Add a secondary control panel to video detail fragment

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

@@ -35,7 +35,7 @@ public void useAsFrontPage(final boolean value) {
     //////////////////////////////////////////////////////////////////////////*/
 
     @Override
-    public void onAttach(final Context context) {
+    public void onAttach(@NonNull final Context context) {
         super.onAttach(context);
         activity = (AppCompatActivity) context;
     }
@@ -61,7 +61,7 @@ public void onCreate(final Bundle savedInstanceState) {
 
 
     @Override
-    public void onViewCreated(final View rootView, final Bundle savedInstanceState) {
+    public void onViewCreated(@NonNull final View rootView, final Bundle savedInstanceState) {
         super.onViewCreated(rootView, savedInstanceState);
         if (DEBUG) {
             Log.d(TAG, "onViewCreated() called with: "
@@ -73,7 +73,7 @@ public void onViewCreated(final View rootView, final Bundle savedInstanceState)
     }
 
     @Override
-    public void onSaveInstanceState(final Bundle outState) {
+    public void onSaveInstanceState(@NonNull final Bundle outState) {
         super.onSaveInstanceState(outState);
         Icepick.saveInstanceState(this, outState);
     }

app/src/main/java/org/schabi/newpipe/fragments/BaseStateFragment.java

@@ -10,6 +10,7 @@
 import android.widget.TextView;
 import android.widget.Toast;
 
+import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.annotation.StringRes;
 
@@ -56,7 +57,7 @@ public abstract class BaseStateFragment<I> extends BaseFragment implements ViewC
     private TextView errorTextView;
 
     @Override
-    public void onViewCreated(final View rootView, final Bundle savedInstanceState) {
+    public void onViewCreated(@NonNull final View rootView, final Bundle savedInstanceState) {
         super.onViewCreated(rootView, savedInstanceState);
         doInitialLoadLogic();
     }

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

@@ -0,0 +1,93 @@
+package org.schabi.newpipe.fragments.detail;
+
+import android.os.Bundle;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.TextView;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.core.text.HtmlCompat;
+
+import org.schabi.newpipe.BaseFragment;
+import org.schabi.newpipe.databinding.FragmentDescriptionBinding;
+import org.schabi.newpipe.extractor.stream.Description;
+import org.schabi.newpipe.extractor.stream.StreamInfo;
+import org.schabi.newpipe.util.Localization;
+import org.schabi.newpipe.util.TextLinkifier;
+
+import icepick.State;
+import io.reactivex.rxjava3.disposables.Disposable;
+
+import static android.text.TextUtils.isEmpty;
+
+public class DescriptionFragment extends BaseFragment {
+
+    @State
+    StreamInfo streamInfo = null;
+    @Nullable
+    Disposable descriptionDisposable = null;
+
+    public DescriptionFragment() {
+    }
+
+    public DescriptionFragment(final StreamInfo streamInfo) {
+        this.streamInfo = streamInfo;
+    }
+
+    @Override
+    public View onCreateView(@NonNull final LayoutInflater inflater,
+                             @Nullable final ViewGroup container,
+                             @Nullable final Bundle savedInstanceState) {
+        final FragmentDescriptionBinding binding =
+                FragmentDescriptionBinding.inflate(inflater, container, false);
+        if (streamInfo != null) {
+            setupUploadDate(binding.detailUploadDateView);
+            setupDescription(binding.detailDescriptionView);
+        }
+        return binding.getRoot();
+    }
+
+    @Override
+    public void onDestroy() {
+        super.onDestroy();
+        if (descriptionDisposable != null) {
+            descriptionDisposable.dispose();
+        }
+    }
+
+    private void setupUploadDate(final TextView uploadDateTextView) {
+        if (streamInfo.getUploadDate() != null) {
+            uploadDateTextView.setText(Localization
+                    .localizeUploadDate(activity, streamInfo.getUploadDate().offsetDateTime()));
+        } else {
+            uploadDateTextView.setVisibility(View.GONE);
+        }
+    }
+
+    private void setupDescription(final TextView descriptionTextView) {
+        final Description description = streamInfo.getDescription();
+        if (description == null || isEmpty(description.getContent())
+                || description == Description.emptyDescription) {
+            descriptionTextView.setText("");
+            return;
+        }
+
+        switch (description.getType()) {
+            case Description.HTML:
+                descriptionDisposable = TextLinkifier.createLinksFromHtmlBlock(requireContext(),
+                        description.getContent(), descriptionTextView,
+                        HtmlCompat.FROM_HTML_MODE_LEGACY);
+                break;
+            case Description.MARKDOWN:
+                descriptionDisposable = TextLinkifier.createLinksFromMarkdownText(requireContext(),
+                        description.getContent(), descriptionTextView);
+                break;
+            case Description.PLAIN_TEXT: default:
+                descriptionDisposable = TextLinkifier.createLinksFromPlainText(requireContext(),
+                        description.getContent(), descriptionTextView);
+                break;
+        }
+    }
+}