AAVE APR

aave.ts

import { fetchMultiReserveInfo, DECIMAL, RAY, YEAR_TO_SECONDS, toBN } from "./subgraph"

const main = async () => {
    const ids = [
        "0x6b175474e89094c44da98b954eedeac495271d0f0xb53c1a33016b2dc2ff3653530bff1848a515c8c5",
        "0x7fc66500c84a76ad7e9c93437bfc5ac33e2ddae90xb53c1a33016b2dc2ff3653530bff1848a515c8c5"
    ]
    const rewardToken = "0x7fc66500c84a76ad7e9c93437bfc5ac33e2ddae9"
    const { reserves } = (await fetchMultiReserveInfo(ids))
    const reward = reserves.filter((r: Record<string, any>) => r.underlyingAsset === rewardToken)[0]
    return reserves.filter((r: Record<string, any>) => r.underlyingAsset !== rewardToken)
      .map((r: Record<string, any>) => {
        let totalVariableDebt = toBN(r.variableBorrowIndex).multipliedBy(toBN(r.totalScaledVariableDebt)).dividedBy(DECIMAL).dividedBy(RAY)
        let totalStableDebt = toBN(r.totalPrincipalStableDebt).dividedBy(DECIMAL)
        let availableLiquidity = toBN(r.availableLiquidity).dividedBy(DECIMAL)
        let totalLiquidity = totalVariableDebt.plus(totalStableDebt).plus(availableLiquidity)
        let rewardPrice = toBN(reward.price.priceInEth)
        let tokenPrice = toBN(r.price.priceInEth)
        let emissionRewards = toBN(r.aEmissionPerSecond).multipliedBy(YEAR_TO_SECONDS).multipliedBy(rewardPrice).dividedBy(DECIMAL)
        let total = totalLiquidity.multipliedBy(tokenPrice)
        return emissionRewards.dividedBy(total).toString()
      })
}

main()
  .then(console.log)
  .catch(console.error)

package.json

{
  "name": "aaveapr",
  "version": "1.0.0",
  "description": "only for test",
  "main": "aave.ts",
  "keywords": [],
  "author": "",
  "license": "",
  "dependencies": {
    "@typescript-eslint/eslint-plugin": "^5.1.0",
    "@typescript-eslint/parser": "^5.1.0",
    "abort-controller": "^3.0.0",
    "bignumber.js": "^9.0.1",
    "graphql": "^15.6.1",
    "graphql-request": "^3.6.1",
    "typescript": "^4.4.4"
  }
}

subgraph.ts

import { GraphQLClient, gql } from 'graphql-request'
import BN from 'bignumber.js'
import AbortController from 'abort-controller'

const AAVE_THE_GRAPH = 'https://api.thegraph.com/subgraphs/name/aave/protocol-v2'
export const DECIMAL = new BN(10 ** 18)
export const RAY = new BN(10 ** 27)
export const YEAR_TO_SECONDS = new BN(31536000)
const timeout = 2 * 60 * 1000

const request = async (url: string, query: any, variables: any = {}) => {
  const controller = new AbortController();
  const timeoutId = setTimeout(() => {
    controller.abort()
  }, timeout)
  const client = new GraphQLClient(url, {
    signal: controller.signal
  })
  try {
    const resp = await client.request(query, variables)
    clearTimeout(timeoutId)
    return resp
  } catch (err) {
    clearTimeout(timeoutId)
    throw err
  }
}

export const fetchMultiReserveInfo = async (reserveIds: string[]) => {
  const query = gql`
    query QueryMultiReserveInfo(
      $reserveIds: [ID!]
    ) {
      reserves(
        where: {
          id_in: $reserveIds
        }
      ) {
        id
        aEmissionPerSecond
        underlyingAsset
        price {
          priceInEth
        }
        underlyingAsset
        totalScaledVariableDebt
        totalPrincipalStableDebt
        variableBorrowIndex
        stableBorrowRate
        availableLiquidity
        lastUpdateTimestamp
      }
    }
  `
  const resp = await request(AAVE_THE_GRAPH, query, {
    reserveIds: reserveIds.map(reserveId => reserveId.toLowerCase())
  })
  return {
    reserves: resp.reserves
  }
}

export const toBN = (n: any): BN => {
    return new BN(n)
}

tsconfig.json

{
  "compilerOptions": {
    "baseUrl": "./",
    "outDir": "dist",
    "strictNullChecks": true,
    "noImplicitAny": true,
    "noImplicitThis": true,
    "resolveJsonModule": true,
    "declaration": true,
    "declarationDir": "lib",
    "experimentalDecorators": true,
    "allowSyntheticDefaultImports": true,
    "forceConsistentCasingInFileNames": true,
    "esModuleInterop": true,
    "moduleResolution": "node",
    "pretty": true,
    "lib": ["ESNext", "DOM"]
  },
  "exclude": ["node_modules"]
}