<?php
require_once dirname(__FILE__).'/config/common.inc.php';
abstract class Util_Db_BaseDB
{
    public $mWDBConf = array();
    public $mRDBConf = array();
    private $mDBNameKey = array();
    private $mSwitchFlag = false;
    protected $mInstance = null;
    private $mBackupInstance = array();
    private $mBackupWriteFlag = array();
    private $mBackupWeight = array();
    private static $mCurrentDBName = '';

    /**
     * 初始化
     */
    public function __construct($db_config=array())
    {
        if(empty($db_config))
        {
            require dirname(__FILE__).'/config/db.inc.php';
        }    
        $this->mWDBConf = $db_config['master'];
        $this->mDBNameKey = array_keys($this->mWDBConf);
        $this->mRDBConf = $db_config['slave'];
        if(!empty(self::$mCurrentDBName))
        {
            self::$mCurrentDBName = BASEDB_DEFAULTCONNECT_DBNAME;
        }

    }

    /**
     * 连接到主数据库服务器
     * 
     * @param string $dbNameKey
     * @return object
     */
    public function conn_master($dbNameKey = BASEDB_DEFAULTCONNECT_DBNAME)
    {
        $host = $this->mWDBConf[$dbNameKey]['host'];
        $user = $this->mWDBConf[$dbNameKey]['user'];
        $pwd  = $this->mWDBConf[$dbNameKey]['pwd'];
        $dbname = $this->mWDBConf[$dbNameKey]['dbname'];
        $port = $this->mWDBConf[$dbNameKey]['port'];
        $link = new mysqli($host, $user, $pwd, $dbname, $port);
        //echo "host: ".$host;
        //error_log('master time: '.date('Y-m-d H:i:s', time())."\n", 3, dirname(__FILE__).'/dbaccess.log');
        //error_log('master host: '.$host."\n", 3,dirname(__FILE__).'/dbaccess.log');
        if(mysqli_connect_errno())
        { 
            $link = false; 
            echo '<h2>'.mysqli_connect_error().'</h2>'; 
            die(); 
        } 
        else
        { 
            $link->set_charset("utf8"); 
        } 
        return $link;
    }
    
    /**
     * 连接到从数据库服务器
     * 
     * @param string $dbNameKey
     * @return object
     */
    public function conn_slave($dbNameKey = BASEDB_DEFAULTCONNECT_DBNAME)
    {
        $offset = $this->weightRandomDB($this->mRDBConf[$dbNameKey], $dbNameKey);
        $host = $this->mRDBConf[$dbNameKey][$offset]['host'];
        $user = $this->mRDBConf[$dbNameKey][$offset]['user'];
        $pwd = $this->mRDBConf[$dbNameKey][$offset]['pwd'];
        $dbName = $this->mRDBConf[$dbNameKey][$offset]['dbname'];
        $port = $this->mRDBConf[$dbNameKey][$offset]['port'];
        $link = new mysqli($host, $user, $pwd, $dbName, $port);
        //如果连接失败
        if(mysqli_connect_errno())
        {
            foreach($this->mRDBConf as $key=>$rDBConf)
            {
                if($key == $offset)
                {
                    continue;
                }
                $host = $this->mRDBConf[$dbNameKey][$offset]['host'];
                $user = $this->mRDBConf[$dbNameKey][$offset]['user'];
                $pwd  = $this->mRDBConf[$dbNameKey][$offset]['pwd'];
                $databasename = $this->mRDBConf[$dbNameKey][$offset]['dbname'];
                $port = $this->mRDBConf[$dbNameKey][$offset]['port'];
                $link = new mysqli($host, $user, $pwd, $dbName, $port);
                if(is_object($link))
                {
                    break;
                }
            }
        }
        //都连接失败，自动切换到主库
        if(!is_object($link))
        {
            return $this->conn_master($dbNameKey);
        }
        else
        {
            //error_log('slave time: '.date('Y-m-d H:i:s', time())."\n", 3, dirname(__FILE__).'/dbaccess.log');
            //error_log('slave host: '.$this->mRDBConf[$dbNameKey][$offset]['host']."\n", 3, dirname(__FILE__).'/dbaccess.log');
            //echo "host: ".$this->mRDBConf[$dbNameKey][$offset]['host'];
            $link->set_charset("utf8"); 
            return $link;
        }
    }
    
     /**
     *设置数据连接
     * 
     * @param boolean $isMaster
     * @return object
     */
    public function setDefaultConnect($isMaster = true)
    {
        if($this->mSwitchFlag)
        {
            return;
        }
        if($isMaster)
        {
            $this->mBackupInstance[self::$mCurrentDBName] = $this->conn_master(self::$mCurrentDBName);
            $this->mBackupWriteFlag[self::$mCurrentDBName] = true;
        }
        else
        {
            $this->mBackupInstance[self::$mCurrentDBName] = $this->conn_slave(self::$mCurrentDBName);
            $this->mBackupWriteFlag[self::$mCurrentDBName] = false;
        }
    }
    
     /**
     * 设置服务器开关
     * 
     * @param boolean $flag
     * @return object
     */
    public function setHostSwitch($flag = true)
    {
        $this->mSwitchFlag = $flag;
        //设置当前的主库
        if($flag)
        {
            $this->mInstance = $this->mBackupInstance[self::$mCurrentDBName];
        }
    }
    
     /**
     * 自动选择服务器
     * 
     * @param string $sql
     * @return object
     */
    public function autoChoiseHost($sql)
    {
        if(!empty($sql))
        {
            $isMaster = $this->checkMaster($sql);
            if(array_key_exists(self::$mCurrentDBName,$this->mBackupInstance) && is_object($this->mBackupInstance[self::$mCurrentDBName]))
            {
                //当前状态是读，判断执行操作是写
                if($this->mBackupWriteFlag[self::$mCurrentDBName]!=$isMaster && $isMaster)
                {
                    //关闭读连接
                    $this->mInstance->close();
                    //切换到主库
                    $this->setDefaultConnect(true);
                    $this->mInstance = $this->mBackupInstance[self::$mCurrentDBName];
                }
                    //当前状态与执行操作相同返回
                else if(($this->mBackupWriteFlag[self::$mCurrentDBName]==$isMaster))
                {
                    return;
                }
            }    
            else
            {
                $this->setDefaultConnect($isMaster);
                $this->mInstance = $this->mBackupInstance[self::$mCurrentDBName];
            }
        }
    }
    
    /**
     * 检查主从
     * 
     * @param string $sql
     * @return boolean
     */
    private function checkMaster($sql)
    {
        $sqls = explode(" ", ltrim($sql));
        $optType = trim(strtolower($sqls[0]));
        $matches = '';
        $rules = array();
        $dbName = '';
        $state = 'read';
        preg_match_all('@\/\*(.+)\*\/@isU',$sql,$matches);
        $result = false;
        if(isset($matches[1][0]))
        {
            $rules = json_decode(str_replace('\'','"', trim($matches[1][0])),true);
        }
        $potPos = strpos($sql,'.');
        $quotePos = strpos($sql,'\'');
        //判断第一次点出现位置，用于处理数据库关键字
        if($potPos<$quotePos||($potPos>0&&$quotePos==false))
        {
            foreach($this->mDBNameKey as $dbNameKey)
            {
                $key = substr($sql,$potPos-strlen($dbNameKey),strlen($dbNameKey));
                if(strcmp($key, $dbNameKey)==0)
                {
                    self::$mCurrentDBName = $dbNameKey;
                    break;
                }
            }
        }
        else
        {
            self::$mCurrentDBName = BASEDB_DEFAULTCONNECT_DBNAME;
        }
        
        //注释规则
        if(count($rules))
        {
            if(isset($rules['dbname']))
            {
                $dbName = strtolower($rules['dbname']);
            }
            if(isset($rules['state']))
            {
                $state = strtolower($rules['state']);
            }
        }
        if(empty($dbName))
        {
            self::$mCurrentDBName = BASEDB_DEFAULTCONNECT_DBNAME;
        }
        else
        {
            self::$mCurrentDBName = $dbName;
        }
        if(strcmp($optType, 'call')==0)
        {
            if(strcmp($state,'read')==0)
            {
                //数据切分
                if(isset($rules['segrule']))
                {
                    self::$mCurrentDBName = $this->dataSegByRouter($sql, $rules['segrule'] ,false);
                }
                $result = false;
            }
            else
            {
                //数据切分
                if(isset($rules['segrule']))
                {
                    self::$mCurrentDBName = $this->dataSegByRouter($sql, $rules['segrule']);
                }
                $result = true;
            }
        }
        else if(strcmp($optType,'select')==0)
        {
            //数据切分
            if(isset($rules['segrule']))
            {
                self::$mCurrentDBName = $this->dataSegByRouter($sql, $rules['segrule'] ,false);
            }
            $result = false;
        }
        else
        {
            //数据切分
            if(isset($rules['segrule']))
            {
                self::$mCurrentDBName = $this->dataSegByRouter($sql, $rules['segrule']);
            }
            $result = true;
        }

        return $result;
    }
    
    /**
     * 加权随机选择
     * 
     * @param array $slaveDBs
     * @param string $dbNameKey
     * @return string 
     */
    private function weightRandomDB($slaveDBs, $dbNameKey)
    {
        $slaveDBsCount = count($slaveDBs);
        //位数
        $median = strlen($slaveDBsCount);
        $totalWeight = 0;
        $sequence = 0;
        if($slaveDBsCount)
        {
            if(empty($this->mBackupWeight[$dbNameKey]))
            {
                //序列
                $this->mBackupWeight[$dbNameKey]['sequence'] = '';
                //总权值
                $this->mBackupWeight[$dbNameKey]['totalWeight'] = 0;
                $weight = 0;
                foreach($slaveDBs as $key=>$slaveDB)
                {
                    if(isset($slaveDB['weight']))
                    {
                        $weight = intval($slaveDB['weight']);
                    }
                    $this->mBackupWeight[$dbNameKey]['totalWeight'] += $weight;
                    if(empty($weight))
                    {
                        continue;
                    }
                    $this->mBackupWeight[$dbNameKey]['sequence'] .= str_repeat(sprintf('%0'.$median.'s',$key), $weight);
                }
            }
            $totalWeight = $this->mBackupWeight[$dbNameKey]['totalWeight'];
            $sequence = $this->mBackupWeight[$dbNameKey]['sequence'];
            //判断总权是否为0
            if(empty($totalWeight))
            {
                $key = rand(0, $slaveDBsCount-1);
            }
            else
            {
                $keyPos = rand(0, $totalWeight-1)*$median;
                $key = intval(substr($sequence, $keyPos, $median));
            }    
            return $key;
        }
    }
    
    /**
     * 数据切分根据路由选择数据库
     * 条件：
     * 
     *  1. 统一放在第一个sql关键字词语后面，用空格分开。
        2. json里面都的关键字变量统一都用小写方式。
        3. json里面标识关键字的双引号，用单引号表示
        
     * 参数：
     * {'dbname':'','state':'','segrule':{'tablename':{'current':'','seg':''},
     * 'readdbs':[],'writedbs':[],'router':''}}
     *
     * dbname:数据库名
       state:数据库状态：变量值: 为read 或write.
       segrule:数据切分规则：(可以不写)
       tablename:表名：
       current:当前表名
       seg:切分后的表名
       readdbs:读数据库群,数组类型
       writedbs写数据库群,数组类型
       router:路由规则，根据路由规则实现数据切分,（没有具体相应的规则）：参数里面：可以传递相应的函数列表。
       
     *  根据router路由规则选择读写数据库
     *  再对sql语句进行处理
     * @param string &$sql
     * @param array $segRule
     * @param boolean $isWriteState
     * @return String
     */
    private function dataSegByRouter(&$sql, $segRule, $isWriteState = true)
    {
       if(empty($segRule))
       {
           return ;
       }
       else
       {
            //array
            $tableName = $segRule['tablename'];
            //array
            $readDBs = $segRule['readdbs'];
            //array
            $writeDBs = $segRule['writedbs'];
            //路由,todo
            $router = $segRule['router'];
            if($router && $isWriteState)
            {
                return $writeDBs[array_rand($writeDBs,1)];
            }
            else
            {
                return $readDBs[array_rand($readDBs,1)];
            }
       }
    }
    
    /**
     * 析构
     */
    public function __destruct()
    {
        foreach($this->mBackupInstance as $instance)
        {
            if(is_object($instance))
            {
                $instance->close();
            }
        }
        unset($this->mBackupWriteFlag);
        unset($this->mBackupWeight);
        self::$mCurrentDBName = '';
    }
}
?>