@signalk/nmea0183-signalk/hooks/ZDA.js

A node.js/javascript parser for NMEA0183 sentences. Sentences are parsed to Signal K format.

/*
 * ZDA codec
 *
 * Copyright 2014, Mikko Vesikkala
 *
 * Licensed under the Apache License, Version 2.0 (the "License")
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

'use strict'

/*
=== ZDA - Time & Date ===

------------------------------------------------------------------------------
*******1         2  3  4    5  6  7
*******|         |  |  |    |  |  |
$--ZDA,hhmmss.ss,xx,xx,xxxx,xx,xx*hh<CR><LF>
------------------------------------------------------------------------------

Field Number:
1. UTC time (hours, minutes, seconds, may have fractional subsecond)
2. Day, 01 to 31
3. Month, 01 to 12
4. Year (4 digits)
5. Local zone description, 00 to +- 13 hours
6. Local zone minutes description, apply same sign as local hours
7. Checksum
*/
const debug = require('debug')('signalk-parser-nmea0183/ZDA')
const utils = require('@signalk/nmea0183-utilities')
const moment = require('moment-timezone')

function isEmpty(mixed) {
  return (
    (typeof mixed !== 'string' && typeof mixed !== 'number') ||
    (typeof mixed === 'string' && mixed.trim() === '')
  )
}

module.exports = function (input) {
  const { id, sentence, parts, tags } = input

  const empty = parts.reduce((e, val) => {
    if (isEmpty(val)) {
      ++e
    }
    return e
  }, 0)

  if (empty > 3) {
    return null
  }

  const time = parts[0] || ''
  const date = parts[1] + parts[2] + (parts[3] || '').slice(-2)

  var delta = {}
  if (time.length >= 6 && date.length === 6 && empty < 3) {
    const year = parts[3]
    const month = parts[2] - 1
    const day = parts[1]
    const hour = (parts[0] || '').substring(0, 2)
    const minute = (parts[0] || '').substring(2, 4)
    const second = (parts[0] || '').substring(4, 6)
    const milliSecond = (parts[0].substring(4) % 1) * 1000
    const d = new Date(
      Date.UTC(year, month, day, hour, minute, second, milliSecond)
    )
    const ts = d.toISOString()
    delta = {
      updates: [
        {
          source: tags.source,
          timestamp: tags.timestamp,
          values: [
            {
              path: 'navigation.datetime',
              value: ts,
            },
          ],
        },
      ],
    }
  }

  const toRemove = []

  delta.updates[0].values.forEach((update, index) => {
    if (
      typeof update.value === 'undefined' ||
      update.value === null ||
      (typeof update.value === 'string' && update.value.trim() === '') ||
      (typeof update.value !== 'string' && isNaN(update.value))
    ) {
      toRemove.push(index)
    }
  })

  if (toRemove.length > 0) {
    toRemove.forEach((index) => {
      delta.updates[0].values.splice(index, 1)
    })
  }

  return delta
}