exchange-gas-costs.ts

// Example using Etherscan API to analyse contract gas usage over time period.
// And .env file with ETHERSCAN API key. Free key from: https://etherscan.io/myapikey.
require('dotenv').config();
const moment = require('moment');
const axios = require('axios').default;
const Decimal = require('decimal.js');

export const BONE = new Decimal(10).pow(18);

// Returns all transactions for block range
export async function fetchTransactions(startBlock, endBlock) {
    // Address of contract of interest
    const proxyAddr = `0x3E66B66Fd1d0b02fDa6C811Da9E0547970DB2f21`;
    console.log(`Fetching Txs For ${proxyAddr} for blocks: ${startBlock}-${endBlock}`);

    // https://etherscan.io/apis#accounts
    const URL = `https://api.etherscan.io/api?module=account&action=txlist&address=${proxyAddr}&startblock=${startBlock}&endblock=${endBlock}&sort=asc&apikey=${process.env.ETHERSCAN}`

    const response = await axios.get(URL);
    // console.log(response.data.status);
    // console.log(response.data.message);

    const data = await response.data.result;
    return data;
}

// Uses API to retrieve block number for timestamp
export async function getBlockForTime(timestamp){
  // const timestamp = `1596240000`;  // 01/08/2020
  // console.log(`timestamp: ${timestamp}`);
  // https://etherscan.io/apis#blocks
  const URL = `https://api.etherscan.io/api?module=block&action=getblocknobytime&timestamp=${timestamp}&closest=before&apikey=${process.env.ETHERSCAN}`;

  const response = await axios.get(URL);
  const data = await response.data.result;
  return data;
}

// Main script
async function run() {
    console.log('Starting');
    // Going to retrieve txs for last 30 days
    const dateNow: any = moment();
    const dateStart: any = dateNow.clone().subtract(30, 'days');

    // Use api to get block numbers for timestamps
    let startBlock = Number(await getBlockForTime(dateStart.unix()));
    let endBlock = Number(await getBlockForTime(dateNow.unix()));
    console.log(`Start: ${dateStart.format()} ${startBlock}`);
    console.log(`End: ${dateNow.format()} ${endBlock}`);

    let txs: any[] = [];
    // Retrieve all txs in range (for max amt) using API
    while(startBlock < endBlock){
        let endRange = startBlock + 15000;
        let txsRange = await fetchTransactions(startBlock, endRange);
        console.log(`No of txs: ${txsRange.length}`);
        txs = txs.concat(txsRange);
        startBlock = endRange + 1;
    }

    console.log(`Total: ${txs.length} transactions in period`);

    let totalGas = Decimal(0);
    let totalGasPrice = Decimal(0);
    let totalCostEth = Decimal(0);
    let gasPriceDist = {};
    // For each tx -
    // Out gasUsed, gasPrice and ethCost (=gasPrice * gasUsed)
    // sum gasUsed for avg
    // sum gasPrice for avg
    // sum ethCost for avg
    // Create hash table of gasPrice distribution
    txs.forEach(tx => {
        let gasUsed = Decimal(tx.gasUsed);
        totalGas = totalGas.plus(gasUsed);
        let gasPrice = Decimal(tx.gasPrice);
        totalGasPrice = totalGasPrice.plus(gasPrice);
        let ethCost = gasPrice.mul(gasUsed);
        totalCostEth = totalCostEth.plus(ethCost);
        console.log(`GasUsed: ${gasUsed}, GasPrice: ${gasPrice}, Eth Cost: ${ethCost}`);
        if(! gasPriceDist[tx.gasPrice])
          gasPriceDist[tx.gasPrice] = 1;
        else
          gasPriceDist[tx.gasPrice] += 1;
    });
    
    // Output results
    console.log(gasPriceDist);
    let avgGasPrice = totalGasPrice.div(txs.length);
    console.log(`Total Gas Used: ${totalGas.toString()}`);
    console.log(`Total Eth: ${totalCostEth.div(BONE).toString()}`);
    console.log(`Average Gas Price: ${avgGasPrice.toString()}`);
    // console.log(txs[txs.length-1]);
}

run();