index.js

const rp = require('request-promise')
const snx = require('synthetix')
const Decimal = require('decimal.js')

const getPriceData = async (synth) => {
  return rp({
    url: 'https://min-api.cryptocompare.com/data/price',
    qs: {
      tsyms: 'USD',
      fsym: synth.symbol
    },
    json: true
  })
}

const calculateIndex = (indexes) => {
  let value = new Decimal(0)
  indexes.forEach(i => {
    const price = i.priceData.USD;
    if (price <= 0)
      throw "invalid price";
    value = value.plus(new Decimal(i.units).times(new Decimal(price)))
  })
  return value.toNumber()
}

const createRequest = async (input, callback) => {
  const asset = input.data.asset || 'sCEX'
  const datas = snx.getSynths({ network: 'mainnet' }).filter(({ index, inverted }) => index && !inverted)
  const data = datas.find(d => d.name.toLowerCase() === asset.toLowerCase())
  await Promise.all(data.index.map(async (synth) => {
    synth.priceData = await getPriceData(synth)
  })).catch(err => {
    callback(500, {
      jobRunID: input.id,
      status: 'errored',
      error: err,
      statusCode: 500
    })
  })

  try {
    data.result = calculateIndex(data.index);
  } catch (e) {
    callback(500, {
      jobRunID: input.id,
      status: 'errored',
      error: "failed getting price",
      statusCode: 500
    });
    return
  }

  callback(200, {
    jobRunID: input.id,
    data: data,
    result: data.result,
    statusCode: 200
  })
}

exports.gcpservice = (req, res) => {
  createRequest(req.body, (statusCode, data) => {
    res.status(statusCode).send(data)
  })
}

exports.handler = (event, context, callback) => {
  createRequest(event, (statusCode, data) => {
    callback(null, data)
  })
}

exports.handlerv2 = (event, context, callback) => {
  createRequest(JSON.parse(event.body), (statusCode, data) => {
    callback(null, {
      statusCode: statusCode,
      body: JSON.stringify(data),
      isBase64Encoded: false
    })
  })
}

module.exports.createRequest = createRequest