/**
 * Disable animations so that they do not interfere with Espresso tests.
 *
 * Source: https://code.google.com/p/android-test-kit/wiki/DisablingAnimations
 */
public final class SystemAnimations extends AndroidJUnitRunner {
    private static final String ANIMATION_PERMISSION = "android.permission.SET_ANIMATION_SCALE";
    private static final float DISABLED = 0.0f;
    private static final float DEFAULT = 1.0f;

    private final Context context;

    SystemAnimations(Context context) {
        this.context = context;
    }

    void disableAll() {
        int permStatus = context.checkCallingOrSelfPermission(ANIMATION_PERMISSION);
        if (permStatus == PackageManager.PERMISSION_GRANTED) {
            setSystemAnimationsScale(DISABLED);
        }
    }

    void enableAll() {
        int permStatus = context.checkCallingOrSelfPermission(ANIMATION_PERMISSION);
        if (permStatus == PackageManager.PERMISSION_GRANTED) {
            setSystemAnimationsScale(DEFAULT);
        }
    }

    private void setSystemAnimationsScale(float animationScale) {
        try {
            Class<?> windowManagerStubClazz = Class.forName("android.view.IWindowManager$Stub");
            Method asInterface = windowManagerStubClazz.getDeclaredMethod("asInterface", IBinder.class);
            Class<?> serviceManagerClazz = Class.forName("android.os.ServiceManager");
            Method getService = serviceManagerClazz.getDeclaredMethod("getService", String.class);
            Class<?> windowManagerClazz = Class.forName("android.view.IWindowManager");
            Method setAnimationScales = windowManagerClazz.getDeclaredMethod("setAnimationScales", float[].class);
            Method getAnimationScales = windowManagerClazz.getDeclaredMethod("getAnimationScales");

            IBinder windowManagerBinder = (IBinder) getService.invoke(null, "window");
            Object windowManagerObj = asInterface.invoke(null, windowManagerBinder);
            float[] currentScales = (float[]) getAnimationScales.invoke(windowManagerObj);
            for (int i = 0; i < currentScales.length; i++) {
                currentScales[i] = animationScale;
            }
            setAnimationScales.invoke(windowManagerObj, new Object[]{currentScales});
        } catch (Exception e) {
            Log.e("SystemAnimations", "Could not change animation scale to " + animationScale + " :'(");
        }
    }
}