Interact web3 with Google Cloud Functions sample

web3_on_GCF.js

const https = require('https')
const fs = require('fs')
const agent = new https.Agent({keepAlive: true})
const qs = require('querystring')
const Web3 = require('web3')
const web3 = new Web3()
const crypto = require('crypto')
const EthereumTx = require('ethereumjs-tx')
const Datastore = require('@google-cloud/datastore');

const config = require('./config.json')
const privateKey = Buffer.from(config.contract_owner_private.replace(/^0x/, ''), 'hex')
const datastore = new Datastore({});

const abi = [{"constant":true,"inputs":[],"name":"mintingFinished","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"name","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_spender","type":"address"},{"name":"_value","type":"uint256"}],"name":"approve","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"totalSupply","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_from","type":"address"},{"name":"_to","type":"address"},{"name":"_value","type":"uint256"}],"name":"transferFrom","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"decimals","outputs":[{"name":"","type":"uint8"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_to","type":"address"},{"name":"_amount","type":"uint256"}],"name":"mint","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"_value","type":"uint256"}],"name":"burn","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"_spender","type":"address"},{"name":"_subtractedValue","type":"uint256"}],"name":"decreaseApproval","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"name":"_owner","type":"address"}],"name":"balanceOf","outputs":[{"name":"balance","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[],"name":"finishMinting","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"owner","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"symbol","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_to","type":"address"},{"name":"_value","type":"uint256"}],"name":"transfer","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"_spender","type":"address"},{"name":"_addedValue","type":"uint256"}],"name":"increaseApproval","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"name":"_owner","type":"address"},{"name":"_spender","type":"address"}],"name":"allowance","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"newOwner","type":"address"}],"name":"transferOwnership","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"inputs":[],"payable":false,"stateMutability":"nonpayable","type":"constructor"},{"anonymous":false,"inputs":[{"indexed":true,"name":"burner","type":"address"},{"indexed":false,"name":"value","type":"uint256"}],"name":"Burn","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"name":"to","type":"address"},{"indexed":false,"name":"amount","type":"uint256"}],"name":"Mint","type":"event"},{"anonymous":false,"inputs":[],"name":"MintFinished","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"name":"previousOwner","type":"address"},{"indexed":true,"name":"newOwner","type":"address"}],"name":"OwnershipTransferred","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"name":"owner","type":"address"},{"indexed":true,"name":"spender","type":"address"},{"indexed":false,"name":"value","type":"uint256"}],"name":"Approval","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"name":"from","type":"address"},{"indexed":true,"name":"to","type":"address"},{"indexed":false,"name":"value","type":"uint256"}],"name":"Transfer","type":"event"}]
const contract_address = config.contract_address
const Contract = web3.eth.contract(abi)
const contract = Contract.at(contract_address)

let gnonce // Global Nonce for security

fs.readFile("./nonce", (err, data) => {
    if (err) {
        console.error('L24: ', err)
    } else {
        gnonce = parseInt(data)
    }
})


exports.mint = (req, res) => {
    const ts = Date.now()

    if (req.method === 'GET') {
        const q = req.query
        const address = q.address
        const amount = q.amount
        const signature = q.signature

        res.set('Content-Type', 'text/plain')

        if (address && amount && signature) {
            var hmac = crypto.createHmac('sha256', config.hmac_secret)

            hmac.on('readable', () => {
              const data = hmac.read()
              if (data) {
                if (data.toString('hex').toLowerCase() === signature.toLowerCase()) {
                  var abidata = contract.mint.getData(address, amount)

                  var countReq = https.request({
                    host: 'api.infura.io',
                    path: '/v1/jsonrpc/ropsten/eth_getTransactionCount?params=%5B%220x5B7Ece121303185Eea3c905fC6D72e6b811bD4F6%22%2C%22latest%22%5D',
                    headers: {
                      'Content-Type': 'application/json',
                      'Accept': 'application/json'
                    },
                    agent: agent,
                  }, countRes => {
                    let countRawData = '';
                    countRes.on('data', chunk => countRawData += chunk)
                    countRes.on('end', () => {
                      try {
                        var countData = JSON.parse(countRawData)
                        } catch (err) {
                          console.error(err)
                          res.status(500).send('internal server error')
                        }

                      var nonce = countData.result

                      const txParams = {
                        nonce: nonce,
                        gasLimit: '0x' + (4700000).toString(16),
                        gasPrice: '0x' + (100000000000).toString(16),
                        to: contract_address,
                        data: abidata
                      }

                      const tx = new EthereumTx(txParams)
                      tx.sign(privateKey)
                      const serializedTx = tx.serialize()

                      const postData = JSON.stringify({
                        jsonrpc: '2.0',
                        id: 1,
                        method: "eth_sendRawTransaction",
                        token: 'hq9l5D1Moq7KjYPgyfNn',
                        params: ['0x' + serializedTx.toString('hex')]
                      })

                      var reqst = https.request({
                        host: 'api.infura.io',
                        path: '/v1/jsonrpc/ropsten',
                        method: 'POST',
                        headers: {
                          'Content-Type': 'application/json',
                          'Accept': 'application/json'
                        },
                        agent: agent,
                      }, resp => {
                        resp.on('data', () => {})
                        resp.on('end', () => {
                          increase_gnonce()
                          res.status(200).send('ok')
                        })
                      })

                      reqst.on('error', e => {
                        console.error(`Error: ${e.message}`)
                        res.status(500).send('internal server error')
                      })

                      reqst.write(postData)
                      reqst.end()
                    })
                  })

                  countReq.on('error', e => {
                    console.error(`Error: ${e.message}`)
                    res.status(500).send('internal server error')
                  })

                  countReq.end()
                } else {
                  res.status(401).send('unauthorized')
                }
              }
            })

            hmac.write(qs.stringify({
              address: address,
              amount: amount,
              nonce: gnonce
            }))
            hmac.end()
        } else {
            res.status(400).send('bad request')
        }
    }
}

exports.setnonce = (req, res) => {
    // var increase_gnonce = function() {
        fs.writeFile("./nonce", (gnonce + 1).toString(), err => {
            // if (err) return console.error('L29: ', err)
            // console.log('Global nonce successfuly increased')
            if (err) {
                res.status(500).send(err)
            } else {
                res.status(200).send(':)')
            }
        })
    // }
}