Getter for repayment amount

[bonomat]

When displaying the loan details in the UI we want to show how much the user has to pay when repaying the loan.
At the moment we can only access the collateral amount but not the repayment amount.

I guess the function repayment_amount on CollateralContrtact just needs to be public for that.

baru/src/loan.rs

Lines 418 to 427 in 87b7677

	fn repayment_amount<C>(&self, secp: &Secp256k1<C>) -> Result<Amount>
	where
	C: Verification,
	{
	let TxOutSecrets { value, .. } = self
	.repayment_principal_output
	.unblind(secp, self.repayment_principal_output_blinder)?;
	Ok(Amount::from_sat(value))
	}

This functionality is needed in :

comit-network/waves#242

[bonomat]

I guess a better solution would be to have a clear getter for this value. That way we don't have to provide secp.

[DeliciousHair]

Two things:

• Is that amount even correct? That is, is the interest included in repayment_principal_output, and if it is maybe it should be re-named to make this clear.
• Would this calculation be better handled on the waves side of things alone?

[bonomat]

Is that amount even correct? That is, is the interest included in repayment_principal_output, and if it is maybe it should be re-named to make this clear.

The number seems to be correct, i.e. it includes the interest amount when paying back the loan.

Would this calculation be better handled on the waves side of things alone?

Imho the calculation is already happening on our side but once sent to Bobtimus it disappears.
We could just add an additional field to our DTOs but it wouldn't give us any guarantees that the values in the repayment transaction are the same.
Have a look here where we construct LoanDetails which is used to show data to the user: https://github.com/comit-network/waves/blob/06701f852298e28bbba69d5d83ed44e36301775a/extension/wallet/src/wallet/extract_loan.rs#L11