Remove special casing of SongsForGenre and thereby fix it.

Also prevent jumping in the random albums list and
don't refresh the album list on back navigation

ultrasonic/src/main/kotlin/org/moire/ultrasonic/fragment/AlbumListFragment.kt

@@ -34,6 +34,11 @@ class AlbumListFragment : EntryListFragment<MusicDirectory.Album>() {
      */
     override val mainLayout: Int = R.layout.list_layout_generic
 
+    /**
+     * Whether to refresh the data onViewCreated
+     */
+    override val refreshOnCreation: Boolean = false
+
     /**
      * The central function to pass a query to the model and return a LiveData object
      */

ultrasonic/src/main/kotlin/org/moire/ultrasonic/fragment/EntryListFragment.kt

@@ -71,7 +71,7 @@ abstract class EntryListFragment<T : GenericEntry> : MultiListFragment<T>() {
      * What to do when the list has changed
      */
     override val defaultObserver: (List<T>) -> Unit = {
-        emptyView.isVisible = it.isEmpty()
+        emptyView.isVisible = it.isEmpty() && !(refreshListView?.isRefreshing?:false)
 
         if (showFolderHeader()) {
             val list = mutableListOf<Identifiable>(folderHeader)

ultrasonic/src/main/kotlin/org/moire/ultrasonic/fragment/MultiListFragment.kt

@@ -89,6 +89,11 @@ abstract class MultiListFragment<T : Identifiable> : Fragment() {
     open val emptyViewId = R.id.empty_list_view
     open val emptyTextId = R.id.empty_list_text
 
+    /**
+     * Whether to refresh the data onViewCreated
+     */
+    open val refreshOnCreation: Boolean = true
+
     open fun setTitle(title: String?) {
         if (title == null) {
             FragmentTitle.setTitle(
@@ -106,7 +111,7 @@ abstract class MultiListFragment<T : Identifiable> : Fragment() {
      * What to do when the list has changed
      */
     internal open val defaultObserver: ((List<T>) -> Unit) = {
-        emptyView.isVisible = it.isEmpty()
+        emptyView.isVisible = it.isEmpty() && !(refreshListView?.isRefreshing?:false)
         viewAdapter.submitList(it)
     }
 
@@ -123,7 +128,7 @@ abstract class MultiListFragment<T : Identifiable> : Fragment() {
         }
 
         // Populate the LiveData. This starts an API request in most cases
-        liveDataItems = getLiveData(arguments, true)
+        liveDataItems = getLiveData(arguments, refreshOnCreation)
 
         // Link view to display text if the list is empty
         emptyView = view.findViewById(emptyViewId)

ultrasonic/src/main/kotlin/org/moire/ultrasonic/fragment/TrackCollectionFragment.kt

@@ -18,7 +18,6 @@ import android.widget.ImageView
 import androidx.core.view.isVisible
 import androidx.fragment.app.viewModels
 import androidx.lifecycle.LiveData
-import androidx.lifecycle.Observer
 import androidx.lifecycle.viewModelScope
 import androidx.navigation.Navigation
 import androidx.recyclerview.widget.LinearLayoutManager
@@ -54,6 +53,8 @@ import org.moire.ultrasonic.util.Util
  * In most cases the data should be just a list of Entries, but there are some cases
  * where the list can contain Albums as well. This happens especially when having ID3 tags disabled,
  * or using Offline mode, both in which Indexes instead of Artists are being used.
+ *
+ * TODO: Remove more button and introduce endless scrolling
  */
 @Suppress("TooManyFunctions")
 open class TrackCollectionFragment : MultiListFragment<MusicDirectory.Child>() {
@@ -97,9 +98,6 @@ open class TrackCollectionFragment : MultiListFragment<MusicDirectory.Child>() {
             getLiveData(arguments, true)
         }
 
-        // TODO: remove special casing for songsForGenre
-        listModel.songsForGenre.observe(viewLifecycleOwner, songsForGenreObserver)
-
         setupButtons(view)
 
         registerForContextMenu(listView!!)
@@ -424,34 +422,6 @@ open class TrackCollectionFragment : MultiListFragment<MusicDirectory.Child>() {
         mediaPlayerController.unpin(songs)
     }
 
-    private val songsForGenreObserver = Observer<MusicDirectory> { musicDirectory ->
-
-        // Hide more button when results are less than album list size
-        if (musicDirectory.size < requireArguments().getInt(
-            Constants.INTENT_ALBUM_LIST_SIZE, 0
-        )
-        ) {
-            moreButton!!.visibility = View.GONE
-        } else {
-            moreButton!!.visibility = View.VISIBLE
-        }
-
-        moreButton!!.setOnClickListener {
-            val theGenre = requireArguments().getString(Constants.INTENT_GENRE_NAME)
-            val size = requireArguments().getInt(Constants.INTENT_ALBUM_LIST_SIZE, 0)
-            val theOffset = requireArguments().getInt(
-                Constants.INTENT_ALBUM_LIST_OFFSET, 0
-            ) + size
-            val bundle = Bundle()
-            bundle.putString(Constants.INTENT_GENRE_NAME, theGenre)
-            bundle.putInt(Constants.INTENT_ALBUM_LIST_SIZE, size)
-            bundle.putInt(Constants.INTENT_ALBUM_LIST_OFFSET, theOffset)
-
-            Navigation.findNavController(requireView())
-                .navigate(R.id.trackCollectionFragment, bundle)
-        }
-    }
-
     override val defaultObserver: (List<MusicDirectory.Child>) -> Unit = {
 
         val entryList: MutableList<MusicDirectory.Child> = it.toMutableList()
@@ -483,18 +453,9 @@ open class TrackCollectionFragment : MultiListFragment<MusicDirectory.Child>() {
             } else {
                 moreButton!!.visibility = View.VISIBLE
                 if (arguments?.getInt(Constants.INTENT_RANDOM, 0) ?: 0 > 0) {
-                    moreButton!!.setOnClickListener {
-                        val offset = requireArguments().getInt(
-                            Constants.INTENT_ALBUM_LIST_OFFSET, 0
-                        ) + listSize
-                        val bundle = Bundle()
-                        bundle.putInt(Constants.INTENT_RANDOM, 1)
-                        bundle.putInt(Constants.INTENT_ALBUM_LIST_SIZE, listSize)
-                        bundle.putInt(Constants.INTENT_ALBUM_LIST_OFFSET, offset)
-                        Navigation.findNavController(requireView()).navigate(
-                            R.id.trackCollectionFragment, bundle
-                        )
-                    }
+                    moreRandomTracks()
+                } else if (arguments?.getString(Constants.INTENT_GENRE_NAME, "") ?: "" != "") {
+                    moreSongsForGenre()
                 }
             }
         }
@@ -536,6 +497,40 @@ open class TrackCollectionFragment : MultiListFragment<MusicDirectory.Child>() {
         listModel.currentListIsSortable = true
     }
 
+    private fun moreSongsForGenre(args: Bundle = requireArguments()) {
+        moreButton!!.setOnClickListener {
+            val theGenre = args.getString(Constants.INTENT_GENRE_NAME)
+            val size = args.getInt(Constants.INTENT_ALBUM_LIST_SIZE, 0)
+            val theOffset = args.getInt(
+                Constants.INTENT_ALBUM_LIST_OFFSET, 0
+            ) + size
+            val bundle = Bundle()
+            bundle.putString(Constants.INTENT_GENRE_NAME, theGenre)
+            bundle.putInt(Constants.INTENT_ALBUM_LIST_SIZE, size)
+            bundle.putInt(Constants.INTENT_ALBUM_LIST_OFFSET, theOffset)
+
+            Navigation.findNavController(requireView())
+                .navigate(R.id.trackCollectionFragment, bundle)
+        }
+    }
+
+    private fun moreRandomTracks() {
+        val listSize = arguments?.getInt(Constants.INTENT_ALBUM_LIST_SIZE, 0) ?: 0
+
+        moreButton!!.setOnClickListener { it: View? ->
+            val offset = requireArguments().getInt(
+                Constants.INTENT_ALBUM_LIST_OFFSET, 0
+            ) + listSize
+            val bundle = Bundle()
+            bundle.putInt(Constants.INTENT_RANDOM, 1)
+            bundle.putInt(Constants.INTENT_ALBUM_LIST_SIZE, listSize)
+            bundle.putInt(Constants.INTENT_ALBUM_LIST_OFFSET, offset)
+            Navigation.findNavController(requireView()).navigate(
+                R.id.trackCollectionFragment, bundle
+            )
+        }
+    }
+
     internal fun getSelectedSongs(): List<MusicDirectory.Entry> {
         // Walk through selected set and get the Entries based on the saved ids.
         return viewAdapter.getCurrentList().mapNotNull {

ultrasonic/src/main/kotlin/org/moire/ultrasonic/model/AlbumListModel.kt

@@ -63,6 +63,12 @@ class AlbumListModel(application: Application) : GenericListModel(application) {
             null
         }
 
+        // If we are refreshing the random list, we want to avoid items moving across the screen,
+        // by clearing the list first
+        if (refresh && albumListType == "random") {
+            list.postValue(listOf())
+        }
+
         // Handle the logic for endless scrolling:
         // If appending the existing list, set the offset from where to load
         if (append) offset += (size + loadedUntil)
@@ -95,7 +101,7 @@ class AlbumListModel(application: Application) : GenericListModel(application) {
             val newList = ArrayList<MusicDirectory.Album>()
             newList.addAll(list.value!!)
             newList.addAll(musicDirectory)
-            this.list.postValue(newList)
+            list.postValue(newList)
         } else {
             list.postValue(musicDirectory)
         }

ultrasonic/src/main/kotlin/org/moire/ultrasonic/model/TrackCollectionModel.kt

@@ -22,7 +22,6 @@ import org.moire.ultrasonic.util.Util
 class TrackCollectionModel(application: Application) : GenericListModel(application) {
 
     val currentList: MutableLiveData<List<MusicDirectory.Child>> = MutableLiveData()
-    val songsForGenre: MutableLiveData<MusicDirectory> = MutableLiveData()
 
     /*
     * Especially when dealing with indexes, this method can return Albums, Entries or a mix of both!
@@ -56,7 +55,7 @@ class TrackCollectionModel(application: Application) : GenericListModel(applicat
         withContext(Dispatchers.IO) {
             val service = MusicServiceFactory.getMusicService()
             val musicDirectory = service.getSongsByGenre(genre, count, offset)
-            songsForGenre.postValue(musicDirectory)
+            updateList(musicDirectory)
         }
     }