IEToken

Interface for EToken smart contracts, these are the capital pools.

Types

Parameter

Enum of the configurable parameters in an EToken.

These are the supported parameter types: - liquidityRequirement: target solvency/liquidity constraint (typically 1, scales the SCR to lock more) - minUtilizationRate: lower bound for utilization rate after deposits (prevents excess idle liquidity) - maxUtilizationRate: upper bound for utilization rate after capital lock (prevents locking all the capital) - internalLoanInterestRate: annualized rate charged on internal loans (wad)

enum Parameter {
  liquidityRequirement,
  minUtilizationRate,
  maxUtilizationRate,
  internalLoanInterestRate
}

Events

SCRLocked

event SCRLocked(uint256 policyId, uint256 interestRate, uint256 value)

Event emitted when part of the funds of the eToken are locked as solvency capital.

Parameters

Name	Type	Description
policyId	uint256	The id of the policy that locks the capital
interestRate	uint256	The annualized interestRate paid for the capital (wad)
value	uint256	The amount locked

SCRUnlocked

event SCRUnlocked(uint256 policyId, uint256 interestRate, uint256 value, int256 adjustment)

Event emitted when the locked funds are unlocked and no longer used as solvency capital.

Parameters

Name	Type	Description
policyId	uint256	The id of the policy that unlocks the capital (should be the that locked before with SCRLocked)
interestRate	uint256	The annualized interestRate that was paid for the capital (wad)
value	uint256	The amount unlocked
adjustment	int256	Discrete amount of adjustment done to the totalSupply to reflect when more or less than the received cost of capital has been accrued since the SCR was locked.

Public Functions

scr

function scr() external view returns (uint256)

Returns the amount of capital that's locked as solvency capital for active policies.

lockScr

function lockScr(uint256 policyId, uint256 scrAmount, uint256 policyInterestRate) external

Locks part of the liquidity of the EToken as solvency capital.

Parameters

Name	Type	Description
policyId	uint256	The id of the policy that locks the capital
scrAmount	uint256	The amount to lock
policyInterestRate	uint256	The annualized interest rate (wad) to be paid for the `scrAmount`

Pre-conditions

Must be called by a borrower (PremiumsAccount) previously added with addBorrower.
scrAmount <= fundsAvailableToLock()

Emits

SCRLocked

unlockScr

function unlockScr(uint256 policyId, uint256 scrAmount, uint256 policyInterestRate, int256 adjustment) external

Unlocks solvency capital previously locked with lockScr.

The capital no longer needed as solvency, enabling withdrawal.

Parameters

Name	Type	Description
policyId	uint256	The id of the policy that locked the scr originally
scrAmount	uint256	The amount to unlock
policyInterestRate	uint256	The annualized interest rate that was paid for the `scrAmount`, must be the same that was sent in `lockScr` call.
adjustment	int256	Discrete amount of adjustment done to the totalSupply to reflect when more or less than the received cost of capital has been accrued since the SCR was locked.

Pre-conditions

Must be called by a borrower (PremiumsAccount) previously added with addBorrower.
scrAmount must be <= {scr}

Emits

SCRUnlocked

unlockScrWithRefund

function unlockScrWithRefund(uint256 policyId, uint256 scrAmount, uint256 policyInterestRate, int256 adjustment, address receiver, uint256 refundAmount) external

Unlocks solvency capital previously locked with lockScr, doing a refund of the CoC previously received

The capital no longer needed as solvency . It refunds part of the Coc received that wasn't accrued (or if it was already accrued, it is adjusted). The refund doesn't affect the totalSupply. It just changes the reserves.

Parameters

Name	Type	Description
policyId	uint256	The id of the policy that locked the scr originally
scrAmount	uint256	The amount to unlock
policyInterestRate	uint256	The annualized interest rate that was paid for the `scrAmount`, must be the same that was sent in `lockScr` call.
adjustment	int256
receiver	address	The address of the receiver of the refund
refundAmount	uint256	The amount to refund

Pre-conditions

Must be called by a borrower previously added with addBorrower.

Emits

SCRUnlocked
CoCRefunded

deposit

function deposit(uint256 amount, address caller, address receiver) external

Registers a deposit of liquidity in the pool.

Called from the PolicyPool, assumes the amount has already been transferred. amount of eToken are minted and given to the provider in exchange of the liquidity provided.

Parameters

Name	Type	Description
amount	uint256	The amount deposited.
caller	address	The user that initiates the deposit
receiver	address	The user that will receive the minted eTokens

Pre-conditions

Must be called by policyPool()
The amount was transferred
utilizationRate() after the deposit is >= minUtilizationRate()
If there is a whitelist, caller must be authorized to deposit. If caller != receiver, then transfer from caller
to received must be authorized

Emits

Transfer: with `from` = 0x0 and to = `provider` (mint)

withdraw

function withdraw(uint256 amount, address caller, address owner, address receiver) external returns (uint256 withdrawn)

Withdraws an amount from an eToken.

withdrawn eTokens are be burned and the user receives the same amount in currency(). If amount == type(uint256).max, it withdraws up to maxWithdraw (i.e., as much as possible). Otherwise, it reverts if amount > maxWithdraw.

Parameters

Name	Type	Description
amount	uint256	The amount to withdraw. If `amount == type(uint256).max`, withdraws up to `maxWithdraw`.
caller	address	The user that initiates the withdrawal
owner	address	The owner of the eTokens (either caller==owner or caller has allowance)
receiver	address	The address that will receive the resulting `currency()`

Pre-conditions

Must be called by policyPool()

Emits

Transfer: with `from` = `provider` and to = `0x0` (burn)

totalWithdrawable

function totalWithdrawable() external view returns (uint256)

Returns the total amount that can be withdrawn

addBorrower

function addBorrower(address borrower) external

Adds an authorized borrower to the eToken. This borrower will be allowed to lock/unlock funds and to take loans.

Borrowers (typically PremiumsAccounts) can: - lock/unlock SCR via {lockScr}/{unlockScr}/{unlockScrWithRefund} - take internal loans via {internalLoan}

Parameters

Name	Type	Description
borrower	address	The address of the borrower, a PremiumsAccount that has this eToken as senior or junior eToken.

Pre-conditions

Must be called by policyPool()

Emits

InternalBorrowerAdded

removeBorrower

function removeBorrower(address borrower) external

Removes an authorized borrower to the eToken. The borrower can't no longer lock funds or take loans.

Parameters

Name	Type	Description
borrower	address	The address of the borrower, a PremiumsAccount that has this eToken as senior or junior eToken.

Pre-conditions

Must be called by policyPool()

Emits

InternalBorrowerRemoved: with the defaulted debt

internalLoan

function internalLoan(uint256 amount, address receiver) external returns (uint256)

Lends amount to the borrower (msg.sender), transferring the money to receiver.

This reduces the totalSupply() of the eToken, and stores a debt that will be repaid (hopefully) with repayLoan.

Parameters

Name	Type	Description
amount	uint256	The amount required
receiver	address	The received of the funds lent. This is usually the policyholder if the loan is used for a payout.

Return Values

Name	Type	Description
[0]	uint256	Returns the amount that wasn't able to fulfil. `amount - lent`

Pre-conditions

Must be called by a borrower previously added with addBorrower.

Emits

{InternalLoan}
{ERC20-Transfer}: transferring `lent` to `receiver`

repayLoan

function repayLoan(uint256 amount, address onBehalfOf) external

Repays a loan taken with internalLoan.

Parameters

Name	Type	Description
amount	uint256	The amount to repaid, that will be transferred from `msg.sender` balance.
onBehalfOf	address	The address of the borrower that took the loan. Usually `onBehalfOf == msg.sender` but we keep it open because in some cases with might need someone else pays the debt.

Pre-conditions

msg.sender approved the spending of currency() for at least amount

Emits

{InternalLoanRepaid}
{ERC20-Transfer}: transferring `amount` from `msg.sender` to `this`

getLoan

function getLoan(address borrower) external view returns (uint256)

Returns the updated debt (principal + interest) of the borrower.

tokenInterestRate

function tokenInterestRate() external view returns (uint256)

The annualized interest rate at which the totalSupply() grows

scrInterestRate

function scrInterestRate() external view returns (uint256)

The weighted average annualized interest rate paid by the currently locked scr().

getCurrentScale

function getCurrentScale(bool updated) external view returns (uint256)

Returns the number that scales the shares to reflect the earnings or losses (rebasing token)

Parameters

Name	Type	Description
updated	bool	When it's false, it returns the last scale stored. When it's true, it projects that scale applying the accrued returns of the scr

redistribute

function redistribute(uint256 amount) external

Redistributes a given amount of eTokens of the caller between the remaining LPs

Parameters

Name	Type	Description
amount	uint256	The amount of eTokens to burn

cooler

function cooler() external view returns (address)

Returns the cooler contract plugged into the eToken