Do not set an initial value for events.

This avoids the empty events being used to show "no events" message.

Fixes: 153622413
Test: atest CarCalendarUnitTests CarCalendarUiTests
Change-Id: Ib02ba2d8682bd92a560b73b0db4702ec4ac45e73

2 files changed, 35 insertions, 26 deletions

diff --git a/src/com/android/car/calendar/CarCalendarView.java b/src/com/android/car/calendar/CarCalendarView.java
index 07b9516..1a63588 100644
--- a/src/com/android/car/calendar/CarCalendarView.java
+++ b/src/com/android/car/calendar/CarCalendarView.java
@@ -17,7 +17,6 @@
 package com.android.car.calendar;
 
 import static com.google.common.base.Verify.verify;
-import static com.google.common.base.Verify.verifyNotNull;
 
 import android.Manifest;
 import android.util.Log;
@@ -25,10 +24,10 @@ import android.view.View;
 import android.view.ViewGroup;
 import android.widget.TextView;
 
-import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.lifecycle.Observer;
 import androidx.recyclerview.widget.RecyclerView;
+import androidx.recyclerview.widget.RecyclerView.ViewHolder;
 
 import com.android.car.calendar.common.CalendarFormatter;
 import com.android.car.calendar.common.Dialer;
@@ -64,15 +63,8 @@ class CarCalendarView {
     /** Holds an instance of either {@link LocalDate} or {@link Event} for each item in the list. */
     private final List<CalendarItem> mRecyclerViewItems = new ArrayList<>();
 
-    private final RecyclerView.Adapter mAdapter = new EventRecyclerViewAdapter();
-    private final Observer<ImmutableList<Event>> mEventsObserver =
-            events -> {
-                if (DEBUG) Log.d(TAG, "Events changed");
-                updateRecyclerViewItems(events);
-
-                // TODO(jdp) Only change the affected items (DiffUtil) to allow animated changes.
-                mAdapter.notifyDataSetChanged();
-            };
+    private final RecyclerView.Adapter<ViewHolder> mAdapter = new EventRecyclerViewAdapter();
+    private final Observer<ImmutableList<Event>> mEventsObserver = this::onEventsChanged;
 
     CarCalendarView(
             CarCalendarActivity carCalendarActivity,
@@ -102,23 +94,30 @@ class CarCalendarView {
     private void showWithPermission() {
         EventsLiveData eventsLiveData = mCarCalendarViewModel.getEventsLiveData();
         eventsLiveData.observe(mCarCalendarActivity, mEventsObserver);
-        updateRecyclerViewItems(verifyNotNull(eventsLiveData.getValue()));
+    }
+
+    private void onEventsChanged(ImmutableList<Event> events) {
+        updateRecyclerViewItems(events);
+
+        // TODO(jdp) Only change the affected items (DiffUtil) to allow animated changes.
+        mAdapter.notifyDataSetChanged();
     }
 
     /**
      * If the events list is null there is no calendar data available. If the events list is empty
      * there is calendar data but no events.
      */
-    private void updateRecyclerViewItems(@Nullable ImmutableList<Event> carCalendarEvents) {
+    private void updateRecyclerViewItems(@Nullable ImmutableList<Event> events) {
+        if (DEBUG) Log.d(TAG, "Update events");
         LocalDate currentDate = null;
         mRecyclerViewItems.clear();
 
-        if (carCalendarEvents == null) {
+        if (events == null) {
             mNoEventsTextView.setVisibility(View.VISIBLE);
             mNoEventsTextView.setText(R.string.no_calendars);
             return;
         }
-        if (carCalendarEvents.isEmpty()) {
+        if (events.isEmpty()) {
             mNoEventsTextView.setVisibility(View.VISIBLE);
             mNoEventsTextView.setText(R.string.no_events);
             return;
@@ -130,7 +129,7 @@ class CarCalendarView {
         // add the event rows after looking at all events for the day.
         List<CalendarItem> eventItems = null;
         List<EventCalendarItem> allDayEventItems = null;
-        for (Event event : carCalendarEvents) {
+        for (Event event : events) {
             LocalDate date =
                     event.getDayStartInstant().atZone(ZoneId.systemDefault()).toLocalDate();
 
@@ -177,17 +176,15 @@ class CarCalendarView {
         mRecyclerViewItems.addAll(eventItems);
     }
 
-    private class EventRecyclerViewAdapter extends RecyclerView.Adapter {
-
-        @NonNull
+    private class EventRecyclerViewAdapter extends RecyclerView.Adapter<ViewHolder> {
         @Override
-        public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
+        public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
             CalendarItem.Type type = CalendarItem.Type.values()[viewType];
             return type.createViewHolder(parent);
         }
 
         @Override
-        public void onBindViewHolder(@NonNull RecyclerView.ViewHolder holder, int position) {
+        public void onBindViewHolder(ViewHolder holder, int position) {
             mRecyclerViewItems.get(position).bind(holder);
         }
 
diff --git a/src/com/android/car/calendar/common/EventsLiveData.java b/src/com/android/car/calendar/common/EventsLiveData.java
index f2df3fe..92ae0bb 100644
--- a/src/com/android/car/calendar/common/EventsLiveData.java
+++ b/src/com/android/car/calendar/common/EventsLiveData.java
@@ -31,7 +31,9 @@ import android.provider.CalendarContract;
 import android.provider.CalendarContract.Instances;
 import android.util.Log;
 
+import androidx.lifecycle.LifecycleOwner;
 import androidx.lifecycle.LiveData;
+import androidx.lifecycle.Observer;
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Iterables;
@@ -54,6 +56,8 @@ import javax.annotation.Nullable;
  * Provider</a>.
  *
  * <p>While in the active state the content provider is observed for changes.
+ *
+ * <p>When the value given to the observer is null it signals that there are no calendars.
  */
 public class EventsLiveData extends LiveData<ImmutableList<Event>> {
 
@@ -72,20 +76,22 @@ public class EventsLiveData extends LiveData<ImmutableList<Event>> {
     private final ContentResolver mContentResolver;
     private final EventDescriptions mEventDescriptions;
     private final EventLocations mLocations;
-    private final Runnable mUpdateRunnable = this::updateIfChanged;
+    private final Runnable mUpdateIfChangedRunnable = this::updateIfChanged;
 
     /** The event instances cursor is a field to allow observers to be managed. */
     @Nullable private Cursor mEventsCursor;
 
     @Nullable private ContentObserver mEventInstancesObserver;
 
+    // This can be updated on the background thread but read from any thread.
+    private volatile boolean mValueUpdated;
+
     public EventsLiveData(
             Clock clock,
             Handler backgroundHandler,
             ContentResolver contentResolver,
             EventDescriptions eventDescriptions,
             EventLocations locations) {
-        super(ImmutableList.of());
         mClock = clock;
         mBackgroundHandler = backgroundHandler;
         mContentResolver = contentResolver;
@@ -95,10 +101,14 @@ public class EventsLiveData extends LiveData<ImmutableList<Event>> {
 
     /** Refreshes the event instances and sets the new value which notifies observers. */
     private void updateIfChanged() {
+        Log.d(TAG, "Update if changed");
         ImmutableList<Event> latest = getEventsUntilTomorrow();
         ImmutableList<Event> current = getValue();
-        if (!Objects.equals(latest, current)) {
+
+        // Always post the first value even if it is null.
+        if (!mValueUpdated || !Objects.equals(latest, current)) {
             postValue(latest);
+            mValueUpdated = true;
         }
     }
 
@@ -187,8 +197,9 @@ public class EventsLiveData extends LiveData<ImmutableList<Event>> {
 
     private void updateWithDelay() {
         // Do not update the events until there have been no changes for a given duration.
-        mBackgroundHandler.removeCallbacks(mUpdateRunnable);
-        mBackgroundHandler.postDelayed(mUpdateRunnable, UPDATE_DELAY_MILLIS);
+        Log.d(TAG, "Events changed");
+        mBackgroundHandler.removeCallbacks(mUpdateIfChangedRunnable);
+        mBackgroundHandler.postDelayed(mUpdateIfChangedRunnable, UPDATE_DELAY_MILLIS);
     }
 
     /** Can return multiple events for a single cursor row when an event spans multiple days. */
@@ -277,6 +288,7 @@ public class EventsLiveData extends LiveData<ImmutableList<Event>> {
         if (DEBUG) Log.d(TAG, "Live data inactive");
         mBackgroundHandler.post(this::cancelScheduledUpdate);
         mBackgroundHandler.post(this::tearDownCursor);
+        mValueUpdated = false;
     }
 
     /** Calls {@link #updateIfChanged()} every minute to keep the displayed time range correct. */