ui: fix back button

Since commit d701f4f0, the back button behaviour has been
broken. We restored the  previous backstack management system.
When cliking the back button, the app displays home. If you are home,
the app closes.

Tuleap: #1162
Change-Id: I919a2697b376d3a54150f6560ba543f2d5d99b8a

ring-android/app/src/main/java/cx/ring/client/HomeActivity.java

@@ -415,14 +415,21 @@ public class HomeActivity extends AppCompatActivity implements LocalService.Call
             mNavigationDrawer.closeDrawer(GravityCompat.START);
             return;
         }
-        super.onBackPressed();
-        FragmentManager fm = getFragmentManager();
-        int count = fm.getBackStackEntryCount();
-        if (count == 0) {
-            fContent = fm.findFragmentByTag(HOME_TAG);
-        } else {
-            FragmentManager.BackStackEntry entry = fm.getBackStackEntryAt(count - 1);
-            fContent = fm.findFragmentById(entry.getId());
+        if (getFragmentManager().getBackStackEntryCount() > 1) {
+            popCustomBackStack();
+            fMenu.getMenu().findItem(R.id.menuitem_home).setChecked(true);
+            return;
+        }
+
+        finish();
+    }
+
+    private void popCustomBackStack() {
+        FragmentManager fragmentManager = getFragmentManager();
+        FragmentManager.BackStackEntry entry = fragmentManager.getBackStackEntryAt(0);
+        fContent = fragmentManager.findFragmentByTag(entry.getName());
+        for (int i = 0; i < fragmentManager.getBackStackEntryCount() - 1; ++i) {
+            fragmentManager.popBackStack();
         }
     }
 
@@ -467,7 +474,7 @@ public class HomeActivity extends AppCompatActivity implements LocalService.Call
             fContent = fragmentManager.findFragmentById(R.id.main_frame);
             if (fContent == null) {
                 fContent = new SmartListFragment();
-                fragmentManager.beginTransaction().replace(R.id.main_frame, fContent, HOME_TAG).addToBackStack(HOME_TAG).commitAllowingStateLoss();
+                fragmentManager.beginTransaction().replace(R.id.main_frame, fContent, HOME_TAG).addToBackStack(HOME_TAG).commit();
             } else if (fContent instanceof Refreshable) {
                 fragmentManager.beginTransaction().replace(R.id.main_frame, fContent).addToBackStack(HOME_TAG).commit();
                 ((Refreshable) fContent).refresh();
@@ -542,8 +549,11 @@ public class HomeActivity extends AppCompatActivity implements LocalService.Call
                 if (fContent instanceof SmartListFragment) {
                     break;
                 }
-                while (getFragmentManager().popBackStackImmediate()) {
+                if (getFragmentManager().getBackStackEntryCount() == 1) {
+                    break;
                 }
+
+                popCustomBackStack();
                 fContent = getFragmentManager().findFragmentByTag(HOME_TAG);
                 break;
             case R.id.menuitem_accounts:
@@ -551,14 +561,20 @@ public class HomeActivity extends AppCompatActivity implements LocalService.Call
                     break;
                 }
                 fContent = new AccountsManagementFragment();
-                getFragmentManager().beginTransaction().setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE).replace(R.id.main_frame, fContent, ACCOUNTS_TAG).addToBackStack(ACCOUNTS_TAG).commit();
+                getFragmentManager().beginTransaction()
+                        .setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE)
+                        .replace(R.id.main_frame, fContent, ACCOUNTS_TAG)
+                        .addToBackStack(ACCOUNTS_TAG).commit();
                 break;
             case R.id.menuitem_about:
                 if (fContent instanceof AboutFragment) {
                     break;
                 }
                 fContent = new AboutFragment();
-                getFragmentManager().beginTransaction().setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE).replace(R.id.main_frame, fContent, ABOUT_TAG).addToBackStack(ABOUT_TAG).commit();
+                getFragmentManager().beginTransaction()
+                        .setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE)
+                        .replace(R.id.main_frame, fContent, ABOUT_TAG)
+                        .addToBackStack(ABOUT_TAG).commit();
                 break;
             case R.id.menuitem_prefs:
                 this.goToSettings();
@@ -585,7 +601,10 @@ public class HomeActivity extends AppCompatActivity implements LocalService.Call
         Bundle args = new Bundle();
         args.putString(ShareFragment.ARG_URI, fMenuHead.getSelectedAccount().getShareURI());
         fContent.setArguments(args);
-        getFragmentManager().beginTransaction().setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE).replace(R.id.main_frame, fContent, SHARE_TAG).addToBackStack(SHARE_TAG).commit();
+        getFragmentManager().beginTransaction()
+                .setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE)
+                .replace(R.id.main_frame, fContent, SHARE_TAG)
+                .addToBackStack(SHARE_TAG).commit();
     }
 
     public void goToSettings() {
@@ -606,8 +625,7 @@ public class HomeActivity extends AppCompatActivity implements LocalService.Call
                 .beginTransaction()
                 .setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE)
                 .replace(R.id.main_frame, fContent, SETTINGS_TAG)
-                .addToBackStack(SETTINGS_TAG)
-                .commit();
+                .addToBackStack(SETTINGS_TAG).commit();
     }
 
     @Override