Add strategy deposit facility

contracts/StrategyDepositFacility.vy

@@ -0,0 +1,247 @@
+# @version 0.3.10
+"""
+@title yETH strategy deposit/withdrawal facility
+@author 0xkorin, Yearn Finance
+@license GNU AGPLv3
+@notice
+    Facility to allow the v3 strategy to mint and burn yETH 
+    in exchange for WETH
+"""
+
+from vyper.interfaces import ERC20
+from vyper.interfaces import ERC4626
+
+interface WETH:
+    def deposit(): payable
+    def withdraw(_amount: uint256): nonpayable
+
+interface Facility:
+    def available() -> (uint256, uint256): view
+    def mint(_recipient: address): payable
+    def burn(_amount: uint256): nonpayable
+
+token: public(immutable(address))
+staking: public(immutable(ERC4626))
+facility: public(immutable(Facility))
+weth: public(immutable(WETH))
+
+management: public(address)
+pending_management: public(address)
+
+treasury: public(address)
+strategy: public(address)
+packed_fee_rates: public(uint256)
+
+event Deposit:
+    amount_in: uint256
+    amount_out: uint256
+    stake: bool
+
+event Withdraw:
+    amount_in: uint256
+    amount_out: uint256
+
+event ClaimFees:
+    amount: uint256
+
+event SetFeeRates:
+    deposit_fee_rate: uint256
+    withdraw_fee_rate: uint256
+
+event SetStrategy:
+    strategy: address
+
+event SetTreasury:
+    treasury: address
+
+event PendingManagement:
+    management: indexed(address)
+
+event SetManagement:
+    management: indexed(address)
+
+FEE_RATE_SCALE: constant(uint256) = 10_000
+MAX_FEE_RATE: constant(uint256) = FEE_RATE_SCALE / 100
+MASK: constant(uint256) = (1 << 128) - 1
+
+@external
+def __init__(_token: address, _staking: address, _facility: address, _weth: address):
+    """
+    @notice Constructor
+    @param _token yETH token contract address
+    @param _staking st-yETH token contract address
+    @param _facility ETH deposit facility address
+    @param _weth Wrapped ETH contract address
+    """
+    token = _token
+    staking = ERC4626(_staking)
+    facility = Facility(_facility)
+    weth = WETH(_weth)
+    self.management = msg.sender
+    self.treasury = msg.sender
+
+    assert ERC20(token).approve(_staking, max_value(uint256), default_return_value=True)
+
+@external
+@payable
+def __default__():
+    """
+    @notice Receive ETH
+    @dev Can only be called by the WETH contract and the ETH facility
+    """
+    assert msg.sender in [weth.address, facility.address]
+
+@external
+@view
+def available() -> (uint256, uint256):
+    """
+    @notice Available capacity of the facility
+    @return Amount of yETH that can be minted, amount of yETH that can be burned
+    """
+    return facility.available()
+
+@external
+def deposit(_amount: uint256, _stake: bool) -> uint256:
+    """
+    @notice Deposit WETH and mint yETH
+    @param _amount Amount of WETH to transfer in
+    @param _stake True: stake the minted into st-yETH
+    @return Amount of (st-)yETH minted
+    @dev Can only be called by the strategy
+    """
+    assert msg.sender == self.strategy
+
+    recipient: address = msg.sender
+    if _stake:
+        recipient = self
+    amount: uint256 = _amount
+
+    assert ERC20(weth.address).transferFrom(msg.sender, self, amount, default_return_value=True)
+    weth.withdraw(amount)
+
+    deposit_fee: uint256 = self.packed_fee_rates >> 128
+    if deposit_fee > 0:
+        deposit_fee = amount * deposit_fee / FEE_RATE_SCALE
+        amount -= deposit_fee
+
+    facility.mint(recipient, value=amount)
+    if _stake:
+        amount = staking.deposit(amount, msg.sender)
+
+    log Deposit(_amount, amount, _stake)
+    return amount
+
+@external
+def withdraw(_amount: uint256) -> uint256:
+    """
+    @notice Withdraw WETH and burn yETH
+    @param _amount Amount of yETH to burn
+    @return Amount of WETH withdrawn
+    @dev Can only be called by the strategy
+    """
+    assert msg.sender == self.strategy
+
+    amount: uint256 = _amount
+    assert ERC20(token).transferFrom(msg.sender, self, amount, default_return_value=True)
+    facility.burn(amount)
+
+    withdraw_fee: uint256 = self.packed_fee_rates & MASK
+    if withdraw_fee > 0:
+        withdraw_fee = amount * withdraw_fee / FEE_RATE_SCALE
+        amount -= withdraw_fee
+
+    weth.deposit(value=amount)
+    assert ERC20(weth.address).transfer(msg.sender, amount, default_return_value=True)
+
+    log Withdraw(_amount, amount)
+    return amount
+
+@external
+@view
+def fee_rates() -> (uint256, uint256):
+    """
+    @notice Get deposit and withdraw fee rates
+    @return Deposit fee rate (bps), withdraw fee rate (bps)
+    """
+    packed_fee_rates: uint256 = self.packed_fee_rates
+    return packed_fee_rates >> 128, packed_fee_rates & MASK
+
+@external
+@view
+def pending_fees() -> uint256:
+    """
+    @notice Get the amount of fees that can be sent to the treasury
+    """
+    return self.balance
+
+@external
+def claim_fees() -> uint256:
+    """
+    @notice Claim the pending fees by sending them to the treasury
+    @return Amount of fees claimed
+    """
+    fees: uint256 = self.balance
+    assert fees > 0
+    raw_call(self.treasury, b"", value=fees)
+    log ClaimFees(fees)
+    return fees
+
+@external
+def set_fee_rates(_deposit_fee_rate: uint256, _withdraw_fee_rate: uint256):
+    """
+    @notice Set deposit and withdraw fee rates
+    @param _deposit_fee_rate Deposit fee rate (bps)
+    @param _withdraw_fee_rate Withdraw fee rate (bps)
+    @dev Can only be called by management
+    """
+    assert msg.sender == self.management
+    assert _deposit_fee_rate <= MAX_FEE_RATE and _withdraw_fee_rate <= MAX_FEE_RATE
+    self.packed_fee_rates = (_deposit_fee_rate << 128) | _withdraw_fee_rate
+    log SetFeeRates(_deposit_fee_rate, _withdraw_fee_rate)
+
+@external
+def set_strategy(_strategy: address):
+    """
+    @notice Set yETH strategy address
+    @param _strategy Strategy address
+    @dev Can only be called by management
+    """
+    assert msg.sender == self.management
+    self.strategy = _strategy
+    log SetStrategy(_strategy)
+
+@external
+def set_treasury(_treasury: address):
+    """
+    @notice Set treasury address
+    @param _treasury Treasury address
+    @dev Can only be called by management
+    """
+    assert msg.sender == self.management
+    assert _treasury != empty(address)
+    self.treasury = _treasury
+    log SetTreasury(_treasury)
+
+@external
+def set_management(_management: address):
+    """
+    @notice 
+        Set the pending management address.
+        Needs to be accepted by that account separately to transfer management over
+    @param _management New pending management address
+    """
+    assert msg.sender == self.management
+    self.pending_management = _management
+    log PendingManagement(_management)
+
+@external
+def accept_management():
+    """
+    @notice 
+        Accept management role.
+        Can only be called by account previously marked as pending management by current management
+    """
+    assert msg.sender == self.pending_management
+    self.pending_management = empty(address)
+    self.management = msg.sender
+    log SetManagement(msg.sender)