module.exports = function (app) {
  return {
    group: 'course data',
    optionKey: 'eta_waypoint',
    title:
      'Estimated time of arrival at the next waypoint using distance and VMG to course',
    derivedFrom: ['navigation.datetime', 'navigation.courseRhumbline.nextPoint.distance', 'navigation.courseRhumbline.nextPoint.velocityMadeGood'],
    calculator: function (datetime, distance, velocityMadeGood) {
                var date

      if (datetime && datetime.length > 0) {
        date = new Date(datetime)
      } else {
        date = new Date()
      }

      var datems = date.getTime()
      var timetopoint = Math.floor((distance / (velocityMadeGood * 0.514444)) * 1000)

//      app.debug(`Using datetime: ${date} ms to point : ${timetopoint} currentms: ${datems}`)
      var etams = datems + timetopoint
//      app.debug(`eta in ms: ${etams} ms to point : ${timetopoint} currentms: ${datems}`)

      if (velocityMadeGood > 0) {
      var etad = new Date(parseInt(etams));
      var eta = etad.toISOString()
      } else {
      var  eta = "--"
      }
      app.debug(`what is eta: ${eta} etams: ${etams} etad: ${etad}`)

      return [
      {
      path: 'navigation.courseGreatCircle.nextPoint.eta', value: eta
         }]
  }}
}