Add documentation and fix SonarCloud issue

app/src/main/java/org/schabi/newpipe/database/playlist/model/PlaylistRemoteEntity.java

@@ -70,7 +70,9 @@ public class PlaylistRemoteEntity implements PlaylistLocalItem {
     @Ignore
     public PlaylistRemoteEntity(final PlaylistInfo info) {
         this(info.getServiceId(), info.getName(), info.getUrl(),
-                ImageStrategy.choosePreferredImage(info.getThumbnails()),
+                // use uploader avatar when no thumbnail is available
+                ImageStrategy.choosePreferredImage(info.getThumbnails().isEmpty()
+                        ? info.getUploaderAvatars() : info.getThumbnails()),
                 info.getUploaderName(), info.getStreamCount());
     }
 
@@ -84,6 +86,8 @@ public class PlaylistRemoteEntity implements PlaylistLocalItem {
                 && getStreamCount() == info.getStreamCount()
                 && TextUtils.equals(getName(), info.getName())
                 && TextUtils.equals(getUrl(), info.getUrl())
+                // we want to update the local playlist data even when either the remote thumbnail
+                // URL changes, or the preferred image quality setting is changed by the user
                 && TextUtils.equals(getThumbnailUrl(),
                 ImageStrategy.choosePreferredImage(info.getThumbnails()))
                 && TextUtils.equals(getUploader(), info.getUploaderName());

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

@@ -224,6 +224,7 @@ public abstract class BaseDescriptionFragment extends BaseFragment {
                     case LOW:
                         urls.append(getString(R.string.image_quality_low));
                         break;
+                    default: // unreachable, Image.ResolutionLevel.UNKNOWN is already filtered out
                     case MEDIUM:
                         urls.append(getString(R.string.image_quality_medium));
                         break;

app/src/main/java/org/schabi/newpipe/util/external_communication/ShareUtils.java

@@ -269,8 +269,8 @@ public final class ShareUtils {
      *
      * <p>
      * For Android 10+ users, a content preview is shown, which includes the title of the shared
-     * content and an image preview the content, if its URL is not null or empty and its
+     * content and an image preview the content, if the preferred image chosen by {@link
-     * corresponding image is in the image cache.
+     * ImageStrategy#choosePreferredImage(List)} is in the image cache.
      * </p>
      *
      * @param context the context to use

app/src/main/java/org/schabi/newpipe/util/image/ImageStrategy.java

@@ -38,19 +38,35 @@ public final class ImageStrategy {
                 // images whose size is completely unknown will be in their own subgroups, so
                 // any one of them will do, hence returning the same value for all of them
                 return 0;
-
             } else {
                 return image.getWidth() * image.getWidth() / widthOverHeight;
             }
-
         } else if (image.getWidth() == WIDTH_UNKNOWN) {
             return image.getHeight() * image.getHeight() * widthOverHeight;
-
         } else {
             return image.getHeight() * image.getWidth();
         }
     }
 
+    /**
+     * Chooses an image amongst the provided list based on the user preference previously set with
+     * {@link #setPreferredImageQuality(PreferredImageQuality)}. {@code null} will be returned in
+     * case the list is empty or the user preference is to not show images.
+     * <br>
+     * These properties will be preferred, from most to least important:
+     * <ol>
+     *     <li>The image's {@link Image#getEstimatedResolutionLevel()} is not unknown and is close
+     *     to {@link #preferredImageQuality}</li>
+     *     <li>At least one of the image's width or height are known</li>
+     *     <li>The highest resolution image is finally chosen if the user's preference is {@link
+     *     PreferredImageQuality#HIGH}, otherwise the chosen image is the one that has the closest
+     *     height to {@link #BEST_LOW_H} or {@link #BEST_MEDIUM_H}</li>
+     * </ol>
+     *
+     * @param images the images from which to choose
+     * @return the chosen preferred image, or {@link null} if the list is empty or the user disabled
+     *         images
+     */
     @Nullable
     public static String choosePreferredImage(@NonNull final List<Image> images) {
         if (preferredImageQuality == PreferredImageQuality.NONE) {

app/src/main/java/org/schabi/newpipe/util/image/PicassoHelper.java

@@ -9,6 +9,7 @@ import android.content.Context;
 import android.graphics.Bitmap;
 import android.util.Log;
 
+import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.core.graphics.BitmapCompat;
 
@@ -49,7 +50,7 @@ public final class PicassoHelper {
         picassoCache = new LruCache(10 * 1024 * 1024);
         picassoDownloaderClient = new OkHttpClient.Builder()
                 .cache(new okhttp3.Cache(new File(context.getExternalCacheDir(), "picasso"),
-                        50 * 1024 * 1024))
+                        50L * 1024L * 1024L))
                 // this should already be the default timeout in OkHttp3, but just to be sure...
                 .callTimeout(15, TimeUnit.SECONDS)
                 .build();
@@ -90,50 +91,50 @@ public final class PicassoHelper {
     }
 
 
-    public static RequestCreator loadAvatar(final List<Image> images) {
+    public static RequestCreator loadAvatar(@NonNull final List<Image> images) {
         return loadImageDefault(images, R.drawable.placeholder_person);
     }
 
-    public static RequestCreator loadAvatar(final String url) {
+    public static RequestCreator loadAvatar(@Nullable final String url) {
         return loadImageDefault(url, R.drawable.placeholder_person);
     }
 
-    public static RequestCreator loadThumbnail(final List<Image> images) {
+    public static RequestCreator loadThumbnail(@NonNull final List<Image> images) {
         return loadImageDefault(images, R.drawable.placeholder_thumbnail_video);
     }
 
-    public static RequestCreator loadThumbnail(final String url) {
+    public static RequestCreator loadThumbnail(@Nullable final String url) {
         return loadImageDefault(url, R.drawable.placeholder_thumbnail_video);
     }
 
-    public static RequestCreator loadDetailsThumbnail(final List<Image> images) {
+    public static RequestCreator loadDetailsThumbnail(@NonNull final List<Image> images) {
         return loadImageDefault(choosePreferredImage(images),
                 R.drawable.placeholder_thumbnail_video, false);
     }
 
-    public static RequestCreator loadBanner(final List<Image> images) {
+    public static RequestCreator loadBanner(@NonNull final List<Image> images) {
         return loadImageDefault(images, R.drawable.placeholder_channel_banner);
     }
 
-    public static RequestCreator loadPlaylistThumbnail(final List<Image> images) {
+    public static RequestCreator loadPlaylistThumbnail(@NonNull final List<Image> images) {
         return loadImageDefault(images, R.drawable.placeholder_thumbnail_playlist);
     }
 
-    public static RequestCreator loadPlaylistThumbnail(final String url) {
+    public static RequestCreator loadPlaylistThumbnail(@Nullable final String url) {
         return loadImageDefault(url, R.drawable.placeholder_thumbnail_playlist);
     }
 
-    public static RequestCreator loadSeekbarThumbnailPreview(final String url) {
+    public static RequestCreator loadSeekbarThumbnailPreview(@Nullable final String url) {
         return picassoInstance.load(url);
     }
 
-    public static RequestCreator loadNotificationIcon(final String url) {
+    public static RequestCreator loadNotificationIcon(@Nullable final String url) {
         return loadImageDefault(url, R.drawable.ic_newpipe_triangle_white);
     }
 
 
     public static RequestCreator loadScaledDownThumbnail(final Context context,
-                                                         final List<Image> images) {
+                                                         @NonNull final List<Image> images) {
         // scale down the notification thumbnail for performance
         return PicassoHelper.loadThumbnail(images)
                 .transform(new Transformation() {
@@ -182,18 +183,18 @@ public final class PicassoHelper {
     }
 
     @Nullable
-    public static Bitmap getImageFromCacheIfPresent(final String imageUrl) {
+    public static Bitmap getImageFromCacheIfPresent(@NonNull final String imageUrl) {
         // URLs in the internal cache finish with \n so we need to add \n to image URLs
         return picassoCache.get(imageUrl + "\n");
     }
 
 
-    private static RequestCreator loadImageDefault(final List<Image> images,
+    private static RequestCreator loadImageDefault(@NonNull final List<Image> images,
                                                    final int placeholderResId) {
         return loadImageDefault(choosePreferredImage(images), placeholderResId);
     }
 
-    private static RequestCreator loadImageDefault(final String url,
+    private static RequestCreator loadImageDefault(@Nullable final String url,
                                                    final int placeholderResId) {
         return loadImageDefault(url, placeholderResId, true);
     }