Added QthConverter.kt class and unit tests

app/src/main/java/com/rtbishop/look4sat/utility/QthConverter.kt

@@ -0,0 +1,64 @@
+/*******************************************************************************
+Look4Sat. Amateur radio satellite tracker and pass predictor.
+Copyright (C) 2019, 2020 Arty Bishop (bishop.arty@gmail.com)
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ ******************************************************************************/
+
+package com.rtbishop.look4sat.utility
+
+import com.github.amsacode.predict4java.GroundStationPosition
+import javax.inject.Inject
+
+class QthConverter @Inject constructor() {
+    
+    fun qthToLocation(qthString: String): GroundStationPosition? {
+        if (!isValidQTH(qthString)) return null
+        val lonFirst = (qthString[0].toUpperCase().toInt() - 65) * 20
+        val latFirst = (qthString[1].toUpperCase().toInt() - 65) * 10
+        val lonSecond = qthString[2].toString().toInt() * 2
+        val latSecond = qthString[3].toString().toInt()
+        val lonThird = (((qthString[4].toLowerCase().toInt() - 97) / 12.0) + (1.0 / 24.0)) - 180
+        val latThird = (((qthString[5].toLowerCase().toInt() - 97) / 24.0) + (1.0 / 48.0)) - 90
+        val longitude = lonFirst + lonSecond + lonThird
+        val latitude = latFirst + latSecond + latThird
+        return GroundStationPosition(latitude, longitude, 0.0)
+    }
+    
+    fun locationToQTH(lat: Double, lon: Double): String? {
+        if (!isValidLoc(lat, lon)) return null
+        val tempLon = if (lon > 180.0) lon - 360 else lon
+        val upper = "ABCDEFGHIJKLMNOPQRSTUVWX"
+        val lower = "abcdefghijklmnopqrstuvwx"
+        val longitude = tempLon + 180
+        val latitude = lat + 90
+        val lonFirst = upper[(longitude / 20).toInt()]
+        val latFirst = upper[(latitude / 10).toInt()]
+        val lonSecond = ((longitude / 2) % 10).toInt().toString()
+        val latSecond = (latitude % 10).toInt().toString()
+        val lonThird = lower[((longitude % 2) * 12).toInt()]
+        val latThird = lower[((latitude % 1) * 24).toInt()]
+        return "$lonFirst$latFirst$lonSecond$latSecond$lonThird$latThird"
+    }
+    
+    private fun isValidQTH(qthString: String): Boolean {
+        val qthPattern = "[a-xA-X][a-xA-X][0-9][0-9][a-xA-X][a-xA-X]".toRegex()
+        return qthString.matches(qthPattern)
+    }
+    
+    private fun isValidLoc(lat: Double, lon: Double): Boolean {
+        return (lat > -90.0 && lat < 90.0) && (lon > -180.0 && lon < 360.0)
+    }
+}