APB.js

'use strict'

/**
 * Copyright 2016 Signal K and Fabian Tollenaar <fabian@signalk.org>.
 *
 * 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.
 */

const debug = require('debug')('signalk-parser-nmea0183/APB')
const utils = require('@signalk/nmea0183-utilities')

/*

       0 1    2 3 4 5 6   7 8    9  10  11 12
       | |    | | | | |   | |    |   |  |  |
$GPAPB,A,A,0.10,R,N,V,V,011,M,DEST,011,M,011,M*3C
where:
        APB       Autopilot format B
0       A         Loran-C blink/SNR warning, general warning
1       A         Loran-C cycle warning
2       0.10      cross-track error distance
3       R         steer Right to correct (or L for Left)
4       N         cross-track error units - nautical miles (K for kilometers)
5       V         arrival alarm - circle
6       V         arrival alarm - perpendicular
7,8     011,M     magnetic bearing, origin to destination
9       DEST      destination waypoint ID
10,11   011,M     magnetic bearing, present position to destination
12,13   011,M     magnetic heading to steer (bearings could True as 033,T)
*3C     Checksum

*/

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

  if(parts[0].toUpperCase() == 'V') {
    // Don't parse this sentence as it's void.
    throw new Error('Not parsing sentence for it\'s void (LORAN-C blink/SNR warning)')
  }

  if(parts[1].toUpperCase() == 'V') {
    throw new Error('Not parsing sentence for it\'s void (LORAN-C cycle warning)')
  }

  const xte = utils.transform(parts[2], (parts[4].toUpperCase() === 'N' ? 'nm' : 'km'), 'm')

  const currentRoute = {
    source: utils.source(id),
    timestamp: utils.timestamp(),
    steer: (parts[3].toUpperCase() == 'R' ? 'right' : 'left'),
    bearingActual: utils.transform(utils.float(parts[10]), 'deg', 'rad'),
    bearingDirect: utils.transform(utils.float(parts[7]), 'deg', 'rad'),
    courseRequired: utils.transform(utils.float(parts[12]), 'deg', 'rad'),
    waypoint: {
      next: parts[9],
      xte: xte
    }
  }

  throw new Error('@FIXME: APB hook needs to be rewritten to fit latest version of SK')
}