app.js

#!/usr/bin/env node

const Dat = require('dat-node')
const rtlsdr = require('./lib/rtlsdr')
const storeEmitter = require('./lib/store').storeEmitter
const store = require('./lib/store').store
const station = require('./package').station

const dataFolder = 'station'
const flightFolder = 'flight_data/'

rtlsdr.start()

Dat(dataFolder, {indexing: false, latest:true, sparse: true}, function(err, dat) {
  if(err) throw err

  dat.joinNetwork()
  console.log('Serving dat://'+dat.key.toString('hex'))

  dat.archive.readFile('station.json', function(err, file) {
    if(err) {
      if(err.notFound) {
        station.radio = rtlsdr.stat();
        dat.archive.writeFile('station.json', JSON.stringify(station), function(err) {
          if(err) throw err
        })
      }
      else throw err
    }
    else {
      station.radio = rtlsdr.stat();
      if(file != JSON.stringify(station)) {
        dat.archive.writeFile('station.json', JSON.stringify(station), function(err) {
          if(err) throw err
        })
      }
    }
  })

  dat.archive.readdir('/' + flightFolder, function(err, files) {
    if(err) {
      if(err.notFound) {
        dat.archive.mkdir(flightFolder, function(err) { if(err) throw err })
      }
      else throw err
    }
    else {
      console.log('Cleaning up Legacy Files')
      files.forEach(function(legacyFile) {
        dat.archive.unlink(flightFolder + legacyFile, function(err) {
          if(err) throw err
        })
      })
      console.log('%d files removed', files.length)
    }

  })

  setInterval(function() {
    store.getAircrafts().filter(function(aircraft) {
      return aircraft.lat
    })
    .forEach(function(aircraft) {
      dat.archive.readFile(flightFolder + aircraft.icao + '.json', 'utf8', (err, data) => {
        if(err) {
          if(err.notFound === true) {
            dat.archive.writeFile(flightFolder + aircraft.icao + '.json', JSON.stringify(aircraft), function(err) {
              if(err) throw err
            })
          }
          else throw err
        }
        else {
          var prevRecord = JSON.parse(data)
          if(prevRecord.lat != aircraft.lat && prevRecord.lng != aircraft.lng) {
            dat.archive.writeFile(flightFolder + aircraft.icao + '.json', JSON.stringify(aircraft), function(err) {
              if(err) throw err
            })
          }
        }
      })
    })
  }, 3000)

  storeEmitter.on('aircraftTimeout', function(icao) {
    dat.archive.unlink(flightFolder + icao + '.json', function(err) {
      // Expect some icao's to not be found as we arn't logging them all.
      if(err && err.status != 404) throw err
    })
  })
})