utils_new.js

const { ethers } = require("ethers")
const Tx = require('ethereumjs-tx').Transaction
const buffer = require('buffer')
const fs = require('fs')
const Common = require('ethereumjs-common').default
const FTM_MAIN = Common.forCustomChain(
  'mainnet', {
      name: 'fantom',
      networkId: 250, 
      chainId: 250
  }, 
  'petersburg'
)

const fantom_rpc = 'https://rpcapi.fantom.network'
const gas_price = 20e10
const gas_limit = 300000

const Rarity_contract_address = '0xce761D788DF608BD21bdd59d6f4B54b2e27F25Bb'
const Rarity_attribute_contract_address = '0xB5F5AF1087A8DA62A23b08C00C6ec9af21F397a1'
const Rarity_gold_contract_address = '0x2069B76Afe6b734Fb65D1d099E7ec64ee9CC76B2'
const Rarity_skills_contract_address = '0x6292f3fB422e393342f257857e744d43b1Ae7e70'
const Rarity_craft_contract_address = '0x2A0F1cB17680161cF255348dDFDeE94ea8Ca196A'
const Rarity_crafting_contract_address = '0xf41270836dF4Db1D28F7fd0935270e3A603e78cC'

function sign_eth_tx(private_key, nonce, from_, data, contract_address)
{
  let rawTx = {
      nonce: nonce,
      gasLimit: '0x' + gas_limit.toString(16, 'hex'), 
      gasPrice: '0x' + gas_price.toString(16, 'hex'),    
      to: contract_address,
      from: from_,
      value: '0x00',
      data: data,
  }

  let tx = new Tx(rawTx, {common: FTM_MAIN})
  tx.sign(Buffer.from(private_key, 'hex'))
  
  return '0x' + tx.serialize().toString('hex')
}

async function send_signed_transaction(provider, signed_tx) {
  const { hash } = await provider.sendTransaction(signed_tx)
  console.log('hash:', hash)
  let confirmations = 0
  await provider.waitForTransaction(hash, confirmations)
  console.log('- done')
}

async function sign_and_send_transaction(provider, private_key, data, contract_address) {

  let wallet = new ethers.Wallet(private_key, provider);
  let from = wallet.address
  console.log('your account: ' + from)
  
  let nonce = await provider.getTransactionCount(from)
  console.log('nonce: ' + nonce)

  let signed_tx = sign_eth_tx(private_key, nonce, from, data, contract_address)
  await send_signed_transaction(provider, signed_tx)
}

async function save_svg(b64, fn) {
  let data = Buffer.from(b64, 'base64').toString()
  let svg = JSON.parse(data).image.slice(JSON.parse(data).image.indexOf('base64,')+7)
  let binaryData = Buffer.from(svg, 'base64').toString('binary');
  fs.writeFile('svg/' + fn + ".svg", binaryData, "binary", function(err) {
    //console.log(err); 
  });
}

function read_from_file(fn) {
  let contents = fs.readFileSync(fn)

  return Buffer.from(contents, 'binary').toString().split('\n')
}

module.exports = {
  sign_and_send_transaction,
  save_svg,  
  read_from_file,

  fantom_rpc,
  Rarity_contract_address,
  Rarity_attribute_contract_address,
  Rarity_gold_contract_address,
  Rarity_skills_contract_address,
  Rarity_craft_contract_address,
  Rarity_crafting_contract_address,
}