Add support for comment replies

app/src/main/java/org/schabi/newpipe/MainActivity.java

@@ -44,13 +44,15 @@
 import android.widget.Spinner;
 
 import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 import androidx.appcompat.app.ActionBar;
 import androidx.appcompat.app.ActionBarDrawerToggle;
 import androidx.appcompat.app.AppCompatActivity;
 import androidx.core.app.ActivityCompat;
 import androidx.core.view.GravityCompat;
 import androidx.drawerlayout.widget.DrawerLayout;
 import androidx.fragment.app.Fragment;
+import androidx.fragment.app.FragmentContainerView;
 import androidx.fragment.app.FragmentManager;
 import androidx.preference.PreferenceManager;
 
@@ -64,11 +66,13 @@
 import org.schabi.newpipe.error.ErrorUtil;
 import org.schabi.newpipe.extractor.NewPipe;
 import org.schabi.newpipe.extractor.StreamingService;
+import org.schabi.newpipe.extractor.comments.CommentsInfoItem;
 import org.schabi.newpipe.extractor.exceptions.ExtractionException;
 import org.schabi.newpipe.extractor.services.peertube.PeertubeInstance;
 import org.schabi.newpipe.fragments.BackPressable;
 import org.schabi.newpipe.fragments.MainFragment;
 import org.schabi.newpipe.fragments.detail.VideoDetailFragment;
+import org.schabi.newpipe.fragments.list.comments.CommentRepliesFragment;
 import org.schabi.newpipe.fragments.list.search.SearchFragment;
 import org.schabi.newpipe.local.feed.notifications.NotificationWorker;
 import org.schabi.newpipe.player.Player;
@@ -546,14 +550,21 @@ public void onBackPressed() {
         // interacts with a fragment inside fragment_holder so all back presses should be
         // handled by it
         if (bottomSheetHiddenOrCollapsed()) {
-            final Fragment fragment = getSupportFragmentManager()
-                    .findFragmentById(R.id.fragment_holder);
+            final FragmentManager fm = getSupportFragmentManager();
+            final Fragment fragment = fm.findFragmentById(R.id.fragment_holder);
             // If current fragment implements BackPressable (i.e. can/wanna handle back press)
             // delegate the back press to it
             if (fragment instanceof BackPressable) {
                 if (((BackPressable) fragment).onBackPressed()) {
                     return;
                 }
+            } else if (fragment instanceof CommentRepliesFragment) {
+                // expand DetailsFragment if CommentRepliesFragment was opened
+                // to show the top level comments again
+                // Expand DetailsFragment if CommentRepliesFragment was opened
+                // and no other CommentRepliesFragments are on top of the back stack
+                // to show the top level comments again.
+                openDetailFragmentFromCommentReplies(fm, false);
             }
 
         } else {
@@ -629,10 +640,17 @@ public void onRequestPermissionsResult(final int requestCode,
      * </pre>
      */
     private void onHomeButtonPressed() {
-        // If search fragment wasn't found in the backstack...
-        if (!NavigationHelper.tryGotoSearchFragment(getSupportFragmentManager())) {
-            // ...go to the main fragment
-            NavigationHelper.gotoMainFragment(getSupportFragmentManager());
+        final FragmentManager fm = getSupportFragmentManager();
+        final Fragment fragment = fm.findFragmentById(R.id.fragment_holder);
+
+        if (fragment instanceof CommentRepliesFragment) {
+            // Expand DetailsFragment if CommentRepliesFragment was opened
+            // and no other CommentRepliesFragments are on top of the back stack
+            // to show the top level comments again.
+            openDetailFragmentFromCommentReplies(fm, true);
+        } else if (!NavigationHelper.tryGotoSearchFragment(fm)) {
+            // If search fragment wasn't found in the backstack go to the main fragment
+            NavigationHelper.gotoMainFragment(fm);
         }
     }
 
@@ -828,6 +846,68 @@ public void onReceive(final Context context, final Intent intent) {
         }
     }
 
+    private void openDetailFragmentFromCommentReplies(
+            @NonNull final FragmentManager fm,
+            final boolean popBackStack
+    ) {
+        // obtain the name of the fragment under the replies fragment that's going to be popped
+        @Nullable final String fragmentUnderEntryName;
+        if (fm.getBackStackEntryCount() < 2) {
+            fragmentUnderEntryName = null;
+        } else {
+            fragmentUnderEntryName = fm.getBackStackEntryAt(fm.getBackStackEntryCount() - 2)
+                    .getName();
+        }
+
+        // the root comment is the comment for which the user opened the replies page
+        @Nullable final CommentRepliesFragment repliesFragment =
+                (CommentRepliesFragment) fm.findFragmentByTag(CommentRepliesFragment.TAG);
+        @Nullable final CommentsInfoItem rootComment =
+                repliesFragment == null ? null : repliesFragment.getCommentsInfoItem();
+
+        // sometimes this function pops the backstack, other times it's handled by the system
+        if (popBackStack) {
+            fm.popBackStackImmediate();
+        }
+
+        // only expand the bottom sheet back if there are no more nested comment replies fragments
+        // stacked under the one that is currently being popped
+        if (CommentRepliesFragment.TAG.equals(fragmentUnderEntryName)) {
+            return;
+        }
+
+        final BottomSheetBehavior<FragmentContainerView> behavior = BottomSheetBehavior
+                .from(mainBinding.fragmentPlayerHolder);
+        // do not return to the comment if the details fragment was closed
+        if (behavior.getState() == BottomSheetBehavior.STATE_HIDDEN) {
+            return;
+        }
+
+        // scroll to the root comment once the bottom sheet expansion animation is finished
+        behavior.addBottomSheetCallback(new BottomSheetBehavior.BottomSheetCallback() {
+            @Override
+            public void onStateChanged(@NonNull final View bottomSheet,
+                                       final int newState) {
+                if (newState == BottomSheetBehavior.STATE_EXPANDED) {
+                    final Fragment detailFragment = fm.findFragmentById(
+                            R.id.fragment_player_holder);
+                    if (detailFragment instanceof VideoDetailFragment && rootComment != null) {
+                        // should always be the case
+                        ((VideoDetailFragment) detailFragment).scrollToComment(rootComment);
+                    }
+                    behavior.removeBottomSheetCallback(this);
+                }
+            }
+
+            @Override
+            public void onSlide(@NonNull final View bottomSheet, final float slideOffset) {
+                // not needed, listener is removed once the sheet is expanded
+            }
+        });
+
+        behavior.setState(BottomSheetBehavior.STATE_EXPANDED);
+    }
+
     private boolean bottomSheetHiddenOrCollapsed() {
         final BottomSheetBehavior<FrameLayout> bottomSheetBehavior =
                 BottomSheetBehavior.from(mainBinding.fragmentPlayerHolder);

app/src/main/java/org/schabi/newpipe/error/UserAction.java

@@ -19,6 +19,7 @@ public enum UserAction {
     REQUESTED_PLAYLIST("requested playlist"),
     REQUESTED_KIOSK("requested kiosk"),
     REQUESTED_COMMENTS("requested comments"),
+    REQUESTED_COMMENT_REPLIES("requested comment replies"),
     REQUESTED_FEED("requested feed"),
     REQUESTED_BOOKMARK("bookmark"),
     DELETE_FROM_HISTORY("delete from history"),

app/src/main/java/org/schabi/newpipe/fragments/detail/VideoDetailFragment.java

@@ -74,6 +74,7 @@
 import org.schabi.newpipe.extractor.Image;
 import org.schabi.newpipe.extractor.InfoItem;
 import org.schabi.newpipe.extractor.NewPipe;
+import org.schabi.newpipe.extractor.comments.CommentsInfoItem;
 import org.schabi.newpipe.extractor.exceptions.ContentNotSupportedException;
 import org.schabi.newpipe.extractor.exceptions.ExtractionException;
 import org.schabi.newpipe.extractor.stream.AudioStream;
@@ -1012,6 +1013,20 @@ public void scrollToTop() {
         updateTabLayoutVisibility();
     }
 
+    public void scrollToComment(final CommentsInfoItem comment) {
+        final int commentsTabPos = pageAdapter.getItemPositionByTitle(COMMENTS_TAB_TAG);
+        final Fragment fragment = pageAdapter.getItem(commentsTabPos);
+        if (!(fragment instanceof CommentsFragment)) {
+            return;
+        }
+
+        // unexpand the app bar only if scrolling to the comment succeeded
+        if (((CommentsFragment) fragment).scrollToComment(comment)) {
+            binding.appBarLayout.setExpanded(false, false);
+            binding.viewPager.setCurrentItem(commentsTabPos, false);
+        }
+    }
+
     /*//////////////////////////////////////////////////////////////////////////
     // Play Utils
     //////////////////////////////////////////////////////////////////////////*/

app/src/main/java/org/schabi/newpipe/fragments/list/BaseListInfoFragment.java

@@ -231,6 +231,8 @@ public void handleResult(@NonNull final L result) {
             if (!result.getRelatedItems().isEmpty()) {
                 infoListAdapter.addInfoItemList(result.getRelatedItems());
                 showListFooter(hasMoreItems());
+            } else if (hasMoreItems()) {
+                loadMoreItems();
             } else {
                 infoListAdapter.clearStreamItemList();
                 showEmptyState();

app/src/main/java/org/schabi/newpipe/fragments/list/comments/CommentRepliesFragment.java

@@ -0,0 +1,168 @@
+package org.schabi.newpipe.fragments.list.comments;
+
+import static org.schabi.newpipe.util.ServiceHelper.getServiceById;
+
+import android.os.Bundle;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.constraintlayout.widget.ConstraintLayout;
+import androidx.core.text.HtmlCompat;
+
+import org.schabi.newpipe.R;
+import org.schabi.newpipe.databinding.CommentRepliesHeaderBinding;
+import org.schabi.newpipe.error.UserAction;
+import org.schabi.newpipe.extractor.ListExtractor;
+import org.schabi.newpipe.extractor.comments.CommentsInfoItem;
+import org.schabi.newpipe.fragments.list.BaseListInfoFragment;
+import org.schabi.newpipe.info_list.ItemViewMode;
+import org.schabi.newpipe.util.DeviceUtils;
+import org.schabi.newpipe.util.ExtractorHelper;
+import org.schabi.newpipe.util.Localization;
+import org.schabi.newpipe.util.NavigationHelper;
+import org.schabi.newpipe.util.image.ImageStrategy;
+import org.schabi.newpipe.util.image.PicassoHelper;
+import org.schabi.newpipe.util.text.TextLinkifier;
+
+import java.util.Queue;
+import java.util.function.Supplier;
+
+import io.reactivex.rxjava3.core.Single;
+import io.reactivex.rxjava3.disposables.CompositeDisposable;
+
+public final class CommentRepliesFragment
+        extends BaseListInfoFragment<CommentsInfoItem, CommentRepliesInfo> {
+
+    public static final String TAG = CommentRepliesFragment.class.getSimpleName();
+
+    private CommentsInfoItem commentsInfoItem; // the comment to show replies of
+    private final CompositeDisposable disposables = new CompositeDisposable();
+
+
+    /*//////////////////////////////////////////////////////////////////////////
+    // Constructors and lifecycle
+    //////////////////////////////////////////////////////////////////////////*/
+
+    // only called by the Android framework, after which readFrom is called and restores all data
+    public CommentRepliesFragment() {
+        super(UserAction.REQUESTED_COMMENT_REPLIES);
+    }
+
+    public CommentRepliesFragment(@NonNull final CommentsInfoItem commentsInfoItem) {
+        this();
+        this.commentsInfoItem = commentsInfoItem;
+        // setting "" as title since the title will be properly set right after
+        setInitialData(commentsInfoItem.getServiceId(), commentsInfoItem.getUrl(), "");
+    }
+
+    @Nullable
+    @Override
+    public View onCreateView(@NonNull final LayoutInflater inflater,
+                             @Nullable final ViewGroup container,
+                             @Nullable final Bundle savedInstanceState) {
+        return inflater.inflate(R.layout.fragment_comments, container, false);
+    }
+
+    @Override
+    public void onDestroyView() {
+        disposables.clear();
+        super.onDestroyView();
+    }
+
+    @Override
+    protected Supplier<View> getListHeaderSupplier() {
+        return () -> {
+            final CommentRepliesHeaderBinding binding = CommentRepliesHeaderBinding
+                    .inflate(activity.getLayoutInflater(), itemsList, false);
+            final CommentsInfoItem item = commentsInfoItem;
+
+            // load the author avatar
+            PicassoHelper.loadAvatar(item.getUploaderAvatars()).into(binding.authorAvatar);
+            binding.authorAvatar.setVisibility(ImageStrategy.shouldLoadImages()
+                    ? View.VISIBLE : View.GONE);
+
+            // setup author name and comment date
+            binding.authorName.setText(item.getUploaderName());
+            binding.uploadDate.setText(Localization.relativeTimeOrTextual(
+                    getContext(), item.getUploadDate(), item.getTextualUploadDate()));
+            binding.authorTouchArea.setOnClickListener(
+                    v -> NavigationHelper.openCommentAuthorIfPresent(requireActivity(), item));
+
+            // setup like count, hearted and pinned
+            binding.thumbsUpCount.setText(
+                    Localization.likeCount(requireContext(), item.getLikeCount()));
+            // for heartImage goneMarginEnd was used, but there is no way to tell ConstraintLayout
+            // not to use a different margin only when both the next two views are gone
+            ((ConstraintLayout.LayoutParams) binding.thumbsUpCount.getLayoutParams())
+                    .setMarginEnd(DeviceUtils.dpToPx(
+                            (item.isHeartedByUploader() || item.isPinned() ? 8 : 16),
+                            requireContext()));
+            binding.heartImage.setVisibility(item.isHeartedByUploader() ? View.VISIBLE : View.GONE);
+            binding.pinnedImage.setVisibility(item.isPinned() ? View.VISIBLE : View.GONE);
+
+            // setup comment content
+            TextLinkifier.fromDescription(binding.commentContent, item.getCommentText(),
+                    HtmlCompat.FROM_HTML_MODE_LEGACY, getServiceById(item.getServiceId()),
+                    item.getUrl(), disposables, null);
+
+            return binding.getRoot();
+        };
+    }
+
+
+    /*//////////////////////////////////////////////////////////////////////////
+    // State saving
+    //////////////////////////////////////////////////////////////////////////*/
+
+    @Override
+    public void writeTo(final Queue<Object> objectsToSave) {
+        super.writeTo(objectsToSave);
+        objectsToSave.add(commentsInfoItem);
+    }
+
+    @Override
+    public void readFrom(@NonNull final Queue<Object> savedObjects) throws Exception {
+        super.readFrom(savedObjects);
+        commentsInfoItem = (CommentsInfoItem) savedObjects.poll();
+    }
+
+
+    /*//////////////////////////////////////////////////////////////////////////
+    // Data loading
+    //////////////////////////////////////////////////////////////////////////*/
+
+    @Override
+    protected Single<CommentRepliesInfo> loadResult(final boolean forceLoad) {
+        return Single.fromCallable(() -> new CommentRepliesInfo(commentsInfoItem,
+                // the reply count string will be shown as the activity title
+                Localization.replyCount(requireContext(), commentsInfoItem.getReplyCount())));
+    }
+
+    @Override
+    protected Single<ListExtractor.InfoItemsPage<CommentsInfoItem>> loadMoreItemsLogic() {
+        // commentsInfoItem.getUrl() should contain the url of the original
+        // ListInfo<CommentsInfoItem>, which should be the stream url
+        return ExtractorHelper.getMoreCommentItems(
+                serviceId, commentsInfoItem.getUrl(), currentNextPage);
+    }
+
+
+    /*//////////////////////////////////////////////////////////////////////////
+    // Utils
+    //////////////////////////////////////////////////////////////////////////*/
+
+    @Override
+    protected ItemViewMode getItemViewMode() {
+        return ItemViewMode.LIST;
+    }
+
+    /**
+     * @return the comment to which the replies are shown
+     */
+    public CommentsInfoItem getCommentsInfoItem() {
+        return commentsInfoItem;
+    }
+}

app/src/main/java/org/schabi/newpipe/fragments/list/comments/CommentRepliesInfo.java

@@ -0,0 +1,22 @@
+package org.schabi.newpipe.fragments.list.comments;
+
+import org.schabi.newpipe.extractor.ListInfo;
+import org.schabi.newpipe.extractor.comments.CommentsInfoItem;
+import org.schabi.newpipe.extractor.linkhandler.ListLinkHandler;
+
+import java.util.Collections;
+
+public final class CommentRepliesInfo extends ListInfo<CommentsInfoItem> {
+    /**
+     * This class is used to wrap the comment replies page into a ListInfo object.
+     *
+     * @param comment the comment from which to get replies
+     * @param name will be shown as the fragment title
+     */
+    public CommentRepliesInfo(final CommentsInfoItem comment, final String name) {
+        super(comment.getServiceId(),
+                new ListLinkHandler("", "", "", Collections.emptyList(), null), name);
+        setNextPage(comment.getReplies());
+        setRelatedItems(Collections.emptyList()); // since it must be non-null
+    }
+}

app/src/main/java/org/schabi/newpipe/fragments/list/comments/CommentsFragment.java

@@ -110,4 +110,14 @@ public void onCreateOptionsMenu(@NonNull final Menu menu,
     protected ItemViewMode getItemViewMode() {
         return ItemViewMode.LIST;
     }
+
+    public boolean scrollToComment(final CommentsInfoItem comment) {
+        final int position = infoListAdapter.getItemsList().indexOf(comment);
+        if (position < 0) {
+            return false;
+        }
+
+        itemsList.scrollToPosition(position);
+        return true;
+    }
 }