feat: added the ability to filter and group downloaded songs

app/src/main/java/com/cappielloantonio/tempo/model/Download.kt

@@ -52,4 +52,10 @@ class Download(@PrimaryKey override val id: String) : Child(id) {
         originalWidth = child.originalWidth
         originalHeight = child.originalHeight
     }
-}
+}
+
+@Keep
+data class DownloadStack(
+    var id: String,
+    var view: String?
+)

app/src/main/java/com/cappielloantonio/tempo/ui/adapter/DownloadHorizontalAdapter.java

@@ -11,25 +11,35 @@ import androidx.recyclerview.widget.RecyclerView;
 
 import com.cappielloantonio.tempo.R;
 import com.cappielloantonio.tempo.databinding.ItemHorizontalDownloadBinding;
+import com.cappielloantonio.tempo.glide.CustomGlideRequest;
 import com.cappielloantonio.tempo.interfaces.ClickCallback;
 import com.cappielloantonio.tempo.subsonic.models.Child;
 import com.cappielloantonio.tempo.util.Constants;
 import com.cappielloantonio.tempo.util.MusicUtil;
+import com.cappielloantonio.tempo.util.Util;
 
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 import java.util.Objects;
+import java.util.stream.Collectors;
 
 @UnstableApi
 public class DownloadHorizontalAdapter extends RecyclerView.Adapter<DownloadHorizontalAdapter.ViewHolder> {
     private final ClickCallback click;
 
+    private String view;
+    private String filterKey;
+    private String filterValue;
+
     private List<Child> songs;
+    private List<Child> grouped;
 
     public DownloadHorizontalAdapter(ClickCallback click) {
         this.click = click;
+        this.view = Constants.DOWNLOAD_TYPE_TRACK;
         this.songs = Collections.emptyList();
+        this.grouped = Collections.emptyList();
     }
 
     @NonNull
@@ -41,31 +51,43 @@ public class DownloadHorizontalAdapter extends RecyclerView.Adapter<DownloadHori
 
     @Override
     public void onBindViewHolder(ViewHolder holder, int position) {
-        Child song = songs.get(position);
+        switch (view) {
-
+            case Constants.DOWNLOAD_TYPE_TRACK:
-        holder.item.downloadedSongTitleTextView.setText(MusicUtil.getReadableString(song.getTitle()));
+                initTrackLayout(holder, position);
-        holder.item.downloadedSongArtistTextView.setText(holder.itemView.getContext().getString(R.string.song_subtitle_formatter, MusicUtil.getReadableString(song.getArtist()), MusicUtil.getReadableDurationString(song.getDuration(), false)));
+                break;
-        holder.item.downloadedSongAlbumTextView.setText(MusicUtil.getReadableString(song.getAlbum()));
+            case Constants.DOWNLOAD_TYPE_ALBUM:
-
+                initAlbumLayout(holder, position);
-        if (position > 0 && songs.get(position - 1) != null && !Objects.equals(songs.get(position - 1).getAlbum(), songs.get(position).getAlbum())) {
+                break;
-            holder.item.divider.setPadding(0, (int) holder.itemView.getContext().getResources().getDimension(R.dimen.downloaded_item_padding), 0, 0);
+            case Constants.DOWNLOAD_TYPE_ARTIST:
-        } else {
+                initArtistLayout(holder, position);
-            if (position > 0) holder.item.divider.setVisibility(View.GONE);
+                break;
+            case Constants.DOWNLOAD_TYPE_GENRE:
+                initGenreLayout(holder, position);
+                break;
+            case Constants.DOWNLOAD_TYPE_YEAR:
+                initYearLayout(holder, position);
+                break;
         }
     }
 
     @Override
     public int getItemCount() {
-        return songs.size();
+        return grouped.size();
     }
 
-    public void setItems(List<Child> songs) {
+    public void setItems(String view, String filterKey, String filterValue, List<Child> songs) {
+        this.view = filterValue != null ? view : filterKey;
+        this.filterKey = filterKey;
+        this.filterValue = filterValue;
+
         this.songs = songs;
+        this.grouped = groupSong(songs);
+
         notifyDataSetChanged();
     }
 
     public Child getItem(int id) {
-        return songs.get(id);
+        return grouped.get(id);
     }
 
     @Override
@@ -78,6 +100,145 @@ public class DownloadHorizontalAdapter extends RecyclerView.Adapter<DownloadHori
         return position;
     }
 
+    private List<Child> groupSong(List<Child> songs) {
+        switch (view) {
+            case Constants.DOWNLOAD_TYPE_TRACK:
+                return filterSong(filterKey, filterValue, songs.stream().filter(song -> Objects.nonNull(song.getId())).filter(Util.distinctByKey(Child::getId)).collect(Collectors.toList()));
+            case Constants.DOWNLOAD_TYPE_ALBUM:
+                return filterSong(filterKey, filterValue, songs.stream().filter(song -> Objects.nonNull(song.getAlbumId())).filter(Util.distinctByKey(Child::getAlbumId)).collect(Collectors.toList()));
+            case Constants.DOWNLOAD_TYPE_ARTIST:
+                return filterSong(filterKey, filterValue, songs.stream().filter(song -> Objects.nonNull(song.getArtistId())).filter(Util.distinctByKey(Child::getArtistId)).collect(Collectors.toList()));
+            case Constants.DOWNLOAD_TYPE_GENRE:
+                return filterSong(filterKey, filterValue, songs.stream().filter(song -> Objects.nonNull(song.getGenre())).filter(Util.distinctByKey(Child::getGenre)).collect(Collectors.toList()));
+            case Constants.DOWNLOAD_TYPE_YEAR:
+                return filterSong(filterKey, filterValue, songs.stream().filter(song -> Objects.nonNull(song.getYear())).filter(Util.distinctByKey(Child::getYear)).collect(Collectors.toList()));
+        }
+
+        return Collections.emptyList();
+    }
+
+    private List<Child> filterSong(String filterKey, String filterValue, List<Child> songs) {
+        if (filterValue != null) {
+            switch (filterKey) {
+                case Constants.DOWNLOAD_TYPE_TRACK:
+                    return songs.stream().filter(child -> child.getId().equals(filterValue)).collect(Collectors.toList());
+                case Constants.DOWNLOAD_TYPE_ALBUM:
+                    return songs.stream().filter(child -> child.getAlbumId().equals(filterValue)).collect(Collectors.toList());
+                case Constants.DOWNLOAD_TYPE_GENRE:
+                    return songs.stream().filter(child -> child.getGenre().equals(filterValue)).collect(Collectors.toList());
+                case Constants.DOWNLOAD_TYPE_YEAR:
+                    return songs.stream().filter(child -> Objects.equals(child.getYear(), Integer.valueOf(filterValue))).collect(Collectors.toList());
+                case Constants.DOWNLOAD_TYPE_ARTIST:
+                    return songs.stream().filter(child -> child.getArtistId().equals(filterValue)).collect(Collectors.toList());
+            }
+        }
+
+        return songs;
+    }
+
+    private String countSong(String filterKey, String filterValue, List<Child> songs) {
+        if (filterValue != null) {
+            switch (filterKey) {
+                case Constants.DOWNLOAD_TYPE_TRACK:
+                    return String.valueOf(songs.stream().filter(child -> child.getId().equals(filterValue)).count());
+                case Constants.DOWNLOAD_TYPE_ALBUM:
+                    return String.valueOf(songs.stream().filter(child -> child.getAlbumId().equals(filterValue)).count());
+                case Constants.DOWNLOAD_TYPE_GENRE:
+                    return String.valueOf(songs.stream().filter(child -> child.getGenre().equals(filterValue)).count());
+                case Constants.DOWNLOAD_TYPE_YEAR:
+                    return String.valueOf(songs.stream().filter(child -> Objects.equals(child.getYear(), Integer.valueOf(filterValue))).count());
+                case Constants.DOWNLOAD_TYPE_ARTIST:
+                    return String.valueOf(songs.stream().filter(child -> child.getArtistId().equals(filterValue)).count());
+            }
+        }
+
+        return "0";
+    }
+
+    private void initTrackLayout(ViewHolder holder, int position) {
+        Child song = grouped.get(position);
+
+        holder.item.downloadedItemTitleTextView.setText(MusicUtil.getReadableString(song.getTitle()));
+        holder.item.downloadedItemSubtitleTextView.setText(holder.itemView.getContext().getString(R.string.song_subtitle_formatter, MusicUtil.getReadableString(song.getArtist()), MusicUtil.getReadableDurationString(song.getDuration(), false)));
+        holder.item.downloadedItemPreTextView.setText(MusicUtil.getReadableString(song.getAlbum()));
+
+        CustomGlideRequest.Builder
+                .from(holder.itemView.getContext(), song.getCoverArtId())
+                .build()
+                .into(holder.item.itemCoverImageView);
+
+        holder.item.itemCoverImageView.setVisibility(View.VISIBLE);
+        holder.item.downloadedItemMoreButton.setVisibility(View.VISIBLE);
+        holder.item.divider.setVisibility(View.VISIBLE);
+
+        if (position > 0 && grouped.get(position - 1) != null && !Objects.equals(grouped.get(position - 1).getAlbum(), grouped.get(position).getAlbum())) {
+            holder.item.divider.setPadding(0, (int) holder.itemView.getContext().getResources().getDimension(R.dimen.downloaded_item_padding), 0, 0);
+        } else {
+            if (position > 0) holder.item.divider.setVisibility(View.GONE);
+        }
+    }
+
+    private void initAlbumLayout(ViewHolder holder, int position) {
+        Child song = grouped.get(position);
+
+        holder.item.downloadedItemTitleTextView.setText(MusicUtil.getReadableString(song.getAlbum()));
+        holder.item.downloadedItemSubtitleTextView.setText(holder.itemView.getContext().getString(R.string.download_item_single_subtitle_formatter, countSong(Constants.DOWNLOAD_TYPE_ALBUM, song.getAlbumId(), songs)));
+        holder.item.downloadedItemPreTextView.setText(MusicUtil.getReadableString(song.getArtist()));
+
+        CustomGlideRequest.Builder
+                .from(holder.itemView.getContext(), song.getCoverArtId())
+                .build()
+                .into(holder.item.itemCoverImageView);
+
+        holder.item.itemCoverImageView.setVisibility(View.VISIBLE);
+        holder.item.downloadedItemMoreButton.setVisibility(View.GONE);
+        holder.item.divider.setVisibility(View.VISIBLE);
+
+        if (position > 0 && grouped.get(position - 1) != null && !Objects.equals(grouped.get(position - 1).getArtist(), grouped.get(position).getArtist())) {
+            holder.item.divider.setPadding(0, (int) holder.itemView.getContext().getResources().getDimension(R.dimen.downloaded_item_padding), 0, 0);
+        } else {
+            if (position > 0) holder.item.divider.setVisibility(View.GONE);
+        }
+    }
+
+    private void initArtistLayout(ViewHolder holder, int position) {
+        Child song = grouped.get(position);
+
+        holder.item.downloadedItemTitleTextView.setText(MusicUtil.getReadableString(song.getArtist()));
+        holder.item.downloadedItemSubtitleTextView.setText(holder.itemView.getContext().getString(R.string.download_item_single_subtitle_formatter, countSong(Constants.DOWNLOAD_TYPE_ARTIST, song.getArtistId(), songs)));
+
+        CustomGlideRequest.Builder
+                .from(holder.itemView.getContext(), song.getCoverArtId())
+                .build()
+                .into(holder.item.itemCoverImageView);
+
+        holder.item.itemCoverImageView.setVisibility(View.VISIBLE);
+        holder.item.downloadedItemMoreButton.setVisibility(View.GONE);
+        holder.item.divider.setVisibility(View.GONE);
+    }
+
+    private void initGenreLayout(ViewHolder holder, int position) {
+        Child song = grouped.get(position);
+
+        holder.item.downloadedItemTitleTextView.setText(MusicUtil.getReadableString(song.getGenre()));
+        holder.item.downloadedItemSubtitleTextView.setText(holder.itemView.getContext().getString(R.string.download_item_single_subtitle_formatter, countSong(Constants.DOWNLOAD_TYPE_GENRE, song.getGenre(), songs)));
+
+        holder.item.itemCoverImageView.setVisibility(View.GONE);
+        holder.item.downloadedItemMoreButton.setVisibility(View.GONE);
+        holder.item.divider.setVisibility(View.GONE);
+    }
+
+    private void initYearLayout(ViewHolder holder, int position) {
+        Child song = grouped.get(position);
+
+        holder.item.downloadedItemTitleTextView.setText(String.valueOf(song.getYear()));
+        holder.item.downloadedItemSubtitleTextView.setText(holder.itemView.getContext().getString(R.string.download_item_single_subtitle_formatter, countSong(Constants.DOWNLOAD_TYPE_YEAR, song.getYear().toString(), songs)));
+
+        holder.item.itemCoverImageView.setVisibility(View.GONE);
+        holder.item.downloadedItemMoreButton.setVisibility(View.GONE);
+        holder.item.divider.setVisibility(View.GONE);
+    }
+
     public class ViewHolder extends RecyclerView.ViewHolder {
         ItemHorizontalDownloadBinding item;
 
@@ -86,30 +247,62 @@ public class DownloadHorizontalAdapter extends RecyclerView.Adapter<DownloadHori
 
             this.item = item;
 
-            item.downloadedSongTitleTextView.setSelected(true);
+            item.downloadedItemTitleTextView.setSelected(true);
-            item.downloadedSongArtistTextView.setSelected(true);
+            item.downloadedItemSubtitleTextView.setSelected(true);
 
             itemView.setOnClickListener(v -> onClick());
             itemView.setOnLongClickListener(v -> onLongClick());
 
-            item.downloadedSongMoreButton.setOnClickListener(v -> onLongClick());
+            item.downloadedItemMoreButton.setOnClickListener(v -> onLongClick());
         }
 
         public void onClick() {
             Bundle bundle = new Bundle();
-            bundle.putParcelableArrayList(Constants.TRACKS_OBJECT, new ArrayList<>(songs));
-            bundle.putInt(Constants.ITEM_POSITION, getBindingAdapterPosition());
 
-            click.onMediaClick(bundle);
+            switch (view) {
+                case Constants.DOWNLOAD_TYPE_TRACK:
+                    bundle.putParcelableArrayList(Constants.TRACKS_OBJECT, new ArrayList<>(songs));
+                    bundle.putInt(Constants.ITEM_POSITION, getBindingAdapterPosition());
+                    click.onMediaClick(bundle);
+                    break;
+                case Constants.DOWNLOAD_TYPE_ALBUM:
+                    bundle.putString(Constants.DOWNLOAD_TYPE_ALBUM, grouped.get(getBindingAdapterPosition()).getAlbumId());
+                    click.onAlbumClick(bundle);
+                    break;
+                case Constants.DOWNLOAD_TYPE_ARTIST:
+                    bundle.putString(Constants.DOWNLOAD_TYPE_ARTIST, grouped.get(getBindingAdapterPosition()).getArtistId());
+                    click.onArtistClick(bundle);
+                    break;
+                case Constants.DOWNLOAD_TYPE_GENRE:
+                    bundle.putString(Constants.DOWNLOAD_TYPE_GENRE, grouped.get(getBindingAdapterPosition()).getGenre());
+                    click.onGenreClick(bundle);
+                    break;
+                case Constants.DOWNLOAD_TYPE_YEAR:
+                    bundle.putString(Constants.DOWNLOAD_TYPE_YEAR, grouped.get(getBindingAdapterPosition()).getYear().toString());
+                    click.onYearClick(bundle);
+                    break;
+            }
         }
 
         private boolean onLongClick() {
             Bundle bundle = new Bundle();
-            bundle.putParcelable(Constants.TRACK_OBJECT, songs.get(getBindingAdapterPosition()));
 
-            click.onMediaLongClick(bundle);
+            switch (view) {
+                case Constants.DOWNLOAD_TYPE_TRACK:
+                    bundle.putParcelable(Constants.TRACK_OBJECT, grouped.get(getBindingAdapterPosition()));
+                    click.onMediaLongClick(bundle);
+                    return true;
+                case Constants.DOWNLOAD_TYPE_ALBUM:
+                    bundle.putString(Constants.DOWNLOAD_TYPE_ALBUM, grouped.get(getBindingAdapterPosition()).getAlbumId());
+                    click.onAlbumLongClick(bundle);
+                    return true;
+                case Constants.DOWNLOAD_TYPE_ARTIST:
+                    bundle.putString(Constants.DOWNLOAD_TYPE_ARTIST, grouped.get(getBindingAdapterPosition()).getArtistId());
+                    click.onArtistLongClick(bundle);
+                    return true;
+            }
 
-            return true;
+            return false;
         }
     }
 }

app/src/main/java/com/cappielloantonio/tempo/ui/fragment/DownloadFragment.java

@@ -5,6 +5,7 @@ import android.os.Bundle;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
+import android.widget.PopupMenu;
 
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
@@ -19,8 +20,10 @@ import androidx.recyclerview.widget.LinearLayoutManager;
 import com.cappielloantonio.tempo.R;
 import com.cappielloantonio.tempo.databinding.FragmentDownloadBinding;
 import com.cappielloantonio.tempo.interfaces.ClickCallback;
+import com.cappielloantonio.tempo.model.DownloadStack;
 import com.cappielloantonio.tempo.service.MediaManager;
 import com.cappielloantonio.tempo.service.MediaService;
+import com.cappielloantonio.tempo.subsonic.models.Child;
 import com.cappielloantonio.tempo.ui.activity.MainActivity;
 import com.cappielloantonio.tempo.ui.adapter.DownloadHorizontalAdapter;
 import com.cappielloantonio.tempo.util.Constants;
@@ -28,6 +31,7 @@ import com.cappielloantonio.tempo.viewmodel.DownloadViewModel;
 import com.google.android.material.appbar.MaterialToolbar;
 import com.google.common.util.concurrent.ListenableFuture;
 
+import java.util.List;
 import java.util.Objects;
 
 @UnstableApi
@@ -59,7 +63,7 @@ public class DownloadFragment extends Fragment implements ClickCallback {
         super.onViewCreated(view, savedInstanceState);
 
         initAppBar();
-        initDownloadedSongView();
+        initDownloadedView();
     }
 
     @Override
@@ -90,11 +94,12 @@ public class DownloadFragment extends Fragment implements ClickCallback {
         Objects.requireNonNull(materialToolbar.getOverflowIcon()).setTint(requireContext().getResources().getColor(R.color.titleTextColor, null));
     }
 
-    private void initDownloadedSongView() {
+    private void initDownloadedView() {
-        bind.downloadedTracksRecyclerView.setHasFixedSize(true);
+        bind.downloadedRecyclerView.setHasFixedSize(true);
 
         downloadHorizontalAdapter = new DownloadHorizontalAdapter(this);
-        bind.downloadedTracksRecyclerView.setAdapter(downloadHorizontalAdapter);
+        bind.downloadedRecyclerView.setAdapter(downloadHorizontalAdapter);
+
         downloadViewModel.getDownloadedTracks(getViewLifecycleOwner()).observe(getViewLifecycleOwner(), songs -> {
             if (songs != null) {
                 if (songs.isEmpty()) {
@@ -102,26 +107,87 @@ public class DownloadFragment extends Fragment implements ClickCallback {
                         bind.emptyDownloadLayout.setVisibility(View.VISIBLE);
                         bind.fragmentDownloadNestedScrollView.setVisibility(View.GONE);
 
-                        bind.downloadDownloadedTracksPlaceholder.placeholder.setVisibility(View.VISIBLE);
+                        bind.downloadDownloadedPlaceholder.placeholder.setVisibility(View.VISIBLE);
-                        bind.downloadDownloadedTracksSector.setVisibility(View.GONE);
+                        bind.downloadDownloadedSector.setVisibility(View.GONE);
+
+                        bind.downloadedGroupByImageView.setVisibility(View.GONE);
                     }
                 } else {
                     if (bind != null) {
                         bind.emptyDownloadLayout.setVisibility(View.GONE);
                         bind.fragmentDownloadNestedScrollView.setVisibility(View.VISIBLE);
 
-                        bind.downloadDownloadedTracksPlaceholder.placeholder.setVisibility(View.GONE);
+                        bind.downloadDownloadedPlaceholder.placeholder.setVisibility(View.GONE);
-                        bind.downloadDownloadedTracksSector.setVisibility(View.VISIBLE);
+                        bind.downloadDownloadedSector.setVisibility(View.VISIBLE);
 
-                        bind.downloadedTracksRecyclerView.setLayoutManager(new LinearLayoutManager(requireContext()));
+                        bind.downloadedGroupByImageView.setVisibility(View.VISIBLE);
 
-                        downloadHorizontalAdapter.setItems(songs);
+                        finishDownloadView(songs);
                     }
                 }
 
                 if (bind != null) bind.loadingProgressBar.setVisibility(View.GONE);
             }
         });
+
+        bind.downloadedGroupByImageView.setOnClickListener(view -> showPopupMenu(view, R.menu.download_popup_menu));
+        bind.downloadedGoBackImageView.setOnClickListener(view -> downloadViewModel.popViewStack());
+    }
+
+    private void finishDownloadView(List<Child> songs) {
+        downloadViewModel.getViewStack().observe(getViewLifecycleOwner(), stack -> {
+            bind.downloadedRecyclerView.setLayoutManager(new LinearLayoutManager(requireContext()));
+
+            DownloadStack lastLevel = stack.get(stack.size() - 1);
+
+            switch (lastLevel.getId()) {
+                case Constants.DOWNLOAD_TYPE_TRACK:
+                    downloadHorizontalAdapter.setItems(Constants.DOWNLOAD_TYPE_TRACK, lastLevel.getId(), lastLevel.getView(), songs);
+                    break;
+                case Constants.DOWNLOAD_TYPE_ALBUM:
+                    downloadHorizontalAdapter.setItems(Constants.DOWNLOAD_TYPE_TRACK, lastLevel.getId(), lastLevel.getView(), songs);
+                    break;
+                case Constants.DOWNLOAD_TYPE_ARTIST:
+                    downloadHorizontalAdapter.setItems(Constants.DOWNLOAD_TYPE_ALBUM, lastLevel.getId(), lastLevel.getView(), songs);
+                    break;
+                case Constants.DOWNLOAD_TYPE_GENRE:
+                    downloadHorizontalAdapter.setItems(Constants.DOWNLOAD_TYPE_TRACK, lastLevel.getId(), lastLevel.getView(), songs);
+                    break;
+                case Constants.DOWNLOAD_TYPE_YEAR:
+                    downloadHorizontalAdapter.setItems(Constants.DOWNLOAD_TYPE_TRACK, lastLevel.getId(), lastLevel.getView(), songs);
+                    break;
+            }
+
+            bind.downloadedGoBackImageView.setVisibility(stack.size() > 1 ? View.VISIBLE : View.GONE);
+        });
+    }
+
+    private void showPopupMenu(View view, int menuResource) {
+        PopupMenu popup = new PopupMenu(requireContext(), view);
+        popup.getMenuInflater().inflate(menuResource, popup.getMenu());
+
+        popup.setOnMenuItemClickListener(menuItem -> {
+            if (menuItem.getItemId() == R.id.menu_download_group_by_track) {
+                downloadViewModel.initViewStack(new DownloadStack(Constants.DOWNLOAD_TYPE_TRACK, null));
+                return true;
+            } else if (menuItem.getItemId() == R.id.menu_download_group_by_album) {
+                downloadViewModel.initViewStack(new DownloadStack(Constants.DOWNLOAD_TYPE_ALBUM, null));
+                return true;
+            } else if (menuItem.getItemId() == R.id.menu_download_group_by_artist) {
+                downloadViewModel.initViewStack(new DownloadStack(Constants.DOWNLOAD_TYPE_ARTIST, null));
+                return true;
+            } else if (menuItem.getItemId() == R.id.menu_download_group_by_genre) {
+                downloadViewModel.initViewStack(new DownloadStack(Constants.DOWNLOAD_TYPE_GENRE, null));
+                return true;
+            } else if (menuItem.getItemId() == R.id.menu_download_group_by_year) {
+                downloadViewModel.initViewStack(new DownloadStack(Constants.DOWNLOAD_TYPE_YEAR, null));
+                return true;
+            }
+
+            return false;
+        });
+
+        popup.show();
     }
 
     private void initializeMediaBrowser() {
@@ -132,6 +198,26 @@ public class DownloadFragment extends Fragment implements ClickCallback {
         MediaBrowser.releaseFuture(mediaBrowserListenableFuture);
     }
 
+    @Override
+    public void onYearClick(Bundle bundle) {
+        downloadViewModel.pushViewStack(new DownloadStack(Constants.DOWNLOAD_TYPE_YEAR, bundle.getString(Constants.DOWNLOAD_TYPE_YEAR)));
+    }
+
+    @Override
+    public void onGenreClick(Bundle bundle) {
+        downloadViewModel.pushViewStack(new DownloadStack(Constants.DOWNLOAD_TYPE_GENRE, bundle.getString(Constants.DOWNLOAD_TYPE_GENRE)));
+    }
+
+    @Override
+    public void onArtistClick(Bundle bundle) {
+        downloadViewModel.pushViewStack(new DownloadStack(Constants.DOWNLOAD_TYPE_ARTIST, bundle.getString(Constants.DOWNLOAD_TYPE_ARTIST)));
+    }
+
+    @Override
+    public void onAlbumClick(Bundle bundle) {
+        downloadViewModel.pushViewStack(new DownloadStack(Constants.DOWNLOAD_TYPE_ALBUM, bundle.getString(Constants.DOWNLOAD_TYPE_ALBUM)));
+    }
+
     @Override
     public void onMediaClick(Bundle bundle) {
         MediaManager.startQueue(mediaBrowserListenableFuture, bundle.getParcelableArrayList(Constants.TRACKS_OBJECT), bundle.getInt(Constants.ITEM_POSITION));

app/src/main/java/com/cappielloantonio/tempo/util/Util.java

@@ -0,0 +1,17 @@
+package com.cappielloantonio.tempo.util;
+
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.function.Function;
+import java.util.function.Predicate;
+
+public class Util {
+    public static <T> Predicate<T> distinctByKey(Function<? super T, Object> keyExtractor) {
+        try {
+            Map<Object, Boolean> uniqueMap = new ConcurrentHashMap<>();
+            return t -> uniqueMap.putIfAbsent(keyExtractor.apply(t), Boolean.TRUE) == null;
+        } catch (NullPointerException exception) {
+            return null;
+        }
+    }
+}

app/src/main/java/com/cappielloantonio/tempo/viewmodel/DownloadViewModel.java

@@ -8,27 +8,55 @@ import androidx.lifecycle.LifecycleOwner;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
 
+import com.cappielloantonio.tempo.model.DownloadStack;
 import com.cappielloantonio.tempo.repository.DownloadRepository;
 import com.cappielloantonio.tempo.subsonic.models.Child;
+import com.cappielloantonio.tempo.util.Constants;
 
+import java.util.ArrayList;
 import java.util.List;
 import java.util.stream.Collectors;
 
 public class DownloadViewModel extends AndroidViewModel {
-    private static final String TAG = "HomeViewModel";
+    private static final String TAG = "DownloadViewModel";
 
     private final DownloadRepository downloadRepository;
 
     private final MutableLiveData<List<Child>> downloadedTrackSample = new MutableLiveData<>(null);
+    private final MutableLiveData<ArrayList<DownloadStack>> viewStack = new MutableLiveData<>(null);
 
     public DownloadViewModel(@NonNull Application application) {
         super(application);
 
         downloadRepository = new DownloadRepository();
+
+        initViewStack(new DownloadStack(Constants.DOWNLOAD_TYPE_TRACK, null));
     }
 
     public LiveData<List<Child>> getDownloadedTracks(LifecycleOwner owner) {
         downloadRepository.getLiveDownload().observe(owner, downloads -> downloadedTrackSample.postValue(downloads.stream().map(download -> (Child) download).collect(Collectors.toList())));
         return downloadedTrackSample;
     }
+
+    public LiveData<ArrayList<DownloadStack>> getViewStack() {
+        return viewStack;
+    }
+
+    public void initViewStack(DownloadStack level) {
+        ArrayList<DownloadStack> stack = new ArrayList<>();
+        stack.add(level);
+        viewStack.setValue(stack);
+    }
+
+    public void pushViewStack(DownloadStack level) {
+        ArrayList<DownloadStack> stack = viewStack.getValue();
+        stack.add(level);
+        viewStack.setValue(stack);
+    }
+
+    public void popViewStack() {
+        ArrayList<DownloadStack> stack = viewStack.getValue();
+        stack.remove(stack.size() - 1);
+        viewStack.setValue(stack);
+    }
 }

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

@@ -62,45 +62,67 @@
         android:visibility="gone"
         app:layout_behavior="@string/appbar_scrolling_view_behavior">
 
-        <LinearLayout
+        <androidx.constraintlayout.widget.ConstraintLayout
-            android:id="@+id/download_linear_layout_container"
+            android:id="@+id/download_downloaded_sector"
             android:layout_width="match_parent"
             android:layout_height="wrap_content"
-            android:orientation="vertical"
+            android:paddingHorizontal="16dp"
+            android:paddingTop="16dp"
             android:paddingBottom="@dimen/global_padding_bottom">
 
-            <!-- Downloaded tracks -->
+            <TextView
-            <LinearLayout
+                android:id="@+id/downloaded_text_view_refreshable"
-                android:id="@+id/download_downloaded_tracks_sector"
+                style="@style/TitleLarge"
+                android:layout_width="0dp"
+                android:layout_height="wrap_content"
+                android:text="@string/download_title_section"
+                android:layout_marginBottom="16dp"
+                app:layout_constraintEnd_toStartOf="@+id/downloaded_go_back_image_view"
+                app:layout_constraintStart_toStartOf="parent"
+                app:layout_constraintTop_toTopOf="parent" />
+
+            <ImageView
+                android:id="@+id/downloaded_go_back_image_view"
+                android:layout_width="24dp"
+                android:layout_height="24dp"
+                android:layout_marginHorizontal="12dp"
+                android:layout_gravity="center"
+                android:background="@drawable/ic_arrow_back"
+                app:layout_constraintBottom_toBottomOf="@+id/downloaded_text_view_refreshable"
+                app:layout_constraintEnd_toStartOf="@id/downloaded_group_by_image_view"
+                app:layout_constraintTop_toTopOf="@+id/downloaded_text_view_refreshable" />
+
+            <ImageView
+                android:id="@+id/downloaded_group_by_image_view"
+                android:layout_width="24dp"
+                android:layout_height="24dp"
+                android:layout_gravity="center"
+                android:background="@drawable/ic_filter_list"
+                app:layout_constraintBottom_toBottomOf="@+id/downloaded_text_view_refreshable"
+                app:layout_constraintEnd_toEndOf="parent"
+                app:layout_constraintTop_toTopOf="@+id/downloaded_text_view_refreshable" />
+
+            <androidx.recyclerview.widget.RecyclerView
+                android:id="@+id/downloaded_recycler_view"
                 android:layout_width="match_parent"
                 android:layout_height="wrap_content"
-                android:orientation="vertical">
+                android:clipToPadding="false"
-
+                android:nestedScrollingEnabled="false"
-                <TextView
+                android:paddingBottom="8dp"
-                    android:id="@+id/downloaded_tracks_text_view_refreshable"
+                app:layout_constraintBottom_toBottomOf="parent"
-                    style="@style/TitleLarge"
+                app:layout_constraintEnd_toEndOf="parent"
-                    android:layout_width="match_parent"
+                app:layout_constraintStart_toStartOf="parent"
-                    android:layout_height="wrap_content"
+                app:layout_constraintTop_toBottomOf="@id/downloaded_text_view_refreshable" />
-                    android:layout_marginBottom="8dp"
-                    android:paddingStart="16dp"
-                    android:paddingTop="16dp"
-                    android:paddingEnd="16dp"
-                    android:text="@string/download_title_section" />
-
-                <androidx.recyclerview.widget.RecyclerView
-                    android:id="@+id/downloaded_tracks_recycler_view"
-                    android:layout_width="match_parent"
-                    android:layout_height="wrap_content"
-                    android:clipToPadding="false"
-                    android:nestedScrollingEnabled="false"
-                    android:paddingBottom="8dp" />
-            </LinearLayout>
 
             <include
-                android:id="@+id/download_downloaded_tracks_placeholder"
+                android:id="@+id/download_downloaded_placeholder"
                 layout="@layout/item_placeholder_horizontal"
-                android:visibility="gone" />
+                android:visibility="gone"
-        </LinearLayout>
+                app:layout_constraintEnd_toEndOf="parent"
+                app:layout_constraintStart_toStartOf="parent"
+                app:layout_constraintTop_toBottomOf="@id/downloaded_text_view_refreshable" />
+
+        </androidx.constraintlayout.widget.ConstraintLayout>
     </androidx.core.widget.NestedScrollView>
 </androidx.coordinatorlayout.widget.CoordinatorLayout>
 

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

@@ -3,8 +3,7 @@
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
     android:clipChildren="false"
-    android:orientation="horizontal"
+    android:orientation="horizontal">
-    android:paddingStart="16dp">
 
     <LinearLayout
         android:id="@+id/divider"
@@ -17,7 +16,7 @@
         app:layout_constraintTop_toTopOf="parent">
 
         <TextView
-            android:id="@+id/downloaded_song_album_text_view"
+            android:id="@+id/downloaded_item_pre_text_view"
             style="@style/LabelExtraSmall"
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
@@ -28,8 +27,20 @@
             android:layout_gravity="center_vertical" />
     </LinearLayout>
 
+    <ImageView
+        android:id="@+id/item_cover_image_view"
+        android:layout_width="52dp"
+        android:layout_height="52dp"
+        android:layout_gravity="center"
+        android:layout_marginTop="8dp"
+        android:layout_marginEnd="12dp"
+        app:layout_constraintEnd_toStartOf="@id/downloaded_item_title_text_view"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toBottomOf="@+id/divider" />
+
     <TextView
-        android:id="@+id/downloaded_song_title_text_view"
+        android:id="@+id/downloaded_item_title_text_view"
         style="@style/LabelMedium"
         android:layout_width="0dp"
         android:layout_height="wrap_content"
@@ -37,12 +48,14 @@
         android:paddingEnd="12dp"
         android:singleLine="true"
         android:text="@string/label_placeholder"
-        app:layout_constraintEnd_toStartOf="@+id/downloaded_song_more_button"
+        app:layout_constraintVertical_chainStyle="packed"
-        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintEnd_toStartOf="@+id/downloaded_item_more_button"
-        app:layout_constraintTop_toBottomOf="@+id/divider" />
+        app:layout_constraintStart_toEndOf="@+id/item_cover_image_view"
+        app:layout_constraintTop_toTopOf="@+id/item_cover_image_view"
+        app:layout_constraintBottom_toTopOf="@id/downloaded_item_subtitle_text_view"/>
 
     <TextView
-        android:id="@+id/downloaded_song_artist_text_view"
+        android:id="@+id/downloaded_item_subtitle_text_view"
         style="@style/LabelSmall"
         android:layout_width="0dp"
         android:layout_height="wrap_content"
@@ -51,16 +64,15 @@
         android:paddingBottom="6dp"
         android:singleLine="true"
         android:text="@string/label_placeholder"
-        app:layout_constraintEnd_toStartOf="@+id/downloaded_song_more_button"
+        app:layout_constraintTop_toBottomOf="@id/downloaded_item_title_text_view"
-        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintEnd_toStartOf="@+id/downloaded_item_more_button"
-        app:layout_constraintTop_toBottomOf="@+id/downloaded_song_title_text_view" />
+        app:layout_constraintStart_toStartOf="@+id/downloaded_item_title_text_view"
+        app:layout_constraintBottom_toBottomOf="@+id/item_cover_image_view" />
 
     <ImageView
-        android:id="@+id/downloaded_song_more_button"
+        android:id="@+id/downloaded_item_more_button"
         android:layout_width="18dp"
         android:layout_height="18dp"
-        android:layout_marginHorizontal="12dp"
-        android:layout_marginTop="10dp"
         android:background="@drawable/ic_more_vert"
         android:foreground="?android:attr/selectableItemBackgroundBorderless"
         app:layout_constraintBottom_toBottomOf="parent"

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

@@ -55,6 +55,8 @@
     <string name="delete_download_storage_dialog_title">Delete saved items</string>
     <string name="download_info_empty_subtitle">Once you download a song, you\'ll find it here</string>
     <string name="download_info_empty_title">No downloads yet!</string>
+    <string name="download_item_multiple_subtitle_formatter">%1$s  •  %2$s items</string>
+    <string name="download_item_single_subtitle_formatter">%1$s items</string>
     <string name="download_title_section">Downloads</string>
     <string name="download_storage_internal_dialog_negative_button">Internal</string>
     <string name="download_storage_external_dialog_positive_button">External</string>
@@ -280,4 +282,9 @@
     <string name="description_empty_title">No description available</string>
     <string name="menu_filter_download">Downloaded</string>
     <string name="menu_filter_all">All</string>
+    <string name="menu_group_by_track">Track</string>
+    <string name="menu_group_by_album">Album</string>
+    <string name="menu_group_by_artist">Artist</string>
+    <string name="menu_group_by_genre">Genre</string>
+    <string name="menu_group_by_year">Year</string>
 </resources>