Implement ConstantLookup

mobile/src/main/java/be/mygod/vpnhotspot/util/ConstantLookup.kt

@@ -0,0 +1,33 @@
+package be.mygod.vpnhotspot.util
+
+import android.os.Build
+import androidx.collection.SparseArrayCompat
+import be.mygod.vpnhotspot.App.Companion.app
+import be.mygod.vpnhotspot.R
+import timber.log.Timber
+
+class ConstantLookup(private val clazz: Class<*>, private val prefix: String, private val lookup29: Array<out String>) {
+    private val lookup by lazy {
+        SparseArrayCompat<String>().apply {
+            for (field in clazz.declaredFields) try {
+                if (field.name.startsWith(prefix)) put(field.get(null) as Int, field.name)
+            } catch (e: Exception) {
+                Timber.w(e)
+            }
+        }
+    }
+    operator fun invoke(reason: Int): String {
+        if (Build.VERSION.SDK_INT >= 30) try {
+            lookup.get(reason)?.let { return it }
+        } catch (e: ReflectiveOperationException) {
+            Timber.w(e)
+        }
+        return lookup29.getOrNull(reason) ?: app.getString(R.string.failure_reason_unknown, reason)
+    }
+}
+
+@Suppress("FunctionName")
+fun ConstantLookup(clazz: Class<*>, prefix: String, vararg lookup29: String) = ConstantLookup(clazz, prefix, lookup29)
+@Suppress("FunctionName")
+inline fun <reified T> ConstantLookup(prefix: String, vararg lookup29: String) =
+        ConstantLookup(T::class.java, prefix, lookup29)