TenderLeverageStrategy.sol

Tender.fi Acquisition

Tender.fi has been acquired by Gemach. This page uses the Tender naming for consistency with the smart contract code.

Tender.fi Docs: https://docs.gemach.io/gemach-dao/products/glend

Properties

Property	Type	Modifier	Description
balancerVault	address	public; constant	The address of the Balancer Vault contract (to facilitate flash loans).
_positionId	uint256	private	The identifier for the strategy position that is maintained by the Factor Leverage Vault.
_vaultManager	IERC721	private	The address of the Vault Manager contract which facilitates vault admin operations (the underlying Leverage Vault contract in this instance).
_asset	IERC20	private	The address of the asset token (i.e. collateral and token being levered).
_debtToken	IERC20	private	The address of the debt token (i.e. borrow asset for flash loan).
_assetPool	address	public	The address of the asset lending pool.
_debtPool	address	public	The address of the debt lending pool.
tenderUniTroller	address	public; constant	The address of the Tender.fi Unitroller contract which proxies Comptroller logic and maintains stores state.
tenderVester	address	public; constant	The address of the Tender.fi Vesting contract which facilitates the vested TND rewards.
tenderVestedToken	address	public; constant	The address of the vested Tender.fi token (i.e. esTND).
tenderToken	address	public; constant	The address of the Tender.fi token (i.e. TND).
weth	address	public; constant	The address of the WETH token.
flMode	uint8	private	The flash loan mode used to determine the relevant operations to receive the flash loan: 1 = addLeverage 2 = removeLeverage 3 = switchAsset 4 = switchDebt 5 = closeLeverage

Events

LeverageAdded()

Emitted when leverage is added to the position (i.e. this Leverage Strategy contract).

Arguments

Argument	Type	Description
amount	uint256	The amount of asset that was supplied to the lending pool.
debt	uint256	The amount of debt that was taken out as a flash loan denominated in _debtToken.

LeverageRemoved()

Emitted when leverage is removed from the leveraged position (i.e. this Leverage Strategy contract).

Arguments

Argument	Type	Description
debt	uint256	The amount of debt that was repaid.

LeverageClosed()

Emitted when the leveraged position is closed (i.e. fully repaid).

Arguments

Argument	Type	Description
assetBalance	uint256	The amount of asset that was returned after closing the position.
debtBalance	uint256	The amount of debt that was returned after closing the position.

AssetSwitched()

Emitted when the underlying collateral asset for the leveraged position is switched.

Arguments

Argument	Type	Description
newAsset	address	The address of the token used to collateralize the newly switched leverage position.
balance	uint256	The amount of newAsset that was collateralized.

DebtSwitched()

Emitted when the debt token for the leveraged position is switched.

Arguments

Argument	Type	Description
newDebt	address	The address of the token that was borrowed (i.e. the debt token).
balance	uint256	The amount of newDebt that is owed (i.e. the debt amount).

Withdraw()

Emitted when asset is withdrawn from the Tender.fi lending pool.

Arguments

Argument	Type	Description
amount	uint256	The amount of asset withdrawn from the Tender.fi lending pool.

Repay()

Emitted when the Tender.fi lending pool debt is repaid.

Arguments

Argument	Type	Description
amount	uint256	The amount of debt that was repaid.

Supply()

Emitted when asset is supplied to the Tender.fi lending pool.

Arguments

Argument	Type	Description
amount	uint256	The amount of asset supplied to the Tender.fi lending pool.

Borrow()

Emitted when debt is borrowed from the Tender.fi lending pool (which collateralizes the provided asset).

Arguments

Argument	Type	Description
amount	uint256	The amount of debt that was borrowed from the Tender.fi lending pool.

WithdrawTokenInCaseStuck()

Emitted when stuck tokens are withdrawn from the Strategy contract.

Arguments

Argument	Type	Description
tokenAddress	address	The address of the token to be withdrawn.
amount	uint256	The amount of asset withdrawn from the Tender.fi lending pool.

RewardClaimed()

Emitted when Tender.fi rewards are claimed as TND tokens and transferred to the msg.sender (i.e. user).

Arguments

Argument	Type	Description
amount	uint256	The amount of rewards claimed denominated in TND tokens.

RewardClaimedSupply()

Emitted when Tender.fi rewards are claimed as asset tokens and transferred to the msg.sender (i.e. user).

Arguments

Argument	Type	Description
amount	uint256	The amount of rewards claimed denominated in TND tokens.

RewardClaimedRepay()

Emitted when Tender.fi rewards are claimed as debt tokens and transferred to the msg.sender (i.e. user).

Arguments

Argument	Type	Description
amount	uint256	The amount of rewards claimed denominated in TND tokens.

LeverageChargeFee()

Emitted when a leverage fee is charged.

Arguments

Argument	Type	Description
amount	uint256	The leverage fee charged denominated in token passed in leverageFeeCharge().

Constructor

Factor Strategy contracts implements OpenZeppelin's upgradeable contracts design and locks the strategy contract upon initialization to avoid contract takeover by an attacker. More info can be found on OpenZeppelin Docs.

Modifiers

onlyOwner()

Checks if the msg.sender address is equal to the owner of the position as maintained by the Leverage Vault contract.

Methods

initialize() - public initializer

Initializes the Strategy contract with the __positionId and initial address configurations.

Parameters

Params	Type	Description
__positionId	uint256	The identifier of the leveraged position as maintained by the underlying Leverage Vault contract.
_vaultManagerAddress	address	The address of the Vault Manager contract (the underlying Leverage Vault contract in this instance).
_assetAddress	address	The address of the Strategy's asset token (i.e. collateral and token being levered).
_debtAddress	address	The address of the Strategy's debt token (i.e. borrow asset for flash loan).
_assetPoolAddress	address	The address of the asset lending pool.
_debtPoolAddress	address	The address of the debt lending pool.

vaultManager() - public view returns

Returns the address of the Factor Vault Manager contract which contains vault admin functions (e.g. upgrade strategy, set fees, etc.).

Returns

Type	Description
address	The address of the Factor Vault Manager.

positionId() - public view returns

Returns the position identifier maintained by the underlying Leverage Vault contract. Each strategy implementation (such as this contract) is tied to a positionId.

Returns

Type	Description
uint256	The identifier of the position on the underlying Leverage Vault contract.

asset() - public view returns

Returns the address of the token configured as the main asset for this leverage Strategy contract (i.e. collateralized asset).

Returns

Type	Description
address	The address of the Strategy's _asset.

debtToken() - public view returns

Returns the address of the debt token which is used for taking out a flash loan (i.e. borrow token) for this Strategy contract.

Returns

Type	Description
address	The address of the Strategy's _debtToken .

assetPool() - public view returns

Returns the address of the Tender.fi lending pool where the _asset is being collateralized.

Returns

Type	Description
address	The address of the Strategy's _assetPool.

debtPool() - public view returns

Returns the address of the Tender.fi lending pool where the _debtToken was borrowed from.

Returns

Type	Description
address	The address of the Strategy's _debtPool.

assetBalance() - public view returns

Returns the total collateralized balance (i.e. _asset supplied) of the Strategy contract that is held by the Tender.fi lending pool.

Returns

Type	Description
uint256	The total _asset supplied to the Tender.fi lending pool.

debtBalance() - public view returns

Returns the outstanding debt balance (i.e. _debtToken borrowed) which the Strategy contract owes to the Tender.fi lending contract.

Returns

Type	Description
uint256	The total _debtToken that needs to be repaid to the Tender.fi lending pool.

owner() - public view returns

Returns the address of the owner of the leveraged position.

Returns

Type	Description
address	The address of the owner of the position.

addLeverage() - external payable

Adds leverage to a position by executing the following:

1. Transfer asset from owner to the Strategy contract

2. Supply asset to the Tender.fi pool

3. If debt is specified, executes a flash loan to borrow configured debt amount on Balancer vault

4. Balancer vault calls receiveFlashLoan() to trigger flash swap and flash loan debt repayment via _flAddLeverage()

Parameters

Params	Type	Description
amount	uint256	The amount of _asset being supplied.
debt	uint256	The amount of _debtToken to be flash loaned.
data	bytes	The Balancer userData which in this context is used for pool-specific instructions needed to do the calculations.

Events

Events	Description
LeverageAdded()	Emits the results of the leverage addition.

_flAddLeverage() - internal

An internal function which is meant to be called by the Balancer vault contract which repays the flash loan on Balancer by borrowing debt against the new asset collateralized amount on Tender.fi.

1. Swap debt for asset (via swapBySelf())
2. Supply newly acquired asset to the Tender.fi pool (i.e. increase total collateral value)

3. Borrow _debtToken from the Tender.fi pool to repay Balancer flash loan

4. Repay the Balancer flash loan

Parameters

Params	Type	Description
params	bytes	Encoded bytes data which consists of: amount = The number of _debtToken that was flash loaned. data = The Balancer userData.
feeAmount	uint256	The flash loan fee amount to be repaid denominated in _debtToken.

removeLeverage() - external onlyOwner

Removes a specified amount of leverage from the Strategy contract by executing the following:

1. Query the outstanding debt on the Tender.fi lending pool

2. Executes a flash loan to borrow debt from the Balancer vault equivalent to the outstanding debt on the Tender.fi pool

3. Balancer vault calls receiveFlashLoan() to trigger flash swap and flash loan debt repayment via _flRemoveLeverage()
4. Transfer withdrawn asset to the owner

Modifiers

Modifier	Description
onlyOwner	Ensures that only the specified owner of the contract is able to execute administrative tasks. More info on OpenZeppelin Docs.

Parameters

Params	Type	Description
amount	uint256	The amount of asset being removed.
data	bytes	The Balancer userData which in this context is used for pool-specific instructions needed to do the calculations.

Events

Events	Description
LeverageRemoved()	Emits the results of the leverage removal.

_flRemoveLeverage() - internal

An internal function which is meant to be called by the Balancer vault contract which repays the flash loan on Balancer by withdrawing asset from the Tender.fi lending pool.

1. Queries the outstanding debt on the Tender.fi lending pool

2. Repays all of the outstanding debt on Tender.fi

3. Withdraws the specified amount of asset (as per removeLeverage())
4. Swap the withdrawn asset for debt (via swapBySelf())
5. Calculates the remaining Balancer flash loan debt outstanding

6. Borrow the oustanding flash loan debt amount (including fees) from Tender.fi lending pool

7. Repay the Balancer flash loan

Parameters

Params	Type	Description
params	bytes	Encoded bytes data which consists of: amount = The number of _asset that is being removed from the Strategy contract. data = The Balancer userData.
feeAmount	uint256	The flash loan fee amount to be repaid denominated in _debtToken.

swapBySelf() - public returns

Allows the msg.sender to conduct a swap via the OpenOcean aggregator.

Parameters

Params	Type	Description
tokenIn	address	The address of the token being swapped from.
tokenOut	address	The address of the token being swapped to.
amount	uint256	The amount of tokenIn being swapped.
data	bytes	The bytes data which consists of the swap method and params.

Returns

Type	Description
uint256	The amount of tokenOut resulting from the swap minus the leverage strategy fees.

supply() - external onlyOwner

Enables the owner to transfer strategy asset from the msg.sender(i.e. depositor) to the Strategy contract which is then supplied to the Tender.fi lending pool. The Strategy contract will hold the balance on behalf of the owner.

Modifiers

Modifier	Description
onlyOwner	Ensures that only the specified owner of the contract is able to execute administrative tasks. More info on OpenZeppelin Docs.

Parameters

Params	Type	Description
amount	uint256	The amount of asset that was used for leverage.

Events

Events	Description
Supply()	Emits the amount of asset that was supplied.

Returns

Type	Description
uint256	The leverage fee charged denominated in token.

borrow() - external onlyOwner

Enables the owner to utilize the collateralized asset in the Tender.fi lending pool to borrow the specified amount of debt. The debt is transferred to the msg.owner (i.e. owner) with the Strategy contract holding the debt on behalf of the owner.

Modifiers

Modifier	Description
onlyOwner	Ensures that only the specified owner of the contract is able to execute administrative tasks. More info on OpenZeppelin Docs.

Parameters

Params	Type	Description
amount	uint256	The amount of debt to be borrowed.

Events

Events	Description
Borrow()	Emits the amount of debt that was borrowed.

repay() - external onlyOwner

Enables the owner to repay a specified amount of the debt for a borrow position on the Tender.fi lending pool. The debt is repaid on behalf of the Strategy contract which holds the owner's debt obligations.

Modifiers

Modifier	Description
onlyOwner	Ensures that only the specified owner of the contract is able to execute administrative tasks. More info on OpenZeppelin Docs.

Parameters

Params	Type	Description
amount	uint256	The amount of debt to be repaid.

Events

Events	Description
Repay()	Emits the amount of debt that was repaid.

withdraw() - external onlyOwner

Enables the owner to withdraw a specified amount of asset from the Tender.fi lending pool. The Strategy contract executes the withdrawal as it holds deposit balance on behalf of the owner. The corresponding amount of asset is transferred to the owner address.

Note that due to accrued fees to the iToken, the amount returned by the Tender.fi lending pool might be higher than the given amount. In such cases, the higher of the expected amount or final amount is returned to the owner.

Modifiers

Modifier	Description
onlyOwner	Ensures that only the specified owner of the contract is able to execute administrative tasks. More info on OpenZeppelin Docs.

Parameters

Params	Type	Description
amount	uint256	The amount of asset to be withdrawn.

Events

Events	Description
Withdraw()	Emits the amount of asset that was withdrawn.

switchAsset() - external onlyOwner

Switches the position's underlying asset to a newly specified newAsset token.

1. Query the outstanding debt on the Tender.fi lending pool

2. Executes a flash loan to borrow debt from the Balancer vault equivalent to the outstanding debt on the Tender.fi vault

3. Balancer vault calls receiveFlashLoan() to trigger flash swap and flash loan debt repayment via _flSwitchAsset()

Allowed New Asset Tokens

The newAsset address must have been registered by the Vault Manager. The list of approved debt tokens is maintained by the Leverage Vault contract.

Amount Validation

The Factor SDK provides convenience functions for the safe handling of the specified amount. By utilizing the Factor SDK, you can avoid spending gas on misconfigured amounts and minimize dust amounts from swaps.

Debt Calculation Tolerance

The function flash loans an additional 1 token to provide a buffer for debt repayments. Balancer flash loans currently do not charge any fees hence there are no adverse outcomes from the additional amount flash loaned.

Parameters

Params	Type	Description
newAsset	address	The address of the token which will be switched with the current asset.
amount	uint256	The amount of existing asset that is being switched for the newAsset.
data	bytes	The Balancer userData which in this context is used for pool-specific instructions needed to do the calculations.

_flSwitchAsset() - internal

An internal function which is meant to be called by the Balancer vault contract which switches the asset collateralizing the leveraged position.

1. Queries the outstanding debt on the Tender.fi lending pool

2. Repays all of the outstanding debt on Tender.fi

3. Withdraws all of the asset from the existing position on Tender.fi

4. Swaps the specified amount (per switchAsset()) of the withdrawn asset for newAsset (via swapBySelf())
5. Change the Factor Strategy contract properties to align with the newAsset

6. Supply the swapped newAsset to the newAsset Tender.fi lending pool

7. Borrow the initial debt balance from Tender.fi using the newAsset as collateral

8. Repay the Balancer flash loan

Parameters

Params	Type	Description
params	bytes	Encoded bytes data which consists of: newAsset = The address of the token that is being used as the new collateral amount = The number of _asset that is being switched. data = The Balancer userData.
feeAmount	uint256	The flash loan fee amount to be repaid denominated in _debtToken.

Events

Events	Description
AssetSwitched()	Emits the results of the asset switch and new asset balance denominated in newAsset.

switchDebt() - external onlyOwner

Switches the debt of the leverage position for a specified newDebtToken.

1. Executes a flash loan to borrow existing debt from the Balancer vault equivalent to the outstanding debt on the Tender.fi lending pool

2. Balancer vault calls receiveFlashLoan() to trigger flash swap and flash loan debt repayment via _flSwitchDebt()

Allowed New Debt Tokens

The newDebtToken address must have been registered by the Vault Manager. The list of approved debt tokens is maintained by the Leverage Vault contract.

Modifiers

Modifier	Description
onlyOwner	Ensures that only the specified owner of the contract is able to execute administrative tasks. More info on OpenZeppelin Docs.

Parameters

Params	Type	Description
newDebtToken	address	The address of the token which will be switched with the current debt.
newDebt	uint256	The amount of newDebtToken that is being switched in place of the old debt.
data	bytes	The Balancer userData which in this context is used for pool-specific instructions needed to do the calculations.

_flSwitchDebt() - internal

An internal function which is meant to be called by the Balancer vault contract which switches the debt of a leveraged position with a provided newDebtToken.

1. Queries the outstanding debt on the Tender.fi lending pool

2. Repays all of the outstanding debt on Tender.fi

3. Change the Factor Strategy contract properties to align with the newDebtToken

4. Borrow the provided newDebt amount of newDebtToken from the corresponding Tender.fi pool using the untouched underlying asset as collateral

5. Swaps the specified newDebt amount (per switchDebt()) of the newDebtToken for the previous debt token (via swapBySelf())
6. Repay the Balancer flash loan using the acquired debt

Parameters

Params	Type	Description
params	bytes	Encoded bytes data which consists of: newDebtToken = The address of the token to be used as the new debt newDebt = The number of newDebtToken that is being borrowed poolAddress = The address of the corresponding Tender.fi lending pool. data = The Balancer userData.
feeAmount	uint256	The flash loan fee amount to be repaid denominated in the old debt.

Events

Events	Description
DebtSwitched()	Emits the results of the asset switch and new asset balance denominated in newAsset.

closeLeverage() - external onlyOwner

Closes the leveraged position and transfers the remaining asset and debt amounts to the owner. If the asset amount specified is greater than the debt value, the position value will be returned in debt tokens.

1. Executes a flash loan to borrow existing debt from the Balancer vault equivalent to the outstanding debt on the Tender.fi lending pool

2. Balancer vault calls receiveFlashLoan() to trigger flash swap and flash loan debt repayment via _flCloseLeverage()
3. Transfers the remaining asset and debt tokens to the owner (i.e. depositor)

Debt Calculation Tolerance

The function flash loans an additional 1 token to provide a buffer for debt repayments. Balancer flash loans currently do not charge any fees hence there are no adverse outcomes from the additional amount flash loaned.

Modifiers

Modifier	Description
onlyOwner	Ensures that only the specified owner of the contract is able to execute administrative tasks. More info on OpenZeppelin Docs.

Parameters

Params	Type	Description
amount	uint256	The amount of asset that will be swapped for debt.
data	bytes	The Balancer userData which in this context is used for pool-specific instructions needed to do the calculations.

Events

Events	Description
LeverageClosed()	Emits the results of the leverage position closure.

_flCloseLeverage() - internal

An internal function which is meant to be called by the Balancer vault contract which switches the debt of the leveraged position with a provided newDebtToken.

1. Queries the outstanding debt on the Tender.fi lending pool

2. Repays all of the outstanding debt on Tender.fi

3. Withdraws all of the asset from the existing position on Tender.fi

4. Swaps the specified amount of asset (per closeLeverage()) for debt (via swapBySelf())
5. Repay the Balancer flash loan using the acquired debt

Parameters

Params	Type	Description
params	bytes	Encoded bytes data which consists of: amount = The number of asset that is swapped for debt data = The Balancer userData.
feeAmount	uint256	The flash loan fee amount to be repaid denominated in the old debt.

version() - external pure returns

Returns the strategy version which is hardcoded based on contract deployment.

Returns

Type	Description
string	The Strategy contract version.

_authorizeUpgrade() - internal view override onlyOnwer

An internal function that is meant to be called by the UUPSUpgradeable contract that checks if the new implementation is registered by the Factor Vault Manager.

Modifiers

Modifier	Description
onlyOwner	Ensures that only the specified owner of the contract is able to execute administrative tasks. More info on OpenZeppelin Docs.

Parameters

Params	Type	Description
newImplementation	address	The address of the proposed Strategy contract.

_claimRewardsInternal() - private onlyOwner

A private function which faciliates the claiming of Tender.fi rewards based on the specified output token. If the token is not specified, the rewards will be claimed as TND else the claimed TND rewards will be swapped for the specified token.

If the claimRewardsSupply (from claimRewardsSupply()) or claimRewardsRepay (from claimRewardsRepay()) selector is specified, the claimed rewards will be swapped for the specified token and supplied/repaid to the corresponding Tender.fi lending pool.

Modifiers

Modifier	Description
onlyOwner	Ensures that only the specified owner of the contract is able to execute administrative tasks. More info on OpenZeppelin Docs.

Parameters

Params	Type	Description
pool	address	The address of the Tender.fi lending pool from which rewards are being claimed.
token	address	The token that the claimed rewards will be received in (i.e. tokenOut).
fnSelector	bytes4	The bytes signature of the target function on the Tender.fi Reward contract.
amountOutMinimum	uint256	The minimum amount of asset received from the claim else the transaction reverts.

Events

Events	Description
RewardClaimed()	Emits the amount of rewards claimed. Denominated in TND.

claimRewards() - external onlyOwner

Allows the position owner to claim Tender.fi rewards in TND tokens.

Modifiers

Modifier	Description
onlyOwner	Ensures that only the specified owner of the contract is able to execute administrative tasks. More info on OpenZeppelin Docs.

claimRewardsSupply() - external onlyOwner

Allows the position owner to claim Tender.fi rewards and supply the claimed value as asset tokens to the relevant Tender.fi lending pool.

Modifiers

Modifier	Description
onlyOwner	Ensures that only the specified owner of the contract is able to execute administrative tasks. More info on OpenZeppelin Docs.

Parameters

Params	Type	Description
amountOutMinimum	uint256	The minimum amount of asset received from swapping the claimed rewards else the transaction reverts.

claimRewardsRepay() - external onlyOwner

Allows the position owner to claim Tender.fi rewards and repay the claimed value as debt tokens to the relevant Tender.fi lending pool.

Modifiers

Modifier	Description
onlyOwner	Ensures that only the specified owner of the contract is able to execute administrative tasks. More info on OpenZeppelin Docs.

Parameters

Params	Type	Description
amountOutMinimum	uint256	The minimum amount of debt received from swapping the claimed rewards else the transaction reverts.

withdrawTokenInCaseStuck() - external onlyOwner

Enables the owner to withdraw any tokenAddress that is stuck in the Strategy contract.

Modifiers

Modifier	Description
onlyOwner	Ensures that only the specified owner of the contract is able to execute administrative tasks. More info on OpenZeppelin Docs.

Parameters

Params	Type	Description
tokenAddress	address	The address of the token to withdraw.
amount	uint256	The amount of tokenAddress to be withdrawn.

Events

Events	Description
WithdrawTokenInCaseStuck()	Emits the amount of tokenAddress that was withdrawn as well as the tokenAddress.

leverageFeeCharge() - internal returns

Charges the fee for the leverage strategy and transfers the fee to the fee recipient. The fee configs are maintained by the Vault Manager contract.

Parameters

Params	Type	Description
amount	uint256	The amount of token that was used for leverage.
token	address	The token which will be collected as fees (i.e. the tokenOut from swapBySelf()).

Events

Events	Description
LeverageChargeFee()	Emits the leverage fee that was charged.

receiveFlashLoan() - external override nonReentrant

An external function meant to be called by the Balancer vault contract to check the validity of the vault receiving the flash loan (i.e. can the flash loan be repaid). Reads the configured flMode at the time of execution to determine the correct operation to call.

Modifiers

Modifier	Description
nonReentrant	Ensures that there are no nested (reentrant calls). More info on OpenZeppelin Docs.

Parameters

Params	Type	Description
tokens	address[]	The list of token addresses associated with the flash loan operations.
amounts	uint256[]	The amount of each token in tokens to be used for the flash loan operation. The order of each token amount must correspond with the order of the token address in tokens.
feeAmounts	uint256[]	The flash loan fee amount of each token in tokens to be used for the flash loan operation. The order of each token amount must correspond with the order of the token address in tokens.
params	bytes	The Balancer userData passed in as calldata.