Part 4/4 in a series on collateralizing ERC721s for loans on Dharma Protocol

returnERC721Collateral.js

/*********************
 *  Setup Dharma.js  *
 *********************/

// Instantiate Dharma
const dharma = new Dharma();

/*****************
 * Repay a Loan  *
 *****************/
const DEBTOR_ADDRESS = "0x601e6e7711b9e3b1b20e1e8016038a32dfc86ddd";
const MAX_GAS = 4712388;
const TX_DEFAULTS = {
    from: DEBTOR_ADDRESS,
    gas: MAX_GAS,
};

const servicingApi = dharma.servicing;

// Retrieve debt agreements for the given debtor.
console.log(`Retrieving debts for ${DEBTOR_ADDRESS}...`);
servicingApi.getDebtsAsync(DEBTOR_ADDRESS).then(async (debts) => {
    // We should have at least one debt to repay.
    if (debts.length === 0) {
        throw new Error("No debts were found!");
    }

    // Take the issuance hash for the first debt.
    const issuanceHash = debts[0];
    console.log(`Getting information for debt with issuance hash ${issuanceHash}`);
    // Find what the principal token is for this debt.
    const debtEntry = await servicingApi.getDebtRegistryEntry(issuanceHash);
    const adapter = dharma.adapters.erc721CollateralizedSimpleInterestLoan;
    const debtOrder = await adapter.fromDebtRegistryEntry(debtEntry);
    const principalTokenSymbol = debtOrder.principalTokenSymbol;
    const principalTokenAttributes = await dharma.token.getTokenAttributesBySymbol(
        principalTokenSymbol
    );
    const principalTokenAddress = principalTokenAttributes.address;

    // Find out how much we need to repay for this debt.
    console.log(`Finding amount to repay for debt.`);
    const amountToRepay = await servicingApi.getTotalExpectedRepayment(issuanceHash);
    console.log(`Expected repayment: ${amountToRepay.toString()} ${principalTokenSymbol}`);

    // Make a repayment.
    console.log("Please sign the transaction to make a full repayment");
    let txHash = await servicingApi.makeRepayment(
        issuanceHash,
        amountToRepay,
        principalTokenAddress,
        TX_DEFAULTS
    );
    console.log("Waiting for transaction to be mined (may take a while)...");
    await dharma.blockchain.awaitTransactionMinedAsync(txHash);

    // Find the new amount to repay.
    console.log(`Transaction mined.`);
    const amountRepaid = await servicingApi.getValueRepaid(issuanceHash);

    if ((amountToRepay.minus(amountRepaid)).greaterThan(0)) {
        throw new Error(
            `Something went wrong and an amount is still outstanding:  
            ${amountToRepay} ${principalTokenSymbol}`,
        );
    }

    /***********************
     *  Return Collateral  *
     **********************/

    // The collateral should now be returnable.
    const isReturnable = await adapter.canReturnCollateral(issuanceHash);
    if (!isReturnable) {
        throw new Error("Something went and the collateral is not returnable yet.");
    }

    console.log("The collateral is now returnable. " +
        "Please sign the transaction to reclaim your ERC721 collateral");
    txHash = await adapter.returnCollateralAsync(issuanceHash, TX_DEFAULTS);
    // Wait fort he transaction to be mined.
    console.log("Waiting for transaction to be mined (may take a while)...");
    await dharma.blockchain.awaitTransactionMinedAsync(txHash);
    
    // Check to see if the collateral was indeed returned.
    const collateralTokenId = debtOrder.tokenReference;
    
    console.log("Checking owner of collateral token...");
    const collateralToken = await dharma.contracts.loadMintableERC721ContractAsync();
    const tokenOwner = await collateralToken.ownerOf.callAsync(collateralTokenId);

    if (tokenOwner !== DEBTOR_ADDRESS) {
        throw new Error(
            `Something went wrong and the debtor is not yet the owner of the collateral token!
            The current owner is ${tokenOwner}`,
        );
    }

    console.log("The collateral has been returned to the debtor!");
});