diff --git a/app/src/main/java/org/mercury_im/messenger/android/crypto/ikey/AndroidIkeyBackupCreationViewModel.java b/app/src/main/java/org/mercury_im/messenger/android/crypto/ikey/AndroidIkeyBackupCreationViewModel.java
index 1af6853..e5ce334 100644
--- a/app/src/main/java/org/mercury_im/messenger/android/crypto/ikey/AndroidIkeyBackupCreationViewModel.java
+++ b/app/src/main/java/org/mercury_im/messenger/android/crypto/ikey/AndroidIkeyBackupCreationViewModel.java
@@ -6,20 +6,15 @@ import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
 import androidx.lifecycle.ViewModel;
 
-import org.bouncycastle.openpgp.PGPException;
-import org.jivesoftware.smack.SmackException;
-import org.jivesoftware.smack.XMPPException;
 import org.jivesoftware.smackx.ox.OpenPgpSecretKeyBackupPassphrase;
-import org.jivesoftware.smackx.pubsub.PubSubException;
 import org.mercury_im.messenger.android.MercuryImApplication;
-import org.mercury_im.messenger.android.ui.MercuryAndroidViewModel;
+import org.mercury_im.messenger.android.ui.base.MercuryAndroidViewModel;
 import org.mercury_im.messenger.android.util.QrCodeGenerator;
 import org.mercury_im.messenger.core.SchedulersFacade;
 import org.mercury_im.messenger.core.crypto.OpenPgpSecretKeyBackupPassphraseGenerator;
 import org.mercury_im.messenger.core.util.Optional;
 import org.mercury_im.messenger.core.viewmodel.ikey.IkeySecretKeyBackupCreationViewModel;
 
-import java.io.IOException;
 import java.util.UUID;
 import java.util.logging.Level;
 import java.util.logging.Logger;
diff --git a/app/src/main/java/org/mercury_im/messenger/android/ui/account/detail/AccountDetailsActivity.java b/app/src/main/java/org/mercury_im/messenger/android/ui/account/detail/AccountDetailsActivity.java
index 36c6670..fea1fed 100644
--- a/app/src/main/java/org/mercury_im/messenger/android/ui/account/detail/AccountDetailsActivity.java
+++ b/app/src/main/java/org/mercury_im/messenger/android/ui/account/detail/AccountDetailsActivity.java
@@ -1,7 +1,6 @@
 package org.mercury_im.messenger.android.ui.account.detail;
 
 import android.os.Bundle;
-import android.view.Menu;
 
 import androidx.annotation.Nullable;
 import androidx.appcompat.app.AppCompatActivity;
@@ -9,7 +8,7 @@ import androidx.appcompat.widget.Toolbar;
 
 import org.mercury_im.messenger.R;
 import org.mercury_im.messenger.android.crypto.ikey.IkeyBackupCreationFragment;
-import org.mercury_im.messenger.android.ui.MercuryActivity;
+import org.mercury_im.messenger.android.ui.base.MercuryActivity;
 import org.mercury_im.messenger.android.ui.account.login.IkeyBackupRestoreOrSkipFragment;
 import org.mercury_im.messenger.android.ui.account.login.IkeyKeyInfoFragment;
 import org.mercury_im.messenger.android.ui.account.login.IkeySetupNavigator;
diff --git a/app/src/main/java/org/mercury_im/messenger/android/ui/account/detail/AndroidAccountDetailsViewModel.java b/app/src/main/java/org/mercury_im/messenger/android/ui/account/detail/AndroidAccountDetailsViewModel.java
index 2a69d5c..f8bab10 100644
--- a/app/src/main/java/org/mercury_im/messenger/android/ui/account/detail/AndroidAccountDetailsViewModel.java
+++ b/app/src/main/java/org/mercury_im/messenger/android/ui/account/detail/AndroidAccountDetailsViewModel.java
@@ -10,15 +10,13 @@ import androidx.lifecycle.ViewModel;
 import androidx.lifecycle.ViewModelProvider;
 
 import org.jxmpp.jid.EntityBareJid;
-import org.jxmpp.jid.impl.JidCreate;
 import org.mercury_im.messenger.android.MercuryImApplication;
-import org.mercury_im.messenger.android.ui.MercuryAndroidViewModel;
+import org.mercury_im.messenger.android.ui.base.MercuryAndroidViewModel;
 import org.mercury_im.messenger.core.SchedulersFacade;
 import org.mercury_im.messenger.core.util.DefaultUtil;
 import org.mercury_im.messenger.core.util.Optional;
 import org.mercury_im.messenger.core.viewmodel.account.detail.AccountDetailsViewModel;
 import org.mercury_im.messenger.core.viewmodel.openpgp.FingerprintViewItem;
-import org.mercury_im.messenger.entity.Account;
 import org.pgpainless.key.OpenPgpV4Fingerprint;
 
 import java.util.ArrayList;
@@ -30,8 +28,6 @@ import java.util.logging.Logger;
 
 import javax.inject.Inject;
 
-import io.reactivex.Completable;
-
 public class AndroidAccountDetailsViewModel extends AndroidViewModel implements MercuryAndroidViewModel<AccountDetailsViewModel> {
 
     private static final Logger LOGGER = Logger.getLogger(AndroidAccountDetailsViewModel.class.getName());
diff --git a/app/src/main/java/org/mercury_im/messenger/android/ui/account/list/AndroidAccountListViewModel.java b/app/src/main/java/org/mercury_im/messenger/android/ui/account/list/AndroidAccountListViewModel.java
index ac83778..d66d330 100644
--- a/app/src/main/java/org/mercury_im/messenger/android/ui/account/list/AndroidAccountListViewModel.java
+++ b/app/src/main/java/org/mercury_im/messenger/android/ui/account/list/AndroidAccountListViewModel.java
@@ -10,7 +10,7 @@ import androidx.lifecycle.MutableLiveData;
 import org.mercury_im.messenger.android.MercuryImApplication;
 import org.mercury_im.messenger.core.viewmodel.account.list.AccountViewItem;
 import org.mercury_im.messenger.entity.Account;
-import org.mercury_im.messenger.android.ui.MercuryAndroidViewModel;
+import org.mercury_im.messenger.android.ui.base.MercuryAndroidViewModel;
 import org.mercury_im.messenger.core.viewmodel.account.list.AccountListViewModel;
 
 import java.util.Collections;
diff --git a/app/src/main/java/org/mercury_im/messenger/android/ui/account/login/AndroidIkeyInfoViewModel.java b/app/src/main/java/org/mercury_im/messenger/android/ui/account/login/AndroidIkeyInfoViewModel.java
index be2b32d..b961b2a 100644
--- a/app/src/main/java/org/mercury_im/messenger/android/ui/account/login/AndroidIkeyInfoViewModel.java
+++ b/app/src/main/java/org/mercury_im/messenger/android/ui/account/login/AndroidIkeyInfoViewModel.java
@@ -9,7 +9,7 @@ import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
 
 import org.mercury_im.messenger.android.MercuryImApplication;
-import org.mercury_im.messenger.android.ui.MercuryAndroidViewModel;
+import org.mercury_im.messenger.android.ui.base.MercuryAndroidViewModel;
 import org.mercury_im.messenger.android.ui.openpgp.OpenPgpV4FingerprintFormatter;
 import org.mercury_im.messenger.core.util.Optional;
 import org.mercury_im.messenger.core.viewmodel.ikey.IkeyInfoViewModel;
diff --git a/app/src/main/java/org/mercury_im/messenger/android/ui/account/login/AndroidIkeySetupViewModel.java b/app/src/main/java/org/mercury_im/messenger/android/ui/account/login/AndroidIkeySetupViewModel.java
index 7b15c1c..95bcfeb 100644
--- a/app/src/main/java/org/mercury_im/messenger/android/ui/account/login/AndroidIkeySetupViewModel.java
+++ b/app/src/main/java/org/mercury_im/messenger/android/ui/account/login/AndroidIkeySetupViewModel.java
@@ -1,8 +1,6 @@
 package org.mercury_im.messenger.android.ui.account.login;
 
 import android.app.Application;
-import android.graphics.Path;
-import android.widget.Toast;
 
 import androidx.annotation.NonNull;
 import androidx.lifecycle.AndroidViewModel;
@@ -13,9 +11,8 @@ import org.bouncycastle.openpgp.PGPException;
 import org.jivesoftware.smackx.ox.OpenPgpSecretKeyBackupPassphrase;
 import org.jivesoftware.smackx.ox.element.SecretkeyElement;
 import org.jivesoftware.smackx.ox.exception.InvalidBackupCodeException;
-import org.mercury_im.messenger.R;
 import org.mercury_im.messenger.android.MercuryImApplication;
-import org.mercury_im.messenger.android.ui.MercuryAndroidViewModel;
+import org.mercury_im.messenger.android.ui.base.MercuryAndroidViewModel;
 import org.mercury_im.messenger.core.util.Optional;
 import org.mercury_im.messenger.core.viewmodel.ikey.IkeySetupViewModel;
 
diff --git a/app/src/main/java/org/mercury_im/messenger/android/ui/account/login/AndroidLoginViewModel.java b/app/src/main/java/org/mercury_im/messenger/android/ui/account/login/AndroidLoginViewModel.java
index 76156ab..c3a7544 100644
--- a/app/src/main/java/org/mercury_im/messenger/android/ui/account/login/AndroidLoginViewModel.java
+++ b/app/src/main/java/org/mercury_im/messenger/android/ui/account/login/AndroidLoginViewModel.java
@@ -8,7 +8,7 @@ import androidx.lifecycle.MutableLiveData;
 
 import org.mercury_im.messenger.R;
 import org.mercury_im.messenger.android.MercuryImApplication;
-import org.mercury_im.messenger.android.ui.MercuryAndroidViewModel;
+import org.mercury_im.messenger.android.ui.base.MercuryAndroidViewModel;
 import org.mercury_im.messenger.android.util.TextChangedListener;
 import org.mercury_im.messenger.core.account.error.PasswordError;
 import org.mercury_im.messenger.core.account.error.UsernameError;
diff --git a/app/src/main/java/org/mercury_im/messenger/android/ui/account/login/IkeyKeyInfoFragment.java b/app/src/main/java/org/mercury_im/messenger/android/ui/account/login/IkeyKeyInfoFragment.java
index 0c17004..dddbb49 100644
--- a/app/src/main/java/org/mercury_im/messenger/android/ui/account/login/IkeyKeyInfoFragment.java
+++ b/app/src/main/java/org/mercury_im/messenger/android/ui/account/login/IkeyKeyInfoFragment.java
@@ -1,6 +1,5 @@
 package org.mercury_im.messenger.android.ui.account.login;
 
-import android.content.Context;
 import android.os.Bundle;
 import android.view.LayoutInflater;
 import android.view.View;
diff --git a/app/src/main/java/org/mercury_im/messenger/android/ui/MercuryActivity.java b/app/src/main/java/org/mercury_im/messenger/android/ui/base/MercuryActivity.java
similarity index 89%
rename from app/src/main/java/org/mercury_im/messenger/android/ui/MercuryActivity.java
rename to app/src/main/java/org/mercury_im/messenger/android/ui/base/MercuryActivity.java
index c317b2c..65d0934 100644
--- a/app/src/main/java/org/mercury_im/messenger/android/ui/MercuryActivity.java
+++ b/app/src/main/java/org/mercury_im/messenger/android/ui/base/MercuryActivity.java
@@ -1,4 +1,4 @@
-package org.mercury_im.messenger.android.ui;
+package org.mercury_im.messenger.android.ui.base;
 
 import android.content.Intent;
 import android.os.Bundle;
diff --git a/app/src/main/java/org/mercury_im/messenger/android/ui/MercuryAndroidViewModel.java b/app/src/main/java/org/mercury_im/messenger/android/ui/base/MercuryAndroidViewModel.java
similarity index 89%
rename from app/src/main/java/org/mercury_im/messenger/android/ui/MercuryAndroidViewModel.java
rename to app/src/main/java/org/mercury_im/messenger/android/ui/base/MercuryAndroidViewModel.java
index 0e984f0..10d9c29 100644
--- a/app/src/main/java/org/mercury_im/messenger/android/ui/MercuryAndroidViewModel.java
+++ b/app/src/main/java/org/mercury_im/messenger/android/ui/base/MercuryAndroidViewModel.java
@@ -1,4 +1,4 @@
-package org.mercury_im.messenger.android.ui;
+package org.mercury_im.messenger.android.ui.base;
 
 import org.mercury_im.messenger.core.viewmodel.MercuryViewModel;
 
diff --git a/app/src/main/java/org/mercury_im/messenger/android/ui/chat/AndroidChatViewModel.java b/app/src/main/java/org/mercury_im/messenger/android/ui/chat/AndroidChatViewModel.java
index 665396d..7b6058d 100644
--- a/app/src/main/java/org/mercury_im/messenger/android/ui/chat/AndroidChatViewModel.java
+++ b/app/src/main/java/org/mercury_im/messenger/android/ui/chat/AndroidChatViewModel.java
@@ -4,35 +4,19 @@ import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
 import androidx.lifecycle.ViewModel;
 
-import org.jxmpp.jid.EntityBareJid;
 import org.mercury_im.messenger.android.MercuryImApplication;
-import org.mercury_im.messenger.android.ui.MercuryAndroidViewModel;
-import org.mercury_im.messenger.core.Messenger;
+import org.mercury_im.messenger.android.ui.base.MercuryAndroidViewModel;
 import org.mercury_im.messenger.core.SchedulersFacade;
-import org.mercury_im.messenger.core.data.repository.DirectChatRepository;
-import org.mercury_im.messenger.core.data.repository.MessageRepository;
-import org.mercury_im.messenger.core.data.repository.PeerRepository;
-import org.mercury_im.messenger.core.util.Optional;
 import org.mercury_im.messenger.core.viewmodel.chat.ChatViewModel;
-import org.mercury_im.messenger.data.repository.RxMessageRepository;
 import org.mercury_im.messenger.entity.chat.DirectChat;
 import org.mercury_im.messenger.entity.contact.Peer;
 import org.mercury_im.messenger.entity.message.Message;
 
 import java.util.List;
 import java.util.UUID;
-import java.util.logging.Level;
-import java.util.logging.Logger;
 
 import javax.inject.Inject;
 
-import io.reactivex.Completable;
-import io.reactivex.Observable;
-import io.reactivex.android.schedulers.AndroidSchedulers;
-import io.reactivex.disposables.CompositeDisposable;
-import io.reactivex.disposables.Disposable;
-import io.reactivex.schedulers.Schedulers;
-
 public class AndroidChatViewModel extends ViewModel implements MercuryAndroidViewModel<ChatViewModel> {
 
     @Inject
diff --git a/app/src/main/java/org/mercury_im/messenger/android/ui/chat/ChatActivity.java b/app/src/main/java/org/mercury_im/messenger/android/ui/chat/ChatActivity.java
index 3799936..616c7c1 100644
--- a/app/src/main/java/org/mercury_im/messenger/android/ui/chat/ChatActivity.java
+++ b/app/src/main/java/org/mercury_im/messenger/android/ui/chat/ChatActivity.java
@@ -16,7 +16,7 @@ import androidx.recyclerview.widget.RecyclerView;
 
 import org.mercury_im.messenger.android.MercuryImApplication;
 import org.mercury_im.messenger.R;
-import org.mercury_im.messenger.android.ui.MercuryActivity;
+import org.mercury_im.messenger.android.ui.base.MercuryActivity;
 import org.mercury_im.messenger.android.util.ArgumentUtils;
 import org.mercury_im.messenger.entity.contact.Peer;
 import org.mercury_im.messenger.android.ui.contacts.detail.ContactDetailActivity;
@@ -25,7 +25,6 @@ import java.util.UUID;
 
 import butterknife.BindView;
 import butterknife.ButterKnife;
-import io.reactivex.disposables.CompositeDisposable;
 import lombok.Value;
 
 public class ChatActivity extends AppCompatActivity
diff --git a/app/src/main/java/org/mercury_im/messenger/android/ui/chatlist/AndroidChatListViewModel.java b/app/src/main/java/org/mercury_im/messenger/android/ui/chatlist/AndroidChatListViewModel.java
index b4b468a..d4dfb40 100644
--- a/app/src/main/java/org/mercury_im/messenger/android/ui/chatlist/AndroidChatListViewModel.java
+++ b/app/src/main/java/org/mercury_im/messenger/android/ui/chatlist/AndroidChatListViewModel.java
@@ -6,10 +6,9 @@ import androidx.annotation.NonNull;
 import androidx.lifecycle.AndroidViewModel;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
-import androidx.lifecycle.ViewModel;
 
 import org.mercury_im.messenger.android.MercuryImApplication;
-import org.mercury_im.messenger.android.ui.MercuryAndroidViewModel;
+import org.mercury_im.messenger.android.ui.base.MercuryAndroidViewModel;
 import org.mercury_im.messenger.core.SchedulersFacade;
 import org.mercury_im.messenger.core.data.repository.DirectChatRepository;
 import org.mercury_im.messenger.core.viewmodel.chat.ChatListViewModel;
@@ -20,8 +19,6 @@ import java.util.List;
 
 import javax.inject.Inject;
 
-import io.reactivex.disposables.CompositeDisposable;
-
 public class AndroidChatListViewModel extends AndroidViewModel implements MercuryAndroidViewModel<ChatListViewModel> {
 
     @Inject
diff --git a/app/src/main/java/org/mercury_im/messenger/android/ui/contacts/AndroidContactListViewModel.java b/app/src/main/java/org/mercury_im/messenger/android/ui/contacts/AndroidContactListViewModel.java
index 8f7a380..0c179a4 100644
--- a/app/src/main/java/org/mercury_im/messenger/android/ui/contacts/AndroidContactListViewModel.java
+++ b/app/src/main/java/org/mercury_im/messenger/android/ui/contacts/AndroidContactListViewModel.java
@@ -8,7 +8,7 @@ import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
 
 import org.mercury_im.messenger.android.MercuryImApplication;
-import org.mercury_im.messenger.android.ui.MercuryAndroidViewModel;
+import org.mercury_im.messenger.android.ui.base.MercuryAndroidViewModel;
 import org.mercury_im.messenger.core.Messenger;
 import org.mercury_im.messenger.core.viewmodel.roster.ContactListViewModel;
 import org.mercury_im.messenger.entity.Account;
diff --git a/app/src/main/java/org/mercury_im/messenger/android/ui/contacts/detail/ContactDetailActivity.java b/app/src/main/java/org/mercury_im/messenger/android/ui/contacts/detail/ContactDetailActivity.java
index 7f518d8..e38f170 100644
--- a/app/src/main/java/org/mercury_im/messenger/android/ui/contacts/detail/ContactDetailActivity.java
+++ b/app/src/main/java/org/mercury_im/messenger/android/ui/contacts/detail/ContactDetailActivity.java
@@ -1,7 +1,6 @@
 package org.mercury_im.messenger.android.ui.contacts.detail;
 
 import android.os.Bundle;
-import android.widget.FrameLayout;
 
 import androidx.annotation.Nullable;
 import androidx.appcompat.app.AppCompatActivity;
@@ -9,12 +8,11 @@ import androidx.lifecycle.ViewModelProvider;
 
 import org.mercury_im.messenger.android.MercuryImApplication;
 import org.mercury_im.messenger.R;
-import org.mercury_im.messenger.android.ui.MercuryActivity;
+import org.mercury_im.messenger.android.ui.base.MercuryActivity;
 import org.mercury_im.messenger.android.util.ArgumentUtils;
 
 import java.util.UUID;
 
-import butterknife.BindView;
 import butterknife.ButterKnife;
 import lombok.Value;
 
diff --git a/app/src/main/java/org/mercury_im/messenger/android/ui/openpgp/AndroidOxSecretKeyBackupRestoreViewModel.java b/app/src/main/java/org/mercury_im/messenger/android/ui/openpgp/AndroidOxSecretKeyBackupRestoreViewModel.java
index fb14ae5..0288e70 100644
--- a/app/src/main/java/org/mercury_im/messenger/android/ui/openpgp/AndroidOxSecretKeyBackupRestoreViewModel.java
+++ b/app/src/main/java/org/mercury_im/messenger/android/ui/openpgp/AndroidOxSecretKeyBackupRestoreViewModel.java
@@ -6,8 +6,7 @@ import androidx.annotation.NonNull;
 import androidx.lifecycle.AndroidViewModel;
 import androidx.lifecycle.MutableLiveData;
 
-import org.mercury_im.messenger.android.MercuryImApplication;
-import org.mercury_im.messenger.android.ui.MercuryAndroidViewModel;
+import org.mercury_im.messenger.android.ui.base.MercuryAndroidViewModel;
 import org.mercury_im.messenger.core.util.Optional;
 import org.mercury_im.messenger.core.viewmodel.openpgp.OxBackupRestoreError;
 import org.mercury_im.messenger.core.viewmodel.openpgp.OxSecretKeyBackupRestoreViewModel;
@@ -15,8 +14,6 @@ import org.mercury_im.messenger.core.viewmodel.openpgp.OxSecretKeyBackupRestoreV
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
-import javax.inject.Inject;
-
 public class AndroidOxSecretKeyBackupRestoreViewModel extends AndroidViewModel
         implements MercuryAndroidViewModel<OxSecretKeyBackupRestoreViewModel> {