[PeerTube] Add utility methods to get avatars and banners of accounts and channels

Four new static methods have been added in PeertubeParsingHelper to do so:
- two public methods to get the corresponding image type:
  getAvatarsFromOwnerAccountOrVideoChannelObject(String, JsonObject) and
  getBannersFromAccountOrVideoChannelObject(String, JsonObject);
- two private methods as helper methods: getImagesFromAvatarsOrBanners(String,
  JsonObject, String, String) and getImagesFromAvatarOrBannerArray(String,
  JsonArray).

extractor/src/main/java/org/schabi/newpipe/extractor/services/peertube/PeertubeParsingHelper.java

@@ -3,6 +3,8 @@ package org.schabi.newpipe.extractor.services.peertube;
 import com.grack.nanojson.JsonArray;
 import com.grack.nanojson.JsonObject;
 
+import org.schabi.newpipe.extractor.Image;
+import org.schabi.newpipe.extractor.Image.ResolutionLevel;
 import org.schabi.newpipe.extractor.InfoItemExtractor;
 import org.schabi.newpipe.extractor.InfoItemsCollector;
 import org.schabi.newpipe.extractor.Page;
@@ -14,12 +16,20 @@ import org.schabi.newpipe.extractor.services.peertube.extractors.PeertubeSepiaSt
 import org.schabi.newpipe.extractor.services.peertube.extractors.PeertubeStreamInfoItemExtractor;
 import org.schabi.newpipe.extractor.utils.JsonUtils;
 import org.schabi.newpipe.extractor.utils.Parser;
-import org.schabi.newpipe.extractor.utils.Utils;
 
+import javax.annotation.Nonnull;
 import java.time.Instant;
 import java.time.OffsetDateTime;
 import java.time.ZoneOffset;
 import java.time.format.DateTimeParseException;
+import java.util.Collections;
+import java.util.List;
+import java.util.stream.Collectors;
+
+import static org.schabi.newpipe.extractor.Image.HEIGHT_UNKNOWN;
+import static org.schabi.newpipe.extractor.Image.WIDTH_UNKNOWN;
+import static org.schabi.newpipe.extractor.utils.Utils.isBlank;
+import static org.schabi.newpipe.extractor.utils.Utils.isNullOrEmpty;
 
 public final class PeertubeParsingHelper {
     public static final String START_KEY = "start";
@@ -32,7 +42,7 @@ public final class PeertubeParsingHelper {
 
     public static void validate(final JsonObject json) throws ContentNotAvailableException {
         final String error = json.getString("error");
-        if (!Utils.isBlank(error)) {
+        if (!isBlank(error)) {
             throw new ContentNotAvailableException(error);
         }
     }
@@ -53,7 +63,7 @@ public final class PeertubeParsingHelper {
         } catch (final Parser.RegexException e) {
             return null;
         }
-        if (Utils.isBlank(prevStart)) {
+        if (isBlank(prevStart)) {
             return null;
         }
 
@@ -128,4 +138,138 @@ public final class PeertubeParsingHelper {
         }
     }
 
+    /**
+     * Get avatars from a {@code ownerAccount} or a {@code videoChannel} {@link JsonObject}.
+     *
+     * <p>
+     * If the {@code avatars} {@link JsonArray} is present and non null or empty, avatars will be
+     * extracted from this array using {@link #getImagesFromAvatarOrBannerArray(String, JsonArray)}.
+     * </p>
+     *
+     * <p>
+     * If that's not the case, an avatar will extracted using the {@code avatar} {@link JsonObject}.
+     * </p>
+     *
+     * <p>
+     * Note that only images for which paths are not null and not empty will be added to the
+     * unmodifiable {@link Image} list returned.
+     * </p>
+     *
+     * @param baseUrl                          the base URL of the PeerTube instance
+     * @param ownerAccountOrVideoChannelObject the {@code ownerAccount} or {@code videoChannel}
+     *                                         {@link JsonObject}
+     * @return an unmodifiable list of {@link Image}s, which may be empty but never null
+     */
+    @Nonnull
+    public static List<Image> getAvatarsFromOwnerAccountOrVideoChannelObject(
+            @Nonnull final String baseUrl,
+            @Nonnull final JsonObject ownerAccountOrVideoChannelObject) {
+        return getImagesFromAvatarsOrBanners(baseUrl, ownerAccountOrVideoChannelObject,
+                "avatars", "avatar");
+    }
+
+    /**
+     * Get banners from a {@code ownerAccount} or a {@code videoChannel} {@link JsonObject}.
+     *
+     * <p>
+     * If the {@code banners} {@link JsonArray} is present and non null or empty, banners will be
+     * extracted from this array using {@link #getImagesFromAvatarOrBannerArray(String, JsonArray)}.
+     * </p>
+     *
+     * <p>
+     * If that's not the case, a banner will extracted using the {@code banner} {@link JsonObject}.
+     * </p>
+     *
+     * <p>
+     * Note that only images for which paths are not null and not empty will be added to the
+     * unmodifiable {@link Image} list returned.
+     * </p>
+     *
+     * @param baseUrl                          the base URL of the PeerTube instance
+     * @param ownerAccountOrVideoChannelObject the {@code ownerAccount} or {@code videoChannel}
+     *                                         {@link JsonObject}
+     * @return an unmodifiable list of {@link Image}s, which may be empty but never null
+     */
+    @Nonnull
+    public static List<Image> getBannersFromAccountOrVideoChannelObject(
+            @Nonnull final String baseUrl,
+            @Nonnull final JsonObject ownerAccountOrVideoChannelObject) {
+        return getImagesFromAvatarsOrBanners(baseUrl, ownerAccountOrVideoChannelObject,
+                "banners", "banner");
+    }
+
+    /**
+     * Utility method to get avatars and banners from video channels and accounts from given name
+     * keys.
+     *
+     * <p>
+     * Only images for which paths are not null and not empty will be added to the unmodifiable
+     * {@link Image} list returned and only the width of avatars or banners is provided by the API,
+     * and so is the only image dimension known.
+     * </p>
+     *
+     * @param baseUrl                          the base URL of the PeerTube instance
+     * @param ownerAccountOrVideoChannelObject the {@code ownerAccount} or {@code videoChannel}
+     *                                         {@link JsonObject}
+     * @param jsonArrayName                    the key name of the {@link JsonArray} to which
+     *                                         extract all images available ({@code avatars} or
+     *                                         {@code banners})
+     * @param jsonObjectName                   the key name of the {@link JsonObject} to which
+     *                                         extract a single image ({@code avatar} or
+     *                                         {@code banner}), used as a fallback if the images
+     *                                         {@link JsonArray} is null or empty
+     * @return an unmodifiable list of {@link Image}s, which may be empty but never null
+     */
+    @Nonnull
+    private static List<Image> getImagesFromAvatarsOrBanners(
+            @Nonnull final String baseUrl,
+            @Nonnull final JsonObject ownerAccountOrVideoChannelObject,
+            @Nonnull final String jsonArrayName,
+            @Nonnull final String jsonObjectName) {
+        final JsonArray images = ownerAccountOrVideoChannelObject.getArray(jsonArrayName);
+
+        if (!isNullOrEmpty(images))  {
+            return getImagesFromAvatarOrBannerArray(baseUrl, images);
+        }
+
+        final JsonObject image = ownerAccountOrVideoChannelObject.getObject(jsonObjectName);
+        final String path = image.getString("path");
+        if (!isNullOrEmpty(path)) {
+            return List.of(new Image(baseUrl + path, HEIGHT_UNKNOWN,
+                    image.getInt("width", WIDTH_UNKNOWN), ResolutionLevel.UNKNOWN));
+        }
+
+        return List.of();
+    }
+
+    /**
+     * Get {@link Image}s from an {@code avatars} or a {@code banners} {@link JsonArray}.
+     *
+     * <p>
+     * Only images for which paths are not null and not empty will be added to the
+     * unmodifiable {@link Image} list returned.
+     * </p>
+     *
+     * <p>
+     * Note that only the width of avatars or banners is provided by the API, and so only is the
+     * only dimension known of images.
+     * </p>
+     *
+     * @param baseUrl               the base URL of the PeerTube instance from which the
+     *                              {@code avatarsOrBannersArray} {@link JsonArray} comes from
+     * @param avatarsOrBannersArray an {@code avatars} or {@code banners} {@link JsonArray}
+     * @return an unmodifiable list of {@link Image}s, which may be empty but never null
+     */
+    @Nonnull
+    private static List<Image> getImagesFromAvatarOrBannerArray(
+            @Nonnull final String baseUrl,
+            @Nonnull final JsonArray avatarsOrBannersArray) {
+        return avatarsOrBannersArray.stream()
+                .filter(JsonObject.class::isInstance)
+                .map(JsonObject.class::cast)
+                .filter(image -> !isNullOrEmpty(image.getString("path")))
+                .map(image -> new Image(baseUrl + image.getString("path"), HEIGHT_UNKNOWN,
+                        image.getInt("width", WIDTH_UNKNOWN), ResolutionLevel.UNKNOWN))
+                .collect(Collectors.toUnmodifiableList());
+    }
 }