1/**
2 * Copyright (C) 2016 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 */
16package com.android.server.vr;
17
18import android.annotation.NonNull;
19import android.content.BroadcastReceiver;
20import android.content.ContentResolver;
21import android.content.Context;
22import android.content.Intent;
23import android.database.ContentObserver;
24import android.net.Uri;
25import android.os.Handler;
26import android.os.UserHandle;
27import android.provider.Settings;
28import android.util.ArraySet;
29
30import java.util.Objects;
31import java.util.Set;
32
33/**
34 * Detects changes in a given setting.
35 *
36 * @hide
37 */
38public class SettingsObserver {
39
40    private final String mSecureSettingName;
41    private final BroadcastReceiver mSettingRestoreReceiver;
42    private final ContentObserver mContentObserver;
43    private final Set<SettingChangeListener> mSettingsListeners = new ArraySet<>();
44
45    /**
46     * Implement this to receive callbacks when the setting tracked by this observer changes.
47     */
48    public interface SettingChangeListener {
49
50        /**
51         * Called when the tracked setting has changed.
52         */
53        void onSettingChanged();
54
55
56        /**
57         * Called when the tracked setting has been restored for a particular user.
58         *
59         * @param prevValue the previous value of the setting.
60         * @param newValue the new value of the setting.
61         * @param userId the user ID for which this setting has been restored.
62         */
63        void onSettingRestored(String prevValue, String newValue, int userId);
64    }
65
66    private SettingsObserver(@NonNull final Context context, @NonNull final Handler handler,
67            @NonNull final Uri settingUri, @NonNull final String secureSettingName) {
68
69        mSecureSettingName = secureSettingName;
70        mSettingRestoreReceiver = new BroadcastReceiver() {
71            @Override
72            public void onReceive(Context context, Intent intent) {
73                if (Intent.ACTION_SETTING_RESTORED.equals(intent.getAction())) {
74                    String element = intent.getStringExtra(Intent.EXTRA_SETTING_NAME);
75                    if (Objects.equals(element, secureSettingName)) {
76                        String prevValue = intent.getStringExtra(Intent.EXTRA_SETTING_PREVIOUS_VALUE);
77                        String newValue = intent.getStringExtra(Intent.EXTRA_SETTING_NEW_VALUE);
78                        sendSettingRestored(prevValue, newValue, getSendingUserId());
79                    }
80                }
81            }
82        };
83
84        mContentObserver = new ContentObserver(handler) {
85            @Override
86            public void onChange(boolean selfChange, Uri uri) {
87                if (uri == null || settingUri.equals(uri)) {
88                    sendSettingChanged();
89                }
90            }
91        };
92
93        ContentResolver resolver = context.getContentResolver();
94        resolver.registerContentObserver(settingUri, false, mContentObserver,
95                UserHandle.USER_ALL);
96    }
97
98    /**
99     * Create a SettingsObserver instance.
100     *
101     * @param context the context to query for settings changes.
102     * @param handler the handler to use for a settings ContentObserver.
103     * @param settingName the setting to track.
104     * @return a SettingsObserver instance.
105     */
106    public static SettingsObserver build(@NonNull Context context, @NonNull Handler handler,
107            @NonNull String settingName) {
108        Uri settingUri = Settings.Secure.getUriFor(settingName);
109
110        return new SettingsObserver(context, handler, settingUri, settingName);
111    }
112
113    /**
114     * Add a listener for setting changes.
115     *
116     * @param listener a {@link SettingChangeListener} instance.
117     */
118    public void addListener(@NonNull SettingChangeListener listener) {
119        mSettingsListeners.add(listener);
120    }
121
122    /**
123     * Remove a listener for setting changes.
124     *
125     * @param listener a {@link SettingChangeListener} instance.
126     */
127    public void removeListener(@NonNull SettingChangeListener listener) {
128        mSettingsListeners.remove(listener);
129
130    }
131
132    private void sendSettingChanged() {
133        for (SettingChangeListener l : mSettingsListeners) {
134            l.onSettingChanged();
135        }
136    }
137
138    private void sendSettingRestored(final String prevValue, final String newValue, final int userId) {
139        for (SettingChangeListener l : mSettingsListeners) {
140            l.onSettingRestored(prevValue, newValue, userId);
141        }
142    }
143
144}
145