Call a contract method at a specific block using ethers.js

main.ts

// Example of using ethers.js to interact with a smart contract
// Call a contract method at a specific block
// This example is to get rate of a token at a block

import { ethers } from "ethers"
import BigNumber from "bignumber.js"

// prettier-ignore
const oracleABI = '[{"inputs":[{"internalType":"contract MultiWrapper","name":"_multiWrapper","type":"address"},{"internalType":"contract IOracle[]","name":"existingOracles","type":"address[]"},{"internalType":"enum OffchainOracle.OracleType[]","name":"oracleTypes","type":"uint8[]"},{"internalType":"contract IERC20[]","name":"existingConnectors","type":"address[]"},{"internalType":"contract IERC20","name":"wBase","type":"address"}],"stateMutability":"nonpayable","type":"constructor"},{"anonymous":false,"inputs":[{"indexed":false,"internalType":"contract IERC20","name":"connector","type":"address"}],"name":"ConnectorAdded","type":"event"},{"anonymous":false,"inputs":[{"indexed":false,"internalType":"contract IERC20","name":"connector","type":"address"}],"name":"ConnectorRemoved","type":"event"},{"anonymous":false,"inputs":[{"indexed":false,"internalType":"contract MultiWrapper","name":"multiWrapper","type":"address"}],"name":"MultiWrapperUpdated","type":"event"},{"anonymous":false,"inputs":[{"indexed":false,"internalType":"contract IOracle","name":"oracle","type":"address"},{"indexed":false,"internalType":"enum OffchainOracle.OracleType","name":"oracleType","type":"uint8"}],"name":"OracleAdded","type":"event"},{"anonymous":false,"inputs":[{"indexed":false,"internalType":"contract IOracle","name":"oracle","type":"address"},{"indexed":false,"internalType":"enum OffchainOracle.OracleType","name":"oracleType","type":"uint8"}],"name":"OracleRemoved","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"internalType":"address","name":"previousOwner","type":"address"},{"indexed":true,"internalType":"address","name":"newOwner","type":"address"}],"name":"OwnershipTransferred","type":"event"},{"inputs":[{"internalType":"contract IERC20","name":"connector","type":"address"}],"name":"addConnector","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"contract IOracle","name":"oracle","type":"address"},{"internalType":"enum OffchainOracle.OracleType","name":"oracleKind","type":"uint8"}],"name":"addOracle","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[],"name":"connectors","outputs":[{"internalType":"contract IERC20[]","name":"allConnectors","type":"address[]"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"contract IERC20","name":"srcToken","type":"address"},{"internalType":"contract IERC20","name":"dstToken","type":"address"},{"internalType":"bool","name":"useWrappers","type":"bool"}],"name":"getRate","outputs":[{"internalType":"uint256","name":"weightedRate","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"contract IERC20","name":"srcToken","type":"address"},{"internalType":"bool","name":"useSrcWrappers","type":"bool"}],"name":"getRateToEth","outputs":[{"internalType":"uint256","name":"weightedRate","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"multiWrapper","outputs":[{"internalType":"contract MultiWrapper","name":"","type":"address"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"oracles","outputs":[{"internalType":"contract IOracle[]","name":"allOracles","type":"address[]"},{"internalType":"enum OffchainOracle.OracleType[]","name":"oracleTypes","type":"uint8[]"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"owner","outputs":[{"internalType":"address","name":"","type":"address"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"contract IERC20","name":"connector","type":"address"}],"name":"removeConnector","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"contract IOracle","name":"oracle","type":"address"},{"internalType":"enum OffchainOracle.OracleType","name":"oracleKind","type":"uint8"}],"name":"removeOracle","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[],"name":"renounceOwnership","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"contract MultiWrapper","name":"_multiWrapper","type":"address"}],"name":"setMultiWrapper","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"newOwner","type":"address"}],"name":"transferOwnership","outputs":[],"stateMutability":"nonpayable","type":"function"}]';

// Create a dApp in Moralis to get the RPC URL
const provider = new ethers.providers.JsonRpcProvider(
    "https://speedy-nodes-nyc.moralis.io/YOUR_KEY_HERE/bsc/mainnet/archive"
)
const oracleContract = new ethers.Contract("0xfbD61B037C325b959c0F6A7e69D8f37770C2c550", oracleABI, provider)

// source: https://github.com/1inch/spot-price-aggregator/blob/master/examples/single-price.js
const getRatesOfToken = async (tokenAddress: string, blockNumber: number) => {
    try {
        // see https://docs.ethers.io/v5/single-page/#/v5/api/contract/ -> contract.functions.METHOD_NAME
        const rate = await oracleContract.functions.getRate(
            tokenAddress, // source token
            "0xe9e7cea3dedca5984780bafc599bd69add087d56", // BUSD
            true, // use source wrappers
            {
                blockTag: blockNumber,
            }
        )

        const denominator = new BigNumber("1e18") // decimals of BUSD
        const price = new BigNumber(rate).div(denominator)
        console.log(price.toString())
    } catch (e) {
        console.error("Error: ", e?.message)
    }
}

await getRatesOfToken("0xfe56d5892bdffc7bf58f2e84be1b2c32d21c308b", 18302553)