`subgraph` - Track loan actions ( create / adjust / close / liquidated )

[0xGingFreecss]

One of the most valuable features we will develop with a subgraph is showing the history of a specific loan.

With a bit of wiring we will be able to get subgraph to do a good part of it for us, namely:

Create a "Loan" document on subgraph that will have all the loan actions associated with it:
Create Loan
All "adjust_loan" calls
Close or Liquidate Loan
Have the current "status" of a loan
To achieve that we have to add a few entities to the schema.graphql

type Loan @entity {
  id: ID!
  account: Bytes!
  market: Bytes!
  collateralAmount: BigInt!
  debtAmount: BigInt!
  createdAt: BigInt!
  lastUpdatedAt: BigInt!
  status: String!
  actions: [LoanAction!]! @derivedFrom(field: "loan")
}

type LoanAction @entity {
  id: ID!
  loan: Loan!
  actionType: String!
  collateralChange: BigInt!
  debtChange: BigInt!
  timestamp: BigInt!
  txHash: Bytes!
}

type AccountMarketLoan @entity {
  id: ID!
  account: Bytes!
  market: Bytes!
  latestLoan: Loan!
}

Adjust the mappings

import { BigInt, Address, Bytes } from "@graphprotocol/graph-ts"
import {
  CreateLoanEvent,
  AdjustLoanEvent,
  CloseLoanEvent,
  LiquidateLoanEvent
} from "../generated/Controller/Controller"
import { Loan, LoanAction, AccountMarketLoan } from "../generated/schema"

export function handleCreateLoan(event: CreateLoanEvent): void {
  let loanId = event.transaction.hash.concatI32(event.logIndex.toI32())
  
  let loan = new Loan(loanId);
  loan.account = event.params.account;
  loan.market = event.params.market;
  loan.collateralAmount = event.params.coll_amount;
  loan.debtAmount = event.params.debt_amount;
  loan.createdAt = event.block.timestamp;
  loan.lastUpdatedAt = event.block.timestamp;
  loan.status = 'OPEN';
  loan.save();

  let action = new LoanAction(loanId);
  action.loan = loanId;
  action.actionType = 'CREATE';
  action.collateralChange = event.params.coll_amount;
  action.debtChange = event.params.debt_amount;
  action.timestamp = event.block.timestamp;
  action.txHash = event.transaction.hash;
  action.save();

  // Update AccountMarketLoan
  let accountMarketId = getAccountMarketId(event.params.account, event.params.market);
  let accountMarketLoan = new AccountMarketLoan(accountMarketId);
  accountMarketLoan.account = event.params.account;
  accountMarketLoan.market = event.params.market;
  accountMarketLoan.latestLoan = loanId;
  accountMarketLoan.save();
}

export function handleAdjustLoan(event: AdjustLoanEvent): void {
  let accountMarketId = getAccountMarketId(event.params.account, event.params.market);
  let accountMarketLoan = AccountMarketLoan.load(accountMarketId);
  if (accountMarketLoan) {
    let loan = Loan.load(accountMarketLoan.latestLoan);
    if (loan) {
      loan.collateralAmount = loan.collateralAmount.plus(event.params.coll_adjustment);
      loan.debtAmount = loan.debtAmount.plus(event.params.debt_adjustment);
      loan.lastUpdatedAt = event.block.timestamp;
      loan.save();

      let actionId = event.transaction.hash.concatI32(event.logIndex.toI32())
      let action = new LoanAction(actionId);
      action.loan = loan.id;
      action.actionType = 'ADJUST';
      action.collateralChange = event.params.coll_adjustment;
      action.debtChange = event.params.debt_adjustment;
      action.timestamp = event.block.timestamp;
      action.txHash = event.transaction.hash;
      action.save();
    }
  }
}

export function handleCloseLoan(event: CloseLoanEvent): void {
  let accountMarketId = getAccountMarketId(event.params.account, event.params.market);
  let accountMarketLoan = AccountMarketLoan.load(accountMarketId);
  if (accountMarketLoan) {
    let loan = Loan.load(accountMarketLoan.latestLoan);
    if (loan) {
      loan.collateralAmount = BigInt.fromI32(0);
      loan.debtAmount = BigInt.fromI32(0);
      loan.lastUpdatedAt = event.block.timestamp;
      loan.status = 'CLOSED';
      loan.save();

      let actionId = event.transaction.hash.concatI32(event.logIndex.toI32())
      let action = new LoanAction(actionId);
      action.loan = loan.id;
      action.actionType = 'CLOSE';
      action.collateralChange = event.params.coll_withdrawn.neg();
      action.debtChange = event.params.debt_withdrawn.neg();
      action.timestamp = event.block.timestamp;
      action.txHash = event.transaction.hash;
      action.save();
    }
  }
}

export function handleLiquidateLoan(event: LiquidateLoanEvent): void {
  let accountMarketId = getAccountMarketId(event.params.account, event.params.market);
  let accountMarketLoan = AccountMarketLoan.load(accountMarketId);
  if (accountMarketLoan) {
    let loan = Loan.load(accountMarketLoan.latestLoan);
    if (loan) {
      loan.collateralAmount = BigInt.fromI32(0);
      loan.debtAmount = BigInt.fromI32(0);
      loan.lastUpdatedAt = event.block.timestamp;
      loan.status = 'LIQUIDATED';
      loan.save();

      let actionId = event.transaction.hash.concatI32(event.logIndex.toI32())
      let action = new LoanAction(actionId);
      action.loan = loan.id;
      action.actionType = 'LIQUIDATE';
      action.collateralChange = event.params.coll_received.neg();
      action.debtChange = event.params.debt_repaid.neg();
      action.timestamp = event.block.timestamp;
      action.txHash = event.transaction.hash;
      action.save();
    }
  }
}

function getAccountMarketId(account: Address, market: Address): string {
  return account.toHexString() + "-" + market.toHexString()
}

Add Loan related entities to subgraph.yaml

     entities:
        - Loan
        - LoanAction
        - AccountMarketLoan

If you could kindly take care of this and write the tests for it would be ace.

The only missing bits here would be to track when a user is swap while being in "COLLATERAL CONVERSION MODE", which i'm still trying to figure out a way of tracking / speaking with @consol3cowboy about it.

[0x33dm]

It would also be good to know the ORACLE PRICE at that block height when tracking the CREATE LOAN, ADJUST LOAN, and CLOSE LOAN.

This way, we can calculate the "base price" for every loan and be able to start calculating "loss" in USD terms.

@consol3cowboy is there any event that would be fired at the same block height with the oracle price for such market? I believe from the subgraph perspective we would only be able to attach an "oracle price" to this event if there is another event on the same block height with the oracle price.

I had a quick look, and I couldn't find anything at first glance.

If there is no event where we can get the oracle price from then i believe we would need to have some custom code to fetch those prices and attach them to the events.