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      1 /*
      2  * Copyright (C) 2013 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.android.systemui.settings;
     18 
     19 import android.app.ActivityManager;
     20 import android.content.BroadcastReceiver;
     21 import android.content.Context;
     22 import android.content.Intent;
     23 import android.content.IntentFilter;
     24 
     25 import com.android.internal.annotations.VisibleForTesting;
     26 
     27 import java.util.ArrayList;
     28 import java.util.List;
     29 import java.util.function.Consumer;
     30 
     31 public abstract class CurrentUserTracker {
     32     private final UserReceiver mUserReceiver;
     33 
     34     private Consumer<Integer> mCallback = this::onUserSwitched;
     35 
     36     public CurrentUserTracker(Context context) {
     37         this(UserReceiver.getInstance(context));
     38     }
     39 
     40     @VisibleForTesting
     41     CurrentUserTracker(UserReceiver receiver) {
     42         mUserReceiver = receiver;
     43     }
     44 
     45     public int getCurrentUserId() {
     46         return mUserReceiver.getCurrentUserId();
     47     }
     48 
     49     public void startTracking() {
     50         mUserReceiver.addTracker(mCallback);
     51     }
     52 
     53     public void stopTracking() {
     54         mUserReceiver.removeTracker(mCallback);
     55     }
     56 
     57     public abstract void onUserSwitched(int newUserId);
     58 
     59     @VisibleForTesting
     60     static class UserReceiver extends BroadcastReceiver {
     61         private static UserReceiver sInstance;
     62 
     63         private Context mAppContext;
     64         private boolean mReceiverRegistered;
     65         private int mCurrentUserId;
     66 
     67         private List<Consumer<Integer>> mCallbacks = new ArrayList<>();
     68 
     69         @VisibleForTesting
     70         UserReceiver(Context context) {
     71             mAppContext = context.getApplicationContext();
     72         }
     73 
     74         static UserReceiver getInstance(Context context) {
     75             if (sInstance == null) {
     76                 sInstance = new UserReceiver(context);
     77             }
     78             return sInstance;
     79         }
     80 
     81         @Override
     82         public void onReceive(Context context, Intent intent) {
     83             if (Intent.ACTION_USER_SWITCHED.equals(intent.getAction())) {
     84                 notifyUserSwitched(intent.getIntExtra(Intent.EXTRA_USER_HANDLE, 0));
     85             }
     86         }
     87 
     88         public int getCurrentUserId() {
     89             return mCurrentUserId;
     90         }
     91 
     92         private void addTracker(Consumer<Integer> callback) {
     93             if (!mCallbacks.contains(callback)) {
     94                 mCallbacks.add(callback);
     95             }
     96             if (!mReceiverRegistered) {
     97                 mCurrentUserId = ActivityManager.getCurrentUser();
     98                 IntentFilter filter = new IntentFilter(Intent.ACTION_USER_SWITCHED);
     99                 mAppContext.registerReceiver(this, filter);
    100                 mReceiverRegistered = true;
    101             }
    102         }
    103 
    104         private void removeTracker(Consumer<Integer> callback) {
    105             if (mCallbacks.contains(callback)) {
    106                 mCallbacks.remove(callback);
    107                 if (mCallbacks.size() == 0 && mReceiverRegistered) {
    108                     mAppContext.unregisterReceiver(this);
    109                     mReceiverRegistered = false;
    110                 }
    111             }
    112         }
    113 
    114         private void notifyUserSwitched(int newUserId) {
    115             if (mCurrentUserId != newUserId) {
    116                 mCurrentUserId = newUserId;
    117                 List<Consumer<Integer>> callbacks = new ArrayList<>(mCallbacks);
    118                 for (Consumer<Integer> consumer : callbacks) {
    119                     // Accepting may modify this list
    120                     if (mCallbacks.contains(consumer)) {
    121                         consumer.accept(newUserId);
    122                     }
    123                 }
    124             }
    125         }
    126     }
    127 }
    128