implement logic to show the status of current user in Sidebar.

app/src/main/java/chat/rocket/android/activity/MainActivity.java

@@ -59,10 +59,17 @@ public class MainActivity extends AbstractAuthedActivity {
   @Override protected void onServerConfigIdUpdated() {
     super.onServerConfigIdUpdated();
 
+    updateSidebarMainFragment();
+    showServerConfigActivityIfNeeded();
+  }
+
+  private void updateSidebarMainFragment() {
     getSupportFragmentManager().beginTransaction()
         .replace(R.id.sidebar_fragment_container, SidebarMainFragment.create(serverConfigId))
         .commit();
+  }
 
+  private void showServerConfigActivityIfNeeded() {
     if (serverConfigId == null) {
       return;
     }

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

@@ -20,7 +20,6 @@ import org.json.JSONObject;
 
 /**
  * Utility class for creating/handling MethodCall or RPC.
- *
  * TODO: separate method into several manager classes (SubscriptionManager, MessageManager, ...).
  */
 public class MethodCallHelper {

app/src/main/java/chat/rocket/android/fragment/sidebar/SidebarMainFragment.java

@@ -3,16 +3,22 @@ package chat.rocket.android.fragment.sidebar;
 import android.os.Bundle;
 import android.support.annotation.Nullable;
 import android.widget.CompoundButton;
+import android.widget.ImageView;
 import android.widget.LinearLayout;
+import android.widget.TextView;
 import chat.rocket.android.R;
 import chat.rocket.android.RocketChatCache;
 import chat.rocket.android.fragment.AbstractFragment;
 import chat.rocket.android.helper.TextUtils;
 import chat.rocket.android.layouthelper.chatroom.RoomListManager;
+import chat.rocket.android.model.ServerConfig;
 import chat.rocket.android.model.ddp.RoomSubscription;
+import chat.rocket.android.model.ddp.User;
 import chat.rocket.android.realm_helper.RealmHelper;
 import chat.rocket.android.realm_helper.RealmListObserver;
+import chat.rocket.android.realm_helper.RealmObjectObserver;
 import chat.rocket.android.realm_helper.RealmStore;
+import chat.rocket.android.renderer.UserRenderer;
 import com.jakewharton.rxbinding.view.RxView;
 import com.jakewharton.rxbinding.widget.RxCompoundButton;
 
@@ -20,11 +26,16 @@ public class SidebarMainFragment extends AbstractFragment {
 
   private String serverConfigId;
   private RoomListManager roomListManager;
+  private String hostname;
   private RealmListObserver<RoomSubscription> roomsObserver;
+  private RealmObjectObserver<User> currentUserObserver;
 
   public SidebarMainFragment() {
   }
 
+  /**
+   * create SidebarMainFragment with serverConfigId.
+   */
   public static SidebarMainFragment create(String serverConfigId) {
     Bundle args = new Bundle();
     args.putString("serverConfigId", serverConfigId);
@@ -40,11 +51,21 @@ public class SidebarMainFragment extends AbstractFragment {
     Bundle args = getArguments();
     serverConfigId = args == null ? null : args.getString("serverConfigId");
     if (!TextUtils.isEmpty(serverConfigId)) {
+      ServerConfig config = RealmStore.getDefault().executeTransactionForRead(realm ->
+          realm.where(ServerConfig.class).equalTo("serverConfigId", serverConfigId).findFirst());
+      if (config != null) {
+        hostname = config.getHostname();
+      }
+
       RealmHelper realmHelper = RealmStore.get(serverConfigId);
       if (realmHelper != null) {
         roomsObserver = realmHelper
             .createListObserver(realm -> realm.where(RoomSubscription.class).findAll())
             .setOnUpdateListener(list -> roomListManager.setRooms(list));
+
+        currentUserObserver = realmHelper
+            .createObjectObserver(realm -> realm.where(User.class).isNotEmpty("emails"))
+            .setOnUpdateListener(this::updateCurrentUser);
       }
     }
   }
@@ -86,15 +107,26 @@ public class SidebarMainFragment extends AbstractFragment {
         .subscribe(RxView.visibility(rootView.findViewById(R.id.user_action_outer_container)));
   }
 
+  private void updateCurrentUser(User user) {
+    if (user != null && !TextUtils.isEmpty(hostname)) {
+      new UserRenderer(getContext(), user)
+          .avatarInto((ImageView) rootView.findViewById(R.id.current_user_avatar), hostname)
+          .usernameInto((TextView) rootView.findViewById(R.id.current_user_name))
+          .statusColorInto((ImageView) rootView.findViewById(R.id.current_user_status));
+    }
+  }
+
   @Override public void onResume() {
     super.onResume();
     if (roomsObserver != null) {
       roomsObserver.sub();
+      currentUserObserver.sub();
     }
   }
 
   @Override public void onPause() {
     if (roomsObserver != null) {
+      currentUserObserver.unsub();
       roomsObserver.unsub();
     }
     super.onPause();

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

@@ -10,6 +10,11 @@ import io.realm.annotations.PrimaryKey;
 @SuppressWarnings({"PMD.ShortClassName", "PMD.ShortVariable",
     "PMD.MethodNamingConventions", "PMD.VariableNamingConventions"})
 public class User extends RealmObject {
+  public static final String STATUS_ONLINE = "online";
+  public static final String STATUS_BUSY = "busy";
+  public static final String STATUS_AWAY = "away";
+  public static final String STATUS_OFFLINE = "offline";
+
   @PrimaryKey private String _id;
   private String username;
   private String status;

app/src/main/java/chat/rocket/android/renderer/UserRenderer.java

+package chat.rocket.android.renderer;
+
+import android.content.Context;
+import android.widget.ImageView;
+import android.widget.TextView;
+import chat.rocket.android.R;
+import chat.rocket.android.helper.Avatar;
+import chat.rocket.android.model.ddp.User;
+
+/**
+ * Renderer for User model.
+ */
+public class UserRenderer extends AbstractRenderer<User> {
+
+  public UserRenderer(Context context, User user) {
+    super(context, user);
+  }
+
+  /**
+   * show Avatar image.
+   */
+  public UserRenderer avatarInto(ImageView imageView, String hostname) {
+    if (!shouldHandle(imageView)) {
+      return this;
+    }
+
+    new Avatar(hostname, object.getUsername()).into(imageView);
+    return this;
+  }
+
+  /**
+   * show Username in textView.
+   */
+  public UserRenderer usernameInto(TextView textView) {
+    if (!shouldHandle(textView)) {
+      return this;
+    }
+
+    textView.setText(object.getUsername());
+    return this;
+  }
+
+  /**
+   * show user's status color into imageView.
+   */
+  public UserRenderer statusColorInto(ImageView imageView) {
+    if (!shouldHandle(imageView)) {
+      return this;
+    }
+
+    String status = object.getStatus();
+    if (User.STATUS_ONLINE.equals(status)) {
+      imageView.setImageResource(R.drawable.userstatus_online);
+    } else if (User.STATUS_AWAY.equals(status)) {
+      imageView.setImageResource(R.drawable.userstatus_away);
+    } else if (User.STATUS_BUSY.equals(status)) {
+      imageView.setImageResource(R.drawable.userstatus_busy);
+    } else if (User.STATUS_OFFLINE.equals(status)) {
+      imageView.setImageResource(R.drawable.userstatus_offline);
+    } else {
+      // unknown status is rendered as "offline" status.
+      imageView.setImageResource(R.drawable.userstatus_offline);
+    }
+
+    return this;
+  }
+}

app/src/main/res/layout/fragment_sidebar_main.xml

@@ -21,7 +21,7 @@
       >
 
     <ImageView
-        android:id="@+id/img_userstatus"
+        android:id="@+id/current_user_status"
         android:layout_width="8dp"
         android:layout_height="8dp"
         android:src="@drawable/userstatus_online"
@@ -33,7 +33,7 @@
         />
 
     <ImageView
-        android:id="@+id/img_my_avatar"
+        android:id="@+id/current_user_avatar"
         android:layout_width="48dp"
         android:layout_height="48dp"
         />
@@ -47,7 +47,7 @@
         >
 
       <TextView
-          android:id="@+id/txt_account_info"
+          android:id="@+id/current_user_name"
           android:layout_width="match_parent"
           android:layout_height="wrap_content"
           android:layout_gravity="center_vertical"