LoanManager Contracts

The "lifecycle" of a loan through the Teller protocol

The LoanManager contract holds all the main borrower-oriented actions of the Teller protocol.

There are 2 types of loans. Loans with Ether as collateral and loans with an ERC20 token as collateral. The main difference is how the loans are created and collateral paid out.

Below are the key methods that reside in the contract. For the complete source code, check out LoanManager.sol on GitHub.

{1} createLoanWithTerms()

function createLoanWithTerms( TellerCommon.LoanRequest calldata request, TellerCommon.LoanResponse[] calldata responses, uint256 collateral )

Creates an instance of a loan with terms on the protocol that has been accepted by a consensus of nodes. There are two special parameters in this method, that are structs specific to the Teller protocol.

TellerCommon.LoanRequest is a request struct/object that is sent to the Teller Nodes and subsequently on-chain, with all the required entries such as:

Variable	Type	Description
borrower	address payable	The wallet address of the borrower
recipient	address	The address where funds will be sent, only applicable in over collateralized loans
consensusAddress	address	The address of the Teller loan consensus contract to which the request should be sent
requestNonce	uint256	The nonce of the borrower wallet address required for authentication
amount	uint256	The number of tokens requested by the borrower for the loan
duration	uint256	The length of time in seconds that the loan has been requested for
requestTime	uint256	The timestamp at which the loan was requested

TellerCommon.LoanResponse[] is an array of signed response structs/objects that are returned from registered Teller nodes that need to be passed on-chain in order to register the loan terms on-chain.

Variable	Type	Description
signer	address	The wallet address of the signer validating the interest request of the lender
consensusAddress	address	The address of the Teller loan consensus contract to which the request should be sent
responseTime	uint256	The timestamp at which the response was sent
interestRate	uint256	The signed interest rate generated by the signer's Credit Risk Algorithm (CRA)
collateralRatio	uint256	The ratio of collateral to loan amount that is generated by the signer's Credit Risk Algorithm (CRA)
maxLoanAmount	uint256	The largest amount of tokens that can be taken out in the loan by the borrower
signature	Signature	The signature generated by the signer in the format of the below Signature struct

The last param collateral is the amount of collateral that needs to be deposited into the protocol in order to be able to take out the funds of the loan.

{2} depositCollateral()

function( address borrower, uint256 loanID, uint256 amount )

In situations where a borrower's collateral drops in value (e.g. price drops 90% in value), the borrower would need to deposit more collateral to keep the loan Active and out of liquidation. This can be done with the depositCollateral() method called by the borrower or developer dApp.

Param	Type	Description
borrower	address	The address of the loan borrower
loanID	uint256	The ID of the loan the collateral is for
amount	uint256	The amount to deposit as collateral

{3} takeOutLoan()

function( uint256 loanID, uint256 amountBorrow )

Once a loan with terms has been created on-chain with createLoanWithTerms() and collateral deposited, a borrower can now take out the loan.

Param	Type	Description
loanID	uint256	The ID of the loan being taken out
amountBorrow	uint256	The number of funds to take out in the loan

{4} repay()

function( uint256 amount, uint256 loanID )

Once the borrower has used the loan he will also need to pay back the loan. This can be done with the repay() method on the respective loan contract.

Param	Type	Description
amount	uint256	The number of funds to pay back into the loan
loanID	uint256	The ID of the loan the payment is for

One thing to note: if a loan is repaid in full with the repay() method, the borrower's collateral is automatically sent to their wallet, no additional calls are needed!

{5} withdrawCollateral()

function( uint256 amount, uint256 loanID )

In situations where the value of the borrower's collateral has risen (hello there new ATH!), a borrower can withdraw a portion of their collateral and still keep the loan active by calling the withdrawCollateral() method on-chain.

Param	Type	Description
amount	uint256	The amount of collateral token or ether the caller is hoping to withdraw
loanID	uint256	The ID of the loan the collateral is for