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      1 /*
      2 * Copyright 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 */
     16 
     17 package com.example.android.directboot.alarms;
     18 
     19 import android.content.Context;
     20 import android.content.SharedPreferences;
     21 import android.support.v4.os.BuildCompat;
     22 import android.util.Log;
     23 
     24 import java.security.SecureRandom;
     25 import java.util.HashSet;
     26 import java.util.Map;
     27 import java.util.Set;
     28 
     29 /**
     30  * Class responsible for saving/retrieving alarms. This class uses SharedPreferences as storage.
     31  */
     32 public class AlarmStorage {
     33 
     34     private static final String TAG = AlarmStorage.class.getSimpleName();
     35     private static final String ALARM_PREFERENCES_NAME = "alarm_preferences";
     36     private static final SecureRandom SECURE_RANDOM = new SecureRandom();
     37 
     38     private SharedPreferences mSharedPreferences;
     39 
     40     public AlarmStorage(Context context) {
     41         Context storageContext;
     42         if (BuildCompat.isAtLeastN()) {
     43             // All N devices have split storage areas, but we may need to
     44             // move the existing preferences to the new device protected
     45             // storage area, which is where the data lives from now on.
     46             final Context deviceContext = context.createDeviceProtectedStorageContext();
     47             if (!deviceContext.moveSharedPreferencesFrom(context,
     48                     ALARM_PREFERENCES_NAME)) {
     49                 Log.w(TAG, "Failed to migrate shared preferences.");
     50             }
     51             storageContext = deviceContext;
     52         } else {
     53             storageContext = context;
     54         }
     55         mSharedPreferences = storageContext
     56                 .getSharedPreferences(ALARM_PREFERENCES_NAME, Context.MODE_PRIVATE);
     57     }
     58 
     59     /**
     60      * Stores an alarm in the SharedPreferences.
     61      *
     62      * @param month the integer represents a month
     63      * @param date the integer represents a date
     64      * @param hour the integer as 24-hour format the alarm goes off
     65      * @param minute the integer of the minute the alarm goes off
     66      * @return the saved {@link Alarm} instance
     67      */
     68     public Alarm saveAlarm(int month, int date, int hour, int minute) {
     69         Alarm alarm = new Alarm();
     70         // Ignore the Id duplication if that happens
     71         alarm.id = SECURE_RANDOM.nextInt();
     72         alarm.month = month;
     73         alarm.date = date;
     74         alarm.hour = hour;
     75         alarm.minute = minute;
     76         SharedPreferences.Editor editor = mSharedPreferences.edit();
     77         editor.putString(String.valueOf(alarm.id), alarm.toJson());
     78         editor.apply();
     79         return alarm;
     80     }
     81 
     82     /**
     83      * Retrieves the alarms stored in the SharedPreferences.
     84      * This method takes linear time as the alarms count.
     85      *
     86      * @return a {@link Set} of alarms.
     87      */
     88     public Set<Alarm> getAlarms() {
     89         Set<Alarm> alarms = new HashSet<>();
     90         for (Map.Entry<String, ?> entry : mSharedPreferences.getAll().entrySet()) {
     91             alarms.add(Alarm.fromJson(entry.getValue().toString()));
     92         }
     93         return alarms;
     94     }
     95 
     96     /**
     97      * Delete the alarm instance passed as an argument from the SharedPreferences.
     98      * This method iterates through the alarms stored in the SharedPreferences, takes linear time
     99      * as the alarms count.
    100      *
    101      * @param toBeDeleted the alarm instance to be deleted
    102      */
    103     public void deleteAlarm(Alarm toBeDeleted) {
    104         for (Map.Entry<String, ?> entry : mSharedPreferences.getAll().entrySet()) {
    105             Alarm alarm = Alarm.fromJson(entry.getValue().toString());
    106             if (alarm.id == toBeDeleted.id) {
    107                 SharedPreferences.Editor editor = mSharedPreferences.edit();
    108                 editor.remove(String.valueOf(alarm.id));
    109                 editor.apply();
    110                 return;
    111             }
    112         }
    113     }
    114 }
    115