implement hasNext for LoadMessageProcedure

app/src/main/java/chat/rocket/android/helper/MethodCallHelper.java

@@ -202,7 +202,9 @@ public class MethodCallHelper {
             if (timestamp == 0) {
               realm.where(Message.class).equalTo("rid", roomId).findAll().deleteAllFromRealm();
             }
-            realm.createOrUpdateAllFromJson(Message.class, messages);
+            if (messages.length() > 0) {
+              realm.createOrUpdateAllFromJson(Message.class, messages);
+            }
             return null;
           });
         });

app/src/main/java/chat/rocket/android/model/ddp/Message.java

 package chat.rocket.android.model.ddp;
 
+import chat.rocket.android.model.SyncState;
 import io.realm.RealmList;
 import io.realm.RealmObject;
 import io.realm.annotations.PrimaryKey;
@@ -12,9 +13,12 @@ import org.json.JSONObject;
 @SuppressWarnings({"PMD.ShortClassName", "PMD.ShortVariable",
     "PMD.MethodNamingConventions", "PMD.VariableNamingConventions"})
 public class Message extends RealmObject {
+  //ref: Rocket.Chat:packages/rocketchat-lib/lib/MessageTypes.coffee
+
   @PrimaryKey private String _id;
   private String t; //type:
   private String rid; //roomId.
+  private int syncstate;
   private long ts;
   private String msg;
   private User u;
@@ -22,11 +26,90 @@ public class Message extends RealmObject {
   private RealmList<MessageAttachment> attachments;
   private RealmList<MessageUrl> urls;
 
+  public String get_id() {
+    return _id;
+  }
+
+  public void set_id(String _id) {
+    this._id = _id;
+  }
+
+  public String getT() {
+    return t;
+  }
+
+  public void setT(String t) {
+    this.t = t;
+  }
+
+  public String getRid() {
+    return rid;
+  }
+
+  public void setRid(String rid) {
+    this.rid = rid;
+  }
+
+  public int getSyncstate() {
+    return syncstate;
+  }
+
+  public void setSyncstate(int syncstate) {
+    this.syncstate = syncstate;
+  }
+
+  public long getTs() {
+    return ts;
+  }
+
+  public void setTs(long ts) {
+    this.ts = ts;
+  }
+
+  public String getMsg() {
+    return msg;
+  }
+
+  public void setMsg(String msg) {
+    this.msg = msg;
+  }
+
+  public User getU() {
+    return u;
+  }
+
+  public void setU(User u) {
+    this.u = u;
+  }
+
+  public boolean isGroupable() {
+    return groupable;
+  }
+
+  public void setGroupable(boolean groupable) {
+    this.groupable = groupable;
+  }
+
+  public RealmList<MessageAttachment> getAttachments() {
+    return attachments;
+  }
+
+  public void setAttachments(RealmList<MessageAttachment> attachments) {
+    this.attachments = attachments;
+  }
+
+  public RealmList<MessageUrl> getUrls() {
+    return urls;
+  }
+
+  public void setUrls(RealmList<MessageUrl> urls) {
+    this.urls = urls;
+  }
 
   public static JSONObject customizeJson(JSONObject messageJson) throws JSONException {
     long ts = messageJson.getJSONObject("ts").getLong("$date");
     messageJson.remove("ts");
-    messageJson.put("ts", ts);
+    messageJson.put("ts", ts).put("syncstate", SyncState.SYNCED);
 
     return messageJson;
   }

app/src/main/java/chat/rocket/android/service/observer/LoadMessageProcedureObserver.java

@@ -5,10 +5,13 @@ import bolts.Task;
 import chat.rocket.android.helper.MethodCallHelper;
 import chat.rocket.android.model.LoadMessageProcedure;
 import chat.rocket.android.model.SyncState;
+import chat.rocket.android.model.ddp.Message;
 import chat.rocket.android.ws.RocketChatWebSocketAPI;
 import io.realm.Realm;
 import io.realm.RealmResults;
+import io.realm.Sort;
 import java.util.List;
+import jp.co.crowdworks.realm_java_helpers.RealmHelper;
 import jp.co.crowdworks.realm_java_helpers_bolts.RealmHelperBolts;
 import org.json.JSONObject;
 import timber.log.Timber;
@@ -51,11 +54,21 @@ public class LoadMessageProcedureObserver extends AbstractModelObserver<LoadMess
             .put("syncstate", SyncState.SYNCING))
     ).onSuccessTask(task ->
         methodCall.loadHistory(roomId, isReset ? 0 : timestamp, count, lastSeen)
-            .onSuccessTask(_task ->
-                RealmHelperBolts.executeTransaction(realm ->
-                    realm.createOrUpdateObjectFromJson(LoadMessageProcedure.class, new JSONObject()
-                        .put("roomId", roomId)
-                        .put("syncstate", SyncState.SYNCED))))
+            .onSuccessTask(_task -> {
+              Message lastMessage = RealmHelper.executeTransactionForRead(realm ->
+                  realm.where(Message.class)
+                      .equalTo("rid", roomId)
+                      .equalTo("syncstate", SyncState.SYNCED)
+                      .findAllSorted("ts", Sort.ASCENDING).last(null));
+              long lastTs = lastMessage != null ? lastMessage.getTs() : 0;
+              return RealmHelperBolts.executeTransaction(realm ->
+                  realm.createOrUpdateObjectFromJson(LoadMessageProcedure.class, new JSONObject()
+                      .put("roomId", roomId)
+                      .put("syncstate", SyncState.SYNCED)
+                      .put("timestamp", lastTs)
+                      .put("hasNext", lastTs > 0))
+              );
+            })
     ).continueWithTask(task -> {
       if (task.isFaulted()) {
         Timber.w(task.getError());