home: fix crash when recreating viewpager

Fix a crash where all HomeListFragments would lose their displayModes
when the activity was recreated [such as in settings].

app/src/main/java/org/oxycblt/auxio/home/HomeFragment.kt

@@ -53,11 +53,7 @@ import org.oxycblt.auxio.recycler.DisplayMode
 class HomeFragment : Fragment() {
     private val playbackModel: PlaybackViewModel by activityViewModels()
     private val detailModel: DetailViewModel by activityViewModels()
-
+    private val homeModel: HomeViewModel by activityViewModels()
-    private val tabs = arrayOf(
-        DisplayMode.SHOW_SONGS, DisplayMode.SHOW_ALBUMS,
-        DisplayMode.SHOW_ARTISTS, DisplayMode.SHOW_GENRES
-    )
 
     override fun onCreateView(
         inflater: LayoutInflater,
@@ -94,7 +90,7 @@ class HomeFragment : Fragment() {
 
             // By default, ViewPager2's sensitivity is high enough to result in vertical
             // scroll events being registered as horizontal scroll events. Reflect into the
-            // internal recyclerview and  change the touch slope so that touch actions will
+            // internal recyclerview and change the touch slope so that touch actions will
             // act more as a scroll than as a swipe.
             // Derived from: https://al-e-shevelev.medium.com/how-to-reduce-scroll-sensitivity-of-viewpager2-widget-87797ad02414
 
@@ -117,7 +113,7 @@ class HomeFragment : Fragment() {
         }
 
         TabLayoutMediator(binding.homeTabs, binding.homePager) { tab, pos ->
-            val labelRes = when (tabs[pos]) {
+            val labelRes = when (requireNotNull(homeModel.tabs.value)[pos]) {
                 DisplayMode.SHOW_SONGS -> R.string.lbl_songs
                 DisplayMode.SHOW_ALBUMS -> R.string.lbl_albums
                 DisplayMode.SHOW_ARTISTS -> R.string.lbl_artists
@@ -162,7 +158,7 @@ class HomeFragment : Fragment() {
     private inner class HomePagerAdapter :
         FragmentStateAdapter(childFragmentManager, viewLifecycleOwner.lifecycle) {
 
-        override fun getItemCount(): Int = tabs.size
+        override fun getItemCount(): Int = requireNotNull(homeModel.tabs.value).size
-        override fun createFragment(position: Int): Fragment = HomeListFragment.new(tabs[position])
+        override fun createFragment(position: Int): Fragment = HomeListFragment.new(position)
     }
 }

app/src/main/java/org/oxycblt/auxio/home/HomeListFragment.kt

@@ -26,6 +26,7 @@ import androidx.fragment.app.Fragment
 import androidx.fragment.app.viewModels
 import androidx.navigation.fragment.findNavController
 import androidx.recyclerview.widget.GridLayoutManager
+import org.oxycblt.auxio.BuildConfig
 import org.oxycblt.auxio.databinding.FragmentHomeListBinding
 import org.oxycblt.auxio.logD
 import org.oxycblt.auxio.music.Album
@@ -37,15 +38,13 @@ import org.oxycblt.auxio.recycler.DisplayMode
 import org.oxycblt.auxio.spans
 import org.oxycblt.auxio.ui.newMenu
 
-/*
+/**
- * Fragment that contains a list of items specified by a [DisplayMode].
+ * Fragment that contains a list of items specified by a [DisplayMode]. This fragment
- * TODO: Fix crash from not saving the display mode. This is getting really tiring.
+ * should be created using the [new] method with it's position in the ViewPager.
- *  Just keep the index for the tab we're working with and then just use that w/homeModel.
  */
 class HomeListFragment : Fragment() {
     private val homeModel: HomeViewModel by viewModels()
     private val playbackModel: PlaybackViewModel by viewModels()
-    private lateinit var displayMode: DisplayMode
 
     override fun onCreateView(
         inflater: LayoutInflater,
@@ -91,7 +90,9 @@ class HomeListFragment : Fragment() {
 
         // --- VIEWMODEL SETUP ---
 
-        val toObserve = when (displayMode) {
+        val pos = requireNotNull(arguments).getInt(ARG_POS)
+
+        val toObserve = when (requireNotNull(homeModel.tabs.value)[pos]) {
             DisplayMode.SHOW_SONGS -> homeModel.songs
             DisplayMode.SHOW_ALBUMS -> homeModel.albums
             DisplayMode.SHOW_ARTISTS -> homeModel.artists
@@ -111,12 +112,16 @@ class HomeListFragment : Fragment() {
     }
 
     companion object {
+        private const val ARG_POS = BuildConfig.APPLICATION_ID + ".key.POS"
+
         /*
          * Instantiates this fragment for use in a ViewPager.
          */
-        fun new(mode: DisplayMode): HomeListFragment {
+        fun new(pos: Int): HomeListFragment {
             val fragment = HomeListFragment()
-            fragment.displayMode = mode
+            fragment.arguments = Bundle().apply {
+                putInt(ARG_POS, pos)
+            }
             return fragment
         }
     }

app/src/main/java/org/oxycblt/auxio/home/HomeViewModel.kt

@@ -26,6 +26,7 @@ import org.oxycblt.auxio.music.Artist
 import org.oxycblt.auxio.music.Genre
 import org.oxycblt.auxio.music.MusicStore
 import org.oxycblt.auxio.music.Song
+import org.oxycblt.auxio.recycler.DisplayMode
 
 class HomeViewModel : ViewModel() {
     private val mGenres = MutableLiveData(listOf<Genre>())
@@ -40,6 +41,9 @@ class HomeViewModel : ViewModel() {
     private val mSongs = MutableLiveData(listOf<Song>())
     val songs: LiveData<List<Song>> get() = mSongs
 
+    private val mTabs = MutableLiveData(arrayOf<DisplayMode>())
+    val tabs: LiveData<Array<DisplayMode>> = mTabs
+
     private val musicStore = MusicStore.getInstance()
 
     init {
@@ -47,5 +51,9 @@ class HomeViewModel : ViewModel() {
         mArtists.value = musicStore.artists
         mAlbums.value = musicStore.albums
         mSongs.value = musicStore.songs
+        mTabs.value = arrayOf(
+            DisplayMode.SHOW_SONGS, DisplayMode.SHOW_ALBUMS,
+            DisplayMode.SHOW_ARTISTS, DisplayMode.SHOW_GENRES
+        )
     }
 }