Heavily refactor Library Management

Remove MusicRepository/All Library models and replace it with a single shared ViewModel, Move MainFragment into MainActivity, and remove the LoadingFragment -> MainFragment navigation path.

app/src/main/java/org/oxycblt/auxio/MainActivity.kt

@@ -5,20 +5,51 @@ import android.os.Bundle
 import android.util.AttributeSet
 import android.util.Log
 import android.view.View
+import androidx.activity.result.ActivityResultLauncher
 import androidx.appcompat.app.AppCompatActivity
 import androidx.appcompat.app.AppCompatDelegate
+import androidx.core.content.ContextCompat
+import androidx.databinding.DataBindingUtil
+import androidx.fragment.app.Fragment
+import androidx.fragment.app.FragmentActivity
+import androidx.lifecycle.ViewModelProvider
+import androidx.viewpager2.adapter.FragmentStateAdapter
+import com.google.android.material.tabs.TabLayout
+import com.google.android.material.tabs.TabLayoutMediator
+import org.oxycblt.auxio.databinding.ActivityMainBinding
+import org.oxycblt.auxio.library.LibraryFragment
+import org.oxycblt.auxio.music.MusicViewModel
+import org.oxycblt.auxio.music.processing.MusicLoaderResponse
+import org.oxycblt.auxio.library.SongsFragment
 import org.oxycblt.auxio.theme.accent
+import org.oxycblt.auxio.theme.getInactiveAlpha
+import org.oxycblt.auxio.theme.getTransparentAccent
+import org.oxycblt.auxio.theme.toColor
 
 class MainActivity : AppCompatActivity() {
 
-    // Debug placeholder so I can test dark and light modes. Ignore.
+    private val shownFragments = listOf(0, 1)
-    override fun onAttachedToWindow() {
-        super.onAttachedToWindow()
 
-        AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_NO)
+    private val libraryFragment: LibraryFragment by lazy { LibraryFragment() }
+    private val songsFragment: SongsFragment by lazy { SongsFragment() }
+
+    private val tabIcons = listOf(
+        R.drawable.ic_library,
+        R.drawable.ic_song
+    )
+
+    private lateinit var binding: ActivityMainBinding
+    private lateinit var permLauncher: ActivityResultLauncher<String>
+
+    private val musicModel: MusicViewModel by lazy {
+        ViewModelProvider(
+            this, MusicViewModel.Factory(application)
+        ).get(MusicViewModel::class.java)
     }
 
     override fun onCreateView(name: String, context: Context, attrs: AttributeSet): View? {
+        AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_NO)
+
         // Apply the theme
         setTheme(accent.second)
 
@@ -27,8 +58,92 @@ class MainActivity : AppCompatActivity() {
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
-        setContentView(R.layout.activity_main)
+        binding = DataBindingUtil.setContentView<ActivityMainBinding>(
+            this, R.layout.activity_main
+        )
+
+        binding.lifecycleOwner = this
+
+        val adapter = PagerAdapter(this)
+        binding.viewPager.adapter = adapter
+
+        val colorActive = accent.first.toColor(baseContext)
+        val colorInactive = getTransparentAccent(
+            baseContext,
+            accent.first,
+            getInactiveAlpha(accent.first)
+        )
+
+        // Link the ViewPager & Tab View
+        TabLayoutMediator(binding.tabs, binding.viewPager) { tab, position ->
+            tab.icon = ContextCompat.getDrawable(baseContext, tabIcons[position])
+
+            // Set the icon tint to deselected if its not the default tab
+            if (position > 0) {
+                tab.icon?.setTint(colorInactive)
+            }
+
+            // Init the fragment
+            fragmentAt(position)
+        }.attach()
+
+        // Set up the selected/deselected colors
+        binding.tabs.addOnTabSelectedListener(
+            object : TabLayout.OnTabSelectedListener {
+
+                override fun onTabSelected(tab: TabLayout.Tab) {
+                    tab.icon?.setTint(colorActive)
+                }
+
+                override fun onTabUnselected(tab: TabLayout.Tab) {
+                    tab.icon?.setTint(colorInactive)
+                }
+
+                override fun onTabReselected(tab: TabLayout.Tab?) {
+                }
+            }
+        )
+
+        musicModel.response.observe(
+            this, {
+                if (it == MusicLoaderResponse.DONE) {
+                    binding.loadingFragment.visibility = View.GONE
+                    binding.viewPager.visibility = View.VISIBLE
+                }
+            }
+        )
+
+        musicModel.go()
 
         Log.d(this::class.simpleName, "Activity Created.")
     }
+
+    private fun fragmentAt(position: Int): Fragment {
+        return when (position) {
+            0 -> libraryFragment
+            1 -> songsFragment
+
+            else -> libraryFragment
+        }
+    }
+
+    private inner class PagerAdapter(activity: FragmentActivity) : FragmentStateAdapter(activity) {
+        override fun getItemCount(): Int = shownFragments.size
+
+        override fun createFragment(position: Int): Fragment {
+            Log.d(this::class.simpleName, "Switching to fragment $position.")
+
+            if (shownFragments.contains(position)) {
+                return fragmentAt(position)
+            }
+
+            // Not sure how this would happen but it might
+            Log.e(
+                this::class.simpleName,
+                "Attempted to index a fragment that shouldn't be shown. Returning libraryFragment."
+            )
+
+            return libraryFragment
+        }
+    }
 }

app/src/main/java/org/oxycblt/auxio/MainFragment.kt

@@ -1,117 +0,0 @@
-package org.oxycblt.auxio
-
-import android.os.Bundle
-import android.util.Log
-import android.view.LayoutInflater
-import android.view.View
-import android.view.ViewGroup
-import androidx.core.content.ContextCompat
-import androidx.databinding.DataBindingUtil
-import androidx.fragment.app.Fragment
-import androidx.fragment.app.FragmentActivity
-import androidx.viewpager2.adapter.FragmentStateAdapter
-import com.google.android.material.tabs.TabLayout
-import com.google.android.material.tabs.TabLayoutMediator
-import org.oxycblt.auxio.databinding.FragmentMainBinding
-import org.oxycblt.auxio.library.LibraryFragment
-import org.oxycblt.auxio.songs.SongsFragment
-import org.oxycblt.auxio.theme.accent
-import org.oxycblt.auxio.theme.getInactiveAlpha
-import org.oxycblt.auxio.theme.getTransparentAccent
-import org.oxycblt.auxio.theme.toColor
-
-class MainFragment : Fragment() {
-
-    private val shownFragments = listOf(0, 1)
-
-    private val libraryFragment: LibraryFragment by lazy { LibraryFragment() }
-    private val songsFragment: SongsFragment by lazy { SongsFragment() }
-
-    private val tabIcons = listOf(
-        R.drawable.ic_library,
-        R.drawable.ic_song
-    )
-
-    override fun onCreateView(
-        inflater: LayoutInflater,
-        container: ViewGroup?,
-        savedInstanceState: Bundle?
-    ): View? {
-        val binding = DataBindingUtil.inflate<FragmentMainBinding>(
-            inflater, R.layout.fragment_main, container, false
-        )
-
-        val adapter = PagerAdapter(requireActivity())
-        binding.viewPager.adapter = adapter
-
-        val colorActive = accent.first.toColor(requireContext())
-        val colorInactive = getTransparentAccent(
-            requireContext(),
-            accent.first,
-            getInactiveAlpha(accent.first)
-        )
-
-        // Link the ViewPager & Tab View
-        TabLayoutMediator(binding.tabs, binding.viewPager) { tab, position ->
-            tab.icon = ContextCompat.getDrawable(requireContext(), tabIcons[position])
-
-            // Set the icon tint to deselected if its not the default tab
-            if (position > 0) {
-                tab.icon?.setTint(colorInactive)
-            }
-
-            // Init the fragment
-            fragmentAt(position)
-        }.attach()
-
-        // Set up the selected/deselected colors
-        binding.tabs.addOnTabSelectedListener(
-            object : TabLayout.OnTabSelectedListener {
-
-                override fun onTabSelected(tab: TabLayout.Tab) {
-                    tab.icon?.setTint(colorActive)
-                }
-
-                override fun onTabUnselected(tab: TabLayout.Tab) {
-                    tab.icon?.setTint(colorInactive)
-                }
-
-                override fun onTabReselected(tab: TabLayout.Tab?) {
-                }
-            }
-        )
-
-        Log.d(this::class.simpleName, "Fragment Created.")
-
-        return binding.root
-    }
-
-    private fun fragmentAt(position: Int): Fragment {
-        return when (position) {
-            0 -> libraryFragment
-            1 -> songsFragment
-
-            else -> libraryFragment
-        }
-    }
-
-    private inner class PagerAdapter(activity: FragmentActivity) : FragmentStateAdapter(activity) {
-        override fun getItemCount(): Int = shownFragments.size
-
-        override fun createFragment(position: Int): Fragment {
-            Log.d(this::class.simpleName, "Switching to fragment $position.")
-
-            if (shownFragments.contains(position)) {
-                return fragmentAt(position)
-            }
-
-            // Not sure how this would happen but it might
-            Log.e(
-                this::class.simpleName,
-                "Attempted to index a fragment that shouldn't be shown. Returning libraryFragment."
-            )
-
-            return libraryFragment
-        }
-    }
-}

app/src/main/java/org/oxycblt/auxio/coil/CoilUtils.kt

@@ -1,5 +1,6 @@
 package org.oxycblt.auxio.coil
 
+import android.content.Context
 import android.net.Uri
 import android.widget.ImageView
 import androidx.databinding.BindingAdapter
@@ -15,13 +16,9 @@ private var artistImageFetcher: ArtistImageFetcher? = null
 // Get the cover art for a song or album
 @BindingAdapter("coverArt")
 fun ImageView.getCoverArt(song: Song) {
-    val request = ImageRequest.Builder(context)
+    val request = getDefaultRequest(context, this)
         .data(song.album.coverUri)
-        .crossfade(true)
+        .error(R.drawable.ic_song)
-        .placeholder(android.R.color.transparent)
-        .error(R.drawable.ic_artist)
-        .crossfade(true)
-        .target(this)
         .build()
 
     Coil.imageLoader(context).enqueue(request)
@@ -29,13 +26,9 @@ fun ImageView.getCoverArt(song: Song) {
 
 @BindingAdapter("coverArt")
 fun ImageView.getCoverArt(album: Album) {
-    val request = ImageRequest.Builder(context)
+    val request = getDefaultRequest(context, this)
         .data(album.coverUri)
-        .crossfade(true)
+        .error(R.drawable.ic_album)
-        .placeholder(android.R.color.transparent)
-        .error(R.drawable.ic_artist)
-        .crossfade(true)
-        .target(this)
         .build()
 
     Coil.imageLoader(context).enqueue(request)
@@ -56,26 +49,25 @@ fun ImageView.getArtistImage(artist: Artist) {
             artistImageFetcher = ArtistImageFetcher(context)
         }
 
-        // Manually create an image request, as that's the only way to add a fetcher that
+        getDefaultRequest(context, this)
-        // takes a list of uris AFAIK.
-        ImageRequest.Builder(context)
             .data(uris)
             .fetcher(artistImageFetcher!!)
-            .crossfade(true)
-            .placeholder(android.R.color.transparent)
             .error(R.drawable.ic_artist)
-            .target(this)
             .build()
     } else {
-        ImageRequest.Builder(context)
+        getDefaultRequest(context, this)
             .data(artist.albums[0].coverUri)
-            .crossfade(true)
-            .placeholder(android.R.color.transparent)
             .error(R.drawable.ic_artist)
-            .crossfade(true)
-            .target(this)
             .build()
     }
 
     Coil.imageLoader(context).enqueue(request)
 }
+
+// Get the base request used across the app.
+private fun getDefaultRequest(context: Context, imageView: ImageView): ImageRequest.Builder {
+    return ImageRequest.Builder(context)
+        .crossfade(true)
+        .placeholder(android.R.color.transparent)
+        .target(imageView)
+}

app/src/main/java/org/oxycblt/auxio/library/LibraryFragment.kt

@@ -7,17 +7,19 @@ import android.view.View
 import android.view.ViewGroup
 import androidx.databinding.DataBindingUtil
 import androidx.fragment.app.Fragment
+import androidx.fragment.app.activityViewModels
 import androidx.lifecycle.ViewModelProvider
 import org.oxycblt.auxio.R
 import org.oxycblt.auxio.databinding.FragmentLibraryBinding
+import org.oxycblt.auxio.music.MusicViewModel
 import org.oxycblt.auxio.recycler.adapters.ArtistAdapter
 import org.oxycblt.auxio.recycler.applyDivider
 import org.oxycblt.auxio.recycler.viewholders.ClickListener
 
 class LibraryFragment : Fragment() {
 
-    private val libraryModel: LibraryViewModel by lazy {
+    private val musicModel: MusicViewModel by activityViewModels {
-        ViewModelProvider(this).get(LibraryViewModel::class.java)
+        MusicViewModel.Factory(requireActivity().application)
     }
 
     override fun onCreateView(
@@ -30,7 +32,7 @@ class LibraryFragment : Fragment() {
         )
 
         binding.libraryRecycler.adapter = ArtistAdapter(
-            libraryModel.artists.value!!,
+            musicModel.artists.value!!,
             ClickListener { artist ->
                 Log.d(this::class.simpleName, artist.name)
             }

app/src/main/java/org/oxycblt/auxio/library/LibraryViewModel.kt

@@ -1,27 +0,0 @@
-package org.oxycblt.auxio.library
-
-import android.util.Log
-import androidx.lifecycle.LiveData
-import androidx.lifecycle.MutableLiveData
-import androidx.lifecycle.ViewModel
-import org.oxycblt.auxio.music.MusicRepository
-import org.oxycblt.auxio.music.models.Album
-import org.oxycblt.auxio.music.models.Artist
-
-class LibraryViewModel : ViewModel() {
-
-    private val mArtists = MutableLiveData<List<Artist>>()
-    private var mAlbums = MutableLiveData<List<Album>>()
-
-    val artists: LiveData<List<Artist>> get() = mArtists
-    val albums: LiveData<List<Album>> get() = mAlbums
-
-    init {
-        val repo = MusicRepository.getInstance()
-
-        mArtists.value = repo.artists
-        mAlbums.value = repo.albums
-
-        Log.d(this::class.simpleName, "ViewModel created.")
-    }
-}

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

@@ -1,9 +1,8 @@
-package org.oxycblt.auxio.loading
+package org.oxycblt.auxio.library
 
 import android.Manifest
 import android.content.pm.PackageManager
 import android.os.Bundle
-import android.transition.TransitionInflater
 import android.util.Log
 import android.view.LayoutInflater
 import android.view.View
@@ -13,21 +12,16 @@ import androidx.activity.result.contract.ActivityResultContracts
 import androidx.core.content.ContextCompat
 import androidx.databinding.DataBindingUtil
 import androidx.fragment.app.Fragment
-import androidx.lifecycle.ViewModelProvider
+import androidx.fragment.app.activityViewModels
-import androidx.navigation.fragment.findNavController
 import org.oxycblt.auxio.R
 import org.oxycblt.auxio.databinding.FragmentLoadingBinding
+import org.oxycblt.auxio.music.MusicViewModel
 import org.oxycblt.auxio.music.processing.MusicLoaderResponse
 
 class LoadingFragment : Fragment(R.layout.fragment_loading) {
 
-    private val loadingModel: LoadingViewModel by lazy {
+    private val musicModel: MusicViewModel by activityViewModels {
-        ViewModelProvider(
+        MusicViewModel.Factory(requireActivity().application)
-            this,
-            LoadingViewModel.Factory(
-                requireActivity().application
-            )
-        ).get(LoadingViewModel::class.java)
     }
 
     private lateinit var binding: FragmentLoadingBinding
@@ -43,23 +37,23 @@ class LoadingFragment : Fragment(R.layout.fragment_loading) {
         )
 
         binding.lifecycleOwner = this
-        binding.loadingModel = loadingModel
+        binding.musicModel = musicModel
 
-        loadingModel.musicRepoResponse.observe(
+        musicModel.response.observe(
             viewLifecycleOwner,
             { response ->
                 onMusicLoadResponse(response)
             }
         )
 
-        loadingModel.doRetry.observe(
+        musicModel.doReload.observe(
             viewLifecycleOwner,
             { retry ->
                 onRetry(retry)
             }
         )
 
-        loadingModel.doGrant.observe(
+        musicModel.doGrant.observe(
             viewLifecycleOwner,
             { grant ->
                 onGrant(grant)
@@ -75,7 +69,7 @@ class LoadingFragment : Fragment(R.layout.fragment_loading) {
                 if (granted) {
                     wipeViews()
 
-                    loadingModel.retry()
+                    musicModel.reload()
                 }
             }
 
@@ -85,7 +79,7 @@ class LoadingFragment : Fragment(R.layout.fragment_loading) {
         if (checkPerms()) {
             onNoPerms()
         } else {
-            loadingModel.go()
+            musicModel.go()
         }
 
         Log.d(this::class.simpleName, "Fragment created.")
@@ -110,28 +104,21 @@ class LoadingFragment : Fragment(R.layout.fragment_loading) {
         repoResponse?.let { response ->
             binding.loadingBar.visibility = View.GONE
 
-            if (response == MusicLoaderResponse.DONE) {
+            if (response != MusicLoaderResponse.DONE) {
-                val inflater = TransitionInflater.from(requireContext())
-                exitTransition = inflater.inflateTransition(R.transition.transition_to_main)
-
-                this.findNavController().navigate(
-                    LoadingFragmentDirections.actionToMain()
-                )
-            } 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.errorText.visibility = View.VISIBLE
-                binding.statusIcon.visibility = View.VISIBLE
-                binding.retryButton.visibility = View.VISIBLE
-
                 binding.errorText.text =
                     if (response == MusicLoaderResponse.NO_MUSIC)
                         getString(R.string.error_no_music)
                     else
                         getString(R.string.error_music_load_failed)
+
+                // 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.errorText.visibility = View.VISIBLE
+                binding.statusIcon.visibility = View.VISIBLE
+                binding.retryButton.visibility = View.VISIBLE
             }
 
-            loadingModel.doneWithResponse()
+            musicModel.doneWithResponse()
         }
     }
 
@@ -152,7 +139,7 @@ class LoadingFragment : Fragment(R.layout.fragment_loading) {
         if (retry) {
             wipeViews()
 
-            loadingModel.doneWithRetry()
+            musicModel.doneWithReload()
         }
     }
 
@@ -160,7 +147,7 @@ class LoadingFragment : Fragment(R.layout.fragment_loading) {
         if (grant) {
             permLauncher.launch(Manifest.permission.READ_EXTERNAL_STORAGE)
 
-            loadingModel.doneWithGrant()
+            musicModel.doneWithGrant()
         }
     }
 

app/src/main/java/org/oxycblt/auxio/library/SongsFragment.kt

@@ -1,4 +1,4 @@
-package org.oxycblt.auxio.songs
+package org.oxycblt.auxio.library
 
 import android.os.Bundle
 import android.util.Log
@@ -7,17 +7,19 @@ import android.view.View
 import android.view.ViewGroup
 import androidx.databinding.DataBindingUtil
 import androidx.fragment.app.Fragment
+import androidx.fragment.app.activityViewModels
 import androidx.lifecycle.ViewModelProvider
 import org.oxycblt.auxio.R
 import org.oxycblt.auxio.databinding.FragmentSongsBinding
+import org.oxycblt.auxio.music.MusicViewModel
 import org.oxycblt.auxio.recycler.adapters.SongAdapter
 import org.oxycblt.auxio.recycler.applyDivider
 import org.oxycblt.auxio.recycler.viewholders.ClickListener
 
 class SongsFragment : Fragment() {
 
-    private val songsModel: SongsViewModel by lazy {
+    private val musicModel: MusicViewModel by activityViewModels {
-        ViewModelProvider(this).get(SongsViewModel::class.java)
+        MusicViewModel.Factory(requireActivity().application)
     }
 
     override fun onCreateView(
@@ -30,7 +32,7 @@ class SongsFragment : Fragment() {
         )
 
         binding.songRecycler.adapter = SongAdapter(
-            songsModel.songs.value!!,
+            musicModel.songs.value!!,
             ClickListener { song ->
                 Log.d(this::class.simpleName, song.name)
             }

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

@@ -1,99 +0,0 @@
-package org.oxycblt.auxio.loading
-
-import android.app.Application
-import androidx.lifecycle.LiveData
-import androidx.lifecycle.MutableLiveData
-import androidx.lifecycle.ViewModel
-import androidx.lifecycle.ViewModelProvider
-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.MusicRepository
-import org.oxycblt.auxio.music.processing.MusicLoaderResponse
-
-class LoadingViewModel(private val app: Application) : ViewModel() {
-
-    private val loadingJob = Job()
-    private val ioScope = CoroutineScope(
-        loadingJob + Dispatchers.IO
-    )
-
-    private val mMusicRepoResponse = MutableLiveData<MusicLoaderResponse>()
-    val musicRepoResponse: LiveData<MusicLoaderResponse> get() = mMusicRepoResponse
-
-    private val mDoRetry = MutableLiveData<Boolean>()
-    val doRetry: LiveData<Boolean> get() = mDoRetry
-
-    private val mDoGrant = MutableLiveData<Boolean>()
-    val doGrant: LiveData<Boolean> get() = mDoGrant
-
-    private var started = false
-
-    // Start the music loading. It has already been called, one needs to call retry() instead.
-    fun go() {
-        if (!started) {
-            started = true
-
-            startMusicRepo()
-        }
-    }
-
-    // Start the music loading sequence.
-    private fun startMusicRepo() {
-        val repo = MusicRepository.getInstance()
-
-        // Allow MusicRepository to scan the file system on the IO thread
-        ioScope.launch {
-            val response = repo.init(app)
-
-            // Then actually notify listeners of the response in the Main thread
-            withContext(Dispatchers.Main) {
-                mMusicRepoResponse.value = response
-            }
-        }
-    }
-
-    // Functions for communicating between LoadingFragment & LoadingViewModel
-
-    fun doneWithResponse() {
-        mMusicRepoResponse.value = null
-    }
-
-    fun retry() {
-        startMusicRepo()
-
-        mDoRetry.value = true
-    }
-
-    fun doneWithRetry() {
-        mDoRetry.value = false
-    }
-
-    fun grant() {
-        mDoGrant.value = true
-    }
-
-    fun doneWithGrant() {
-        mDoGrant.value = false
-    }
-
-    override fun onCleared() {
-        super.onCleared()
-
-        // Cancel the current loading job if the app has been stopped
-        loadingJob.cancel()
-    }
-
-    class Factory(private val application: Application) : ViewModelProvider.Factory {
-        @Suppress("unchecked_cast")
-        override fun <T : ViewModel?> create(modelClass: Class<T>): T {
-            if (modelClass.isAssignableFrom(LoadingViewModel::class.java)) {
-                return LoadingViewModel(application) as T
-            }
-
-            throw IllegalArgumentException("Unknown ViewModel class.")
-        }
-    }
-}

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

@@ -1,87 +0,0 @@
-package org.oxycblt.auxio.music
-
-import android.app.Application
-import android.util.Log
-import org.oxycblt.auxio.R
-import org.oxycblt.auxio.music.models.Album
-import org.oxycblt.auxio.music.models.Artist
-import org.oxycblt.auxio.music.models.Genre
-import org.oxycblt.auxio.music.models.Song
-import org.oxycblt.auxio.music.processing.MusicLoader
-import org.oxycblt.auxio.music.processing.MusicLoaderResponse
-import org.oxycblt.auxio.music.processing.MusicSorter
-
-// Storage for music data.
-class MusicRepository {
-
-    lateinit var genres: List<Genre>
-    lateinit var artists: List<Artist>
-    lateinit var albums: List<Album>
-    lateinit var songs: List<Song>
-
-    fun init(app: Application): MusicLoaderResponse {
-        Log.i(this::class.simpleName, "Starting initial music load...")
-
-        val start = System.currentTimeMillis()
-
-        val loader = MusicLoader(app.contentResolver)
-
-        if (loader.response == MusicLoaderResponse.DONE) {
-            // If the loading succeeds, then process the songs and set them.
-            val sorter = MusicSorter(
-                loader.genres,
-                loader.artists,
-                loader.albums,
-                loader.songs,
-
-                app.getString(R.string.placeholder_unknown_genre),
-                app.getString(R.string.placeholder_unknown_artist),
-                app.getString(R.string.placeholder_unknown_album)
-            )
-
-            songs = sorter.songs.toList()
-            albums = sorter.albums.toList()
-            artists = sorter.artists.toList()
-            genres = sorter.genres.toList()
-
-            val elapsed = System.currentTimeMillis() - start
-
-            Log.i(
-                this::class.simpleName,
-                "Music load completed successfully in ${elapsed}ms."
-            )
-        }
-
-        return loader.response
-    }
-
-    companion object {
-        @Volatile
-        private var INSTANCE: MusicRepository? = null
-
-        fun getInstance(): MusicRepository {
-            val tempInstance = INSTANCE
-
-            if (tempInstance != null) {
-                Log.d(
-                    this::class.simpleName,
-                    "Passed an existing instance of MusicRepository."
-                )
-
-                return tempInstance
-            }
-
-            synchronized(this) {
-                val newInstance = MusicRepository()
-                INSTANCE = newInstance
-
-                Log.d(
-                    this::class.simpleName,
-                    "Created an instance of MusicRepository."
-                )
-
-                return newInstance
-            }
-        }
-    }
-}

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

@@ -0,0 +1,142 @@
+package org.oxycblt.auxio.music
+
+import android.app.Application
+import android.util.Log
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.MutableLiveData
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.ViewModelProvider
+import kotlinx.coroutines.*
+import org.oxycblt.auxio.R
+import org.oxycblt.auxio.music.models.Album
+import org.oxycblt.auxio.music.models.Artist
+import org.oxycblt.auxio.music.models.Genre
+import org.oxycblt.auxio.music.models.Song
+import org.oxycblt.auxio.music.processing.MusicLoader
+import org.oxycblt.auxio.music.processing.MusicLoaderResponse
+import org.oxycblt.auxio.music.processing.MusicSorter
+
+// Storage for music data.
+class MusicViewModel(private val app: Application) : ViewModel() {
+
+    // Coroutine
+    private val loadingJob = Job()
+    private val ioScope = CoroutineScope(
+        loadingJob + Dispatchers.IO
+    )
+
+    // Values
+    private val mGenres = MutableLiveData<List<Genre>>()
+    val genres: LiveData<List<Genre>> get() = mGenres
+
+    private val mArtists = MutableLiveData<List<Artist>>()
+    val artists: LiveData<List<Artist>> get() = mArtists
+
+    private val mAlbums = MutableLiveData<List<Album>>()
+    val albums: LiveData<List<Album>> get() = mAlbums
+
+    private val mSongs = MutableLiveData<List<Song>>()
+    val songs: LiveData<List<Song>> get() = mSongs
+
+    private val mResponse = MutableLiveData<MusicLoaderResponse>()
+    val response: LiveData<MusicLoaderResponse> get() = mResponse
+
+    // UI control
+    private val mRedo = MutableLiveData<Boolean>()
+    val doReload: LiveData<Boolean> get() = mRedo
+
+    private val mDoGrant = MutableLiveData<Boolean>()
+    val doGrant: LiveData<Boolean> get() = mDoGrant
+
+    private var started = false
+
+    // Start the music loading sequence.
+    // This should only be ran once, use redo() for all other loads.
+    fun go() {
+        if (!started) {
+            started = true
+            doLoad()
+        }
+    }
+
+    private fun doLoad() {
+        Log.i(this::class.simpleName, "Starting initial music load...")
+
+        ioScope.launch {
+            val start = System.currentTimeMillis()
+
+            val loader = MusicLoader(app.contentResolver)
+
+            withContext(Dispatchers.Main) {
+                if (loader.response == MusicLoaderResponse.DONE) {
+                    // If the loading succeeds, then process the songs and set them.
+                    val sorter = MusicSorter(
+                        loader.genres,
+                        loader.artists,
+                        loader.albums,
+                        loader.songs,
+
+                        app.getString(R.string.placeholder_unknown_genre),
+                        app.getString(R.string.placeholder_unknown_artist),
+                        app.getString(R.string.placeholder_unknown_album)
+                    )
+
+                    mSongs.value = sorter.songs.toList()
+                    mAlbums.value = sorter.albums.toList()
+                    mArtists.value = sorter.artists.toList()
+                    mGenres.value = sorter.genres.toList()
+                }
+
+                mResponse.value = loader.response
+
+                val elapsed = System.currentTimeMillis() - start
+
+                Log.i(
+                    this::class.simpleName,
+                    "Music load completed successfully in ${elapsed}ms."
+                )
+            }
+        }
+    }
+
+    // UI communication functions
+    fun doneWithResponse() {
+        mResponse.value = null
+    }
+
+    fun reload() {
+        mRedo.value = true
+
+        doLoad()
+    }
+
+    fun doneWithReload() {
+        mRedo.value = false
+    }
+
+    fun grant() {
+        mDoGrant.value = true
+    }
+
+    fun doneWithGrant() {
+        mDoGrant.value = false
+    }
+
+    override fun onCleared() {
+        super.onCleared()
+
+        // Cancel the current loading job if the app has been stopped
+        loadingJob.cancel()
+    }
+
+    class Factory(private val application: Application) : ViewModelProvider.Factory {
+        @Suppress("unchecked_cast")
+        override fun <T : ViewModel?> create(modelClass: Class<T>): T {
+            if (modelClass.isAssignableFrom(MusicViewModel::class.java)) {
+                return MusicViewModel(application) as T
+            }
+
+            throw IllegalArgumentException("Unknown ViewModel class.")
+        }
+    }
+}

app/src/main/java/org/oxycblt/auxio/songs/SongsViewModel.kt

@@ -1,22 +0,0 @@
-package org.oxycblt.auxio.songs
-
-import android.util.Log
-import androidx.lifecycle.LiveData
-import androidx.lifecycle.MutableLiveData
-import androidx.lifecycle.ViewModel
-import org.oxycblt.auxio.music.MusicRepository
-import org.oxycblt.auxio.music.models.Song
-
-class SongsViewModel : ViewModel() {
-
-    private val mSongs = MutableLiveData<List<Song>>()
-    val songs: LiveData<List<Song>> get() = mSongs
-
-    init {
-        val repo = MusicRepository.getInstance()
-
-        mSongs.value = repo.songs
-
-        Log.d(this::class.simpleName, "ViewModel created.")
-    }
-}

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

@@ -1,15 +1,53 @@
 <?xml version="1.0" encoding="utf-8"?>
 <layout xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:app="http://schemas.android.com/apk/res-auto"
-    xmlns:tools="http://schemas.android.com/tools"
+    xmlns:tools="http://schemas.android.com/tools">
-    tools:context=".MainActivity">
 
-    <androidx.fragment.app.FragmentContainerView
+    <data>
-        android:id="@+id/nav_host_fragment"
+
-        android:name="androidx.navigation.fragment.NavHostFragment"
+        <variable
+            name="musicModel"
+            type="org.oxycblt.auxio.music.MusicViewModel" />
+    </data>
+
+    <androidx.constraintlayout.widget.ConstraintLayout
         android:layout_width="match_parent"
         android:layout_height="match_parent"
-        app:defaultNavHost="true"
+        android:animateLayoutChanges="true">
-        app:navGraph="@navigation/nav_main"
+
-        tools:ignore="FragmentTagUsage" />
+        <androidx.viewpager2.widget.ViewPager2
+            android:id="@+id/viewPager"
+            android:layout_width="match_parent"
+            android:layout_height="0dp"
+            android:visibility="gone"
+            app:layout_constraintBottom_toTopOf="@+id/tabs"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toTopOf="parent" />
+
+        <androidx.fragment.app.FragmentContainerView
+            android:id="@+id/loading_fragment"
+            android:name="org.oxycblt.auxio.loading.LoadingFragment"
+            android:layout_width="match_parent"
+            android:layout_height="0dp"
+            app:layout_constraintBottom_toTopOf="@+id/tabs"
+            app:layout_constraintTop_toTopOf="parent" />
+
+        <com.google.android.material.tabs.TabLayout
+            android:id="@+id/tabs"
+            android:layout_width="match_parent"
+            android:layout_height="@dimen/tab_menu_size"
+            android:layout_gravity="bottom"
+            android:background="?android:attr/windowBackground"
+            android:elevation="@dimen/elevation_normal"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:tabGravity="fill"
+            app:tabIconTint="?android:attr/colorPrimary"
+            app:tabIconTintMode="src_in"
+            app:tabIndicator="@drawable/indicator"
+            app:tabIndicatorColor="?android:attr/colorPrimary"
+            app:tabMode="fixed"
+            app:tabRippleColor="@color/selection_color" />
+
+    </androidx.constraintlayout.widget.ConstraintLayout>
 </layout>

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

@@ -8,8 +8,8 @@
     <data>
 
         <variable
-            name="loadingModel"
+            name="musicModel"
-            type="org.oxycblt.auxio.loading.LoadingViewModel" />
+            type="org.oxycblt.auxio.music.MusicViewModel" />
     </data>
 
     <androidx.constraintlayout.widget.ConstraintLayout
@@ -69,7 +69,7 @@
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
             android:fontFamily="@font/inter_semibold"
-            android:onClick="@{() -> loadingModel.retry()}"
+            android:onClick="@{() -> musicModel.reload()}"
             android:text="@string/label_retry"
             android:textColor="?attr/colorPrimary"
             android:visibility="gone"
@@ -89,7 +89,7 @@
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
             android:fontFamily="@font/inter_semibold"
-            android:onClick="@{() -> loadingModel.grant()}"
+            android:onClick="@{() -> musicModel.grant()}"
             android:text="@string/label_grant"
             android:textColor="?attr/colorPrimary"
             android:visibility="gone"

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

@@ -1,33 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<layout xmlns:android="http://schemas.android.com/apk/res/android"
-    xmlns:app="http://schemas.android.com/apk/res-auto"
-    xmlns:tools="http://schemas.android.com/tools">
-
-    <LinearLayout
-        android:layout_width="match_parent"
-        android:layout_height="match_parent"
-        android:orientation="vertical">
-
-        <androidx.viewpager2.widget.ViewPager2
-            android:id="@+id/viewPager"
-            android:layout_width="match_parent"
-            android:layout_height="0dp"
-            android:layout_weight="1" />
-
-        <com.google.android.material.tabs.TabLayout
-            android:id="@+id/tabs"
-            android:layout_width="match_parent"
-            android:layout_height="@dimen/tab_menu_size"
-            android:layout_gravity="bottom"
-            android:background="?android:attr/windowBackground"
-            android:elevation="@dimen/elevation_normal"
-            app:tabIndicatorColor="?android:attr/colorPrimary"
-            app:tabGravity="fill"
-            app:tabMode="fixed"
-            app:tabIconTint="?android:attr/colorPrimary"
-            app:tabIconTintMode="src_in"
-            app:tabIndicator="@drawable/indicator"
-            app:tabRippleColor="@color/selection_color" />
-
-    </LinearLayout>
-</layout>

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

@@ -1,24 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<navigation xmlns:android="http://schemas.android.com/apk/res/android"
-    xmlns:app="http://schemas.android.com/apk/res-auto"
-    xmlns:tools="http://schemas.android.com/tools"
-    android:id="@+id/nav_main"
-    app:startDestination="@id/loadingFragment">
-
-    <fragment
-        android:id="@+id/loadingFragment"
-        android:name="org.oxycblt.auxio.loading.LoadingFragment"
-        android:label="LoadingFragment"
-        tools:layout="@layout/fragment_loading">
-        <action
-            android:id="@+id/action_to_main"
-            app:destination="@id/mainFragment"
-            app:popUpTo="@id/loadingFragment"
-            app:popUpToInclusive="true" />
-    </fragment>
-    <fragment
-        android:id="@+id/mainFragment"
-        android:name="org.oxycblt.auxio.MainFragment"
-        android:label="LibraryFragment"
-        tools:layout="@layout/fragment_main" />
-</navigation>

app/src/main/res/transition/transition_to_main.xml

@@ -1,3 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<fade xmlns:android="http://schemas.android.com/apk/res/android"
-    android:duration="@android:integer/config_longAnimTime"></fade>

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

@@ -7,7 +7,7 @@
 
     <string name="error_no_music">No music found.</string>
     <string name="error_music_load_failed">Music loading failed.</string>
-    <string name="error_no_perms">Auxio needs permission to access to your music library.</string>
+    <string name="error_no_perms">Permissions to read storage are needed.</string>
 
     <string name="label_retry">Retry</string>
     <string name="label_grant">Grant</string>