Destroy pushed screen if back is pressed during push animation

Closes #3894

lib/android/app/src/main/java/com/reactnativenavigation/anim/NavigationAnimator.java

 
 import java.util.Collection;
 import java.util.Collections;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 
 import static com.reactnativenavigation.utils.CollectionUtils.merge;
 
 public class NavigationAnimator extends BaseAnimator {
 
     private final ElementTransitionManager transitionManager;
+    private Map<View, Animator> runningPushAnimations = new HashMap<>();
 
     public NavigationAnimator(Context context, ElementTransitionManager transitionManager) {
         super(context);
         Collection<Animator> elementTransitions = transitionManager.createTransitions(transitions, fromElements, toElements);
         set.playTogether(merge(push.getChildAnimations(), elementTransitions));
         set.addListener(new AnimatorListenerAdapter() {
+            private boolean isCancelled;
+
             @Override
             public void onAnimationStart(Animator animation) {
                 view.setAlpha(1);
             }
 
             @Override
-            public void onAnimationEnd(Animator animation) {
+            public void onAnimationCancel(Animator animation) {
+                isCancelled = true;
+                runningPushAnimations.remove(view);
                 onAnimationEnd.run();
             }
+
+            @Override
+            public void onAnimationEnd(Animator animation) {
+                if (!isCancelled) {
+                    runningPushAnimations.remove(view);
+                    onAnimationEnd.run();
+                }
+            }
         });
+        runningPushAnimations.put(view, set);
         set.start();
     }
 
     public void pop(View view, NestedAnimationsOptions pop, Runnable onAnimationEnd) {
+        if (runningPushAnimations.containsKey(view)) {
+            runningPushAnimations.get(view).cancel();
+            onAnimationEnd.run();
+            return;
+        }
         AnimatorSet set = pop.content.getAnimation(view, getDefaultPopAnimation(view));
         set.addListener(new AnimatorListenerAdapter() {
+            private boolean cancelled;
+
+            @Override
+            public void onAnimationCancel(Animator animation) {
+                this.cancelled = true;
+            }
+
             @Override
             public void onAnimationEnd(Animator animation) {
-                onAnimationEnd.run();
+                if (!cancelled) onAnimationEnd.run();
             }
         });
         set.start();

lib/android/app/src/main/java/com/reactnativenavigation/viewcontrollers/ViewController.java

     private ViewVisibilityListener viewVisibilityListener = new ViewVisibilityListenerAdapter();
     protected FabOptionsPresenter fabOptionsPresenter;
 
+    public boolean isDestroyed() {
+        return isDestroyed;
+    }
+
     public ViewController(Activity activity, String id, YellowBoxDelegate yellowBoxDelegate, Options initialOptions) {
         this.activity = activity;
         this.id = id;
         }
     }
 
-    protected boolean isDestroyed() {
-        return isDestroyed;
-    }
-
     @Override
     public void onGlobalLayout() {
         if (!isShown && isViewShown()) {

lib/android/app/src/main/java/com/reactnativenavigation/viewcontrollers/stack/StackController.java

                     }));
                 } else {
                     animator.push(child.getView(), resolvedOptions.animations.push, () -> {
-                        getView().removeView(toRemove.getView());
+                        if (!toRemove.equals(peek())) {
+                            getView().removeView(toRemove.getView());
+                        }
                         listener.onSuccess(child.getId());
                     });
                 }
             appearingView.setLayoutParams(new RelativeLayout.LayoutParams(MATCH_PARENT, MATCH_PARENT));
             presenter.applyLayoutParamsOptions(resolvedOptions, appearingView);
         }
-        getView().addView(appearingView, 0);
+        if (appearingView.getParent() == null) {
+            getView().addView(appearingView, 0);
+        }
         presenter.onChildWillAppear(appearing.options, disappearing.options);
         if (disappearing.options.animations.pop.enable.isTrueOrUndefined()) {
             animator.pop(disappearing.getView(), resolvedOptions.animations.pop, () -> finishPopping(disappearing, listener));
     }
 
     private void finishPopping(ViewController disappearing, CommandListener listener) {
-        getView().removeView(disappearing.getView());
         disappearing.destroy();
         listener.onSuccess(disappearing.getId());
     }

lib/android/app/src/test/java/com/reactnativenavigation/viewcontrollers/stack/StackControllerTest.java

 import com.reactnativenavigation.views.Component;
 import com.reactnativenavigation.views.ReactComponent;
 import com.reactnativenavigation.views.StackLayout;
+import com.reactnativenavigation.views.element.ElementTransitionManager;
 import com.reactnativenavigation.views.topbar.TopBar;
 
 import org.assertj.core.api.iterable.Extractor;
     @Override
     public void beforeEach() {
         super.beforeEach();
-        animator = Mockito.mock(NavigationAnimator.class);
         backButtonHelper = spy(new BackButtonHelper());
         activity = newActivity();
+        animator = spy(new NavigationAnimator(activity, Mockito.mock(ElementTransitionManager.class)));
         childRegistry = new ChildControllersRegistry();
         presenter = spy(new StackOptionsPresenter(activity, new TitleBarReactViewCreatorMock(), new TopBarButtonCreatorMock(), ImageLoaderMock.mock(), new Options()));
         child1 = spy(new SimpleViewController(activity, childRegistry, "child1", new Options()));
         verify(animator, times(0)).push(eq(child1.getView()), eq(child1.options.animations.push), any());
     }
 
+    @Test
+    public void push_backPressedDuringPushAnimationDestroysPushedScreenImmediately() {
+        disablePushAnimation(child1);
+        uut.push(child1, new CommandListenerAdapter());
+
+        CommandListenerAdapter pushListener = spy(new CommandListenerAdapter());
+        uut.push(child2, pushListener);
+        CommandListenerAdapter backListener = spy(new CommandListenerAdapter());
+        uut.handleBack(backListener);
+        assertThat(uut.size()).isOne();
+        assertThat(child1.getView().getParent()).isEqualTo(uut.getView());
+        assertThat(child2.isDestroyed()).isTrue();
+
+        InOrder inOrder = inOrder(pushListener, backListener);
+        inOrder.verify(pushListener).onSuccess(any());
+        inOrder.verify(backListener).onSuccess(any());
+    }
+
     @Test
     public void animateSetRoot() {
         disablePushAnimation(child1, child2, child3);