nodeUtils.js

const http = require('http')

const nodeStats = {}

function getEpoch() {

  return nodeStats.cardano_node_ChainDB_metrics_epoch_int
}

function getSlot() {

  return nodeStats.cardano_node_ChainDB_metrics_slotNum_int
}

function getSlotInEpoch() {

  return nodeStats.cardano_node_ChainDB_metrics_slotInEpoch_int
}

function getShelleyTransitionEpoch(byron, shelley) {

  const slotInEpoch         = getSlotInEpoch()
  const slot                = getSlot()

  const byronEpochLength    = 10 * byron.protocolConsts.k
  let   byronEpochs         = getEpoch()
  let   shelleyEpochs       = 0
  let   calcSlot            = 0

  while(byronEpochs >= 0) {

    calcSlot = (byronEpochs * byronEpochLength) + (shelleyEpochs * shelley.epochLength) + slotInEpoch

    if(calcSlot === slot) {

      break
    }

    byronEpochs--
    shelleyEpochs++
  }

  if (calcSlot !== slot || shelleyEpochs === 0) {

    return -1
  }

  return byronEpochs
}

function getFirstSlotOfEpoch(byron, shelley, absoluteSlot) {

  const shelleyTransitionEpoch = getShelleyTransitionEpoch(byron, shelley)

  if(shelleyTransitionEpoch === -1) { return -1 }

  const byronEpochLength    = 10 * byron.protocolConsts.k
  const byronSlots          = byronEpochLength * shelleyTransitionEpoch
  const shelleySlots        = absoluteSlot - byronSlots
  const shelleySlotInEpoch  = shelleySlots % shelley.epochLength

  return absoluteSlot - shelleySlotInEpoch
}

function updateNodeStats(nodeStatsURL) {

  return new Promise((resolve, reject) => {

    http.get(nodeStatsURL, (res) => {

      let data = '';

      res.on('data', (chunk) => { data += chunk; });

      res.on('end', () => {

        const nodeStatsArray  = data.split('\n')

        for(let i = 0; i < nodeStatsArray.length; i++) {

          const entry = nodeStatsArray[i].split(' ')

          if(entry[0] && entry[0].length > 0) {

            nodeStats[entry[0]] = Number.parseFloat(entry[1])
          }
        }

        // console.log('updateNodeStats:', nodeStats)

        resolve()
      });

    }).on("error", (err) => {

      reject(err)
    });
  })
}

module.exports = {
  getEpoch,
  getSlot,
  getSlotInEpoch,
  getFirstSlotOfEpoch,
  updateNodeStats
}