feat(Preference): add migration support

Introduces a new function, that checks for preferences, that need to be
migrated, and migrates them if necessary.

Author: FineFindus

app/src/main/java/com/github/libretube/LibreTubeApp.kt

@@ -26,6 +26,7 @@ class LibreTubeApp : Application() {
          * Initialize the [PreferenceHelper]
          */
         PreferenceHelper.initialize(applicationContext)
+        PreferenceHelper.migrate()
 
         /**
          * Set the api and the auth api url

app/src/main/java/com/github/libretube/constants/PreferenceKeys.kt

@@ -145,6 +145,7 @@ object PreferenceKeys {
     const val SELECTED_CHANNEL_GROUP = "selected_channel_group"
     const val SELECTED_DOWNLOAD_SORT_TYPE = "selected_download_sort_type"
     const val LAST_SHOWN_INFO_MESSAGE_VERSION_CODE = "last_shown_info_message_version"
+    const val PREFERENCE_VERSION = "PREFERENCE_VERSION"
 
     // use the helper methods at PreferenceHelper to access these
     const val LAST_USER_SEEN_FEED_TIME = "last_watched_feed_time"

app/src/main/java/com/github/libretube/helpers/PreferenceHelper.kt

@@ -2,11 +2,15 @@ package com.github.libretube.helpers
 
 import android.content.Context
 import android.content.SharedPreferences
+import android.util.Log
 import androidx.core.content.edit
 import androidx.preference.PreferenceManager
+import com.github.libretube.BuildConfig
 import com.github.libretube.constants.PreferenceKeys
 
 object PreferenceHelper {
+    private val TAG = PreferenceHelper::class.simpleName
+
     /**
      * for normal preferences
      */
@@ -30,6 +34,19 @@ object PreferenceHelper {
         authSettings = getAuthenticationPreferences(context)
     }
 
+    /**
+     * Migrate preference to a new version
+     */
+    fun migrate() {
+        val prefVersion = getInt(PreferenceKeys.PREFERENCE_VERSION, -1)
+        // check if there are any prefs to migrate
+        if (prefVersion == BuildConfig.VERSION_CODE)
+            return
+
+        // mark as successfully migrated
+        putInt(PreferenceKeys.PREFERENCE_VERSION, BuildConfig.VERSION_CODE)
+    }
+
     fun putString(key: String, value: String) {
         settings.edit(commit = true) { putString(key, value) }
     }