feat: folder navigation

app/src/main/java/com/cappielloantonio/play/interfaces/ClickCallback.java

@@ -39,4 +39,16 @@ public interface ClickCallback {
     default void onInternetRadioStationClick(Bundle bundle) {}
 
     default void onInternetRadioStationLongClick(Bundle bundle) {}
+
+    default void onMusicFolderClick(Bundle bundle) {}
+
+    default void onMusicFolderLongClick(Bundle bundle) {}
+
+    default void onMusicDirectoryClick(Bundle bundle) {}
+
+    default void onMusicDirectoryLongClick(Bundle bundle) {}
+
+    default void onMusicIndexClick(Bundle bundle) {}
+
+    default void onMusicIndexLongClick(Bundle bundle) {}
 }

app/src/main/java/com/cappielloantonio/play/repository/DirectoryRepository.java

@@ -0,0 +1,89 @@
+package com.cappielloantonio.play.repository;
+
+import androidx.annotation.NonNull;
+import androidx.lifecycle.MutableLiveData;
+
+import com.cappielloantonio.play.App;
+import com.cappielloantonio.play.subsonic.base.ApiResponse;
+import com.cappielloantonio.play.subsonic.models.Directory;
+import com.cappielloantonio.play.subsonic.models.Indexes;
+import com.cappielloantonio.play.subsonic.models.MusicFolder;
+
+import java.util.List;
+
+import retrofit2.Call;
+import retrofit2.Callback;
+import retrofit2.Response;
+
+public class DirectoryRepository {
+    private static final String TAG = "DirectoryRepository";
+
+    public MutableLiveData<List<MusicFolder>> getMusicFolders() {
+        MutableLiveData<List<MusicFolder>> liveMusicFolders = new MutableLiveData<>();
+
+        App.getSubsonicClientInstance(false)
+                .getBrowsingClient()
+                .getMusicFolders()
+                .enqueue(new Callback<ApiResponse>() {
+                    @Override
+                    public void onResponse(@NonNull Call<ApiResponse> call, @NonNull Response<ApiResponse> response) {
+                        if (response.isSuccessful() && response.body() != null && response.body().getSubsonicResponse().getMusicFolders() != null) {
+                            liveMusicFolders.setValue(response.body().getSubsonicResponse().getMusicFolders().getMusicFolders());
+                        }
+                    }
+
+                    @Override
+                    public void onFailure(@NonNull Call<ApiResponse> call, @NonNull Throwable t) {
+
+                    }
+                });
+
+        return liveMusicFolders;
+    }
+
+    public MutableLiveData<Indexes> getIndexes(String musicFolderId, Long ifModifiedSince) {
+        MutableLiveData<Indexes> liveIndexes = new MutableLiveData<>();
+
+        App.getSubsonicClientInstance(false)
+                .getBrowsingClient()
+                .getIndexes(musicFolderId, ifModifiedSince)
+                .enqueue(new Callback<ApiResponse>() {
+                    @Override
+                    public void onResponse(@NonNull Call<ApiResponse> call, @NonNull Response<ApiResponse> response) {
+                        if (response.isSuccessful() && response.body() != null && response.body().getSubsonicResponse().getIndexes() != null) {
+                            liveIndexes.setValue(response.body().getSubsonicResponse().getIndexes());
+                        }
+                    }
+
+                    @Override
+                    public void onFailure(@NonNull Call<ApiResponse> call, @NonNull Throwable t) {
+
+                    }
+                });
+
+        return liveIndexes;
+    }
+
+    public MutableLiveData<Directory> getMusicDirectory(String id) {
+        MutableLiveData<Directory> liveMusicDirectory = new MutableLiveData<>();
+
+        App.getSubsonicClientInstance(false)
+                .getBrowsingClient()
+                .getMusicDirectory(id)
+                .enqueue(new Callback<ApiResponse>() {
+                    @Override
+                    public void onResponse(@NonNull Call<ApiResponse> call, @NonNull Response<ApiResponse> response) {
+                        if (response.isSuccessful() && response.body() != null && response.body().getSubsonicResponse().getDirectory() != null) {
+                            liveMusicDirectory.setValue(response.body().getSubsonicResponse().getDirectory());
+                        }
+                    }
+
+                    @Override
+                    public void onFailure(@NonNull Call<ApiResponse> call, @NonNull Throwable t) {
+                        t.printStackTrace();
+                    }
+                });
+
+        return liveMusicDirectory;
+    }
+}

app/src/main/java/com/cappielloantonio/play/subsonic/api/browsing/BrowsingClient.java

@@ -24,9 +24,9 @@ public class BrowsingClient {
         return browsingService.getMusicFolders(subsonic.getParams());
     }
 
-    public Call<ApiResponse> getIndexes() {
+    public Call<ApiResponse> getIndexes(String musicFolderId, Long ifModifiedSince) {
         Log.d(TAG, "getIndexes()");
-        return browsingService.getIndexes(subsonic.getParams());
+        return browsingService.getIndexes(subsonic.getParams(), musicFolderId, ifModifiedSince);
     }
 
     public Call<ApiResponse> getMusicDirectory(String id) {

app/src/main/java/com/cappielloantonio/play/subsonic/api/browsing/BrowsingService.java

@@ -15,7 +15,7 @@ public interface BrowsingService {
     Call<ApiResponse> getMusicFolders(@QueryMap Map<String, String> params);
 
     @GET("getIndexes")
-    Call<ApiResponse> getIndexes(@QueryMap Map<String, String> params);
+    Call<ApiResponse> getIndexes(@QueryMap Map<String, String> params, @Query("musicFolderId") String musicFolderId, @Query("ifModifiedSince") Long ifModifiedSince);
 
     @GET("getMusicDirectory")
     Call<ApiResponse> getMusicDirectory(@QueryMap Map<String, String> params, @Query("id") String id);

app/src/main/java/com/cappielloantonio/play/subsonic/models/Artist.kt

@@ -1,8 +1,11 @@
 package com.cappielloantonio.play.subsonic.models
 
-import java.util.*
+import android.os.Parcelable
+import kotlinx.parcelize.Parcelize
+import java.util.Date
 
-class Artist {
+@Parcelize
+class Artist : Parcelable {
     var id: String? = null
     var name: String? = null
     var starred: Date? = null

app/src/main/java/com/cappielloantonio/play/subsonic/models/Directory.kt

@@ -1,10 +1,16 @@
 package com.cappielloantonio.play.subsonic.models
 
-import java.util.*
+import android.os.Parcelable
+import com.google.gson.annotations.SerializedName
+import kotlinx.parcelize.Parcelize
+import java.util.Date
 
-class Directory {
+@Parcelize
+class Directory : Parcelable {
+    @SerializedName("child")
     var children: List<Child>? = null
     var id: String? = null
+    @SerializedName("parent")
     var parentId: String? = null
     var name: String? = null
     var starred: Date? = null

app/src/main/java/com/cappielloantonio/play/subsonic/models/Index.kt

@@ -1,6 +1,9 @@
 package com.cappielloantonio.play.subsonic.models
 
+import com.google.gson.annotations.SerializedName
+
 class Index {
+    @SerializedName("artist")
     var artists: List<Artist>? = null
     var name: String? = null
 }

app/src/main/java/com/cappielloantonio/play/subsonic/models/Indexes.kt

@@ -1,7 +1,10 @@
 package com.cappielloantonio.play.subsonic.models
 
+import com.google.gson.annotations.SerializedName
+
 class Indexes {
     var shortcuts: List<Artist>? = null
+    @SerializedName("index")
     var indices: List<Index>? = null
     var children: List<Child>? = null
     var lastModified: Long = 0

app/src/main/java/com/cappielloantonio/play/subsonic/models/MusicFolder.kt

@@ -1,6 +1,10 @@
 package com.cappielloantonio.play.subsonic.models
 
-class MusicFolder {
+import android.os.Parcelable
-    var id = 0
+import kotlinx.parcelize.Parcelize
+
+@Parcelize
+class MusicFolder : Parcelable {
+    var id: String? = null
     var name: String? = null
 }

app/src/main/java/com/cappielloantonio/play/subsonic/models/MusicFolders.kt

@@ -1,5 +1,8 @@
 package com.cappielloantonio.play.subsonic.models
 
+import com.google.gson.annotations.SerializedName
+
 class MusicFolders {
+    @SerializedName("musicFolder")
     var musicFolders: List<MusicFolder>? = null
 }

app/src/main/java/com/cappielloantonio/play/ui/adapter/MusicDirectoryAdapter.java

@@ -0,0 +1,99 @@
+package com.cappielloantonio.play.ui.adapter;
+
+import android.os.Bundle;
+import android.view.LayoutInflater;
+import android.view.ViewGroup;
+
+import androidx.annotation.NonNull;
+import androidx.media3.common.util.UnstableApi;
+import androidx.recyclerview.widget.RecyclerView;
+
+import com.cappielloantonio.play.databinding.ItemLibraryMusicDirectoryBinding;
+import com.cappielloantonio.play.glide.CustomGlideRequest;
+import com.cappielloantonio.play.interfaces.ClickCallback;
+import com.cappielloantonio.play.subsonic.models.Child;
+import com.cappielloantonio.play.util.Constants;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+@UnstableApi
+public class MusicDirectoryAdapter extends RecyclerView.Adapter<MusicDirectoryAdapter.ViewHolder> {
+    private final ClickCallback click;
+
+    private List<Child> children;
+
+    public MusicDirectoryAdapter(ClickCallback click) {
+        this.click = click;
+        this.children = Collections.emptyList();
+    }
+
+    @NonNull
+    @Override
+    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
+        ItemLibraryMusicDirectoryBinding view = ItemLibraryMusicDirectoryBinding.inflate(LayoutInflater.from(parent.getContext()), parent, false);
+        return new ViewHolder(view);
+    }
+
+    @Override
+    public void onBindViewHolder(ViewHolder holder, int position) {
+        Child child = children.get(position);
+
+        holder.item.musicDirectoryTitleTextView.setText(child.getTitle());
+
+        CustomGlideRequest.Builder
+                .from(holder.itemView.getContext(), child.getCoverArtId())
+                .build()
+                .into(holder.item.musicDirectoryCoverImageView);
+    }
+
+    @Override
+    public int getItemCount() {
+        return children.size();
+    }
+
+    public void setItems(List<Child> children) {
+        this.children = children != null ? children : Collections.emptyList();
+        notifyDataSetChanged();
+    }
+
+    public class ViewHolder extends RecyclerView.ViewHolder {
+        ItemLibraryMusicDirectoryBinding item;
+
+        ViewHolder(ItemLibraryMusicDirectoryBinding item) {
+            super(item.getRoot());
+
+            this.item = item;
+
+            item.musicDirectoryTitleTextView.setSelected(true);
+
+            itemView.setOnClickListener(v -> onClick());
+            itemView.setOnLongClickListener(v -> onLongClick());
+
+            item.musicDirectoryMoreButton.setOnClickListener(v -> onLongClick());
+        }
+
+        public void onClick() {
+            Bundle bundle = new Bundle();
+
+            if (children.get(getBindingAdapterPosition()).isDir()) {
+                bundle.putParcelable(Constants.MUSIC_DIRECTORY_OBJECT, children.get(getBindingAdapterPosition()));
+                click.onMusicDirectoryClick(bundle);
+            } else {
+                bundle.putParcelableArrayList(Constants.TRACKS_OBJECT, new ArrayList<>(children));
+                bundle.putInt(Constants.ITEM_POSITION, getBindingAdapterPosition());
+                click.onMediaClick(bundle);
+            }
+        }
+
+        private boolean onLongClick() {
+            Bundle bundle = new Bundle();
+            bundle.putParcelable(Constants.MUSIC_DIRECTORY_OBJECT, children.get(getBindingAdapterPosition()));
+
+            click.onMusicDirectoryLongClick(bundle);
+
+            return true;
+        }
+    }
+}

app/src/main/java/com/cappielloantonio/play/ui/adapter/MusicFolderAdapter.java

@@ -0,0 +1,95 @@
+package com.cappielloantonio.play.ui.adapter;
+
+import android.os.Bundle;
+import android.view.LayoutInflater;
+import android.view.ViewGroup;
+
+import androidx.annotation.NonNull;
+import androidx.media3.common.util.UnstableApi;
+import androidx.recyclerview.widget.RecyclerView;
+
+import com.cappielloantonio.play.databinding.ItemLibraryMusicFolderBinding;
+import com.cappielloantonio.play.glide.CustomGlideRequest;
+import com.cappielloantonio.play.interfaces.ClickCallback;
+import com.cappielloantonio.play.subsonic.models.MusicFolder;
+import com.cappielloantonio.play.util.Constants;
+
+import java.util.Collections;
+import java.util.List;
+
+@UnstableApi
+public class MusicFolderAdapter extends RecyclerView.Adapter<MusicFolderAdapter.ViewHolder> {
+    private final ClickCallback click;
+
+    private List<MusicFolder> musicFolders;
+
+    public MusicFolderAdapter(ClickCallback click) {
+        this.click = click;
+        this.musicFolders = Collections.emptyList();
+    }
+
+    @NonNull
+    @Override
+    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
+        ItemLibraryMusicFolderBinding view = ItemLibraryMusicFolderBinding.inflate(LayoutInflater.from(parent.getContext()), parent, false);
+        return new ViewHolder(view);
+    }
+
+    @Override
+    public void onBindViewHolder(ViewHolder holder, int position) {
+        MusicFolder musicFolder = musicFolders.get(position);
+
+        holder.item.musicFolderTitleTextView.setText(musicFolder.getName());
+
+        CustomGlideRequest.Builder
+                .from(holder.itemView.getContext(), musicFolder.getName())
+                .build()
+                .into(holder.item.musicFolderCoverImageView);
+    }
+
+    @Override
+    public int getItemCount() {
+        return musicFolders.size();
+    }
+
+    public void setItems(List<MusicFolder> musicFolders) {
+        this.musicFolders = musicFolders;
+        notifyDataSetChanged();
+    }
+
+    public MusicFolder getItem(int position) {
+        return musicFolders.get(position);
+    }
+
+    public class ViewHolder extends RecyclerView.ViewHolder {
+        ItemLibraryMusicFolderBinding item;
+
+        ViewHolder(ItemLibraryMusicFolderBinding item) {
+            super(item.getRoot());
+
+            this.item = item;
+
+            item.musicFolderTitleTextView.setSelected(true);
+
+            itemView.setOnClickListener(v -> onClick());
+            itemView.setOnLongClickListener(v -> onLongClick());
+
+            item.musicFolderMoreButton.setOnClickListener(v -> onLongClick());
+        }
+
+        public void onClick() {
+            Bundle bundle = new Bundle();
+            bundle.putParcelable(Constants.MUSIC_FOLDER_OBJECT, musicFolders.get(getBindingAdapterPosition()));
+            click.onMusicFolderClick(bundle);
+        }
+
+        private boolean onLongClick() {
+            Bundle bundle = new Bundle();
+            bundle.putParcelable(Constants.MUSIC_FOLDER_OBJECT, musicFolders.get(getBindingAdapterPosition()));
+
+            click.onMusicFolderLongClick(bundle);
+
+            return true;
+        }
+    }
+}

app/src/main/java/com/cappielloantonio/play/ui/adapter/MusicIndexAdapter.java

@@ -0,0 +1,91 @@
+package com.cappielloantonio.play.ui.adapter;
+
+import android.os.Bundle;
+import android.view.LayoutInflater;
+import android.view.ViewGroup;
+
+import androidx.annotation.NonNull;
+import androidx.media3.common.util.UnstableApi;
+import androidx.recyclerview.widget.RecyclerView;
+
+import com.cappielloantonio.play.databinding.ItemLibraryMusicIndexBinding;
+import com.cappielloantonio.play.glide.CustomGlideRequest;
+import com.cappielloantonio.play.interfaces.ClickCallback;
+import com.cappielloantonio.play.subsonic.models.Artist;
+import com.cappielloantonio.play.util.Constants;
+
+import java.util.Collections;
+import java.util.List;
+
+@UnstableApi
+public class MusicIndexAdapter extends RecyclerView.Adapter<MusicIndexAdapter.ViewHolder> {
+    private final ClickCallback click;
+
+    private List<Artist> artists;
+
+    public MusicIndexAdapter(ClickCallback click) {
+        this.click = click;
+        this.artists = Collections.emptyList();
+    }
+
+    @NonNull
+    @Override
+    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
+        ItemLibraryMusicIndexBinding view = ItemLibraryMusicIndexBinding.inflate(LayoutInflater.from(parent.getContext()), parent, false);
+        return new ViewHolder(view);
+    }
+
+    @Override
+    public void onBindViewHolder(ViewHolder holder, int position) {
+        Artist artist = artists.get(position);
+
+        holder.item.musicIndexTitleTextView.setText(artist.getName());
+
+        CustomGlideRequest.Builder
+                .from(holder.itemView.getContext(), artist.getName())
+                .build()
+                .into(holder.item.musicIndexCoverImageView);
+    }
+
+    @Override
+    public int getItemCount() {
+        return artists.size();
+    }
+
+    public void setItems(List<Artist> artists) {
+        this.artists = artists;
+        notifyDataSetChanged();
+    }
+
+    public class ViewHolder extends RecyclerView.ViewHolder {
+        ItemLibraryMusicIndexBinding item;
+
+        ViewHolder(ItemLibraryMusicIndexBinding item) {
+            super(item.getRoot());
+
+            this.item = item;
+
+            item.musicIndexTitleTextView.setSelected(true);
+
+            itemView.setOnClickListener(v -> onClick());
+            itemView.setOnLongClickListener(v -> onLongClick());
+
+            item.musicIndexMoreButton.setOnClickListener(v -> onLongClick());
+        }
+
+        public void onClick() {
+            Bundle bundle = new Bundle();
+            bundle.putParcelable(Constants.MUSIC_INDEX_OBJECT, artists.get(getBindingAdapterPosition()));
+            click.onMusicIndexClick(bundle);
+        }
+
+        private boolean onLongClick() {
+            Bundle bundle = new Bundle();
+            bundle.putParcelable(Constants.MUSIC_INDEX_OBJECT, artists.get(getBindingAdapterPosition()));
+
+            click.onMusicIndexLongClick(bundle);
+
+            return true;
+        }
+    }
+}

app/src/main/java/com/cappielloantonio/play/ui/fragment/DirectoryFragment.java

@@ -0,0 +1,178 @@
+package com.cappielloantonio.play.ui.fragment;
+
+import android.content.ComponentName;
+import android.os.Bundle;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.Toast;
+
+import androidx.annotation.NonNull;
+import androidx.core.view.ViewCompat;
+import androidx.fragment.app.Fragment;
+import androidx.lifecycle.ViewModelProvider;
+import androidx.media3.common.util.UnstableApi;
+import androidx.media3.session.MediaBrowser;
+import androidx.media3.session.SessionToken;
+import androidx.recyclerview.widget.LinearLayoutManager;
+
+import com.cappielloantonio.play.R;
+import com.cappielloantonio.play.databinding.FragmentDirectoryBinding;
+import com.cappielloantonio.play.interfaces.ClickCallback;
+import com.cappielloantonio.play.service.MediaManager;
+import com.cappielloantonio.play.service.MediaService;
+import com.cappielloantonio.play.subsonic.models.Artist;
+import com.cappielloantonio.play.subsonic.models.Child;
+import com.cappielloantonio.play.ui.activity.MainActivity;
+import com.cappielloantonio.play.ui.adapter.MusicDirectoryAdapter;
+import com.cappielloantonio.play.util.Constants;
+import com.cappielloantonio.play.viewmodel.DirectoryViewModel;
+import com.google.common.util.concurrent.ListenableFuture;
+
+import java.util.Collections;
+import java.util.Objects;
+
+@UnstableApi
+public class DirectoryFragment extends Fragment implements ClickCallback {
+    private static final String TAG = "DirectoryFragment";
+
+    private FragmentDirectoryBinding bind;
+    private MainActivity activity;
+    private DirectoryViewModel directoryViewModel;
+
+    private MusicDirectoryAdapter musicDirectoryAdapter;
+
+    private ListenableFuture<MediaBrowser> mediaBrowserListenableFuture;
+
+    @Override
+    public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
+        activity = (MainActivity) getActivity();
+
+        bind = FragmentDirectoryBinding.inflate(inflater, container, false);
+        View view = bind.getRoot();
+        directoryViewModel = new ViewModelProvider(requireActivity()).get(DirectoryViewModel.class);
+
+        initAppBar();
+        initButtons();
+        initDirectoryListView();
+        init();
+
+        return view;
+    }
+
+    @Override
+    public void onStart() {
+        super.onStart();
+        initializeMediaBrowser();
+    }
+
+    @Override
+    public void onStop() {
+        releaseMediaBrowser();
+        super.onStop();
+    }
+
+    @Override
+    public void onDestroyView() {
+        super.onDestroyView();
+        bind = null;
+    }
+
+    private void init() {
+        Artist artist = getArguments().getParcelable(Constants.MUSIC_INDEX_OBJECT);
+
+        if (artist != null) {
+            directoryViewModel.setMusicDirectoryId(artist.getId());
+            directoryViewModel.setMusicDirectoryName(artist.getName());
+        }
+
+        directoryViewModel.loadMusicDirectory(getViewLifecycleOwner());
+    }
+
+    private void initAppBar() {
+        activity.setSupportActionBar(bind.toolbar);
+
+        if (activity.getSupportActionBar() != null) {
+            activity.getSupportActionBar().setDisplayHomeAsUpEnabled(true);
+            activity.getSupportActionBar().setDisplayShowHomeEnabled(true);
+        }
+
+        if (bind != null)
+            bind.toolbar.setNavigationOnClickListener(v -> activity.navController.navigateUp());
+
+        if (bind != null)
+            bind.appBarLayout.addOnOffsetChangedListener((appBarLayout, verticalOffset) -> {
+                if ((bind.directoryInfoSector.getHeight() + verticalOffset) < (2 * ViewCompat.getMinimumHeight(bind.toolbar))) {
+                    directoryViewModel.getDirectory().observe(getViewLifecycleOwner(), directory -> {
+                        if (directory != null) {
+                            bind.toolbar.setTitle(directory.getName());
+                        }
+                    });
+                } else {
+                    bind.toolbar.setTitle(R.string.empty_string);
+                }
+            });
+
+        directoryViewModel.getDirectory().observe(getViewLifecycleOwner(), directory -> {
+            if (directory != null) {
+                bind.directoryTitleLabel.setText(directory.getName());
+            }
+        });
+    }
+
+    private void initButtons() {
+        directoryViewModel.getDirectory().observe(getViewLifecycleOwner(), directory -> {
+            if (directory != null && directory.getParentId() != null && !Objects.equals(directory.getParentId(), "-1")) {
+                bind.directoryBackImageView.setVisibility(View.VISIBLE);
+            } else {
+                bind.directoryBackImageView.setVisibility(View.GONE);
+            }
+        });
+
+        bind.directoryBackImageView.setOnClickListener(v -> directoryViewModel.goBack());
+    }
+
+    private void initDirectoryListView() {
+        bind.directoryRecyclerView.setLayoutManager(new LinearLayoutManager(requireContext()));
+        bind.directoryRecyclerView.setHasFixedSize(true);
+
+        musicDirectoryAdapter = new MusicDirectoryAdapter(this);
+        bind.directoryRecyclerView.setAdapter(musicDirectoryAdapter);
+
+        directoryViewModel.getDirectory().observe(getViewLifecycleOwner(), directory -> {
+            if (directory != null) {
+                musicDirectoryAdapter.setItems(directory.getChildren());
+            } else {
+                musicDirectoryAdapter.setItems(Collections.emptyList());
+            }
+        });
+    }
+
+    private void initializeMediaBrowser() {
+        mediaBrowserListenableFuture = new MediaBrowser.Builder(requireContext(), new SessionToken(requireContext(), new ComponentName(requireContext(), MediaService.class))).buildAsync();
+    }
+
+    private void releaseMediaBrowser() {
+        MediaBrowser.releaseFuture(mediaBrowserListenableFuture);
+    }
+
+    @Override
+    public void onMediaClick(Bundle bundle) {
+        MediaManager.startQueue(mediaBrowserListenableFuture, bundle.getParcelableArrayList(Constants.TRACKS_OBJECT), bundle.getInt(Constants.ITEM_POSITION));
+    }
+
+    @Override
+    public void onMusicDirectoryClick(Bundle bundle) {
+        Child child = bundle.getParcelable(Constants.MUSIC_DIRECTORY_OBJECT);
+
+        if (child != null) {
+            directoryViewModel.setMusicDirectoryId(child.getId());
+            directoryViewModel.setMusicDirectoryName(child.getTitle());
+        }
+    }
+
+    @Override
+    public void onMusicDirectoryLongClick(Bundle bundle) {
+        Toast.makeText(requireContext(), "Long click!", Toast.LENGTH_SHORT).show();
+    }
+}

app/src/main/java/com/cappielloantonio/play/ui/fragment/IndexFragment.java

@@ -0,0 +1,111 @@
+package com.cappielloantonio.play.ui.fragment;
+
+import android.os.Bundle;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.Toast;
+
+import androidx.annotation.NonNull;
+import androidx.core.view.ViewCompat;
+import androidx.fragment.app.Fragment;
+import androidx.lifecycle.ViewModelProvider;
+import androidx.media3.common.util.UnstableApi;
+import androidx.navigation.Navigation;
+import androidx.recyclerview.widget.LinearLayoutManager;
+
+import com.cappielloantonio.play.R;
+import com.cappielloantonio.play.databinding.FragmentIndexBinding;
+import com.cappielloantonio.play.interfaces.ClickCallback;
+import com.cappielloantonio.play.subsonic.models.MusicFolder;
+import com.cappielloantonio.play.ui.activity.MainActivity;
+import com.cappielloantonio.play.ui.adapter.MusicIndexAdapter;
+import com.cappielloantonio.play.util.Constants;
+import com.cappielloantonio.play.util.IndexUtil;
+import com.cappielloantonio.play.viewmodel.IndexViewModel;
+
+@UnstableApi
+public class IndexFragment extends Fragment implements ClickCallback {
+    private static final String TAG = "IndexFragment";
+
+    private FragmentIndexBinding bind;
+    private MainActivity activity;
+    private IndexViewModel indexViewModel;
+
+    private MusicIndexAdapter musicIndexAdapter;
+
+    @Override
+    public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
+        activity = (MainActivity) getActivity();
+
+        bind = FragmentIndexBinding.inflate(inflater, container, false);
+        View view = bind.getRoot();
+        indexViewModel = new ViewModelProvider(requireActivity()).get(IndexViewModel.class);
+
+        initAppBar();
+        initDirectoryListView();
+        init();
+
+        return view;
+    }
+
+    @Override
+    public void onDestroyView() {
+        super.onDestroyView();
+        bind = null;
+    }
+
+    private void init() {
+        MusicFolder musicFolder = getArguments().getParcelable(Constants.MUSIC_FOLDER_OBJECT);
+
+        if (musicFolder != null) {
+            indexViewModel.setMusicFolder(musicFolder);
+            bind.indexTitleLabel.setText(musicFolder.getName());
+        }
+    }
+
+    private void initAppBar() {
+        activity.setSupportActionBar(bind.toolbar);
+
+        if (activity.getSupportActionBar() != null) {
+            activity.getSupportActionBar().setDisplayHomeAsUpEnabled(true);
+            activity.getSupportActionBar().setDisplayShowHomeEnabled(true);
+        }
+
+        if (bind != null)
+            bind.toolbar.setNavigationOnClickListener(v -> activity.navController.navigateUp());
+
+        if (bind != null)
+            bind.appBarLayout.addOnOffsetChangedListener((appBarLayout, verticalOffset) -> {
+                if ((bind.indexInfoSector.getHeight() + verticalOffset) < (2 * ViewCompat.getMinimumHeight(bind.toolbar))) {
+                    bind.toolbar.setTitle(indexViewModel.getMusicFolderName());
+                } else {
+                    bind.toolbar.setTitle(R.string.empty_string);
+                }
+            });
+    }
+
+    private void initDirectoryListView() {
+        bind.indexRecyclerView.setLayoutManager(new LinearLayoutManager(requireContext()));
+        bind.indexRecyclerView.setHasFixedSize(true);
+
+        musicIndexAdapter = new MusicIndexAdapter(this);
+        bind.indexRecyclerView.setAdapter(musicIndexAdapter);
+
+        indexViewModel.getIndexes().observe(getViewLifecycleOwner(), indexes -> {
+            if (indexes != null) {
+                musicIndexAdapter.setItems(IndexUtil.getArtist(indexes));
+            }
+        });
+    }
+
+    @Override
+    public void onMusicIndexClick(Bundle bundle) {
+        Navigation.findNavController(requireView()).navigate(R.id.directoryFragment, bundle);
+    }
+
+    @Override
+    public void onMusicIndexLongClick(Bundle bundle) {
+        Toast.makeText(requireContext(), "Long click!", Toast.LENGTH_SHORT).show();
+    }
+}

app/src/main/java/com/cappielloantonio/play/ui/fragment/LibraryFragment.java

@@ -1,12 +1,14 @@
 package com.cappielloantonio.play.ui.fragment;
 
 import android.os.Bundle;
+import android.util.Log;
 import android.view.LayoutInflater;
 import android.view.Menu;
 import android.view.MenuInflater;
 import android.view.MenuItem;
 import android.view.View;
 import android.view.ViewGroup;
+import android.widget.Toast;
 
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
@@ -25,6 +27,7 @@ import com.cappielloantonio.play.ui.activity.MainActivity;
 import com.cappielloantonio.play.ui.adapter.AlbumAdapter;
 import com.cappielloantonio.play.ui.adapter.ArtistAdapter;
 import com.cappielloantonio.play.ui.adapter.GenreAdapter;
+import com.cappielloantonio.play.ui.adapter.MusicFolderAdapter;
 import com.cappielloantonio.play.ui.adapter.PlaylistHorizontalAdapter;
 import com.cappielloantonio.play.ui.dialog.PlaylistEditorDialog;
 import com.cappielloantonio.play.util.Constants;
@@ -35,10 +38,13 @@ import java.util.Objects;
 
 @UnstableApi
 public class LibraryFragment extends Fragment implements ClickCallback {
+    private static final String TAG = "LibraryFragment";
+
     private FragmentLibraryBinding bind;
     private MainActivity activity;
     private LibraryViewModel libraryViewModel;
 
+    private MusicFolderAdapter musicFolderAdapter;
     private AlbumAdapter albumAdapter;
     private ArtistAdapter artistAdapter;
     private GenreAdapter genreAdapter;
@@ -77,6 +83,7 @@ public class LibraryFragment extends Fragment implements ClickCallback {
         super.onViewCreated(view, savedInstanceState);
 
         initAppBar();
+        initMusicFolderView();
         initAlbumView();
         initArtistView();
         initGenreView();
@@ -141,6 +148,28 @@ public class LibraryFragment extends Fragment implements ClickCallback {
         Objects.requireNonNull(bind.toolbar.getOverflowIcon()).setTint(requireContext().getResources().getColor(R.color.titleTextColor, null));
     }
 
+    private void initMusicFolderView() {
+        bind.musicFolderRecyclerView.setLayoutManager(new LinearLayoutManager(requireContext()));
+        bind.musicFolderRecyclerView.setHasFixedSize(true);
+
+        musicFolderAdapter = new MusicFolderAdapter(this);
+        bind.musicFolderRecyclerView.setAdapter(musicFolderAdapter);
+        libraryViewModel.getMusicFolders(getViewLifecycleOwner()).observe(getViewLifecycleOwner(), musicFolders -> {
+            if (musicFolders == null) {
+                if (bind != null)
+                    bind.libraryMusicFolderPlaceholder.placeholder.setVisibility(View.VISIBLE);
+                if (bind != null) bind.libraryMusicFolderSector.setVisibility(View.GONE);
+            } else {
+                if (bind != null)
+                    bind.libraryMusicFolderPlaceholder.placeholder.setVisibility(View.GONE);
+                if (bind != null)
+                    bind.libraryMusicFolderSector.setVisibility(!musicFolders.isEmpty() ? View.VISIBLE : View.GONE);
+
+                musicFolderAdapter.setItems(musicFolders);
+            }
+        });
+    }
+
     private void initAlbumView() {
         bind.albumRecyclerView.setLayoutManager(new LinearLayoutManager(requireContext(), LinearLayoutManager.HORIZONTAL, false));
         bind.albumRecyclerView.setHasFixedSize(true);
@@ -273,4 +302,14 @@ public class LibraryFragment extends Fragment implements ClickCallback {
         dialog.setArguments(bundle);
         dialog.show(activity.getSupportFragmentManager(), null);
     }
+
+    @Override
+    public void onMusicFolderClick(Bundle bundle) {
+        Navigation.findNavController(requireView()).navigate(R.id.indexFragment, bundle);
+    }
+
+    @Override
+    public void onMusicFolderLongClick(Bundle bundle) {
+        Toast.makeText(requireContext(), "Long click!", Toast.LENGTH_SHORT).show();
+    }
 }

app/src/main/java/com/cappielloantonio/play/util/Constants.kt

@@ -14,6 +14,9 @@ object Constants {
     const val PODCAST_OBJECT = "PODCAST_OBJECT"
     const val PODCAST_CHANNEL_OBJECT = "PODCAST_CHANNEL_OBJECT"
     const val INTERNET_RADIO_STATION_OBJECT = "INTERNET_RADIO_STATION_OBJECT"
+    const val MUSIC_FOLDER_OBJECT = "MUSIC_FOLDER_OBJECT"
+    const val MUSIC_DIRECTORY_OBJECT = "MUSIC_DIRECTORY_OBJECT"
+    const val MUSIC_INDEX_OBJECT = "MUSIC_DIRECTORY_OBJECT"
 
     const val ALBUM_RECENTLY_PLAYED = "ALBUM_RECENTLY_PLAYED"
     const val ALBUM_MOST_PLAYED = "ALBUM_MOST_PLAYED"

app/src/main/java/com/cappielloantonio/play/util/IndexUtil.java

@@ -0,0 +1,29 @@
+package com.cappielloantonio.play.util;
+
+import androidx.annotation.OptIn;
+import androidx.media3.common.util.UnstableApi;
+
+import com.cappielloantonio.play.subsonic.models.Artist;
+import com.cappielloantonio.play.subsonic.models.Index;
+import com.cappielloantonio.play.subsonic.models.Indexes;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+@OptIn(markerClass = UnstableApi.class)
+public class IndexUtil {
+    public static List<Artist> getArtist(Indexes indexes) {
+        if (indexes.getIndices() == null) return Collections.emptyList();
+
+        ArrayList<Artist> toReturn = new ArrayList<>();
+
+        for (Index index : indexes.getIndices()) {
+            if (index.getArtists() != null) {
+                toReturn.addAll(index.getArtists());
+            }
+        }
+
+        return toReturn;
+    }
+}

app/src/main/java/com/cappielloantonio/play/viewmodel/DirectoryViewModel.java

@@ -0,0 +1,47 @@
+package com.cappielloantonio.play.viewmodel;
+
+import android.app.Application;
+
+import androidx.annotation.NonNull;
+import androidx.lifecycle.AndroidViewModel;
+import androidx.lifecycle.LifecycleOwner;
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.MutableLiveData;
+
+import com.cappielloantonio.play.repository.DirectoryRepository;
+import com.cappielloantonio.play.subsonic.models.Directory;
+
+public class DirectoryViewModel extends AndroidViewModel {
+    private final DirectoryRepository directoryRepository;
+
+    private MutableLiveData<String> id = new MutableLiveData<>(null);
+    private MutableLiveData<String> name = new MutableLiveData<>(null);
+
+    private MutableLiveData<Directory> directory = new MutableLiveData<>(null);
+
+    public DirectoryViewModel(@NonNull Application application) {
+        super(application);
+
+        directoryRepository = new DirectoryRepository();
+    }
+
+    public LiveData<Directory> getDirectory() {
+        return directory;
+    }
+
+    public void setMusicDirectoryId(String id) {
+        this.id.setValue(id);
+    }
+
+    public void setMusicDirectoryName(String name) {
+        this.name.setValue(name);
+    }
+
+    public void loadMusicDirectory(LifecycleOwner owner) {
+        this.id.observe(owner, id -> directoryRepository.getMusicDirectory(id).observe(owner, directory -> this.directory.setValue(directory)));
+    }
+
+    public void goBack() {
+        this.id.setValue(this.directory.getValue().getParentId());
+    }
+}

app/src/main/java/com/cappielloantonio/play/viewmodel/IndexViewModel.java

@@ -0,0 +1,37 @@
+package com.cappielloantonio.play.viewmodel;
+
+import android.app.Application;
+
+import androidx.annotation.NonNull;
+import androidx.lifecycle.AndroidViewModel;
+import androidx.lifecycle.MutableLiveData;
+
+import com.cappielloantonio.play.repository.DirectoryRepository;
+import com.cappielloantonio.play.subsonic.models.Indexes;
+import com.cappielloantonio.play.subsonic.models.MusicFolder;
+
+public class IndexViewModel extends AndroidViewModel {
+    private final DirectoryRepository directoryRepository;
+
+    private MusicFolder musicFolder;
+
+    private MutableLiveData<Indexes> indexes = new MutableLiveData<>(null);
+
+    public IndexViewModel(@NonNull Application application) {
+        super(application);
+
+        directoryRepository = new DirectoryRepository();
+    }
+
+    public MutableLiveData<Indexes> getIndexes() {
+        return directoryRepository.getIndexes(null, null);
+    }
+
+    public String getMusicFolderName() {
+        return musicFolder != null ? musicFolder.getName() : "";
+    }
+
+    public void setMusicFolder(MusicFolder musicFolder) {
+        this.musicFolder = musicFolder;
+    }
+}

app/src/main/java/com/cappielloantonio/play/viewmodel/LibraryViewModel.java

@@ -10,11 +10,14 @@ import androidx.lifecycle.MutableLiveData;
 
 import com.cappielloantonio.play.repository.AlbumRepository;
 import com.cappielloantonio.play.repository.ArtistRepository;
+import com.cappielloantonio.play.repository.DirectoryRepository;
 import com.cappielloantonio.play.repository.GenreRepository;
 import com.cappielloantonio.play.repository.PlaylistRepository;
 import com.cappielloantonio.play.subsonic.models.AlbumID3;
 import com.cappielloantonio.play.subsonic.models.ArtistID3;
 import com.cappielloantonio.play.subsonic.models.Genre;
+import com.cappielloantonio.play.subsonic.models.Indexes;
+import com.cappielloantonio.play.subsonic.models.MusicFolder;
 import com.cappielloantonio.play.subsonic.models.Playlist;
 
 import java.util.List;
@@ -22,11 +25,14 @@ import java.util.List;
 public class LibraryViewModel extends AndroidViewModel {
     private static final String TAG = "LibraryViewModel";
 
+    private final DirectoryRepository directoryRepository;
     private final AlbumRepository albumRepository;
     private final ArtistRepository artistRepository;
     private final GenreRepository genreRepository;
     private final PlaylistRepository playlistRepository;
 
+    private final MutableLiveData<List<MusicFolder>> musicFolders = new MutableLiveData<>(null);
+    private final MutableLiveData<Indexes> indexes = new MutableLiveData<>(null);
     private final MutableLiveData<List<Playlist>> playlistSample = new MutableLiveData<>(null);
     private final MutableLiveData<List<AlbumID3>> sampleAlbum = new MutableLiveData<>(null);
     private final MutableLiveData<List<ArtistID3>> sampleArtist = new MutableLiveData<>(null);
@@ -35,12 +41,29 @@ public class LibraryViewModel extends AndroidViewModel {
     public LibraryViewModel(@NonNull Application application) {
         super(application);
 
+        directoryRepository = new DirectoryRepository();
         albumRepository = new AlbumRepository();
         artistRepository = new ArtistRepository();
         genreRepository = new GenreRepository();
         playlistRepository = new PlaylistRepository();
     }
 
+    public LiveData<List<MusicFolder>> getMusicFolders(LifecycleOwner owner) {
+        if (musicFolders.getValue() == null) {
+            directoryRepository.getMusicFolders().observe(owner, musicFolders::postValue);
+        }
+
+        return musicFolders;
+    }
+
+    public LiveData<Indexes> getIndexes(LifecycleOwner owner) {
+        if (indexes.getValue() == null) {
+            directoryRepository.getIndexes("0", null).observe(owner, indexes::postValue);
+        }
+
+        return indexes;
+    }
+
     public LiveData<List<AlbumID3>> getAlbumSample(LifecycleOwner owner) {
         if (sampleAlbum.getValue() == null) {
             albumRepository.getAlbums("random", 10, null, null).observe(owner, sampleAlbum::postValue);

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

@@ -0,0 +1,76 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:orientation="vertical">
+
+    <com.google.android.material.appbar.MaterialToolbar
+        android:id="@+id/toolbar"
+        android:layout_width="match_parent"
+        android:layout_height="?attr/actionBarSize"
+        app:layout_collapseMode="pin"
+        app:navigationIcon="@drawable/ic_arrow_back" />
+
+    <androidx.coordinatorlayout.widget.CoordinatorLayout
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:paddingTop="8dp">
+
+        <com.google.android.material.appbar.AppBarLayout
+            android:id="@+id/app_bar_layout"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content">
+
+            <androidx.constraintlayout.widget.ConstraintLayout
+                android:id="@+id/directory_info_sector"
+                android:layout_width="match_parent"
+                android:layout_height="172dp"
+                android:background="?attr/colorSurface"
+                android:clipChildren="false"
+                app:layout_scrollFlags="scroll|exitUntilCollapsed|snap">
+
+                <TextView
+                    android:id="@+id/directory_title_label"
+                    style="@style/TitleLarge"
+                    android:layout_width="0dp"
+                    android:layout_height="wrap_content"
+                    android:paddingStart="16dp"
+                    android:paddingTop="16dp"
+                    android:paddingEnd="16dp"
+                    android:paddingBottom="24dp"
+                    android:text="@string/label_placeholder"
+                    app:layout_constraintBottom_toBottomOf="parent"
+                    app:layout_constraintEnd_toEndOf="parent"
+                    app:layout_constraintStart_toStartOf="parent" />
+
+                <Button
+                    android:id="@+id/directory_back_image_view"
+                    style="@style/Widget.Material3.Button.TonalButton.Icon"
+                    android:layout_width="52dp"
+                    android:layout_height="52dp"
+                    android:layout_marginStart="16dp"
+                    android:layout_marginTop="16dp"
+                    android:layout_marginEnd="16dp"
+                    android:layout_marginBottom="12dp"
+                    android:insetLeft="0dp"
+                    android:insetTop="0dp"
+                    android:insetRight="0dp"
+                    android:insetBottom="0dp"
+                    app:cornerRadius="30dp"
+                    app:icon="@drawable/ic_arrow_back"
+                    app:layout_constraintBottom_toBottomOf="parent"
+                    app:layout_constraintEnd_toEndOf="parent" />
+            </androidx.constraintlayout.widget.ConstraintLayout>
+        </com.google.android.material.appbar.AppBarLayout>
+
+        <androidx.recyclerview.widget.RecyclerView
+            android:id="@+id/directory_recycler_view"
+            android:layout_width="match_parent"
+            android:layout_height="match_parent"
+            android:clipToPadding="false"
+            android:paddingBottom="@dimen/global_padding_bottom"
+            app:layout_behavior="@string/appbar_scrolling_view_behavior" />
+    </androidx.coordinatorlayout.widget.CoordinatorLayout>
+</LinearLayout>
+

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

@@ -0,0 +1,59 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:orientation="vertical">
+
+    <com.google.android.material.appbar.MaterialToolbar
+        android:id="@+id/toolbar"
+        android:layout_width="match_parent"
+        android:layout_height="?attr/actionBarSize"
+        app:layout_collapseMode="pin"
+        app:navigationIcon="@drawable/ic_arrow_back" />
+
+    <androidx.coordinatorlayout.widget.CoordinatorLayout
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:paddingTop="8dp">
+
+        <com.google.android.material.appbar.AppBarLayout
+            android:id="@+id/app_bar_layout"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content">
+
+            <androidx.constraintlayout.widget.ConstraintLayout
+                android:id="@+id/index_info_sector"
+                android:layout_width="match_parent"
+                android:layout_height="172dp"
+                android:background="?attr/colorSurface"
+                android:clipChildren="false"
+                app:layout_scrollFlags="scroll|exitUntilCollapsed|snap">
+
+                <TextView
+                    android:id="@+id/index_title_label"
+                    style="@style/TitleLarge"
+                    android:layout_width="0dp"
+                    android:layout_height="wrap_content"
+                    android:paddingStart="16dp"
+                    android:paddingTop="16dp"
+                    android:paddingEnd="16dp"
+                    android:paddingBottom="24dp"
+                    android:text="@string/label_placeholder"
+                    app:layout_constraintBottom_toBottomOf="parent"
+                    app:layout_constraintEnd_toEndOf="parent"
+                    app:layout_constraintStart_toStartOf="parent" />
+
+            </androidx.constraintlayout.widget.ConstraintLayout>
+        </com.google.android.material.appbar.AppBarLayout>
+
+        <androidx.recyclerview.widget.RecyclerView
+            android:id="@+id/index_recycler_view"
+            android:layout_width="match_parent"
+            android:layout_height="match_parent"
+            android:clipToPadding="false"
+            android:paddingBottom="@dimen/global_padding_bottom"
+            app:layout_behavior="@string/appbar_scrolling_view_behavior" />
+    </androidx.coordinatorlayout.widget.CoordinatorLayout>
+</LinearLayout>
+

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

@@ -52,6 +52,41 @@
             android:orientation="vertical"
             android:paddingBottom="@dimen/global_padding_bottom">
 
+            <!--  Music Folder  -->
+            <LinearLayout
+                android:id="@+id/library_music_folder_sector"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:orientation="vertical"
+                android:paddingBottom="8dp">
+
+                <TextView
+                    style="@style/TitleLarge"
+                    android:layout_width="match_parent"
+                    android:layout_height="wrap_content"
+                    android:paddingStart="16dp"
+                    android:paddingTop="8dp"
+                    android:paddingEnd="16dp"
+                    android:text="@string/library_title_music_folder" />
+
+                <androidx.recyclerview.widget.RecyclerView
+                    android:id="@+id/music_folder_recycler_view"
+                    android:layout_width="match_parent"
+                    android:layout_height="match_parent"
+                    android:layout_marginTop="8dp"
+                    android:layout_marginBottom="8dp"
+                    android:clipToPadding="false"
+                    android:paddingStart="16dp"
+                    android:paddingTop="8dp"
+                    android:paddingEnd="8dp"
+                    android:paddingBottom="8dp" />
+            </LinearLayout>
+
+            <include
+                android:id="@+id/library_music_folder_placeholder"
+                layout="@layout/item_placeholder_album"
+                android:visibility="gone" />
+
             <!--  Album  -->
             <LinearLayout
                 android:id="@+id/library_album_sector"
@@ -67,6 +102,7 @@
                     android:layout_height="wrap_content"
                     android:orientation="horizontal"
                     android:paddingStart="8dp"
+                    android:paddingTop="8dp"
                     android:paddingEnd="8dp">
 
                     <TextView

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

@@ -0,0 +1,56 @@
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:background="?attr/selectableItemBackground"
+    android:clipChildren="false"
+    android:orientation="horizontal"
+    android:paddingStart="16dp"
+    android:paddingTop="3dp"
+    android:paddingBottom="3dp">
+
+    <ImageView
+        android:id="@+id/music_directory_cover_image_view"
+        android:layout_width="52dp"
+        android:layout_height="52dp"
+        android:layout_gravity="center"
+        android:layout_margin="2dp"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toTopOf="parent" />
+
+    <View
+        android:id="@+id/cover_image_separator"
+        android:layout_width="12dp"
+        android:layout_height="52dp"
+        app:layout_constraintBottom_toBottomOf="@+id/music_directory_cover_image_view"
+        app:layout_constraintEnd_toStartOf="@+id/music_directory_title_text_view"
+        app:layout_constraintStart_toEndOf="@+id/music_directory_cover_image_view"
+        app:layout_constraintTop_toTopOf="@+id/music_directory_cover_image_view" />
+
+    <TextView
+        android:id="@+id/music_directory_title_text_view"
+        style="@style/LabelMedium"
+        android:layout_width="0dp"
+        android:layout_height="wrap_content"
+        android:ellipsize="marquee"
+        android:paddingEnd="12dp"
+        android:singleLine="true"
+        android:text="@string/label_placeholder"
+        app:layout_constraintBottom_toBottomOf="@id/music_directory_cover_image_view"
+        app:layout_constraintEnd_toStartOf="@+id/music_directory_more_button"
+        app:layout_constraintStart_toEndOf="@+id/cover_image_separator"
+        app:layout_constraintTop_toTopOf="@+id/music_directory_cover_image_view" />
+
+    <ImageView
+        android:id="@+id/music_directory_more_button"
+        android:layout_width="18dp"
+        android:layout_height="18dp"
+        android:layout_marginStart="12dp"
+        android:layout_marginEnd="12dp"
+        android:background="@drawable/ic_more_vert"
+        android:foreground="?android:attr/selectableItemBackgroundBorderless"
+        app:layout_constraintBottom_toBottomOf="@id/music_directory_title_text_view"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintTop_toTopOf="@+id/music_directory_title_text_view" />
+</androidx.constraintlayout.widget.ConstraintLayout>

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

@@ -0,0 +1,52 @@
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:background="?attr/selectableItemBackground"
+    android:clipChildren="false"
+    android:orientation="horizontal">
+
+    <ImageView
+        android:id="@+id/music_folder_cover_image_view"
+        android:layout_width="52dp"
+        android:layout_height="52dp"
+        android:layout_gravity="center"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toTopOf="parent" />
+
+    <View
+        android:id="@+id/cover_image_separator"
+        android:layout_width="12dp"
+        android:layout_height="52dp"
+        app:layout_constraintBottom_toBottomOf="@+id/music_folder_cover_image_view"
+        app:layout_constraintEnd_toStartOf="@+id/music_folder_title_text_view"
+        app:layout_constraintStart_toEndOf="@+id/music_folder_cover_image_view"
+        app:layout_constraintTop_toTopOf="@+id/music_folder_cover_image_view" />
+
+    <TextView
+        android:id="@+id/music_folder_title_text_view"
+        style="@style/LabelMedium"
+        android:layout_width="0dp"
+        android:layout_height="wrap_content"
+        android:ellipsize="marquee"
+        android:paddingEnd="12dp"
+        android:singleLine="true"
+        android:text="@string/label_placeholder"
+        app:layout_constraintBottom_toBottomOf="@id/music_folder_cover_image_view"
+        app:layout_constraintEnd_toStartOf="@+id/music_folder_more_button"
+        app:layout_constraintStart_toEndOf="@+id/cover_image_separator"
+        app:layout_constraintTop_toTopOf="@+id/music_folder_cover_image_view" />
+
+    <ImageView
+        android:id="@+id/music_folder_more_button"
+        android:layout_width="18dp"
+        android:layout_height="18dp"
+        android:layout_marginStart="4dp"
+        android:layout_marginEnd="4dp"
+        android:background="@drawable/ic_more_vert"
+        android:foreground="?android:attr/selectableItemBackgroundBorderless"
+        app:layout_constraintBottom_toBottomOf="@id/music_folder_title_text_view"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintTop_toTopOf="@+id/music_folder_title_text_view" />
+</androidx.constraintlayout.widget.ConstraintLayout>

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

@@ -0,0 +1,56 @@
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:background="?attr/selectableItemBackground"
+    android:clipChildren="false"
+    android:orientation="horizontal"
+    android:paddingStart="16dp"
+    android:paddingTop="3dp"
+    android:paddingBottom="3dp">
+
+    <ImageView
+        android:id="@+id/music_index_cover_image_view"
+        android:layout_width="52dp"
+        android:layout_height="52dp"
+        android:layout_gravity="center"
+        android:layout_margin="2dp"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toTopOf="parent" />
+
+    <View
+        android:id="@+id/cover_image_separator"
+        android:layout_width="12dp"
+        android:layout_height="52dp"
+        app:layout_constraintBottom_toBottomOf="@+id/music_index_cover_image_view"
+        app:layout_constraintEnd_toStartOf="@+id/music_index_title_text_view"
+        app:layout_constraintStart_toEndOf="@+id/music_index_cover_image_view"
+        app:layout_constraintTop_toTopOf="@+id/music_index_cover_image_view" />
+
+    <TextView
+        android:id="@+id/music_index_title_text_view"
+        style="@style/LabelMedium"
+        android:layout_width="0dp"
+        android:layout_height="wrap_content"
+        android:ellipsize="marquee"
+        android:paddingEnd="12dp"
+        android:singleLine="true"
+        android:text="@string/label_placeholder"
+        app:layout_constraintBottom_toBottomOf="@id/music_index_cover_image_view"
+        app:layout_constraintEnd_toStartOf="@+id/music_index_more_button"
+        app:layout_constraintStart_toEndOf="@+id/cover_image_separator"
+        app:layout_constraintTop_toTopOf="@+id/music_index_cover_image_view" />
+
+    <ImageView
+        android:id="@+id/music_index_more_button"
+        android:layout_width="18dp"
+        android:layout_height="18dp"
+        android:layout_marginStart="12dp"
+        android:layout_marginEnd="12dp"
+        android:background="@drawable/ic_more_vert"
+        android:foreground="?android:attr/selectableItemBackgroundBorderless"
+        app:layout_constraintBottom_toBottomOf="@id/music_index_title_text_view"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintTop_toTopOf="@+id/music_index_title_text_view" />
+</androidx.constraintlayout.widget.ConstraintLayout>

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

@@ -107,6 +107,9 @@
         <action
             android:id="@+id/action_libraryFragment_to_albumListPageFragment"
             app:destination="@id/albumListPageFragment" />
+        <action
+            android:id="@+id/action_libraryFragment_to_indexFragment"
+            app:destination="@id/indexFragment" />
     </fragment>
     <fragment
         android:id="@+id/downloadFragment"
@@ -279,6 +282,21 @@
         android:name="com.cappielloantonio.play.ui.fragment.PodcastChannelPageFragment"
         android:label="PodcastChannelPageFragment"
         tools:layout="@layout/fragment_podcast_channel_page" />
+    <fragment
+        android:id="@+id/directoryFragment"
+        android:name="com.cappielloantonio.play.ui.fragment.DirectoryFragment"
+        android:label="DirectoryFragment"
+        tools:layout="@layout/fragment_directory" />
+    <fragment
+        android:id="@+id/indexFragment"
+        android:name="com.cappielloantonio.play.ui.fragment.IndexFragment"
+        android:label="IndexFragment"
+        tools:layout="@layout/fragment_index">
+
+        <action
+            android:id="@+id/action_indexFragment_to_directoryFragment"
+            app:destination="@id/directoryFragment" />
+    </fragment>
     <dialog
         android:id="@+id/songBottomSheetDialog"
         android:name="com.cappielloantonio.play.ui.fragment.bottomsheetdialog.SongBottomSheetDialog"

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

@@ -83,6 +83,7 @@
     <string name="home_title_podcast_channels_see_all_button">See all</string>
     <string name="label_dot_separator">•</string>
     <string name="label_placeholder">--</string>
+    <string name="library_title_music_folder">Music folders</string>
     <string name="library_title_album">Albums</string>
     <string name="library_title_album_see_all_button">See all</string>
     <string name="library_title_artist">Artists</string>