Merge "Share one receiver for CurrentUserTracker"

import android.content.Intent;

import android.content.IntentFilter;

public abstract class CurrentUserTracker extends BroadcastReceiver {

import java.util.ArrayList;

import java.util.List;

import java.util.function.Consumer;

    private Context mContext;

    private int mCurrentUserId;

public abstract class CurrentUserTracker {

    private final UserReceiver mUserReceiver;

    private Consumer<Integer> mCallback = this::onUserSwitched;

    public CurrentUserTracker(Context context) {

        mContext = context;

        mUserReceiver = UserReceiver.getInstance(context);

    }

    public int getCurrentUserId() {

        return mCurrentUserId;

        return mUserReceiver.getCurrentUserId();

    }

    public void startTracking() {

        mUserReceiver.addTracker(mCallback);

    }

    public void stopTracking() {

        mUserReceiver.removeTracker(mCallback);

    }

    public abstract void onUserSwitched(int newUserId);

    private static class UserReceiver extends BroadcastReceiver {

        private static UserReceiver sInstance;

        private Context mAppContext;

        private boolean mReceiverRegistered;

        private int mCurrentUserId;

        private List<Consumer<Integer>> mCallbacks = new ArrayList<>();

        private UserReceiver(Context context) {

            mAppContext = context.getApplicationContext();

        }

        static UserReceiver getInstance(Context context) {

            if (sInstance == null) {

                sInstance = new UserReceiver(context);

            }

            return sInstance;

        }

        @Override

        public void onReceive(Context context, Intent intent) {

            if (Intent.ACTION_USER_SWITCHED.equals(intent.getAction())) {

            int oldUserId = mCurrentUserId;

            mCurrentUserId = intent.getIntExtra(Intent.EXTRA_USER_HANDLE, 0);

            if (oldUserId != mCurrentUserId) {

                onUserSwitched(mCurrentUserId);

                notifyUserSwitched(intent.getIntExtra(Intent.EXTRA_USER_HANDLE, 0));

            }

        }

        public int getCurrentUserId() {

            return mCurrentUserId;

        }

    public void startTracking() {

        private void addTracker(Consumer<Integer> callback) {

            if (!mCallbacks.contains(callback)) {

                mCallbacks.add(callback);

            }

            if (!mReceiverRegistered) {

                mCurrentUserId = ActivityManager.getCurrentUser();

                IntentFilter filter = new IntentFilter(Intent.ACTION_USER_SWITCHED);

        mContext.registerReceiver(this, filter);

                mAppContext.registerReceiver(this, filter);

                mReceiverRegistered = true;

            }

        }

    public void stopTracking() {

        mContext.unregisterReceiver(this);

        private void removeTracker(Consumer<Integer> callback) {

            if (mCallbacks.contains(callback)) {

                mCallbacks.remove(callback);

                if (mCallbacks.size() == 0 && mReceiverRegistered) {

                    mAppContext.unregisterReceiver(this);

                    mReceiverRegistered = false;

                }

            }

        }

    public abstract void onUserSwitched(int newUserId);

        private void notifyUserSwitched(int newUserId) {

            if (mCurrentUserId != newUserId) {

                mCurrentUserId = newUserId;

                for (Consumer<Integer> consumer : mCallbacks) {

                    consumer.accept(newUserId);

                }

            }

        }

    }

}