feature: Guild member avatars (closes #557)

Author: queer

src/main/java/com/mewna/catnip/entity/guild/Member.java

@@ -35,7 +35,9 @@
 import com.mewna.catnip.entity.partials.Permissable;
 import com.mewna.catnip.entity.user.User;
 import com.mewna.catnip.entity.user.VoiceState;
+import com.mewna.catnip.entity.util.ImageOptions;
 import com.mewna.catnip.entity.util.Permission;
+import com.mewna.catnip.util.CDNFormat;
 import com.mewna.catnip.util.PermissionUtil;
 import com.mewna.catnip.util.rx.RxHelpers;
 import io.reactivex.rxjava3.core.Completable;
@@ -196,6 +198,23 @@ default Maybe<VoiceState> voiceState() {
     @CheckReturnValue
     OffsetDateTime premiumSince();
 
+    /**
+     * @return The hash of the user's per-guild avatar.
+     */
+    @Nullable
+    @CheckReturnValue
+    String avatarHash();
+    
+    @Nullable
+    @CheckReturnValue
+    default String avatarUrl(@Nonnull final ImageOptions options) {
+        if(avatarHash() == null) {
+            return null;
+        }
+        //noinspection ConstantConditions
+        return CDNFormat.guildAvatarUrl(guildId(), id(), avatarHash(), options);
+    }
+    
     /**
      * The member's color, as shown in the official Discord Client, or {@code null} if they have no roles with a color.
      * <br>This will iterate over all the roles this member has, so try to avoid calling this method multiple times

src/main/java/com/mewna/catnip/entity/impl/EntityBuilder.java

@@ -728,6 +728,7 @@ public Member createMember(@Nonnull final String guildId, @Nonnull final String
                 .roleIds(toStringSet(data.getArray("roles")))
                 .joinedAt(joinedAt)
                 .premiumSince(data.getString("premium_since", null))
+                .avatarHash(data.getString("avatar"))
                 .build());
     }
 

src/main/java/com/mewna/catnip/entity/impl/guild/MemberImpl.java

@@ -58,6 +58,7 @@ public class MemberImpl implements Member, RequiresCatnip, Timestamped {
     private Set<String> roleIds;
     private String joinedAt;
     private String premiumSince;
+    private String avatarHash;
 
     @Nonnull
     @Override

src/main/java/com/mewna/catnip/util/CDNFormat.java

@@ -138,4 +138,11 @@ public static String roleIconUrl(@Nonnull final String roleId, @Nonnull final St
                                      @Nonnull final ImageOptions options) {
         return options.buildUrl(String.format("https://cdn.discordapp.com/role-icons/%s/%s", roleId, iconHash));
     }
+    
+    @Nonnull
+    @CheckReturnValue
+    public static String guildAvatarUrl(@Nonnull final String guildId, @Nonnull final String userId,
+                                        @Nonnull final String hash, @Nonnull final ImageOptions options) {
+        return options.buildUrl(String.format("https://cdn.discordapp.com/guilds/%s/%s/%s", guildId, userId, hash));
+    }
 }