/*
 * Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *        http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package net.micode.notes.ui;

import android.app.AlarmManager;
import android.app.PendingIntent;
import android.content.BroadcastReceiver;
import android.content.ContentUris;
import android.content.Context;
import android.content.Intent;
import android.database.Cursor;

import net.micode.notes.data.Notes;
import net.micode.notes.data.Notes.NoteColumns;

//用来接收来自系统和应用中的广播
public class AlarmInitReceiver extends BroadcastReceiver {
    //声明PROJECTION，每个元素包括id和提醒日期
    private static final String [] PROJECTION = new String [] {
        NoteColumns.ID,
        NoteColumns.ALERTED_DATE
    };
    //初始化闹钟提醒的ID号和提醒日期
    private static final int COLUMN_ID                = 0;
    private static final int COLUMN_ALERTED_DATE      = 1;
    //AlarmInitReceiver的配置“android.intent.action.BOOT_COMPLETED”，表明
//  Android手机开机后，会发送android.intent.action.BOOT_COMPLETED广播，监听这个广播就能监听开机。
//  开机之后，就处理已有的便签，逐条比较日期，如果有到期的，就用AlarmManager提醒用户。
    @Override
    //2. 接收广播后的处理方法,上下文context，消息传递工具intent
    public void onReceive(Context context, Intent intent) {
        //System.currentTimeMillis()产生一个当前的毫秒
        long currentDate = System.currentTimeMillis();
        //Cursor在这里的作用是通过查找数据库中的标签内容，找到和当前系统时间相等的标签
        Cursor c = context.getContentResolver().query(Notes.CONTENT_NOTE_URI,
                PROJECTION,
                //获取的是当前时间大于设置提醒时间的便签项
                NoteColumns.ALERTED_DATE + ">? AND " + NoteColumns.TYPE + "=" + Notes.TYPE_NOTE,
                //类型转换，将long类型的currentDate转变为String类
                new String[] { String.valueOf(currentDate) },
                null);
//如果在数据库中找到了这样的便签（提醒时间  > 现在时间），便将光标移到第一个，从头遍历,设立一个闹钟的机制
        if (c != null) {
            //游标移动到开始位置
            if (c.moveToFirst()) {
                do {
                    long alertDate = c.getLong(COLUMN_ALERTED_DATE);
                    //通过定义一个Intent方法，与AlarmReceiver类建立连接
                    Intent sender = new Intent(context, AlarmReceiver.class);
                    // 设置新的便签的uri和id
                    sender.setData(ContentUris.withAppendedId(Notes.CONTENT_NOTE_URI, c.getLong(COLUMN_ID)));
                    PendingIntent pendingIntent = PendingIntent.getBroadcast(context, 0, sender, 0);
                    //设置闹钟 当提醒时间到达时发送Intent并且唤醒设备
                    AlarmManager alermManager = (AlarmManager) context
                            .getSystemService(Context.ALARM_SERVICE);
                    alermManager.set(AlarmManager.RTC_WAKEUP, alertDate, pendingIntent);
                } while (c.moveToNext());//游标移动到下一位置
            }
            c.close();
        }
    }
}