take if withdrawing from this strategy
    e.g. if the strategy has unrealised losses for 10% of its current debt and the user 
    wants to withdraw 1000 tokens, the losses that he will take are 100 token
    """
    # Minimum of how much debt the debt should be worth.
    strategy_current_debt: uint256 = self.strategies[strategy].current_debt
    # The actual amount that the debt is currently worth.
    vault_shares: uint256 = IStrategy(strategy).balanceOf(self)
    strategy_assets: uint256 = IStrategy(strategy).convertToAssets(vault_shares)
    
    # If no losses, return 0
    if strategy_assets >= strategy_current_debt or strategy_current_debt == 0:
        return 0

    # Users will withdraw assets_to_withdraw divided by loss ratio (strategy_assets / strategy_current_debt - 1),
    # but will only receive assets_to_withdraw.
    # NOTE: If there are unrealised losses, the user will take his share.
    losses_user_share: uint256 = assets_needed - assets_needed * strategy_assets / strategy_current_debt

    return losses_user_share

@internal
def _redeem(
    sender: address, 
    receiver: address, 
    owner: address, 
    shares_to_burn: uint256, 
    strategies: DynArray[address, MAX_QUEUE]
) -> uint256:
    """
    This will attempt to free up the full amount of assets equivalant to
    `shares_to_burn` and transfer them to the `receiver`. If the vault does
    not have enough idle funds it will go through any strategies provided by
    either the withdrawer or the queue_manaager to free up enough funds to 
    service the request.

    The vault will attempt to account for any unrealized losses taken on from
    strategies since their respective last reports.

    Any losses realized during the withdraw from a strategy will be passed on
    to the user that is redeeming their vault shares.
    """
    shares: uint256 = shares_to_burn
    shares_balance: uint256 = self.balance_of[owner]

    assert shares > 0, "no shares to redeem"
    assert shares_balance >= shares, "insufficient shares to redeem"
    
    if sender != owner:
        self._spend_allowance(owner, sender, shares_to_burn)

    # The amount of the underlying token to withdraw.
    requested_assets: uint256 = self._convert_to_assets(shares, Rounding.ROUND_DOWN)

    # load to memory to save gas
    curr_total_idle: uint256 = self.total_idle
    
    # If there are not enough assets in the Vault contract, we try to free 
    # funds from strategies.
    if requested_assets > curr_total_idle:

        # Cache the input withdrawal queue.
        _strategies: DynArray[address, MAX_QUEUE] = strategies

        # If no queue was passed.
        if len(_strategies) == 0:
                # Use the default queue.
                _strategies = self.default_queue

        # load to memory to save gas
        curr_total_debt: uint256 = self.total_debt

        # Withdraw from strategies only what idle doesnt cover.
        # `assets_needed` is the total amount we need to fill the request.
        assets_needed: uint256 = requested_assets - curr_total_idle
        # `assets_to_withdraw` is the amount to request from the current strategy.
        assets_to_withdraw: uint256 = 0

        # To compare against real withdrawals from strategies
        previous_balance: uint256 = ASSET.balanceOf(self)

        for strategy in _strategies:
            # Make sure we have a valid strategy.
            assert self.strategies[strategy].activation != 0, "inactive strategy"

            # How much should the strategy have.
            current_debt: uint256 = self.strategies[strategy].current_debt

            # What is the max amount to withdraw from this strategy.
            assets_to_withdraw = min(assets_needed, current_debt)

            # Cache max_withdraw now for use if unrealized loss > 0
            max_withdraw: uint256 = IStrategy(strategy).maxWithdraw(self)

            # CHECK FOR UNREALISED LOSSES
            # If unrealised losses > 0, then the user will take the proportional share 
            # and realize it (required to avoid users withdrawing from lossy strategies).
            # NOTE: strategies need to manage the fact that realising part of the loss can 
            # mean the realisation of 100% of the loss!! (i.e. if for withdrawing 10% of the
            # strategy it needs to unwind the whole position, generated losses might be bigger)
            unrealised_losses_share: uint256 = self._assess_share_of_unrealised_losses(strategy, assets_to_withdraw)
            if unrealised_losses_share > 0:
                # If max withdraw is limiting the amount to pull, we need to adjust the portion of 
                # the unrealized loss the user should take.
                if max_withdraw < assets_to_withdraw - unrealised_losses_share:
                    # How much would we want to withdraw
                    wanted: uint256 = assets_to_withdraw - unrealised_losses_share
                    # Get the proportion of unrealised comparing what we want vs. what we can get
                    unrealised_losses_share = unrealised_losses_share * max_withdraw / wanted
                    # Adjust assets_to_withdraw so all future calcultations work correctly
                    assets_to_withdraw = max_withdraw + unrealised_losses_share
                
                # User now "needs" less assets to be unlocked (as he took some as losses)
                assets_to_withdraw -= unrealised_losses_share
                requested_assets -= unrealised_losses_share
                # NOTE: done here instead of waiting for regular update of these values 
                # because it's a rare case (so we can save minor amounts of gas)
                assets_needed -= unrealised_losses_share
                curr_total_debt -= unrealised_losses_share

                # If max withdraw is 0 and unrealised loss is still > 0 then the strategy likely
                # realized a 100% loss and we will need to realize that loss before moving on.
                if max_withdraw == 0 and unrealised_losses_share > 0:
                    # Adjust the strategy debt accordingly.
                    new_debt: uint256 = current_debt - unrealised_losses_share
        
                    # Update strategies storage
                    self.strategies[strategy].current_debt = new_debt
                    # Log the debt update
                    log DebtUpdated(strategy, current_debt, new_debt)

            # Adjust based on the max withdraw of the strategy.
            assets_to_withdraw = min(assets_to_withdraw, max_withdraw)

            # Can't withdraw 0.
            if assets_to_withdraw == 0:
                continue
            
            # WITHDRAW FROM STRATEGY
            IStrategy(strategy).withdraw(assets_to_withdraw, self, self)
            post_balance: uint256 = ASSET.balanceOf(self)
            
            loss: uint256 = 0
            # If we have not received what we expected, we consider the difference a loss.
            if(previous_balance + assets_to_withdraw > post_balance):
                loss = previous_balance + assets_to_withdraw - post_balance

            # NOTE: strategy's debt decreases by the full amount but the total idle increases 
            # by the actual amount only (as the difference is considered lost).
            curr_total_idle += (assets_to_withdraw - loss)
            requested_assets -= loss
            curr_total_debt -= assets_to_withdraw

            # Vault will reduce debt because the unrealised loss has been taken by user
            new_debt: uint256 = current_debt - (assets_to_withdraw + unrealised_losses_share)
        
            # Update strategies storage
            self.strategies[strategy].current_debt = new_debt
            # Log the debt update
            log DebtUpdated(strategy, current_debt, new_debt)

            # Break if we have enough total idle to serve initial request.
            if requested_assets <= curr_total_idle:
                break

            # We update the previous_balance variable here to save gas in next iteration.
            previous_balance = post_balance

            # Reduce what we still need.
            assets_needed -= assets_to_withdraw

        # If we exhaust the queue and still have insufficient total idle, revert.
        assert curr_total_idle >= requested_assets, "insufficient assets in vault"
        # Commit memory to storage.
        self.total_debt = curr_total_debt

    # First burn the corresponding shares from the redeemer.
    self._burn_shares(shares, owner)
    # Commit memory to storage.
    self.total_idle = curr_total_idle - requested_assets
    # Transfer the requested amount to the receiver.
    self._erc20_safe_transfer(ASSET.address, receiver, requested_assets)

    log Withdraw(sender, receiver, owner, requested_assets, shares)
    return requested_assets

## STRATEGY MANAGEMENT ##
@internal
def _add_strategy(new_strategy: address):
    assert new_strategy not in [self, empty(address)], "strategy cannot be zero address"
    assert IStrategy(new_strategy).asset() == ASSET.address, "invalid asset"
    assert self.strategies[new_strategy].activation == 0, "strategy already active"

    # Add the new strategy to the mapping.
    self.strategies[new_strategy] = StrategyParams({
        activation: block.timestamp,
        last_report: block.timestamp,
        current_debt: 0,
        max_debt: 0
    })

    # If the default queue has space, add the strategy.
    if len(self.default_queue) < MAX_QUEUE:
        self.default_queue.append(new_strategy)        
        
    log StrategyChanged(new_strategy, StrategyChangeType.ADDED)

@internal
def _revoke_strategy(strategy: address, force: bool=False):
    assert self.strategies[strategy].activation != 0, "strategy not active"

    # If force revoking a strategy, it will cause a loss.
    loss: uint256 = 0
    
    if self.strategies[strategy].current_debt != 0:
        assert force, "strategy has debt"
        # Vault realizes the full loss of outstanding debt.
        loss = self.strategies[strategy].current_debt
        # Adjust total vault debt.
        self.total_debt -= loss

        log StrategyReported(strategy, 0, loss, 0, 0, 0, 0)

    # Set strategy params all back to 0 (WARNING: it can be readded).
    self.strategies[strategy] = StrategyParams({
      activation: 0,
      last_report: 0,
      current_debt: 0,
      max_debt: 0
    })

    # Remove strategy if it is in the default queue.
    new_queue: DynArray[address, MAX_QUEUE] = []
    for _strategy in self.default_queue:
        # Add all strategies to the new queue besides the one revoked.
        if _strategy != strategy:
            new_queue.append(_strategy)
        
    # Set the default queue to our updated queue.
    self.default_queue = new_queue

    log StrategyChanged(strategy, StrategyChangeType.REVOKED)

# DEBT MANAGEMENT #
@internal
def _update_debt(strategy: address, target_debt: uint256) -> uint256:
    """
    The vault will rebalance the debt vs target debt. Target debt must be
    smaller or equal to strategy's max_debt. This function will compare the 
    current debt with the target debt and will take funds or deposit new 
    funds to the strategy. 

    The strategy can require a maximum amount of funds that it wants to receive
    to invest. The strategy can also reject freeing funds if they are locked.
    """
    # How much we want the strategy to have.
    new_debt: uint256 = target_debt
    # How much the strategy currently has.
    current_debt: uint256 = self.strategies[strategy].current_debt

    # If the vault is shutdown we can only pull funds.
    if self.shutdown:
        new_debt = 0

    assert new_debt != current_debt, "new debt equals current debt"

    if current_debt > new_debt:
        # Reduce debt.
        assets_to_withdraw: uint256 = current_debt - new_debt

        # Ensure we always have minimum_total_idle when updating debt.
        minimum_total_idle: uint256 = self.minimum_total_idle
        total_idle: uint256 = self.total_idle
        
        # Respect minimum total idle in vault
        if total_idle + assets_to_withdraw < minimum_total_idle:
            assets_to_withdraw = minimum_total_idle - total_idle
            # Cant withdraw more than the strategy has.
            if assets_to_withdraw > current_debt:
                assets_to_withdraw = current_debt

        # Check how much we are able to withdraw.
        withdrawable: uint256 = IStrategy(strategy).maxWithdraw(self)
        assert withdrawable != 0, "nothing to withdraw"

        # If insufficient withdrawable, withdraw what we can.
        if withdrawable < assets_to_withdraw:
            assets_to_withdraw = withdrawable

        # If there are unrealised losses we don't let the vault reduce its debt until there is a new report
        unrealised_losses_share: uint256 = self._assess_share_of_unrealised_losses(strategy, assets_to_withdraw)
        assert unrealised_losses_share == 0, "strategy has unrealised losses"
        
        # Always check the actual amount withdrawn.
        pre_balance: uint256 = ASSET.balanceOf(self)
        IStrategy(strategy).withdraw(assets_to_withdraw, self, self)
        post_balance: uint256 = ASSET.balanceOf(self)
        
        # making sure we are changing according to the real result no matter what. 
        # This will spend more gas but makes it more robust. Also prevents issues
        # from a faulty strategy that either under or over delievers 'assets_to_withdraw'
        assets_to_withdraw = min(post_balance - pre_balance, current_debt)

        # Update storage.
        self.total_idle += assets_to_withdraw
        self.total_debt -= assets_to_withdraw
  
        new_debt = current_debt - assets_to_withdraw
    else: 
        # We are increasing the strategies debt

        # Revert if target_debt cannot be achieved due to configured max_debt for given strategy
        assert new_debt <= self.strategies[strategy].max_debt, "target debt higher than max debt"

        # Vault is increasing debt with the strategy by sending more funds.
        max_deposit: uint256 = IStrategy(strategy).maxDeposit(self)
        assert max_deposit != 0, "nothing to deposit"

        # Deposit the difference between desired and current.
        assets_to_deposit: uint256 = new_debt - current_debt
        if assets_to_deposit > max_deposit:
            # Deposit as much as possible.
            assets_to_deposit = max_deposit
        
        # Ensure we always have minimum_total_idle when updating debt.
        minimum_total_idle: uint256 = self.minimum_total_idle
        total_idle: uint256 = self.total_idle

        assert total_idle > minimum_total_idle, "no funds to deposit"
        available_idle: uint256 = total_idle - minimum_total_idle

        # If insufficient funds to deposit, transfer only what is free.
        if assets_to_deposit > available_idle:
            assets_to_deposit = available_idle

        # Can't Deposit 0.
        if assets_to_deposit > 0:
            # Approve the strategy to pull only what we are giving it.
            self._erc20_safe_approve(ASSET.address, strategy, assets_to_deposit)

            # Always update based on actual amounts deposited.
            pre_balance: uint256 = ASSET.balanceOf(self)
            IStrategy(strategy).deposit(assets_to_deposit, self)
            post_balance: uint256 = ASSET.balanceOf(self)

            # Make sure our approval is always back to 0.
            self._erc20_safe_approve(ASSET.address, strategy, 0)

            # Making sure we are changing according to the real result no 
            # matter what. This will spend more gas but makes it more robust.
            assets_to_deposit = pre_balance - post_balance

            # Update storage.
            self.total_idle -= assets_to_deposit
            self.total_debt += assets_to_deposit

        new_debt = current_debt + assets_to_deposit

    # Commit memory to storage.
    self.strategies[strategy].current_debt = new_debt

    log DebtUpdated(strategy, current_debt, new_debt)
    return new_debt

## ACCOUNTING MANAGEMENT ##
@internal
def _process_report(strategy: address) -> (uint256, uint256):
    """
    Processing a report means comparing the debt that the strategy has taken 
    with the current amount of funds it is reporting. If the strategy owes 
    less than it currently has, it means it has had a profit, else (assets < debt) 
    it has had a loss.

    Different strategies might choose different reporting strategies: pessimistic, 
    only realised P&L, ... The best way to report depends on the strategy.

    The profit will be distributed following a smooth curve over the vaults 
    profit_max_unlock_time seconds. Losses will be taken immediately, first from the 
    profit buffer (avoiding an impact in pps), then will reduce pps.

    Any applicable fees are charged and distributed during the report as well
    to the specified recipients.
    """
    # Make sure we have a valid strategy.
    assert self.strategies[strategy].activation != 0, "inactive strategy"

    # Burn shares that have been unlocked since the last update
    self._burn_unlocked_shares()

    # Vault asseses profits using 4626 compliant interface. 
    # NOTE: It is important that a strategies `convertToAssets` implementation
    # cannot be manipulated or else the vault could report incorrect gains/losses.
    strategy_shares: uint256 = IStrategy(strategy).balanceOf(self)
    # How much the vaults position is worth.
    total_assets: uint256 = IStrategy(strategy).convertToAssets(strategy_shares)
    # How much the vault had deposited to the strategy.
    current_debt: uint256 = self.strategies[strategy].current_debt

    gain: uint256 = 0
    loss: uint256 = 0

    # Compare reported assets vs. the current debt.
    if total_assets > current_debt:
        # We have a gain.
        gain = total_assets - current_debt
    else:
        # We have a loss.
        loss = current_debt - total_assets

    # For Accountant fee assessment.
    total_fees: uint256 = 0
    total_refunds: uint256 = 0
    # For Protocol fee assessment.
    protocol_fees: uint256 = 0
    protocol_fee_recipient: address = empty(address)

    accountant: address = self.accountant
    # If accountant is not set, fees and refunds remain unchanged.
    if accountant != empty(address):
        total_fees, total_refunds = IAccountant(accountant).report(strategy, gain, loss)

        # Protocol fees will be 0 if accountant fees are 0.
        if total_fees > 0:
            protocol_fee_bps: uint16 = 0
            # Get the config for this vault.
            protocol_fee_bps, protocol_fee_recipient = IFactory(FACTORY).protocol_fee_config()

            if(protocol_fee_bps > 0):
                # Protocol fees are a percent of the fees the accountant is charging.
                protocol_fees = total_fees * convert(protocol_fee_bps, uint256) / MAX_BPS

    # `shares_to_burn` is derived from amounts that would reduce the vaullts PPS.
    # NOTE: this needs to be done before any pps changes
    shares_to_burn: uint256 = 0
    accountant_fees_shares: uint256 = 0
    protocol_fees_shares: uint256 = 0
    # Only need to burn shares if there is a loss or fees.
    if loss + total_fees > 0:
        # The amount of shares we will want to burn to offset losses and fees.
        shares_to_burn += self._convert_to_shares(loss + total_fees, Rounding.ROUND_UP)

        # Vault calculates the amount of shares to mint as fees before changing totalAssets / totalSupply.
        if total_fees > 0:
            # Accountant fees are total fees - protocol fees.
            accountant_fees_shares = self._convert_to_shares(total_fees - protocol_fees, Rounding.ROUND_DOWN)
            if protocol_fees > 0:
              protocol_fees_shares = self._convert_to_shares(protocol_fees, Rounding.ROUND_DOWN)

    # Shares to lock is any amounts that would otherwise increase the vaults PPS.
    newly_locked_shares: uint256 = 0
    if total_refunds > 0:
        # Make sure we have enough approval and enough asset to pull.
        total_refunds = min(total_refunds, min(ASSET.balanceOf(accountant), ASSET.allowance(accountant, self)))
        # Transfer the refunded amount of asset to the vault.
        self._erc20_safe_transfer_from(ASSET.address, accountant, self, total_refunds)
        # Update storage to increase total assets.
        self.total_idle += total_refunds
        # Mint new shares corresponding to the refunded assets to self.
        newly_locked_shares += self._issue_shares_for_amount(total_refunds, self)

    # Record any reported gains.
    if gain > 0:
        # NOTE: this will increase total_assets
        self.strategies[strategy].current_debt += gain
        self.total_debt += gain

        # Vault will issue shares worth the profit to itself to lock avoid instant pps change.
        newly_locked_shares += self._issue_shares_for_amount(gain, self)

    # Strategy is reporting a loss
    if loss > 0:
        self.strategies[strategy].current_debt -= loss
        self.total_debt -= loss

    # NOTE: should be precise (no new unlocked shares due to above's burn of shares)
    # newly_locked_shares have already been minted / transfered to the vault, so they need to be substracted
    # no risk of underflow because they have just been minted.
    previously_locked_shares: uint256 = self.balance_of[self] - newly_locked_shares

    # Now that pps has updated, we can burn the shares we intended to burn as a result of losses/fees.
    # NOTE: If a value reduction (losses / fees) has occured, prioritize burning locked profit to avoid
    # negative impact on price per share. Price per share is reduced only if losses exceed locked value.
    if shares_to_burn > 0:
        # Cant burn more than the vault owns.
        shares_to_burn = min(shares_to_burn, previously_locked_shares + newly_locked_shares)
        self._burn_shares(shares_to_burn, self)

        # We burn first the newly locked shares, then the previously locked shares.
        shares_not_to_lock: uint256 = min(shares_to_burn, newly_locked_shares)
        # Reduce the amounts to lock by how much we burned
        newly_locked_shares -= shares_not_to_lock
        previously_locked_shares -= (shares_to_burn - shares_not_to_lock)

    # Issue shares for fees that were calculated above if applicable.
    if accountant_fees_shares > 0:
        self._issue_shares(accountant_fees_shares, accountant)

    if protocol_fees_shares > 0:
        self._issue_shares(protocol_fees_shares, protocol_fee_recipient)

    # Update unlocking rate and time to fully unlocked.
    total_locked_shares: uint256 = previously_locked_shares + newly_locked_shares
    if total_locked_shares > 0:
        previously_locked_time: uint256 = 0
        _full_profit_unlock_date: uint256 = self.full_profit_unlock_date
        # Check if we need to account for shares still unlocking.
        if _full_profit_unlock_date > block.timestamp: 
            # There will only be previously locked shares if time remains.
            # We calculate this here since it will not occur every time we lock shares.
            previously_locked_time = previously_locked_shares * (_full_profit_unlock_date - block.timestamp)

        # new_profit_locking_period is a weighted average between the remaining time of the previously locked shares and the profit_max_unlock_time
        new_profit_locking_period: uint256 = (previously_locked_time + newly_locked_shares * self.profit_max_unlock_time) / total_locked_shares
        # Calculate how many shares unlock per second.
        self.profit_unlocking_rate = total_locked_shares * MAX_BPS_EXTENDED / new_profit_locking_period
        # Calculate how long until the full amount of shares is unlocked.
        self.full_profit_unlock_date = block.timestamp + new_profit_locking_period
        # Update the last profitable report timestamp.
        self.last_profit_update = block.timestamp

    else:
        # NOTE: only setting this to 0 will turn in the desired effect, no need 
        # to update last_profit_update or full_profit_unlock_date
        self.profit_unlocking_rate = 0

    # Record the report of profit timestamp.
    self.strategies[strategy].last_report = block.timestamp

    # We have to recalculate the fees paid for cases with an overall loss.
    log StrategyReported(
        strategy,
        gain,
        loss,
        self.strategies[strategy].current_debt,
        self._convert_to_assets(protocol_fees_shares, Rounding.ROUND_DOWN),
        self._convert_to_assets(protocol_fees_shares + accountant_fees_shares, Rounding.ROUND_DOWN),
        total_refunds
    )

    return (gain, loss)

# SETTERS #
@external
def set_accountant(new_accountant: address):
    """
    @notice Set the new accountant address.
    @param new_accountant The new accountant address.
    """
    self._enforce_role(msg.sender, Roles.ACCOUNTANT_MANAGER)
    self.accountant = new_accountant

    log UpdateAccountant(new_accountant)

@external
def set_default_queue(new_default_queue: DynArray[address, MAX_QUEUE]):
    """
    @notice Set the new default queue array.
    @dev Will check each strategy to make sure it is active.
    @param new_default_queue The new default queue array.
    """
    self._enforce_role(msg.sender, Roles.QUEUE_MANAGER)

    # Make sure every strategy in the new queue is active.
    for strategy in new_default_queue:
        assert self.strategies[strategy].activation != 0, "!inactive"

    # Save the new queue.
    self.default_queue = new_default_queue

    log UpdateDefaultQueue(new_default_queue)

@external
def set_deposit_limit(deposit_limit: uint256):
    """
    @notice Set the new deposit limit.
    @dev Can not be changed if shutdown.
    @param deposit_limit The new deposit limit.
    """
    assert self.shutdown == False # Dev: shutdown
    self._enforce_role(msg.sender, Roles.DEPOSIT_LIMIT_MANAGER)
    self.deposit_limit = deposit_limit

    log UpdateDepositLimit(deposit_limit)

@external
def set_minimum_total_idle(minimum_total_idle: uint256):
    """
    @notice Set the new minimum total idle.
    @param minimum_total_idle The new minimum total idle.
    """
    self._enforce_role(msg.sender, Roles.MINIMUM_IDLE_MANAGER)
    self.minimum_total_idle = minimum_total_idle

    log UpdateMinimumTotalIdle(minimum_total_idle)

@external
def set_profit_max_unlock_time(new_profit_max_unlock_time: uint256):
    """
    @notice Set the new profit max unlock time.
    @dev The time is denominated in seconds and must be more than 0
        and less than 1 year. We don't need to update locking period
        since the current period will use the old rate and on the next
        report it will be reset with the new unlocking time.
    @param new_profit_max_unlock_time The new profit max unlock time.
    """
    self._enforce_role(msg.sender, Roles.PROFIT_UNLOCK_MANAGER)
    
    # Must be > 0 so we can unlock shares
    assert new_profit_max_unlock_time > 0, "profit unlock time too low"
    # Must be less than one year for report cycles
    assert new_profit_max_unlock_time <= 31_556_952, "profit unlock time too long"

    self.profit_max_unlock_time = new_profit_max_unlock_time

    log UpdateProfitMaxUnlockTime(new_profit_max_unlock_time)

# ROLE MANAGEMENT #
@internal
def _enforce_role(account: address, role: Roles):
    # Make sure the sender either holds the role or it has been opened.
    assert role in self.roles[account] or self.open_roles[role], "not allowed"

@external
def set_role(account: address, role: Roles):
    """
    @notice Set the role of an account.
    @param account The account to set the role for.
    @param role The role to set.
    """
    assert msg.sender == self.role_manager
    self.roles[account] = role

    log RoleSet(account, role)

@external
def set_open_role(role: Roles):
    """
    @notice Set a role to be open.
    @param role The role to set.
    """
    assert msg.sender == self.role_manager
    self.open_roles[role] = True

    log RoleStatusChanged(role, RoleStatusChange.OPENED)

@external
def close_open_role(role: Roles):
    """
    @notice Close a opened role.
    @param role The role to close.
    """
    assert msg.sender == self.role_manager
    self.open_roles[role] = False

    log RoleStatusChanged(role, RoleStatusChange.CLOSED)
    
@external
def transfer_role_manager(role_manager: address):
    """
    @notice Step 1 of 2 in order to transfer the 
        role manager to a new address. This will set
        the future_role_manager. Which will then need
        to be accepted by the new manager.
    @param role_manager The new role manager address.
    """
    assert msg.sender == self.role_manager
    self.future_role_manager = role_manager

@external
def accept_role_manager():
    """
    @notice Accept the role manager transfer.
    """
    assert msg.sender == self.future_role_manager
    self.role_manager = msg.sender
    self.future_role_manager = empty(address)

    log UpdateRoleManager(msg.sender)

# VAULT STATUS VIEWS
@view
@external
def unlocked_shares() -> uint256:
    """
    @notice Get the amount of shares that have been unlocked.
    @return The amount of shares that are have been unlocked.
    """
    return self._unlocked_shares()

@view
@external
def pricePerShare() -> uint256:
    """
    @notice Get the price per share (pps) of the vault.
    @dev This value offers limited precision. Integrations that require 
        exact precision should use convertToAssets or convertToShares instead.
    @return The price per share.
    """
    return self._convert_to_assets(10 ** DECIMALS, Rounding.ROUND_DOWN)

@view
@external
def availableDepositLimit() -> uint256:
    """
    @notice Get the available deposit limit.
    @return The available deposit limit.
    """
    if self.deposit_limit > self._total_assets():
        return self.deposit_limit - self._total_assets()
    return 0

@view
@external
def get_default_queue() -> DynArray[address, 10]:
    """
    @notice Get the full default queue currently set.
    @return The current default withdrawal queue.
    """
    return self.default_queue

## REPORTING MANAGEMENT ##
@external
@nonreentrant("lock")
def process_report(strategy: address) -> (uint256, uint256):
    """
    @notice Process the report of a strategy.
    @param strategy The strategy to process the report for.
    @return The gain and loss of the strategy.
    """
    self._enforce_role(msg.sender, Roles.REPORTING_MANAGER)
    return self._process_report(strategy)

@external
@nonreentrant("lock")
def buy_debt(strategy: address, amount: uint256):
    """
    @notice Used for governance to buy bad debt from the vault.
    @dev This should only ever be used in an emergency in place
    of force revoking a strategy in order to not report a loss.
    It allows the DEBT_PURCHASER role to buy the strategies debt
    for an equal amount of `asset`. It's important to note that 
    this does rely on the strategies `convertToShares` function to
    determine the amount of shares to buy.
    @param strategy The strategy to buy the debt for
    @param amount The amount of debt to buy from the vault.
    """
    self._enforce_role(msg.sender, Roles.DEBT_PURCHASER)
    assert self.strategies[strategy].activation != 0, "not active"
    
    # Cache the current debt.
    current_debt: uint256 = self.strategies[strategy].current_debt
    
    assert current_debt > 0, "nothing to buy"
    assert amount > 0, "nothing to buy with"

    # Get the current shares value for the amount.
    shares: uint256 = IStrategy(strategy).convertToShares(amount)

    assert shares > 0, "can't buy 0"
    assert shares <= IStrategy(strategy).balanceOf(self), "not enough shares"

    self._erc20_safe_transfer_from(ASSET.address, msg.sender, self, amount)

    # Adjust if needed to not underflow on math
    bought: uint256 = min(current_debt, amount)

    # Lower strategy debt
    self.strategies[strategy].current_debt -= bought
    # lower total debt
    self.total_debt -= bought
    # Increase total idle
    self.total_idle += bought

    # log debt change
    log DebtUpdated(strategy, current_debt, current_debt - bought)

    # Transfer the strategies shares out.
    self._erc20_safe_transfer(strategy, msg.sender, shares)

    log DebtPurchased(strategy, bought)

## STRATEGY MANAGEMENT ##
@external
def add_strategy(new_strategy: address):
    """
    @notice Add a new strategy.
    @param new_strategy The new strategy to add.
    """
    self._enforce_role(msg.sender, Roles.ADD_STRATEGY_MANAGER)
    self._add_strategy(new_strategy)

@external
def revoke_strategy(strategy: address):
    """
    @notice Revoke a strategy.
    @param strategy The strategy to revoke.
    """
    self._enforce_role(msg.sender, Roles.REVOKE_STRATEGY_MANAGER)
    self._revoke_strategy(strategy)

@external
def force_revoke_strategy(strategy: address):
    """
    @notice Force revoke a strategy.
    @dev The vault will remove the inputed strategy and write off any debt left 
        in it as a loss. This function is a dangerous function as it can force a 
        strategy to take a loss. All possible assets should be removed from the 
        strategy first via update_debt. If a strategy is removed erroneously it 
        can be re-added and the loss will be credited as profit. Fees will apply.
    @param strategy The strategy to force revoke.
    """
    self._enforce_role(msg.sender, Roles.FORCE_REVOKE_MANAGER)
    self._revoke_strategy(strategy, True)

## DEBT MANAGEMENT ##
@external
def update_max_debt_for_strategy(strategy: address, new_max_debt: uint256):
    """
    @notice Update the max debt for a strategy.
    @param strategy The strategy to update the max debt for.
    @param new_max_debt The new max debt for the strategy.
    """
    self._enforce_role(msg.sender, Roles.MAX_DEBT_MANAGER)
    assert self.strategies[strategy].activation != 0, "inactive strategy"
    self.strategies[strategy].max_debt = new_max_debt

    log UpdatedMaxDebtForStrategy(msg.sender, strategy, new_max_debt)

@external
@nonreentrant("lock")
def update_debt(strategy: address, target_debt: uint256) -> uint256:
    """
    @notice Update the debt for a strategy.
    @param strategy The strategy to update the debt for.
    @param target_debt The target debt for the strategy.
    @return The amount of debt added or removed.
    """
    self._enforce_role(msg.sender, Roles.DEBT_MANAGER)
    return self._update_debt(strategy, target_debt)

## EMERGENCY MANAGEMENT ##
@external
def shutdown_vault():
    """
    @notice Shutdown the vault.
    """
    self._enforce_role(msg.sender, Roles.EMERGENCY_MANAGER)
    assert self.shutdown == False
    
    # Shutdown the vault.
    self.shutdown = True

    # Set deposit limit to 0.
    self.deposit_limit = 0
    log UpdateDepositLimit(0)

    self.roles[msg.sender] = self.roles[msg.sender] | Roles.DEBT_MANAGER
    log Shutdown()


## SHARE MANAGEMENT ##
## ERC20 + ERC4626 ##
@external
@nonreentrant("lock")
def deposit(assets: uint256, receiver: address) -> uint256:
    """
    @notice Deposit assets into the vault.
    @param assets The amount of assets to deposit.
    @param receiver The address to receive the shares.
    @return The amount of shares minted.
    """
    return self._deposit(msg.sender, receiver, assets)

@external
@nonreentrant("lock")
def mint(shares: uint256, receiver: address) -> uint256:
    """
    @notice Mint shares for the receiver.
    @param shares The amount of shares to mint.
    @param receiver The address to receive the shares.
    @return The amount of assets deposited.
    """
    assets: uint256 = self._convert_to_assets(shares, Rounding.ROUND_UP)
    self._deposit(msg.sender, receiver, assets)
    return assets

@external
@nonreentrant("lock")
def withdraw(
    assets: uint256, 
    receiver: address, 
    owner: address, 
    strategies: DynArray[address, MAX_QUEUE] = []
) -> uint256:
    """
    @notice Withdraw an amount of asset to `receiver` burning `owner`s shares.
    @param assets The amount of asset to withdraw.
    @param receiver The address to receive the assets.
    @param owner The address whos shares are being burnt.
    @param strategies Optional array of strategies to withdraw from.
    @return The amount of shares actually burnt.
    """
    shares: uint256 = self._convert_to_shares(assets, Rounding.ROUND_UP)
    self._redeem(msg.sender, receiver, owner, shares, strategies)
    return shares

@external
@nonreentrant("lock")
def redeem(
    shares: uint256, 
    receiver: address, 
    owner: address, 
    strategies: DynArray[address, MAX_QUEUE] = []
) -> uint256:
    """
    @notice Redeems an amount of shares of `owners` shares sending funds to `receiver`.
    @param shares The amount of shares to burn.
    @param receiver The address to receive the assets.
    @param owner The address whos shares are being burnt.
    @param strategies Optional array of strategies to withdraw from.
    @return The amount of assets actually withdrawn.
    """
    assets: uint256 = self._redeem(msg.sender, receiver, owner, shares, strategies)
    return assets

@external
def approve(spender: address, amount: uint256) -> bool:
    """
    @notice Approve an address to spend the vault's shares.
    @param spender The address to approve.
    @param amount The amount of shares to approve.
    @return True if the approval was successful.
    """
    return self._approve(msg.sender, spender, amount)

@external
def transfer(receiver: address, amount: uint256) -> bool:
    """
    @notice Transfer shares to a receiver.
    @param receiver The address to transfer shares to.
    @param amount The amount of shares to transfer.
    @return True if the transfer was successful.
    """
    assert receiver not in [self, empty(address)]
    self._transfer(msg.sender, receiver, amount)
    return True

@external
def transferFrom(sender: address, receiver: address, amount: uint256) -> bool:
    """
    @notice Transfer shares from a sender to a receiver.
    @param sender The address to transfer shares from.
    @param receiver The address to transfer shares to.
    @param amount The amount of shares to transfer.
    @return True if the transfer was successful.
    """
    assert receiver not in [self, empty(address)]
    return self._transfer_from(sender, receiver, amount)

## ERC20+4626 compatibility
@external
def increaseAllowance(spender: address, amount: uint256) -> bool:
    """
    @notice Increase the allowance for a spender.
    @param spender The address to increase the allowance for.
    @param amount The amount to increase the allowance by.
    @return True if the increase was successful.
    """
    return self._increase_allowance(msg.sender, spender, amount)

@external
def decreaseAllowance(spender: address, amount: uint256) -> bool:
    """
    @notice Decrease the allowance for a spender.
    @param spender The address to decrease the allowance for.
    @param amount The amount to decrease the allowance by.
    @return True if the decrease was successful.
    """
    return self._decrease_allowance(msg.sender, spender, amount)

@external
def permit(
    owner: address, 
    spender: address, 
    amount: uint256, 
    deadline: uint256, 
    v: uint8, 
    r: bytes32, 
    s: bytes32
) -> bool:
    """
    @notice Approve an address to spend the vault's shares.
    @param owner The address to approve.
    @param spender The address to approve.
    @param amount The amount of shares to approve.
    @param deadline The deadline for the permit.
    @param v The v component of the signature.
    @param r The r component of the signature.
    @param s The s component of the signature.
    @return True if the approval was successful.
    """
    return self._permit(owner, spender, amount, deadline, v, r, s)

@view
@external
def balanceOf(addr: address) -> uint256:
    """
    @notice Get the balance of a user.
    @param addr The address to get the balance of.
    @return The balance of the user.
    """
    if(addr == self):
        # If the address is the vault, account for locked shares.
        return self.balance_of[addr] - self._unlocked_shares()

    return self.balance_of[addr]

@view
@external
def totalSupply() -> uint256:
    """
    @notice Get the total supply of shares.
    @return The total supply of shares.
    """
    return self._total_supply()

@view
@external
def asset() -> address:
    """
    @notice Get the address of the asset.
    @return The address of the asset.
    """
    return ASSET.address

@view
@external
def decimals() -> uint8:
    """
    @notice Get the number of decimals of the asset/share.
    @return The number of decimals of the asset/share.
    """
    return convert(DECIMALS, uint8)

@view
@external
def totalAssets() -> uint256:
    """
    @notice Get the total assets held by the vault.
    @return The total assets held by the vault.
    """
    return self._total_assets()

@view
@external
def totalIdle() -> uint256:
    """
    @notice Get the amount of loose `asset` the vault holds.
    @return The current total idle.
    """
    return self.total_idle

@view
@external
def totalDebt() -> uint256:
    """
    @notice Get the the total amount of funds invested
    across all strategies.
    @return The current total debt.
    """
    return self.total_debt

@view
@external
def convertToShares(assets: uint256) -> uint256:
    """
    @notice Convert an amount of assets to shares.
    @param assets The amount of assets to convert.
    @return The amount of shares.
    """
    return self._convert_to_shares(assets, Rounding.ROUND_DOWN)

@view
@external
def previewDeposit(assets: uint256) -> uint256:
    """
    @notice Preview the amount of shares that would be minted for a deposit.
    @param assets The amount of assets to deposit.
    @return The amount of shares that would be minted.
    """
    return self._convert_to_shares(assets, Rounding.ROUND_DOWN)

@view
@external
def previewMint(shares: uint256) -> uint256:
    """
    @notice Preview the amount of assets that would be deposited for a mint.
    @param shares The amount of shares to mint.
    @return The amount of assets that would be deposited.
    """
    return self._convert_to_assets(shares, Rounding.ROUND_UP)

@view
@external
def convertToAssets(shares: uint256) -> uint256:
    """
    @notice Convert an amount of shares to assets.
    @param shares The amount of shares to convert.
    @return The amount of assets.
    """
    return self._convert_to_assets(shares, Rounding.ROUND_DOWN)

@view
@external
def maxDeposit(receiver: address) -> uint256:
    """
    @notice Get the maximum amount of assets that can be deposited.
    @param receiver The address that will receive the shares.
    @return The maximum amount of assets that can be deposited.
    """
    return self._max_deposit(receiver)

@view
@external
def maxMint(receiver: address) -> uint256:
    """
    @notice Get the maximum amount of shares that can be minted.
    @param receiver The address that will receive the shares.
    @return The maximum amount of shares that can be minted.
    """
    max_deposit: uint256 = self._max_deposit(receiver)
    return self._convert_to_shares(max_deposit, Rounding.ROUND_DOWN)

@view
@external
def maxWithdraw(owner: address) -> uint256:
    """
    @notice Get the maximum amount of assets that can be withdrawn.
    @param owner The address that owns the shares.
    @return The maximum amount of assets that can be withdrawn.
    """
    return self._max_withdraw(owner)

@view
@external
def maxRedeem(owner: address) -> uint256:
    """
    @notice Get the maximum amount of shares that can be redeemed.
    @param owner The address that owns the shares.
    @return The maximum amount of shares that can be redeemed.
    """
    return self._max_redeem(owner)

@view
@external
def previewWithdraw(assets: uint256) -> uint256:
    """
    @notice Preview the amount of shares that would be redeemed for a withdraw.
    @param assets The amount of assets to withdraw.
    @return The amount of shares that would be redeemed.
    """
    return self._convert_to_shares(assets, Rounding.ROUND_UP)

@view
@external
def previewRedeem(shares: uint256) -> uint256:
    """
    @notice Preview the amount of assets that would be withdrawn for a redeem.
    @param shares The amount of shares to redeem.
    @return The amount of assets that would be withdrawn.
    """
    return self._convert_to_assets(shares, Rounding.ROUND_DOWN)

@view
@external
def api_version() -> String[28]:
    """
    @notice Get the API version of the vault.
    @return The API version of the vault.
    """
    return API_VERSION

@view
@external
def assess_share_of_unrealised_losses(strategy: address, assets_needed: uint256) -> uint256:
    """
    @notice Assess the share of unrealised losses that a strategy has.
    @param strategy The address of the strategy.
    @param assets_needed The amount of assets needed to be withdrawn.
    @return The share of unrealised losses that the strategy has.
    """
    assert self.strategies[strategy].current_debt >= assets_needed

    return self._assess_share_of_unrealised_losses(strategy, assets_needed)

## Profit locking getter functions ##

@view
@external
def profitMaxUnlockTime() -> uint256:
    """
    @notice Gets the current time profits are set to unlock over.
    @return The current profit max unlock time.
    """
    return self.profit_max_unlock_time

@view
@external
def fullProfitUnlockDate() -> uint256:
    """
    @notice Gets the timestamp at which all profits will be unlocked.
    @return The full profit unlocking timestamp
    """
    return self.full_profit_unlock_date

@view
@external
def profitUnlockingRate() -> uint256:
    """
    @notice The per second rate at which profits are unlocking.
    @dev This is denominated in EXTENDED_BPS decimals.
    @return The current profit unlocking rate.
    """
    return self.profit_unlocking_rate


@view
@external
def lastReport() -> uint256:
    """
    @notice The timestamp of the last time protocol fees were charged.
    @return The last report.
    """
    return self.last_profit_update

# eip-1344
@view
@internal
def domain_separator() -> bytes32:
    return keccak256(
        concat(
            DOMAIN_TYPE_HASH,
            keccak256(convert("Yearn Vault", Bytes[11])),
            keccak256(convert(API_VERSION, Bytes[28])),
            convert(chain.id, bytes32),
            convert(self, bytes32)
        )
    )

@view
@external
def DOMAIN_SEPARATOR() -> bytes32:
    """
    @notice Get the domain separator.
    @return The domain separator.
    """
    return self.domain_separator()