Add Loading fallback states

Add fallback states for when there is no music & if the load fails, along with a retry button if that happens.

app/src/main/java/org/oxycblt/auxio/loading/LoadingFragment.kt

@@ -17,8 +17,11 @@ import org.oxycblt.auxio.music.MusicLoadResponse
 class LoadingFragment : Fragment() {
 
     private val loadingModel: LoadingViewModel by lazy {
-        ViewModelProvider(this, LoadingViewModel.Factory(
+        ViewModelProvider(
-            requireActivity().application)
+            this,
+            LoadingViewModel.Factory(
+                requireActivity().application
+            )
         ).get(LoadingViewModel::class.java)
     }
 
@@ -34,21 +37,62 @@ class LoadingFragment : Fragment() {
         )
 
         binding.lifecycleOwner = this
+        binding.loadingModel = loadingModel
 
-        loadingModel.musicRepoResponse.observe(viewLifecycleOwner, Observer { response ->
+        loadingModel.musicRepoResponse.observe(
-            onMusicLoadResponse(response)
+            viewLifecycleOwner,
-        })
+            Observer { response ->
+                onMusicLoadResponse(response)
+            }
+        )
+
+        loadingModel.doRetry.observe(
+            viewLifecycleOwner,
+            Observer { retry ->
+                onRetry(retry)
+            }
+        )
 
         Log.d(this::class.simpleName, "Fragment created.")
 
         return binding.root
     }
 
-    private fun onMusicLoadResponse(response: MusicLoadResponse) {
+    private fun onMusicLoadResponse(repoResponse: MusicLoadResponse?) {
-        if (response == MusicLoadResponse.DONE) {
+
-            this.findNavController().navigate(
+        // Don't run this if the value is null, Which is what the value changes to after
-                LoadingFragmentDirections.actionToLibrary()
+        // this is run.
-            )
+        repoResponse?.let { response ->
+            if (response == MusicLoadResponse.DONE) {
+                this.findNavController().navigate(
+                    LoadingFragmentDirections.actionToLibrary()
+                )
+            } else {
+                // If the response wasn't a success, then show the specific error message
+                // depending on which error response was given, along with a retry button
+
+                binding.loadingBar.visibility = View.GONE
+                binding.statusText.visibility = View.VISIBLE
+                binding.resetButton.visibility = View.VISIBLE
+
+                if (response == MusicLoadResponse.NO_MUSIC) {
+                    binding.statusText.text = getString(R.string.error_no_music)
+                } else {
+                    binding.statusText.text = getString(R.string.error_music_load_failed)
+                }
+            }
+
+            loadingModel.doneWithResponse()
         }
     }
-}
+
+    private fun onRetry(retry: Boolean) {
+        if (retry) {
+            binding.loadingBar.visibility = View.VISIBLE
+            binding.statusText.visibility = View.GONE
+            binding.resetButton.visibility = View.GONE
+
+            loadingModel.doneWithRetry()
+        }
+    }
+}

app/src/main/java/org/oxycblt/auxio/loading/LoadingViewModel.kt

@@ -6,12 +6,16 @@ import androidx.lifecycle.LiveData
 import androidx.lifecycle.MutableLiveData
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.ViewModelProvider
-import kotlinx.coroutines.*
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
 import org.oxycblt.auxio.music.MusicLoadResponse
 import org.oxycblt.auxio.music.MusicRepository
 
 class LoadingViewModel(private val app: Application) : ViewModel() {
-    
+
     private val loadingJob = Job()
     private val ioScope = CoroutineScope(
         Dispatchers.IO
@@ -20,6 +24,9 @@ class LoadingViewModel(private val app: Application) : ViewModel() {
     private val mMusicRepoResponse = MutableLiveData<MusicLoadResponse>()
     val musicRepoResponse: LiveData<MusicLoadResponse> get() = mMusicRepoResponse
 
+    private val mDoRetry = MutableLiveData<Boolean>()
+    val doRetry: LiveData<Boolean> get() = mDoRetry
+
     init {
         startMusicRepo()
 
@@ -40,6 +47,20 @@ class LoadingViewModel(private val app: Application) : ViewModel() {
         }
     }
 
+    fun doneWithResponse() {
+        mMusicRepoResponse.value = null
+    }
+
+    fun retry() {
+        mDoRetry.value = true
+
+        startMusicRepo()
+    }
+
+    fun doneWithRetry() {
+        mDoRetry.value = false
+    }
+
     override fun onCleared() {
         super.onCleared()
 
@@ -53,7 +74,8 @@ class LoadingViewModel(private val app: Application) : ViewModel() {
             if (modelClass.isAssignableFrom(LoadingViewModel::class.java)) {
                 return LoadingViewModel(application) as T
             }
-            throw IllegalArgumentException("Unknown ViewModel class")
+
+            throw IllegalArgumentException("Unknown ViewModel class.")
         }
     }
-}
+}

app/src/main/java/org/oxycblt/auxio/music/MusicRepository.kt

@@ -149,7 +149,6 @@ class MusicRepository {
             )
 
             return songList
-
         } catch (error: Exception) {
             // TODO: Add better error handling
 

app/src/main/res/layout/activity_main.xml

@@ -19,5 +19,4 @@
             tools:ignore="FragmentTagUsage" />
 
     </FrameLayout>
-
 </layout>

app/src/main/res/layout/fragment_library.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
-<layout
+<layout xmlns:app="http://schemas.android.com/apk/res-auto"
-    xmlns:app="http://schemas.android.com/apk/res-auto"
     xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools">
 

app/src/main/res/layout/fragment_loading.xml

@@ -3,6 +3,13 @@
     xmlns:app="http://schemas.android.com/apk/res-auto"
     xmlns:android="http://schemas.android.com/apk/res/android">
 
+    <data>
+
+        <variable
+            name="loadingModel"
+            type="org.oxycblt.auxio.loading.LoadingViewModel" />
+    </data>
+
     <androidx.constraintlayout.widget.ConstraintLayout
         android:layout_width="match_parent"
         android:layout_height="match_parent">
@@ -14,22 +21,37 @@
             android:indeterminateTint="?attr/colorAccent"
             android:indeterminateTintMode="src_in"
             android:paddingBottom="@dimen/padding_small"
-            app:layout_constraintBottom_toTopOf="@+id/text_indexing_library"
+            app:layout_constraintBottom_toTopOf="@+id/status_text"
             app:layout_constraintEnd_toEndOf="parent"
             app:layout_constraintHorizontal_bias="0.5"
             app:layout_constraintStart_toStartOf="parent"
             app:layout_constraintTop_toTopOf="parent"
-            app:layout_constraintVertical_chainStyle="packed"/>
+            app:layout_constraintVertical_chainStyle="packed" />
 
         <TextView
-            android:id="@+id/text_indexing_library"
+            android:id="@+id/status_text"
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
-            android:text="@string/label_loading_music"
+            android:text="@string/status_loading_music"
-            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintBottom_toTopOf="@+id/reset_button"
             app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintHorizontal_bias="0.5"
             app:layout_constraintStart_toStartOf="parent"
             app:layout_constraintTop_toBottomOf="@+id/loading_bar" />
 
+        <Button
+            android:id="@+id/reset_button"
+            style="@style/Widget.AppCompat.Button.Borderless.Colored"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:text="@string/label_retry"
+            android:onClick="@{() -> loadingModel.retry()}"
+            android:visibility="gone"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintHorizontal_bias="0.5"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toBottomOf="@+id/status_text" />
+
     </androidx.constraintlayout.widget.ConstraintLayout>
 </layout>

app/src/main/res/navigation/nav_main.xml

@@ -9,7 +9,7 @@
         android:id="@+id/loadingFragment"
         android:name="org.oxycblt.auxio.loading.LoadingFragment"
         android:label="LoadingFragment"
-        tools:layout="@layout/fragment_loading" >
+        tools:layout="@layout/fragment_loading">
         <action
             android:id="@+id/action_to_library"
             app:destination="@id/libraryFragment" />

app/src/main/res/values/strings.xml

@@ -2,7 +2,12 @@
 <resources>
     <string name="app_name">Auxio</string>
 
-    <string name="label_loading_music">Scanning your music library for the first time...</string>
+    <string name="status_loading_music">Scanning your music library for the first time...</string>
+
+    <string name="error_no_music">No music found.</string>
+    <string name="error_music_load_failed">Music loading failed.</string>
+
+    <string name="label_retry">Retry</string>
 
     <string name="title_library_fragment">Library</string>
 </resources>