<?php
// +----------------------------------------------------------------------
// | ThinkPHP [ WE CAN DO IT JUST THINK ]
// +----------------------------------------------------------------------
// | Copyright (c) 2006~2016 http://thinkphp.cn All rights reserved.
// +----------------------------------------------------------------------
// | Licensed ( http://www.apache.org/licenses/LICENSE-2.0 )
// +----------------------------------------------------------------------
// | Author: liu21st <liu21st@gmail.com>
// +----------------------------------------------------------------------

namespace think\cache;

/**
 * 缓存基础类
 */
abstract class Driver
{
    protected $options = [];
    protected $tag;

    /**
     * 判断缓存是否存在
     * @access public
     * @param string $name 缓存变量名
     * @return bool
     */
    abstract public function has($name);

    /**
     * 读取缓存
     * @access public
     * @param string $name 缓存变量名
     * @param mixed  $default 默认值
     * @return mixed
     */
    abstract public function get($name, $default = false);

    /**
     * 写入缓存
     * @access public
     * @param string    $name 缓存变量名
     * @param mixed     $value  存储数据
     * @param int       $expire  有效时间 0为永久
     * @return boolean
     */
    abstract public function set($name, $value, $expire = null);

    /**
     * 自增缓存（针对数值缓存）
     * @access public
     * @param string    $name 缓存变量名
     * @param int       $step 步长
     * @return false|int
     */
    abstract public function inc($name, $step = 1);

    /**
     * 自减缓存（针对数值缓存）
     * @access public
     * @param string    $name 缓存变量名
     * @param int       $step 步长
     * @return false|int
     */
    abstract public function dec($name, $step = 1);

    /**
     * 删除缓存
     * @access public
     * @param string $name 缓存变量名
     * @return boolean
     */
    abstract public function rm($name);

    /**
     * 清除缓存
     * @access public
     * @param string $tag 标签名
     * @return boolean
     */
    abstract public function clear($tag = null);

    /**
     * 缓存标签
     * @access public
     * @param string $name 标签名
     * @return $this
     */
    public function tag($name)
    {
        $this->tag = $name;
        return $this;
    }

    /**
     * 更新标签
     * @access public
     * @param string $name 缓存标识
     * @return void
     */
    protected function setTagItem($name)
    {
        if ($this->tag) {
            $key       = 'tag_' . md5($this->tag);
            $this->tag = null;
            if ($this->has($key)) {
                $value = $this->get($key);
                $value .= ',' . $name;
            } else {
                $value = $name;
            }
            $this->set($key, $value);
        }
    }

    /**
     * 获取标签包含的缓存标识
     * @access public
     * @param string $tag 缓存标签
     * @return array
     */
    protected function getTagItem($tag)
    {
        $key   = 'tag_' . md5($tag);
        $value = $this->get($key);
        if ($value) {
            return explode(',', $value);
        } else {
            return [];
        }
    }
}