Guard against starting multiple instances of IntroActivity or AuthActivity

Apparently onResume of MainActivity is sometimes called even if it's not the top
level activity, causing IntroActivity or AuthActivity to be launched twice. This
patch (uglily) prevents that from happening.

app/src/main/java/com/beemdevelopment/aegis/ui/MainActivity.java

@@ -20,6 +20,7 @@ import android.view.View;
 import android.widget.LinearLayout;
 import android.widget.Toast;
 
+import androidx.annotation.NonNull;
 import androidx.appcompat.view.ActionMode;
 import androidx.appcompat.widget.SearchView;
 
@@ -76,6 +77,9 @@ public class MainActivity extends AegisActivity implements EntryListView.Listene
     private String _selectedGroup;
     private boolean _searchSubmitted;
 
+    private boolean _isAuthenticating;
+    private boolean _isDoingIntro;
+
     private List<VaultEntry> _selectedEntries;
     private ActionMode _actionMode;
 
@@ -92,13 +96,16 @@ public class MainActivity extends AegisActivity implements EntryListView.Listene
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_main);
 
         _app = (AegisApplication) getApplication();
         _vault = _app.getVaultManager();
         _loaded = false;
 
-        // set up the main view
-        setContentView(R.layout.activity_main);
+        if (savedInstanceState != null) {
+            _isAuthenticating = savedInstanceState.getBoolean("isAuthenticating");
+            _isDoingIntro = savedInstanceState.getBoolean("isDoingIntro");
+        }
 
         // set up the entry view
         _entryListView = (EntryListView) getSupportFragmentManager().findFragmentById(R.id.key_profiles);
@@ -137,6 +144,13 @@ public class MainActivity extends AegisActivity implements EntryListView.Listene
         _selectedEntries = new ArrayList<>();
     }
 
+    @Override
+    protected void onSaveInstanceState(@NonNull Bundle outState) {
+        super.onSaveInstanceState(outState);
+        outState.putBoolean("isAuthenticating", _isAuthenticating);
+        outState.putBoolean("isDoingIntro", _isDoingIntro);
+    }
+
     @Override
     protected void onDestroy() {
         _entryListView.setListener(null);
@@ -162,6 +176,9 @@ public class MainActivity extends AegisActivity implements EntryListView.Listene
 
     @Override
     protected void onActivityResult(int requestCode, int resultCode, Intent data) {
+        _isAuthenticating = false;
+        _isDoingIntro = false;
+
         if (resultCode != RESULT_OK) {
             return;
         }
@@ -449,12 +466,13 @@ public class MainActivity extends AegisActivity implements EntryListView.Listene
 
         if (_vault == null) {
             // start the intro if the vault file doesn't exist
-            if (!VaultManager.fileExists(this)) {
+            if (!_isDoingIntro && !VaultManager.fileExists(this)) {
                 if (getPreferences().isIntroDone()) {
                     Toast.makeText(this, getString(R.string.vault_not_found), Toast.LENGTH_SHORT).show();
                 }
                 Intent intro = new Intent(this, IntroActivity.class);
                 startActivityForResult(intro, CODE_DO_INTRO);
+                _isDoingIntro = true;
                 return;
             }
 
@@ -635,10 +653,13 @@ public class MainActivity extends AegisActivity implements EntryListView.Listene
     }
 
     private void startAuthActivity(boolean inhibitBioPrompt) {
-        Intent intent = new Intent(this, AuthActivity.class);
-        intent.putExtra("cancelAction", CancelAction.KILL);
-        intent.putExtra("inhibitBioPrompt", inhibitBioPrompt);
-        startActivityForResult(intent, CODE_DECRYPT);
+        if (!_isAuthenticating) {
+            Intent intent = new Intent(this, AuthActivity.class);
+            intent.putExtra("cancelAction", CancelAction.KILL);
+            intent.putExtra("inhibitBioPrompt", inhibitBioPrompt);
+            startActivityForResult(intent, CODE_DECRYPT);
+            _isAuthenticating = true;
+        }
     }
 
     private void updateLockIcon() {