store roster groups in DB

src/main/java/im/conversations/android/database/dao/RosterDao.java

@@ -6,8 +6,10 @@ import androidx.room.Dao;
 import androidx.room.Insert;
 import androidx.room.Query;
 import androidx.room.Transaction;
+import com.google.common.collect.Collections2;
 import eu.siacs.conversations.xmpp.Jid;
 import im.conversations.android.database.entity.RosterItemEntity;
+import im.conversations.android.database.entity.RosterItemGroupEntity;
 import im.conversations.android.database.model.Account;
 import im.conversations.android.xmpp.model.roster.Item;
 import java.util.Collection;
@@ -33,7 +35,9 @@ public abstract class RosterDao {
         clear(account.id);
         for (final Item item : rosterItems) {
             final long id = insert(RosterItemEntity.of(account.id, item));
-            // TODO insert groups
+            insertRosterGroups(
+                    Collections2.transform(
+                            item.getGroups(), name -> RosterItemGroupEntity.of(id, name)));
         }
         setRosterVersion(account.id, version);
     }
@@ -50,8 +54,13 @@ public abstract class RosterDao {
             }
             final RosterItemEntity entity = RosterItemEntity.of(account.id, item);
             final long id = insert(entity);
-            // TODO groups
+            insertRosterGroups(
+                    Collections2.transform(
+                            item.getGroups(), name -> RosterItemGroupEntity.of(id, name)));
         }
         setRosterVersion(account.id, version);
     }
+
+    @Insert
+    protected abstract void insertRosterGroups(Collection<RosterItemGroupEntity> entities);
 }

src/main/java/im/conversations/android/database/entity/RosterItemGroupEntity.java

@@ -23,4 +23,11 @@ public class RosterItemGroupEntity {
     @NonNull public Long rosterItemId;
 
     public String name;
+
+    public static RosterItemGroupEntity of(long rosterItemId, final String name) {
+        final var entity = new RosterItemGroupEntity();
+        entity.rosterItemId = rosterItemId;
+        entity.name = name;
+        return entity;
+    }
 }

src/main/java/im/conversations/android/xmpp/model/roster/Group.java

@@ -0,0 +1,10 @@
+package im.conversations.android.xmpp.model.roster;
+
+import im.conversations.android.xmpp.model.Extension;
+
+public class Group extends Extension {
+
+    public Group() {
+        super(Group.class);
+    }
+}

src/main/java/im/conversations/android/xmpp/model/roster/Item.java

@@ -1,11 +1,15 @@
 package im.conversations.android.xmpp.model.roster;
 
+import com.google.common.collect.Collections2;
+import eu.siacs.conversations.xml.Element;
 import eu.siacs.conversations.xmpp.Jid;
 import im.conversations.android.annotation.XmlElement;
 import im.conversations.android.xmpp.model.Extension;
 import java.util.Arrays;
+import java.util.Collection;
 import java.util.List;
 import java.util.Locale;
+import java.util.Objects;
 
 @XmlElement
 public class Item extends Extension {
@@ -38,6 +42,12 @@ public class Item extends Extension {
         }
     }
 
+    public Collection<String> getGroups() {
+        return Collections2.filter(
+                Collections2.transform(getExtensions(Group.class), Element::getContent),
+                Objects::nonNull);
+    }
+
     public enum Subscription {
         NONE,
         TO,