fix :Back Pressed Event not work in Explore tab when user not login (commons-app#4404)

* fix :Back Pressed Event not work in Explore tab

* minor changes

Author: Prince-kushwaha

app/src/main/java/fr/free/nrw/commons/contributions/MainActivity.java

@@ -281,7 +281,11 @@ public void onBackPressed() {
             }
         } else if (exploreFragment != null && activeFragment == ActiveFragment.EXPLORE) {
             // Means that explore fragment is visible
-            exploreFragment.onBackPressed();
+            if (!exploreFragment.onBackPressed()) {
+                if (applicationKvStore.getBoolean("login_skipped")) {
+                    super.onBackPressed();
+                }
+            }
         } else if (bookmarkFragment != null && activeFragment == ActiveFragment.BOOKMARK) {
             // Means that bookmark fragment is visible
             bookmarkFragment.onBackPressed();

app/src/main/java/fr/free/nrw/commons/explore/ExploreFragment.java

@@ -17,10 +17,13 @@
 import fr.free.nrw.commons.ViewPagerAdapter;
 import fr.free.nrw.commons.contributions.MainActivity;
 import fr.free.nrw.commons.di.CommonsDaggerSupportFragment;
+import fr.free.nrw.commons.kvstore.JsonKvStore;
 import fr.free.nrw.commons.theme.BaseActivity;
 import fr.free.nrw.commons.utils.ActivityUtils;
 import java.util.ArrayList;
 import java.util.List;
+import javax.inject.Inject;
+import javax.inject.Named;
 
 public class ExploreFragment extends CommonsDaggerSupportFragment {
 
@@ -35,6 +38,9 @@ public class ExploreFragment extends CommonsDaggerSupportFragment {
     ViewPagerAdapter viewPagerAdapter;
     private ExploreListRootFragment featuredRootFragment;
     private ExploreListRootFragment mobileRootFragment;
+    @Inject
+    @Named("default_preferences")
+    public JsonKvStore applicationKvStore;
 
     public void setScroll(boolean canScroll){
         viewPager.setCanScroll(canScroll);
@@ -95,20 +101,21 @@ public void setTabs() {
         viewPagerAdapter.notifyDataSetChanged();
     }
 
-    public void onBackPressed() {
+    public boolean onBackPressed() {
         if (tabLayout.getSelectedTabPosition() == 0) {
-            if(featuredRootFragment.backPressed()){
-                // Event is handled by the Fragment we need not do anything.
-                return;
+            if (featuredRootFragment.backPressed()) {
+                ((BaseActivity) getActivity()).getSupportActionBar()
+                    .setDisplayHomeAsUpEnabled(false);
+                return true;
             }
         } else {
-            if(mobileRootFragment.backPressed()){
-                // Event is handled by the Fragment we need not do anything.
-                return;
+            if (mobileRootFragment.backPressed()) {
+                ((BaseActivity) getActivity()).getSupportActionBar()
+                    .setDisplayHomeAsUpEnabled(false);
+                return true;
             }
         }
-        // Event is not handled by the fragment ( i.e performed back action ) therefore change action bar.
-        ((BaseActivity)getActivity()).getSupportActionBar().setDisplayHomeAsUpEnabled(false);
+        return false;
     }
 
     /**

app/src/main/java/fr/free/nrw/commons/explore/ExploreListRootFragment.java

@@ -2,7 +2,6 @@
 
 import android.content.Context;
 import android.os.Bundle;
-import android.os.Handler;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
@@ -182,20 +181,23 @@ public void viewPagerNotifyDataSetChanged() {
    * @return
    */
   public boolean backPressed() {
-    if (null!=mediaDetails && mediaDetails.isVisible()) {
+    if (null != mediaDetails && mediaDetails.isVisible()) {
       // todo add get list fragment
-      if(mediaDetails.backButtonClicked()) {
+      if (mediaDetails.backButtonClicked()) {
         // MediaDetails handled the event no further action required.
         return true;
+      } else {
+        ((ExploreFragment) getParentFragment()).tabLayout.setVisibility(View.VISIBLE);
+        removeFragment(mediaDetails);
+        ((ExploreFragment) getParentFragment()).setScroll(true);
+        setFragment(listFragment, mediaDetails);
+        ((MainActivity) getActivity()).showTabs();
+        return true;
       }
-      ((ExploreFragment)getParentFragment()).tabLayout.setVisibility(View.VISIBLE);
-      removeFragment(mediaDetails);
-      ((ExploreFragment) getParentFragment()).setScroll(true);
-      setFragment(listFragment, mediaDetails);
     } else {
       ((MainActivity) getActivity()).setSelectedItemId(NavTab.CONTRIBUTIONS.code());
     }
-    ((MainActivity)getActivity()).showTabs();
+    ((MainActivity) getActivity()).showTabs();
     return false;
   }
 }