Refactoring Android logging (#511)

Refactoring Android logging

client/android/utils/src/main/kotlin/Prefs.kt

@@ -0,0 +1,58 @@
+package org.amnezia.vpn.util
+
+import android.app.Application
+import android.content.Context
+import android.content.SharedPreferences
+import androidx.security.crypto.EncryptedSharedPreferences
+import androidx.security.crypto.MasterKey
+import kotlin.reflect.typeOf
+
+private const val TAG = "Prefs"
+private const val PREFS_FILE = "org.amnezia.vpn.prefs"
+private const val SECURE_PREFS_FILE = "$PREFS_FILE.secure"
+
+object Prefs {
+    private lateinit var app: Application
+    val prefs: SharedPreferences
+        get() = try {
+            EncryptedSharedPreferences(
+                app,
+                SECURE_PREFS_FILE,
+                MasterKey(app)
+            )
+        } catch (e: Exception) {
+            Log.e(TAG, "Getting Encryption Storage failed: $e, plaintext fallback")
+            app.getSharedPreferences(PREFS_FILE, Context.MODE_PRIVATE)
+        }
+
+    fun init(app: Application) {
+        Log.v(TAG, "Init Prefs")
+        this.app = app
+    }
+
+    fun save(key: String, value: Boolean) =
+        prefs.edit().putBoolean(key, value).apply()
+
+    fun save(key: String, value: String?) =
+        prefs.edit().putString(key, value).apply()
+
+    fun save(key: String, value: Int) =
+        prefs.edit().putInt(key, value).apply()
+
+    fun save(key: String, value: Long) =
+        prefs.edit().putLong(key, value).apply()
+
+    fun save(key: String, value: Float) =
+        prefs.edit().putFloat(key, value).apply()
+
+    inline fun <reified T> load(key: String): T {
+        return when (typeOf<T>()) {
+            typeOf<Boolean>() -> prefs.getBoolean(key, false)
+            typeOf<String>() -> prefs.getString(key, "")
+            typeOf<Int>() -> prefs.getInt(key, 0)
+            typeOf<Long>() -> prefs.getLong(key, 0L)
+            typeOf<Float>() -> prefs.getFloat(key, 0f)
+            else -> throw IllegalArgumentException("SharedPreferences does not support type: ${typeOf<T>()}")
+        } as T
+    }
+}