Added functionality for auto night theme.

- Added a checkbox option in menu.
- If auto theme is enabled then irrespective of preffered theme, it
will be overridden by auto theme (depending on time).
- User can switch theme even if auto theme is enabled, but it is for that instance
only.

Author: jainkuniya

app/src/main/java/com/zulip/android/ZulipApp.java

@@ -7,6 +7,7 @@
 import android.content.pm.PackageInfo;
 import android.content.pm.PackageManager.NameNotFoundException;
 import android.os.Handler;
+import android.support.v7.app.AppCompatDelegate;
 import android.util.Log;
 
 import com.crashlytics.android.Crashlytics;
@@ -135,11 +136,13 @@ public void onCreate() {
         if (!BuildConfig.DEBUG)
             Fabric.with(this, new Crashlytics());
         ZulipApp.setInstance(this);
-
         // This used to be from HumbugActivity.getPreferences, so we keep that
         // file name.
         this.settings = getSharedPreferences("HumbugActivity", Context.MODE_PRIVATE);
-
+        //check for auto theme is enabled or not
+        if (getSettings().getBoolean(Constants.AUTO_NIGHT_THEME, false)) {
+            AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_AUTO);
+        }
         max_message_id = settings.getInt("max_message_id", -1);
         eventQueueId = settings.getString("eventQueueId", null);
         lastEventId = settings.getInt("lastEventId", -1);
@@ -609,4 +612,15 @@ public void makeNightThemeDefault(boolean nightTheme) {
         editor.putBoolean(Constants.NIGHT_THEME, nightTheme);
         editor.apply();
     }
+
+    /**
+     * update auto night theme preference
+     * @param value preference value
+     */
+    public void setAutoNightTheme(boolean value) {
+        SharedPreferences.Editor editor = getSettings().edit();
+
+        editor.putBoolean(Constants.AUTO_NIGHT_THEME, value);
+        editor.apply();
+    }
 }

app/src/main/java/com/zulip/android/activities/ZulipActivity.java

@@ -357,7 +357,8 @@ protected void onCreate(Bundle savedInstanceState) {
         boolean isCurrentThemeNight = (AppCompatDelegate.getDefaultNightMode() == AppCompatDelegate.MODE_NIGHT_YES);
 
         //apply preferred theme
-       if (app.getSettings().getBoolean(Constants.NIGHT_THEME, false) && !isCurrentThemeNight) {
+       if (app.getSettings().getBoolean(Constants.NIGHT_THEME, false) && !isCurrentThemeNight
+               && !app.getSettings().getBoolean(Constants.AUTO_NIGHT_THEME,false)) {
             setNightMode(AppCompatDelegate.MODE_NIGHT_YES);
         }
 
@@ -2258,6 +2259,8 @@ public boolean onCreateOptionsMenu(Menu menu) {
             getMenuInflater().inflate(R.menu.options, menu);
             prepareSearchView(menu);
             this.menu = menu;
+            menu.findItem(R.id.autoTheme).setChecked(app.getSettings()
+                    .getBoolean(Constants.AUTO_NIGHT_THEME,false));
             return true;
         }
 
@@ -2373,6 +2376,13 @@ public void onClick(
                         break;
                 }
                 break;
+            case R.id.autoTheme:
+                item.setChecked(!item.isChecked());
+                app.setAutoNightTheme(item.isChecked());
+                if (item.isChecked()) {
+                    setNightMode(AppCompatDelegate.MODE_NIGHT_AUTO);
+                }
+                break;
             case R.id.refresh:
                 Log.w("menu", "Refreshed manually by user. We shouldn't need this.");
                 commonProgressDialog.showWithMessage(getString(R.string.refreshing));

app/src/main/java/com/zulip/android/util/Constants.java

@@ -28,4 +28,5 @@ public class Constants {
     public static long HIDE_TIMESTAMP_THRESHOLD = 60 * 1000;// 1 minute
     public static String ACTION_MESSAGE_PUSH_NOTIFICATION = "ACTION_MESSAGE_PUSH_NOTIFICATION";
     public static String NIGHT_THEME = "NIGHT_THEME";
+    public static String AUTO_NIGHT_THEME = "AUTO_NIGHT_THEME";
 }

app/src/main/res/menu/options.xml

@@ -35,8 +35,20 @@
     </item>
 
     <item
-        android:id="@+id/daynight"
-        android:title="@string/switch_theme" />
+        android:id="@+id/theme"
+        android:title="@string/theme">
+        <menu>
+            <item
+                android:id="@+id/daynight"
+                android:title="@string/switch_theme" />
+            <item
+                android:id="@+id/autoTheme"
+                android:checkable="true"
+                android:title="@string/autoTheme"
+                app:actionViewClass="android.widget.CheckBox" />
+        </menu>
+    </item>
+
     <item
         android:id="@+id/isStarred"
         android:title="@string/starred_messages" />

app/src/main/res/values/strings.xml

@@ -173,13 +173,15 @@
     <string name="no_message_to_display">Sorry, no messages to display!</string>
     <string name="crop">Crop</string>
     <string name="logout_title">Are you sure you want to logout?</string>
+    <string name="autoTheme">Auto Night Theme</string>
+    <string name="theme">Theme</string>
+    <string name="terms">Terms of Service</string>
     <!--Placeholder strings-->
     <string name="placeholder_my_stream">MyStream</string>
     <string name="placeholder_short_stream">Short stream</string>
     <string name="placeholder_topic">Topic</string>
     <string name="placeholder_message_here">Message here</string>
     <string name="placeholder_sender_name">Sender name</string>
     <string name="placeholder_social">Social</string>
-    <!--Placeholder strings-->
-    <string name="terms">Terms of Service</string>
+
 </resources>