faucet.js

import express from 'express';
import bodyParser from 'body-parser'
import cors from 'cors'
import Datastore from 'nedb'
import Web3 from 'web3'

const faucetAccount = '0x0b64e7dcb7d1580f8898c78610b38e71ddc79236';

const app = express(),
            sentFundsdb = new Datastore({ filename: './sentFunds', autoload: true }),
            provider = new Web3.providers.HttpProvider('http://localhost:8545/'),
            web3 = new Web3(provider);

app.use(cors());
app.use(bodyParser.json());


app.post('/api/faucet/', async function(req, res) {
    const isValidRequest = (req, res) => {
            // Check the request body has at least an address.
            if (!req.body || !req.body.address || !web3.utils.isAddress(req.body.address)) {
                // Not a valid address.
                res.status(400);
                res.setHeader('Content-Type', 'application/json');
                res.send(JSON.stringify({
                    error: {
                        id: 'no-address',
                        message: 'Request must have an address.'
                    }
                }));
                return false;
            }
            return true;
        };
    console.log("valid request: " + isValidRequest(req, res))

    // get address from request
    const requestAccount = req.body.address;

        // check that we have not sent to this address before
    const previouslySent = await getTransactionsFromDatabase(requestAccount);
    if (previouslySent.length) {
        console.log('previously requested')
        res.status(400);
        res.setHeader('Content-Type', 'application/json');
        res.send(JSON.stringify({
            error: {
                id: 'duplicate-address',
                message: 'Address must be unique.'
            }
        }));
    } else {
        let transaction;
        console.log('attempting to send')
        // send to this address
        transaction = web3.eth.sendTransaction({
            from: faucetAccount, 
            to:requestAccount, 
            value:web3.utils.toWei('1', 'ether'), 
            gasLimit: 21000, 
        // check this gasPrice
            gasPrice: 20*10**9})
        .on('transactionHash', async function(hash){
            try {
                await saveTransactionToDatabase({requestAccount, hash});
            } catch(e) {
                console.log('failed to save transaction to db' + requestAccount);
            }
            res.setHeader('Content-Type', 'application/json');
            res.send(JSON.stringify({ data: { success: true } }));
        })
        .on('error', function(error) {
            console.log(error)
            console.log('failed to send ether to: ' + requestAccount);
            res.status(400);
            res.setHeader('Content-Type', 'application/json');
            res.send(JSON.stringify({
                error: {
                    id: 'send-failed',
                    message: 'Transaction send failure'
                }
            }));
        })
    }
})


function getTransactionsFromDatabase(address) {
        console.log("attempting to load transactions from db");

        return new Promise(function(resolve, reject) {
            // todo search by address here
                sentFundsdb.find({requestAccount: address}, function (err, docs) {
                        if (err) {
                                console.log("error:" + err)
                                reject(err);
                                return;
                        }
                        resolve(docs);
                });
        })
}

function saveTransactionToDatabase(transaction) {
    console.log("transaction save attempted")
    return new Promise(function(resolve, reject) {
        sentFundsdb.insert(transaction, function(err, newDoc) {
            if (err) {
                console.log("error:" + err)
                reject(err);
                return;
            }

            resolve(newDoc._id);
        });
    });
};

app.listen(5001, () => console.log('Facuet up and listening on port 5001'))