From 0e54d67a6d32dd7accfa2075412364910bc689d2 Mon Sep 17 00:00:00 2001
From: Teppo Kurki <teppo.kurki@iki.fi>
Date: Mon, 20 Nov 2023 22:24:21 +0200
Subject: [PATCH] fix: pass null through true/mag conversions

Input value null should result in null output values.

Fixes #120.
---
 README.md                         |  2 +-
 calcs/courseOverGroundMagnetic.js | 10 ++++++++++
 calcs/courseOverGroundTrue.js     | 14 +++++++++++++-
 calcs/headingTrue.js              | 11 ++++++++++-
 calcs/windDirectionMagnetic.js    | 11 ++++++++++-
 5 files changed, 44 insertions(+), 4 deletions(-)

diff --git a/README.md b/README.md
index 1ddfbe4..da08b65 100644
--- a/README.md
+++ b/README.md
@@ -24,7 +24,7 @@ It currently calculates:
  * True Wind Direction (based on AWA and headingTrue)
  * Ground Wind Angle and Speed (based on SOG, AWA and AWS)
  * Magnetic Wind Direction (based on AWA and headingMagnetic)
- * Magnetic Wind Direction (based on wind.directionTrue and magneticVarition)
+ * Magnetic Wind Direction (based on wind.directionTrue and magneticVariation)
  * Wind Shift (experimental)
  * Moon illumination and times (based on time and navigation.position)
  * Sunlight Times: sunrise, sunriseEnd, goldenHourEnd, solarNoon, goldenHour, sunsetStart, sunset, dusk, nauticalDusk, night, nadir, nightEnd, nauticalDawn, dawn (based on time and navigation.position)
diff --git a/calcs/courseOverGroundMagnetic.js b/calcs/courseOverGroundMagnetic.js
index 631f2b4..f79bf3b 100644
--- a/calcs/courseOverGroundMagnetic.js
+++ b/calcs/courseOverGroundMagnetic.js
@@ -19,6 +19,12 @@ module.exports = function (app, plugin) {
           return
         }
       }
+      if (
+        _.isUndefined(courseOverGroundTrue) ||
+        courseOverGroundTrue === null
+      ) {
+        return [{ path: 'navigation.courseOverGroundMagnetic', value: null }]
+      }
       var courseOverGroundMagnetic = courseOverGroundTrue - magneticVariation
       if (courseOverGroundMagnetic < 0) {
         courseOverGroundMagnetic = Math.PI * 2 + courseOverGroundMagnetic
@@ -36,6 +42,10 @@ module.exports = function (app, plugin) {
       {
         input: [1.0, 0.1],
         expected: [{ path: 'navigation.courseOverGroundMagnetic', value: 0.9 }]
+      },
+      {
+        input: [null, -0.01],
+        expected: [{ path: 'navigation.courseOverGroundMagnetic', value: null }]
       }
     ]
   }
diff --git a/calcs/courseOverGroundTrue.js b/calcs/courseOverGroundTrue.js
index 2589d28..e520bb9 100644
--- a/calcs/courseOverGroundTrue.js
+++ b/calcs/courseOverGroundTrue.js
@@ -19,6 +19,12 @@ module.exports = function (app, plugin) {
           return
         }
       }
+      if (
+        _.isUndefined(courseOverGroundMagnetic) ||
+        courseOverGroundMagnetic === null
+      ) {
+        return [{ path: 'navigation.courseOverGroundTrue', value: null }]
+      }
       var courseOverGroundTrue = courseOverGroundMagnetic + magneticVariation
       if (courseOverGroundTrue < 0) {
         courseOverGroundTrue = Math.PI * 2 + courseOverGroundTrue
@@ -28,6 +34,12 @@ module.exports = function (app, plugin) {
       return [
         { path: 'navigation.courseOverGroundTrue', value: courseOverGroundTrue }
       ]
-    }
+    },
+    tests: [
+      {
+        input: [null, 0.01],
+        expected: [{ path: 'navigation.courseOverGroundTrue', value: null }]
+      }
+    ]
   }
 }
diff --git a/calcs/headingTrue.js b/calcs/headingTrue.js
index 05b1fbb..946ebb6 100644
--- a/calcs/headingTrue.js
+++ b/calcs/headingTrue.js
@@ -16,6 +16,9 @@ module.exports = function (app, plugin) {
           return
         }
       }
+      if (_.isUndefined(heading) || heading === null) {
+        return [{ path: 'navigation.headingTrue', value: null }]
+      }
       var headingTrue = heading + magneticVariation
       if (headingTrue < 0) {
         headingTrue = Math.PI * 2 + headingTrue
@@ -23,6 +26,12 @@ module.exports = function (app, plugin) {
         headingTrue = headingTrue - Math.PI * 2
       }
       return [{ path: 'navigation.headingTrue', value: headingTrue }]
-    }
+    },
+    tests: [
+      {
+        input: [null, 0.01],
+        expected: [{ path: 'navigation.headingTrue', value: null }]
+      }
+    ]
   }
 }
diff --git a/calcs/windDirectionMagnetic.js b/calcs/windDirectionMagnetic.js
index a864b73..986f737 100644
--- a/calcs/windDirectionMagnetic.js
+++ b/calcs/windDirectionMagnetic.js
@@ -8,6 +8,9 @@ module.exports = function (app, plugin) {
       'navigation.magneticVariation'
     ],
     calculator: function (directionTrue, magneticVariation) {
+      if (directionTrue === null) {
+        return [{ path: 'environment.wind.directionMagnetic', value: null }]
+      }
       var directionMagnetic = directionTrue - magneticVariation
       if (directionMagnetic < 0) {
         directionMagnetic = Math.PI * 2 + directionMagnetic
@@ -17,6 +20,12 @@ module.exports = function (app, plugin) {
       return [
         { path: 'environment.wind.directionMagnetic', value: directionMagnetic }
       ]
-    }
+    },
+    tests: [
+      {
+        input: [null, -0.01],
+        expected: [{ path: 'environment.wind.directionMagnetic', value: null }]
+      }
+    ]
   }
 }