From 226135be90496eb83155be573cfa4df052709a08 Mon Sep 17 00:00:00 2001
From: Scott Bender <scott@scottbender.net>
Date: Fri, 14 Jun 2019 02:00:29 -0400
Subject: [PATCH] fix: handle "not available" values in VDM messages (#148)

---
 hooks/VDM.js |  6 +++---
 test/VDM.js  | 11 +++++++++++
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/hooks/VDM.js b/hooks/VDM.js
index 130551cb..1e8bf4ac 100644
--- a/hooks/VDM.js
+++ b/hooks/VDM.js
@@ -75,21 +75,21 @@ module.exports = function (input, session) {
     })
   }
 
-  if (typeof data.sog != 'undefined') {
+  if (typeof data.sog != 'undefined' && data.sog != 102.3 ) {
     values.push({
       path: 'navigation.speedOverGround',
       value: utils.transform(data.sog, 'knots', 'ms')
     })
   }
 
-  if (typeof data.cog != 'undefined') {
+  if (typeof data.cog != 'undefined' && data.cog != 360 ) {
     values.push({
       path: 'navigation.courseOverGroundTrue',
       value: utils.transform(data.cog, 'deg', 'rad')
     })
   }
 
-  if (typeof data.hdg != 'undefined') {
+  if (typeof data.hdg != 'undefined' && data.hdg != 511) {
     values.push({
       path: 'navigation.headingTrue',
       value: utils.transform(data.hdg, 'deg', 'rad')
diff --git a/test/VDM.js b/test/VDM.js
index d3c5f5f8..88cc41db 100644
--- a/test/VDM.js
+++ b/test/VDM.js
@@ -54,6 +54,17 @@ describe('VDM', function() {
     delta.context.should.equal('vessels.urn:mrn:imo:mmsi:244670316')
   })
 
+  it('Unavailable values don\'t convert', () => {
+    const delta = new Parser().parse('!AIVDM,1,1,,A,33@nwqwP?w<ovH0kOqP>4?wp0000,0*0B\n')
+    delta.context.should.equal('vessels.urn:mrn:imo:mmsi:219004903')
+
+    let findPath = 
+    should.not.exist(delta.updates[0].values.find((pv) => { return pv.path === 'navigation.headingTrue'}))
+    should.not.exist(delta.updates[0].values.find((pv) => { return pv.path === 'navigation.courseOverGroundTrue'}))
+    should.not.exist(delta.updates[0].values.find((pv) => { return pv.path === 'navigation.speedOverGround'}))
+    should.not.exist(delta.updates[0].values.find((pv) => { return pv.path === 'navigation.state'}))
+  })
+
   it('AtoN converts ok', () => {
     const delta = new Parser().parse('!AIVDM,1,1,,A,E>k`sUoJK@@@@@@@@@@@@@@@@@@MAhJS;@neP00000N000,0*0D\n')
     delta.context.should.equal('atons.urn:mrn:imo:mmsi:993672087')