/*
 * 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.data;

import android.content.Context;
import android.database.Cursor;
import android.provider.ContactsContract.CommonDataKinds.Phone;
import android.provider.ContactsContract.Data;
import android.telephony.PhoneNumberUtils;
import android.util.Log;

import java.util.HashMap;

/**
 * <b>联系人查询工具类</b>
 * <p>
 * 主要负责根据电话号码从Android数据库中检索联系人姓名。
 * </p>
 *
 * <h3>核心功能：</h3>
 * <ul>
 *   <li>基于电话号码查找姓名。</li>
 *   <li>维护 {@code HashMap} 缓存，减少 IPC 调用次数。</li>
 *   <li>处理国际化号码格式匹配问题。</li>
 * </ul>
 *
 * @author 林迪文
 * @version 1.0
 * @see android.provider.ContactsContract
 */
public class Contact {
    //键值对，用于缓存<姓名,文本>，提高查找速度。
    private static HashMap<String, String> sContactCache;
    //fianl意思是常量，TAG为Contact的“别名”。
    private static final String TAG = "Contact";

    //这是个SQL语句，CALLER_ID_SELECTION是个字符串，作用是构建匹配模式，用and连接了3个部分：电话匹配、数据类型需是电话、号码必须存在于快速查找表中
    private static final String CALLER_ID_SELECTION = "PHONE_NUMBERS_EQUAL(" + Phone.NUMBER
    + ",?) AND " + Data.MIMETYPE + "='" + Phone.CONTENT_ITEM_TYPE + "'"
    + " AND " + Data.RAW_CONTACT_ID + " IN "    //Data哪来的
            + "(SELECT raw_contact_id "
            + " FROM phone_lookup"
            + " WHERE min_match = '+')";

    //主函数，输入电话，根据context，返回人名
    public static String getContact(Context context, String phoneNumber) {
        if(sContactCache == null) {
            sContactCache = new HashMap<String, String>();
        }   //初次调用getContact时，创建缓存

        if(sContactCache.containsKey(phoneNumber)) {
            return sContactCache.get(phoneNumber);
        }   //缓存命中

        String selection = CALLER_ID_SELECTION.replace("+",
                PhoneNumberUtils.toCallerIDMinMatch(phoneNumber));  //用处理过的电话号码，替代CALLER_ID_SELECTION的+。
        Cursor cursor = context.getContentResolver().query(
                Data.CONTENT_URI,   //查找对象
                new String [] { Phone.DISPLAY_NAME },   //需要返回的是名字这一列
                selection,  //查找条件
                new String[] { phoneNumber },   //query可以将phoneNumber填到selection的'？'中
                null);  //不需排序

        if (cursor != null && cursor.moveToFirst()) {   //cursor.moveToFirst()为true代表至少有一条记录
            try {
                String name = cursor.getString(0);
                sContactCache.put(phoneNumber, name);
                return name;
            } catch (IndexOutOfBoundsException e) {     //越界报错
                Log.e(TAG, " Cursor get string error " + e.toString());
                return null;
            } finally {
                cursor.close(); //关闭进程，防止内存泄露
            }
        }
        else {
            Log.d(TAG, "No contact matched with number:" + phoneNumber);    //没找到
            return null;
        }
    }
}