<?php
/**
 * session 数据库存储类
 */
class Session {
 private static $session_id  = 0;
 private static $session_data = array();
 private static $is_update  = FALSE;
 private static $is_del  = FALSE;
 private static $is_gc  = FALSE;
 private static $dbo  = NULL; //数据库连接句柄
 private static $gc_max_time = 1440;
 private static $table  = 'sessions';
 private static $pre_key  = 'weige';//session 密钥
 //捆绑使用哈
 private static $gc_rate_de = 100;//代表分母
 private static $gc_rate_co = 20;//代表分子
 private static $path  = '/';//保存路径
 private static $domain  = null; //域
 private static $secure  = false;//默认
 private static $httponly = false;//默认
 /**
 * 获取数据库句柄 私有
 */
 private static function open() 
 {
 if (!self::$dbo) 
 {
  self::$dbo = Db::factory();
 }
 return TRUE;
 }
 /**
 * 设置
 * */
 public static function set($key, $val=NULL) 
 {
 self::open();
 $data = self::read();
 if ($data === FALSE)
 {
  $data = array();
 }
 if (!$val && is_array($key))
 {
  $data = $key;
 } 
 else if ($val && is_string($key))
 {
  $data[$key] = $val;
 }
 self::write($data);
 self::close();
 }
 /**
 *获取值 
 * 
 */
 public static function get($key=NULL) {
 self::open();
 self::$session_data = self::read();
 $ret = '';
 if (!$key) {
  $ret = self::$session_data;
 } else if(is_array(self::$session_data) && isset(self::$session_data[$key])) {
  $ret = self::$session_data[$key];
 }
 self::update(); 
 self::close();
 return $ret;
 }
 /**
 * 删除或者重置
 * */
 public static function del($key)
 {
 if (!self::$is_del) 
 {
  self::open();
  $val = self::read();
  if (isset($val[$key])) 
  {
  unset($val[$key]);
  }
  $session_id = self::$session_id;
  $session_data = serialize($val);
  $session_expire = TIME + self::get_gc_maxtime();
  self::$dbo->query("update ".self::$table." set value='$session_data', expiry='$session_expire' where session_id='$session_id'");
  self::close();
 }
 self::$is_del = TRUE;
 }
 /**
 * 销毁
 * 
 * */
 public static function destroy() 
 {
 $session_id  = self::get_session_id();
 $_COOKIE['WBSID'] = '';
 self::open();
 self::$dbo->query("delete from ".self::$table." where session_id='$session_id'");
 self::close();
 }
 /**
 * 读取 私有
 * */
 private static function read()
 {
 $session_id = self::$session_id;
 if (!$session_id) {
  $session_id = self::get_session_id();
 }
 if (!$session_id) return array();
 $user_agent = isset($_SERVER['HTTP_USER_AGENT']) ? md5($_SERVER['HTTP_USER_AGENT']) : '';
 $client_ip = Fun::getIp();
 $session_expire = TIME - self::get_gc_maxtime();
 $rs = self::$dbo->fetchRow("select session_id, value, agent, ip from ".self::$table."
  where session_id='$session_id' and expiry>'$session_expire'");
 if (!$rs || $rs['agent'] != $user_agent || $rs['ip'] != $client_ip) 
 {
  return FALSE;
 }
 self::$session_id = $rs['session_id'];
 return unserialize($rs['value']);
 }
 /**
 * session 写入 私有
 * */
 private static function write(array $session_data) 
 {
 $session_id = self::$session_id;
 if (!$session_id)
 {
  $session_id = self::get_session_id();
 }
 $session_expire = TIME + self::get_gc_maxtime();
 $user_agent = isset($_SERVER['HTTP_USER_AGENT']) ? md5($_SERVER['HTTP_USER_AGENT']) : '';
 $client_ip = Fun::getIp();
 $session_data = serialize($session_data);
 if (self::$session_id && self::$session_id === $session_id) 
 {
  self::$dbo->query("update ".self::$table." set value='$session_data', expiry='$session_expire', agent='$user_agent', ip='$client_ip' where session_id='$session_id'");
 } 
 else 
 {
  self::$session_id = $session_id = self::create_session_id();
  self::$dbo->query("insert into ".self::$table."(session_id, value, expiry, agent, ip) 
  values('$session_id', '$session_data', '$session_expire', '$user_agent', '$client_ip')");
 }
 return true;
 }
 /**
 * session 更新 私有
 * */
 private static function update() 
 {
 if (!self::$is_update) 
 {
  $session_id = self::$session_id;
  $session_expire = TIME + self::get_gc_maxtime();
  self::$dbo->query("update ".self::$table." set expiry='$session_expire' where session_id='$session_id'");
 }
 self::$is_update = TRUE;
 }
 private static function close() 
 {
 if (!self::$is_gc && mt_rand(1, self::$gc_rate_de)%self::$gc_rate_co == 0) 
 {
  self::gc();
 }
 self::$is_gc = TRUE;
 }
 /**
 * 过期session 清除 随机触发
 * */
 private static function gc() 
 {
 $session_expire = TIME - self::get_gc_maxtime();
  self::$dbo->query("delete from ".self::$table." where expiry<'$session_expire'");
 }
 private static function get_session_id() 
 {
 if (isset($_COOKIE['WBSID']) && strlen($_COOKIE['WBSID'])==32) 
 {
  $sid = $_COOKIE['WBSID'];
  setcookie('WBSID', $sid, TIME + self::get_gc_maxtime(), self::$path, self::$domain, self::$secure, self::$httponly);
  return $sid;
 }
 return null;
 }
 private static function create_session_id() 
 {
 $sid = self::get_session_id();
 if (!$sid) 
 {
  $sid = Fun::getIp() . TIME . microtime(TRUE) . mt_rand(mt_rand(0, 100), mt_rand(100000, 90000000));
  $sid = md5(self::$pre_key . $sid);
  setcookie('WBSID', substr($sid, 0, 32), TIME + self::get_gc_maxtime(), self::$path, self::$domain, self::$secure, self::$httponly);
 }
 return $sid;
 }
 public static function get_gc_maxtime()
 {
 return self::$gc_max_time;
 }
}