/*
事务脚本模式: 类似于thinkphp中的model层，或者说就是操作数据库的类。
个人觉得实践中使用起来还是挺简单方便的，就是SQL语句写死了的话，灵活性就不够。
示例代码如下：

*/

namespace woo\process;

abstract class Base{
    static $DB;                 //pdo对象
    static $stmts = array(); //sql语句句柄
    
    function __construct (){
        $dsn = \woo\base\ApplicationRegistry::getDSN();
        if(is_null($dsn)){
            throw new \woo\base\AppException("No DSN");
        }
        self::$DB = new PDO($dsn);
        self::$DB->setAttribute(\PDO::ATTR_ERRMODE,\PDO::ERRMODE_EXCEPTION);
    }
    
    function prepareStatement($stmt_s){   //缓存sql语句句柄
        if(isset(self::$stmts($stmt_s)){
            return self::$stmts[$stmt_s];
        }
        $stmt_handle = self::$DB->prepare($stmt_s);
        self::$stmts[$stmt_s] = $stmt_handle;
        return $stmt_handle;
    }
    
    protected function doStatement($stmt_s,$values_a){    //执行sql并获取一个语句资源
        $sth = $this->prepareStatement($stmt_s);
        $sth->closeCursor();
        $db_result = $sth->execute($values_a);
        return $sth;
    }
}

//这个类就是向数据库中写入一些数据，比较简单没什么好多说的
class VenueManager extends Base{
    static $add_venue = "INSERT INTO venue (name) values(?)";
    static $add_space = "INSERT INTO space (name,venue) values(?,?)";
    static $check_slot = "SELECT id,name FROM event WHERE space = ? AND (start+duration)>? AND start <?";
    static $add_event = "INSERT INTO event (name,space,start,duration) values(?,?,?,?)";
    
    function addVenue($name,$space_array){
        $ret = array();
        $ret[‘venue‘] = array($name);
        $this->doStatement(self::$add_venue,$ret[‘venue‘]);
        $v_id = self::$DB->lastInsertId();
        $ret[‘spaces‘] = array();
        foreach($space_array as $space_name){
            $values = array($space_name,$v_id);
            $this->doStatement(self::$add_space,$values);
            $s_id = self::$DB->lastInsertId();
            array_unshift($values,$s_id);
            $ret[‘spaces‘][] = $values;
        }
        return $ret;
    }
    
    function bookEvent ($space_id,$name,$time,$duration){
        $values = array($space_id,$time,($time+$duration));
        $stmt = $this->doStatement(self::$check_slot,$values,false);
        if($result = $stmt->fetch()){
            throw new \woo\base\AppException("double booked! try again");
        }
        $this->doStatement(self::$add_event,array($name,$space_id,$time,$duration));
    }
}

//客户端,使用起来还是比较简便的
$venue =  new VenueManager();
$venue->addVenue(‘test‘,array(‘test1‘,‘test2‘,‘test3‘));