Configured OS specific directories for user data

BankingPersistence/src/jvmMain/kotlin/net/codinux/banking/persistence/BankingRepository.jvm.kt

@@ -36,9 +36,40 @@ private fun determineDataDirectory(): File {
     val dataDir = if (Files.isWritable(currentDir)) { // couldn't believe it, but java.io.File returned folder is writable for "C:\\Program Files\\"
         File(currentDir.absolutePathString(), "data")
     } else { // otherwise use .bankmeister dir in user's home dir (the default for releases)
-        val userHome = System.getProperty("user.home")
-        File(userHome, ".bankmeister")
+        File(determineOsDependentUserDataDir(), ".bankmeister")
     }
 
     return dataDir.also { it.mkdirs() }
+}
+
+private fun determineOsDependentUserDataDir(): File {
+    val userHomeString = System.getProperty("user.home")
+    val userHome = File(userHomeString)
+    val windowsLocalAppDataDir = System.getenv("LOCALAPPDATA")?.takeUnless { it.isBlank() }
+
+    return if (windowsLocalAppDataDir != null) {
+        File(windowsLocalAppDataDir)
+    } else if (userHomeString.startsWith("/")) {
+        val osName = System.getProperty("os.name")
+        if (osName.contains("mac", true) || osName.contains("darwin", true)) { // macOS
+            File(userHome, "Library/Application Support")
+        } else if (osName.contains("nux")) { // Linux
+            val localShareDirectory = File(userHome, ".local/share")
+            val configDir = File(userHome, ".config")
+
+            if (localShareDirectory.exists()) {
+                localShareDirectory
+            } else if (configDir.exists()) {
+                configDir
+            } else {
+                userHome
+            }
+        } else { // unknown
+            userHome
+        }
+    } else if (userHomeString.length > 3 && userHomeString[1] == ':' && userHomeString[2] == '\\') { // Windows, but LOCALAPPDATA is not set
+        userHome // File(userHome, "AppData\Local")
+    } else {
+        userHome
+    }
 }