<?php
// +----------------------------------------------------------------------
// | TOPThink [ WE CAN DO IT JUST THINK ]
// +----------------------------------------------------------------------
// | Copyright (c) 2011 http://topthink.com All rights reserved.
// +----------------------------------------------------------------------
// | Licensed ( http://www.apache.org/licenses/LICENSE-2.0 )
// +----------------------------------------------------------------------
// | Author: liu21st <liu21st@gmail.com>
// +----------------------------------------------------------------------

namespace Think\Db;
use Think\Config;
use Think\Debug;
use Think\Log;
use PDO;

abstract class Driver {
    // PDO操作实例
    protected $PDOStatement = null;
    // 当前操作所属的模型名
    protected $model      = '_think_';
    // 当前SQL指令
    protected $queryStr   = '';
    protected $modelSql   = [];
    // 最后插入ID
    protected $lastInsID  = null;
    // 返回或者影响记录数
    protected $numRows    = 0;
    // 事务指令数
    protected $transTimes = 0;
    // 错误信息
    protected $error      = '';
    // 数据库连接ID 支持多个连接
    protected $linkID     = [];
    // 当前连接ID
    protected $_linkID    = null;
    // 数据库连接参数配置
    protected $config     = [
        'dbms'              =>  '',     // 数据库类型
        'connection'        =>  [
            'hostname'          =>  '127.0.0.1', // 服务器地址
            'database'          =>  '',          // 数据库名
            'username'          =>  'root',      // 用户名
            'password'          =>  '',          // 密码
            'hostport'          =>  '',        // 端口     
            'socket'            =>  '',   
            'dsn'               =>  '', //          
        ],
        'params'            =>  [], // 数据库连接参数        
        'charset'           =>  'utf8',      // 数据库编码默认采用utf8  
        'prefix'            =>  '',    // 数据库表前缀
        'debug'             =>  false, // 数据库调试模式
        'deploy'            =>  0, // 数据库部署方式:0 集中式(单一服务器),1 分布式(主从服务器)
        'rw_separate'       =>  false,       // 数据库读写是否分离 主从式有效
        'master_num'        =>  1, // 读写分离后 主服务器数量
        'slave_no'          =>  '', // 指定从服务器序号
    ];
    // 数据库表达式
    protected $comparison = ['eq'=>'=','neq'=>'<>','gt'=>'>','egt'=>'>=','lt'=>'<','elt'=>'<=','notlike'=>'NOT LIKE','like'=>'LIKE','in'=>'IN','notin'=>'NOT IN'];
    // 查询表达式
    protected $selectSql  = 'SELECT%DISTINCT% %FIELD% FROM %TABLE%%JOIN%%WHERE%%GROUP%%HAVING%%ORDER%%LIMIT% %UNION%%COMMENT%';
    // 查询次数
    protected $queryTimes   =   0;
    // 执行次数
    protected $executeTimes =   0;
    // PDO连接参数
	protected $options = [
        PDO::ATTR_CASE              =>  PDO::CASE_LOWER,
        PDO::ATTR_ERRMODE           =>  PDO::ERRMODE_EXCEPTION,
        PDO::ATTR_ORACLE_NULLS      =>  PDO::NULL_NATURAL,
        PDO::ATTR_STRINGIFY_FETCHES =>  false,
	];

    /**
     * 架构函数 读取数据库配置信息
     * @access public
     * @param array $config 数据库配置数组
     */
    public function __construct($config=''){
        if(!empty($config)) {
            $this->config           =   array_merge($this->config,$config);
            $this->config['params'] =   $this->options+$this->config['params'];
        }
    }

    /**
     * 连接数据库方法
     * @access public
     */
    public function connect($config='',$linkNum=0) {
        if ( !isset($this->linkID[$linkNum]) ) {
            if(empty($config))  $config =   $this->config['connection'];
            try{
                if(empty($config['dsn'])) {
                    $config['dsn']  =   $this->config['dbms'].':dbname='.$config['database'].';host='.$config['hostname'];
                    if(!empty($config['hostport'])) {
                        $config['dsn']  .= ';port='.$config['hostport'];
                    }elseif(!empty($config['socket'])){
                        $config['dsn']  .= ';unix_socket='.$config['socket'];
                    }
                }
                $this->linkID[$linkNum] = new PDO( $config['dsn'], $config['username'], $config['password'],$this->config['params']);
            }catch (\PDOException $e) {
                E($e->getMessage());
            }
            if(!empty($this->config['charset'])) {
                $this->linkID[$linkNum]->exec('SET NAMES '.$this->config['charset']);
            }
        }
        return $this->linkID[$linkNum];
    }

    /**
     * 释放查询结果
     * @access public
     */
    public function free() {
        $this->PDOStatement = null;
    }

    /**
     * 执行查询 返回数据集
     * @access public
     * @param string $str  sql指令
     * @return mixed
     */
    public function query($str,$bind=[]) {
        $this->initConnect(false);
        if ( !$this->_linkID ) return false;
        $this->queryStr = $str;
        //释放前次的查询结果
        if ( !empty($this->PDOStatement) ) $this->free();
        $this->queryTimes++;
        // 调试开始
        $this->debug(true);
        $this->PDOStatement = $this->_linkID->prepare($str);
        if(false === $this->PDOStatement)
            E($this->error());
        $result =   $this->PDOStatement->execute($bind);
        // 调试结束
        $this->debug(false);
        if ( false === $result ) {
            $this->error();
            return false;
        } else {
            return $this->getResult();
        }
    }

    /**
     * 执行语句
     * @access public
     * @param string $str  sql指令
     * @return integer
     */
    public function execute($str,$bind=[]) {
        $this->initConnect(true);
        if ( !$this->_linkID ) return false;
        $this->queryStr = $str;
        //释放前次的查询结果
        if ( !empty($this->PDOStatement) ) $this->free();
        $this->executeTimes++;
        // 记录开始执行时间
        $this->debug(true);
        $this->PDOStatement	=	$this->_linkID->prepare($str);
        if(false === $this->PDOStatement) {
            E($this->error());
        }
        $result	=	$this->PDOStatement->execute($bind);
        $this->debug(false);
        if ( false === $result) {
            $this->error();
            return false;
        } else {
            $this->numRows = $this->PDOStatement->rowCount();
            if(preg_match("/^\s*(INSERT\s+INTO|REPLACE\s+INTO)\s+/i", $str)) {
                $this->lastInsID = $this->getLastInsertId();
            }
            return $this->numRows;
        }
    }

    /**
     * 获取最后插入id
     * @access public
     * @return integer
     */
    public function getLastInsertId() {
        return $this->_linkID->lastInsertId();
    }

    /**
     * 启动事务
     * @access public
     * @return void
     */
    public function startTrans() {
        $this->initConnect(true);
        if ( !$this->_linkID ) return false;
        //数据rollback 支持
        if ($this->transTimes == 0) {
            $this->_linkID->beginTransaction();
        }
        $this->transTimes++;
        return ;
    }

    /**
     * 用于非自动提交状态下面的查询提交
     * @access public
     * @return boolen
     */
    public function commit() {
        if ($this->transTimes > 0) {
            $result = $this->_linkID->commit();
            $this->transTimes = 0;
            if(!$result){
                $this->error();
                return false;
            }
        }
        return true;
    }

    /**
     * 事务回滚
     * @access public
     * @return boolen
     */
    public function rollback() {
        if ($this->transTimes > 0) {
            $result = $this->_linkID->rollback();
            $this->transTimes = 0;
            if(!$result){
                $this->error();
                return false;
            }
        }
        return true;
    }

    /**
     * 获得所有的查询数据
     * @access private
     * @return array
     */
    private function getResult() {
        //返回数据集
        $result =   $this->PDOStatement->fetchAll(PDO::FETCH_ASSOC);
        $this->numRows = count( $result );
        return $result;
    }

    /**
     * 获得查询次数
     * @access public
     * @param boolean $execute 是否包含所有查询
     * @return integer
     */
    public function getQueryTimes($execute=false){
        return $execute?$this->queryTimes+$this->executeTimes:$this->queryTimes;
    }

    /**
     * 获得执行次数
     * @access public
     * @return integer
     */
    public function getExecuteTimes(){
        return $this->executeTimes;
    }

    /**
     * 关闭数据库
     * @access public
     */
    public function close() {
        $this->_linkID = null;
    }

    /**
     * 数据库错误信息
     * 并显示当前的SQL语句
     * @access public
     * @return string
     */
    public function error() {
        if($this->PDOStatement) {
            $error = $this->PDOStatement->errorInfo();
            $this->error = $error[1].':'.$error[2];
        }else{
            $this->error = '';
        }
        if('' != $this->queryStr){
            $this->error .= "\n [ SQL语句 ] : ".$this->queryStr;
        }
        Log::record($this->error,'ERR');
        return $this->error;
    }

    /**
     * 设置锁机制
     * @access protected
     * @return string
     */
    protected function parseLock($lock=false) {
        return $lock?   ' FOR UPDATE '  :   '';
    }

    /**
     * set分析
     * @access protected
     * @param array $data
     * @return string
     */
    protected function parseSet($data) {
        foreach ($data as $key=>$val){
            $value   =  $this->parseValue($val);
            if(is_scalar($value)) // 过滤非标量数据
                $set[]    = $this->parseKey($key).'='.$value;
        }
        return ' SET '.implode(',',$set);
    }

    /**
     * 字段名分析
     * @access protected
     * @param string $key
     * @return string
     */
    protected function parseKey(&$key) {
        return $key;
    }
    
    /**
     * value分析
     * @access protected
     * @param mixed $value
     * @return string
     */
    protected function parseValue($value) {
        if(is_string($value)) {
            $value =  strpos($value,':') === 0 ? $this->escapeString($value) : '\''.$this->escapeString($value).'\'';
        }elseif(isset($value[0]) && is_string($value[0]) && strtolower($value[0]) == 'exp'){
            $value =  $this->escapeString($value[1]);
        }elseif(is_array($value)) {
            $value =  array_map([$this, 'parseValue'],$value);
        }elseif(is_bool($value)){
            $value =  $value ? '1' : '0';
        }elseif(is_null($value)){
            $value =  'null';
        }
        return $value;
    }

    /**
     * field分析
     * @access protected
     * @param mixed $fields
     * @return string
     */
    protected function parseField($fields) {
        if(is_string($fields) && strpos($fields,',')) {
            $fields    = explode(',',$fields);
        }
        if(is_array($fields)) {
            // 完善数组方式传字段名的支持
            // 支持 'field1'=>'field2' 这样的字段别名定义
            $array   =  [];
            foreach ($fields as $key=>$field){
                if(!is_numeric($key))
                    $array[] =  $this->parseKey($key).' AS '.$this->parseKey($field);
                else
                    $array[] =  $this->parseKey($field);
            }
            $fieldsStr = implode(',', $array);
        }elseif(is_string($fields) && !empty($fields)) {
            $fieldsStr = $this->parseKey($fields);
        }else{
            $fieldsStr = '*';
        }
        //TODO 如果是查询全部字段，并且是join的方式，那么就把要查的表加个别名，以免字段被覆盖
        return $fieldsStr;
    }

    /**
     * table分析
     * @access protected
     * @param mixed $table
     * @return string
     */
    protected function parseTable($tables) {
        if(is_array($tables)) {// 支持别名定义
            $array   =  [];
            foreach ($tables as $table=>$alias){
                if(!is_numeric($table))
                    $array[] =  $this->parseKey($table).' '.$this->parseKey($alias);
                else
                    $array[] =  $this->parseKey($table);
            }
            $tables  =  $array;
        }elseif(is_string($tables)){
            $tables  =  explode(',',$tables);
            array_walk($tables, [&$this, 'parseKey']);
        }
        return implode(',',$tables);
    }

    /**
     * where分析
     * @access protected
     * @param mixed $where
     * @return string
     */
    protected function parseWhere($where) {
        $whereStr = '';
        if(is_string($where)) {
            // 直接使用字符串条件
            $whereStr = $where;
        }else{ // 使用数组表达式
            $operate  = isset($where['_logic'])?strtoupper($where['_logic']):'';
            if(in_array($operate,['AND','OR','XOR'])){
                // 定义逻辑运算规则 例如 OR XOR AND NOT
                $operate    =   ' '.$operate.' ';
                unset($where['_logic']);
            }else{
                // 默认进行 AND 运算
                $operate    =   ' AND ';
            }
            foreach ($where as $key=>$val){
                $whereStr .= '( ';
                if(0===strpos($key,'_')) {
                    // 解析特殊条件表达式
                    $whereStr   .= $this->parseThinkWhere($key,$val);
                }else{
                    // 查询字段的安全过滤
                    if(!preg_match('/^[A-Z_\|\&\-.a-z0-9\(\)\,]+$/',trim($key))){
                        E(L('_EXPRESS_ERROR_').':'.$key);
                    }
                    // 多条件支持
                    $multi  = is_array($val) &&  isset($val['_multi']);
                    $key    = trim($key);
                    if(strpos($key,'|')) { // 支持 name|title|nickname 方式定义查询字段
                        $array =  explode('|',$key);
                        $str   =  [];
                        foreach ($array as $m=>$k){
                            $v =  $multi?$val[$m]:$val;
                            $str[]   = '('.$this->parseWhereItem($this->parseKey($k),$v).')';
                        }
                        $whereStr .= implode(' OR ',$str);
                    }elseif(strpos($key,'&')){
                        $array =  explode('&',$key);
                        $str   =  [];
                        foreach ($array as $m=>$k){
                            $v =  $multi?$val[$m]:$val;
                            $str[]   = '('.$this->parseWhereItem($this->parseKey($k),$v).')';
                        }
                        $whereStr .= implode(' AND ',$str);
                    }else{
                        $whereStr .= $this->parseWhereItem($this->parseKey($key),$val);
                    }
                }
                $whereStr .= ' )'.$operate;
            }
            $whereStr = substr($whereStr,0,-strlen($operate));
        }
        return empty($whereStr)?'':' WHERE '.$whereStr;
    }

    // where子单元分析
    protected function parseWhereItem($key,$val) {
        $whereStr = '';
        if(is_array($val)) {
            if(is_string($val[0])) {
                if(preg_match('/^(EQ|NEQ|GT|EGT|LT|ELT)$/i',$val[0])) { // 比较运算
                    $whereStr .= $key.' '.$this->comparison[strtolower($val[0])].' '.$this->parseValue($val[1]);
                }elseif(preg_match('/^(NOTLIKE|LIKE)$/i',$val[0])){// 模糊查找
                    if(is_array($val[1])) {
                        $likeLogic  =   isset($val[2])?strtoupper($val[2]):'OR';
                        if(in_array($likeLogic,['AND','OR','XOR'])){
                            $likeStr    =   $this->comparison[strtolower($val[0])];
                            $like       =   [];
                            foreach ($val[1] as $item){
                                $like[] = $key.' '.$likeStr.' '.$this->parseValue($item);
                            }
                            $whereStr .= '('.implode(' '.$likeLogic.' ',$like).')';                          
                        }
                    }else{
                        $whereStr .= $key.' '.$this->comparison[strtolower($val[0])].' '.$this->parseValue($val[1]);
                    }
                }elseif('bind'==strtolower($val[0])){ // 使用表达式
                    $whereStr .= ' ('.$key.' = :'.$val[1].') ';
                }elseif('exp'==strtolower($val[0])){ // 使用表达式
                    $whereStr .= ' ('.$key.' '.$val[1].') ';
                }elseif(preg_match('/IN/i',$val[0])){ // IN 运算
                    if(isset($val[2]) && 'exp'==$val[2]) {
                        $whereStr .= $key.' '.strtoupper($val[0]).' '.$val[1];
                    }else{
                        if(is_string($val[1])) {
                             $val[1] =  explode(',',$val[1]);
                        }
                        $zone      =   implode(',',$this->parseValue($val[1]));
                        $whereStr .= $key.' '.strtoupper($val[0]).' ('.$zone.')';
                    }
                }elseif(preg_match('/BETWEEN/i',$val[0])){ // BETWEEN运算
                    $data = is_string($val[1])? explode(',',$val[1]):$val[1];
                    $whereStr .=  ' ('.$key.' '.strtoupper($val[0]).' '.$this->parseValue($data[0]).' AND '.$this->parseValue($data[1]).' )';
                }else{
                    E(L('_EXPRESS_ERROR_').':'.$val[0]);
                }
            }else {
                $count = count($val);
                $rule  = isset($val[$count-1])?strtoupper($val[$count-1]):'';
                if(in_array($rule,['AND','OR','XOR'])) {
                    $count  = $count -1;
                }else{
                    $rule   = 'AND';
                }
                for($i=0;$i<$count;$i++) {
                    $data = is_array($val[$i])?$val[$i][1]:$val[$i];
                    if('exp'==strtolower($val[$i][0])) {
                        $whereStr .= '('.$key.' '.$data.') '.$rule.' ';
                    }else{
                        $op = is_array($val[$i])?$this->comparison[strtolower($val[$i][0])]:'=';
                        $whereStr .= '('.$key.' '.$op.' '.$this->parseValue($data).') '.$rule.' ';
                    }
                }
                $whereStr = substr($whereStr,0,-4);
            }
        }else {
            //对字符串类型字段采用模糊匹配
            if($this->conf['db_like_fields'] && preg_match('/('.$this->conf['db_like_fields'].')/i',$key)) {
                $val  =  '%'.$val.'%';
                $whereStr .= $key.' LIKE '.$this->parseValue($val);
            }else {
                $whereStr .= $key.' = '.$this->parseValue($val);
            }
        }
        return $whereStr;
    }

    /**
     * 特殊条件分析
     * @access protected
     * @param string $key
     * @param mixed $val
     * @return string
     */
    protected function parseThinkWhere($key,$val) {
        $whereStr   = '';
        switch($key) {
            case '_string':
                // 字符串模式查询条件
                $whereStr = $val;
                break;
            case '_complex':
                // 复合查询条件
                $whereStr = substr($this->parseWhere($val),6);
                break;
            case '_query':
                // 字符串模式查询条件
                parse_str($val,$where);
                if(isset($where['_logic'])) {
                    $op   =  ' '.strtoupper($where['_logic']).' ';
                    unset($where['_logic']);
                }else{
                    $op   =  ' AND ';
                }
                $array   =  [];
                foreach ($where as $field=>$data)
                    $array[] = $this->parseKey($field).' = '.$this->parseValue($data);
                $whereStr   = implode($op,$array);
                break;
        }
        return $whereStr;
    }

    /**
     * limit分析
     * @access protected
     * @param mixed $lmit
     * @return string
     */
    protected function parseLimit($limit) {
        return !empty($limit)?   ' LIMIT '.$limit.' ':'';
    }

    /**
     * join分析
     * @access protected
     * @param mixed $join
     * @return string
     */
    protected function parseJoin($join) {
        $joinStr = '';
        if(!empty($join)) {
            if(is_array($join)) {
                foreach ($join as $key=>$_join){
                    if(false !== stripos($_join,'JOIN'))
                        $joinStr .= ' '.$_join;
                    else
                        $joinStr .= ' LEFT JOIN ' .$_join;
                }
            }else{
                $joinStr .= ' LEFT JOIN ' .$join;
            }
        }
		//将__TABLE_NAME__这样的字符串替换成正规的表名,并且带上前缀和后缀
		$joinStr = preg_replace("/__([A-Z_-]+)__/esU",$this->config['prefix'].".strtolower('$1')",$joinStr);
        return $joinStr;
    }

    /**
     * order分析
     * @access protected
     * @param mixed $order
     * @return string
     */
    protected function parseOrder($order) {
        if(is_array($order)) {
            $array   =  [];
            foreach ($order as $key=>$val){
                if(is_numeric($key)) {
                    $array[] =  $this->parseKey($val);
                }else{
                    $array[] =  $this->parseKey($key).' '.$val;
                }
            }
            $order   =  implode(',',$array);
        }
        return !empty($order)?  ' ORDER BY '.$order:'';
    }

    /**
     * group分析
     * @access protected
     * @param mixed $group
     * @return string
     */
    protected function parseGroup($group) {
        return !empty($group)? ' GROUP BY '.$group:'';
    }

    /**
     * having分析
     * @access protected
     * @param string $having
     * @return string
     */
    protected function parseHaving($having) {
        return  !empty($having)?   ' HAVING '.$having:'';
    }

    /**
     * comment分析
     * @access protected
     * @param string $comment
     * @return string
     */
    protected function parseComment($comment) {
        return  !empty($comment)?   ' /* '.$comment.' */':'';
    }

    /**
     * distinct分析
     * @access protected
     * @param mixed $distinct
     * @return string
     */
    protected function parseDistinct($distinct) {
        return !empty($distinct)?   ' DISTINCT ' :'';
    }

    /**
     * union分析
     * @access protected
     * @param mixed $union
     * @return string
     */
    protected function parseUnion($union) {
        if(empty($union)) return '';
        if(isset($union['_all'])) {
            $str  =   'UNION ALL ';
            unset($union['_all']);
        }else{
            $str  =   'UNION ';
        }
        foreach ($union as $u){
            $sql[] = $str.(is_array($u)?$this->buildSelectSql($u):$u);
        }
        return implode(' ',$sql);
    }

    /**
     * 插入记录
     * @access public
     * @param mixed $data 数据
     * @param array $options 参数表达式
     * @param boolean $replace 是否replace
     * @return false | integer
     */
    public function insert($data,$options=[],$replace=false) {
        $values  =  $fields    = [];
        $this->model  =   $options['model'];
        foreach ($data as $key=>$val){
            $value   =  $this->parseValue($val);
            if(is_scalar($value)) { // 过滤非标量数据
                $values[]   =  $value;
                $fields[]   =  $this->parseKey($key);
            }
        }
        $sql   =  ($replace?'REPLACE':'INSERT').' INTO '.$this->parseTable($options['table']).' ('.implode(',', $fields).') VALUES ('.implode(',', $values).')';
        $sql   .= $this->parseLock(isset($options['lock'])?$options['lock']:false);
        $sql   .= $this->parseComment(!empty($options['comment'])?$options['comment']:'');
        return $this->execute($sql,!empty($options['bind'])?$options['bind']:[]);
    }

    /**
     * 通过Select方式插入记录
     * @access public
     * @param string $fields 要插入的数据表字段名
     * @param string $table 要插入的数据表名
     * @param array $option  查询数据参数
     * @return false | integer
     */
    public function selectInsert($fields,$table,$options=[]) {
        $this->model  =   $options['model'];
        if(is_string($fields))   $fields    = explode(',',$fields);
        array_walk($fields, [$this, 'parseKey']);
        $sql   =    'INSERT INTO '.$this->parseTable($table).' ('.implode(',', $fields).') ';
        $sql   .= $this->buildSelectSql($options);
        return $this->execute($sql);
    }

    /**
     * 更新记录
     * @access public
     * @param mixed $data 数据
     * @param array $options 表达式
     * @return false | integer
     */
    public function update($data,$options) {
        $this->model  =   $options['model'];
        $sql   = 'UPDATE '
            .$this->parseTable($options['table'])
            .$this->parseSet($data)
            .$this->parseWhere(!empty($options['where'])?$options['where']:'')
            .$this->parseOrder(!empty($options['order'])?$options['order']:'')
            .$this->parseLimit(!empty($options['limit'])?$options['limit']:'')
            .$this->parseLock(isset($options['lock'])?$options['lock']:false)
            .$this->parseComment(!empty($options['comment'])?$options['comment']:'');
        return $this->execute($sql,!empty($options['bind'])?$options['bind']:[]);
    }

    /**
     * 删除记录
     * @access public
     * @param array $options 表达式
     * @return false | integer
     */
    public function delete($options=[]) {
        $this->model  =   $options['model'];
        $sql   = 'DELETE FROM '
            .$this->parseTable($options['table'])
            .$this->parseWhere(!empty($options['where'])?$options['where']:'')
            .$this->parseOrder(!empty($options['order'])?$options['order']:'')
            .$this->parseLimit(!empty($options['limit'])?$options['limit']:'')
            .$this->parseLock(isset($options['lock'])?$options['lock']:false)
            .$this->parseComment(!empty($options['comment'])?$options['comment']:'');
        return $this->execute($sql,!empty($options['bind'])?$options['bind']:[]);
    }

    /**
     * 查找记录
     * @access public
     * @param array $options 表达式
     * @return mixed
     */
    public function select($options=[]) {
        $this->model  =   $options['model'];
        $sql    = $this->buildSelectSql($options);
        $cache  =  isset($options['cache'])?$options['cache']:false;
        if($cache) { // 查询缓存检测
            $key    =  is_string($cache['key'])?$cache['key']:md5($sql);
            $value  =  S($key,'',$cache);
            if(false !== $value) {
                return $value;
            }
        }
        $result   = $this->query($sql,!empty($options['bind'])?$options['bind']:[]);
        if($cache && false !== $result ) { // 查询缓存写入
            S($key,$result,$cache);
        }
        return $result;
    }

    /**
     * 生成查询SQL
     * @access public
     * @param array $options 表达式
     * @return string
     */
    public function buildSelectSql($options=[]) {
        if(isset($options['page'])) {
            // 根据页数计算limit
            if(strpos($options['page'],',')) {
                list($page,$listRows) =  explode(',',$options['page']);
            }else{
                $page = $options['page'];
            }
            $page    =  $page?$page:1;
            $listRows=  isset($listRows)?$listRows:(is_numeric($options['limit'])?$options['limit']:20);
            $offset  =  $listRows*((int)$page-1);
            $options['limit'] =  $offset.','.$listRows;
        }
        $sql  =   $this->parseSql($this->selectSql,$options);
        $sql .= $this->parseLock(isset($options['lock'])?$options['lock']:false);
        return $sql;
    }

    /**
     * 替换SQL语句中表达式
     * @access public
     * @param array $options 表达式
     * @return string
     */
    public function parseSql($sql,$options=[]){
        $sql   = str_replace(
            ['%TABLE%','%DISTINCT%','%FIELD%','%JOIN%','%WHERE%','%GROUP%','%HAVING%','%ORDER%','%LIMIT%','%UNION%','%COMMENT%'],
            [
                $this->parseTable($options['table']),
                $this->parseDistinct(isset($options['distinct'])?$options['distinct']:false),
                $this->parseField(!empty($options['field'])?$options['field']:'*'),
                $this->parseJoin(!empty($options['join'])?$options['join']:''),
                $this->parseWhere(!empty($options['where'])?$options['where']:''),
                $this->parseGroup(!empty($options['group'])?$options['group']:''),
                $this->parseHaving(!empty($options['having'])?$options['having']:''),
                $this->parseOrder(!empty($options['order'])?$options['order']:''),
                $this->parseLimit(!empty($options['limit'])?$options['limit']:''),
                $this->parseUnion(!empty($options['union'])?$options['union']:''),
                $this->parseComment(!empty($options['comment'])?$options['comment']:'')
            ],$sql);
        return $sql;
    }

    /**
     * 获取最近一次查询的sql语句 
     * @param string $model  模型名
     * @access public
     * @return string
     */
    public function getLastSql($model='') {
        return $model?$this->modelSql[$model]:$this->queryStr;
    }

    /**
     * 获取最近插入的ID
     * @access public
     * @return string
     */
    public function getLastInsID() {
        return $this->lastInsID;
    }

    /**
     * 获取最近的错误信息
     * @access public
     * @return string
     */
    public function getError() {
        return $this->error;
    }

    /**
     * SQL指令安全过滤
     * @access public
     * @param string $str  SQL字符串
     * @return string
     */
    public function escapeString($str) {
        return addslashes($str);
    }

    /**
     * 设置当前操作模型
     * @access public
     * @param string $model  模型名
     * @return void
     */
    public function setModel($model){
        $this->model =  $model;
    }

    /**
     * 数据库调试 记录当前SQL
     * @access protected
     * @param boolean $start  调试开始标记 true 开始 false 结束
     */
    protected function debug($start) {
        if($this->config['debug']) {// 开启数据库调试模式
            if($start) {
                Debug::remark('queryStartTime','time');
            }else{
                $this->modelSql[$this->model]   =  $this->queryStr;
                //$this->model  =   '_think_';
                // 记录操作结束时间
                Debug::remark('queryEndTime','time');
                Log::record($this->queryStr.' [ RunTime:'.Debug::getUseTime('queryStartTime','queryEndTime').'s ]','SQL');
            }
        }
    }

    /**
     * 初始化数据库连接
     * @access protected
     * @param boolean $master 主服务器
     * @return void
     */
    protected function initConnect($master=true) {
        if(!empty($this->config['deploy']))
            // 采用分布式数据库
            $this->_linkID = $this->multiConnect($master);
        else
            // 默认单数据库
            if ( !$this->_linkID ) $this->_linkID = $this->connect();
    }

    /**
     * 连接分布式服务器
     * @access protected
     * @param boolean $master 主服务器
     * @return void
     */
    protected function multiConnect($master=false) {
        static $_config = [];
        if(empty($_config)) {
            // 缓存分布式数据库配置解析
            foreach ($this->config['connection'] as $key=>$val){
                $_config[$key]      =   explode(',',$val);
            }
        }
        // 数据库读写是否分离
        if($this->config['rw_separate']){
            // 主从式采用读写分离
            if($master)
                // 主服务器写入
                $r  =   floor(mt_rand(0,$this->config['master_num']-1));
            else{
                if(is_numeric($this->config['slave_no'])) {// 指定服务器读
                    $r = $this->config['slave_no'];
                }else{
                    // 读操作连接从服务器
                    $r = floor(mt_rand($this->config['master_num'],count($_config['hostname'])-1));   // 每次随机连接的数据库
                }
            }
        }else{
            // 读写操作不区分服务器
            $r = floor(mt_rand(0,count($_config['hostname'])-1));   // 每次随机连接的数据库
        }
        $db_config = [
            'username'  =>  isset($_config['username'][$r])?$_config['username'][$r]:$_config['username'][0],
            'password'  =>  isset($_config['password'][$r])?$_config['password'][$r]:$_config['password'][0],
            'hostname'  =>  isset($_config['hostname'][$r])?$_config['hostname'][$r]:$_config['hostname'][0],
            'hostport'  =>  isset($_config['hostport'][$r])?$_config['hostport'][$r]:$_config['hostport'][0],
            'database'  =>  isset($_config['database'][$r])?$_config['database'][$r]:$_config['database'][0],
            'dsn'       =>  isset($_config['dsn'][$r])?$_config['dsn'][$r]:$_config['dsn'][0],
        ];
        return $this->connect($db_config,$r);
    }

   /**
     * 析构方法
     * @access public
     */
    public function __destruct() {
        // 释放查询
        if ($this->PDOStatement){
            $this->free();
        }
        // 关闭连接
        $this->close();
    }
}