main.js

/**
 * Usage:
 * 1.  Paste this into a main.js file in some empty directory.
 * 2.  Run: `yarn add web3 ethers abi-decoder`.
 * 3.  Go to contract's page
 *     https://etherscan.io/address/0x25ed58c027921E14D86380eA2646E3a1B5C55A8b
 *     and then to code and then copy "Contract ABI" and save it in the same dir
 *     as abi.json.
 * 4.  Create empty file backup.txt.
 * 5.  Download CSV data with transactions from etherscan page and save as
 *     data.csv. Please note that this solution will fall apart once more than
 *     5k transactions happen since that's the limit for etherscan CSV.
 * 6.  Register for free on infura.io, get your token and create a file
 *     API_KEY.json with content
 *     { "key": "THE_KEY" }
 * 7.  Make sure about your preferred top of the range in line 83.
 * 8.  Run: `node main.js` (line 73 limits to the first 10 entries, it is for
 *     safety to check that setup works).
 * 9.  Re-run again without line 73 and claimed IDs will be saved to results.txt
 *     as the execution proceeds and the unclaimed ones will be sorted and
 *     printed after fetching is over.
 * 10. Now you can use your chosen free token on the contract page. Enjoy!
 */
const fs = require("fs");
const Web3 = require("web3");
const ethers = require("ethers");
const abiDecoder = require("abi-decoder");
const API_KEY = require("./API_KEY.json").key;
const ABI = require("./abi.json");

abiDecoder.addABI(ABI);

const data = fs.readFileSync("./data.csv", "utf-8");
const lines = data
  .split("\n")
  .filter((_, index) => index > 0)
  .map((line) =>
    line
      .split(",")
      .map((string) => string.replaceAll('"', "").replaceAll("\r", ""))
  );

const columns = [
  "Txhash",
  "Blockno",
  "UnixTimestamp",
  "DateTime",
  "From",
  "To",
  "ContractAddress",
  "Value_IN(ETH)",
  "Value_OUT(ETH)",
  "CurrentValue @ $3850.44/Eth",
  "TxnFee(ETH)",
  "TxnFee(USD)",
  "Historical $Price/Eth",
  "Status",
  "ErrCode",
  "Method",
  "PrivateNote",
];

const reverseKeys = columns.reduce((accumulator, column, index) => {
  accumulator[column] = index;
  return accumulator;
}, {});

const web3 = new Web3(`wss://mainnet.infura.io/ws/v3/${API_KEY}`);

const eth = new ethers.providers.Web3Provider(web3.currentProvider);
const claimed = [];

const run = async () => {
  const hashes = lines
    .filter((line) => line[reverseKeys["Method"]] === "Claim")
    .filter((_, i) => i < 10)
    .map((line) => line[reverseKeys["Txhash"]]);

  for await (const hash of hashes) {
    const tx = await eth.getTransaction(hash);
    const input = abiDecoder.decodeMethod(tx.data);
    const id = input.params[0].value;
    claimed.push(id);
    fs.appendFileSync("backup.txt", `${id}\n`);
  }

  const BOTTOM_OF_THE_RANGE = 0;
  const TOP_OF_THE_RANGE = 1000;

  const set = new Set(claimed.map((a) => Number(a)).sort((a, b) => a - b));

  for (let i = BOTTOM_OF_THE_RANGE; i < TOP_OF_THE_RANGE; i++) {
    if (!set.has(i)) {
      console.log(i);
    }
  }

  process.exit(0);
};

run();