<?php

if (!defined('BASEPATH'))
    exit('No direct script access allowed');

class MY_Output extends CI_Output
{
	
	// --------------------------------------------------------------------

	/**
	 * Write a Cache File
	 *
	 * @access	public
	 * @param 	string
	 * @return	void
	 */
	function _write_cache($output)
	{
		$CI =& get_instance();
		$path = $CI->config->item('cache_path');

		$cache_path = ($path == '') ? APPPATH.'cache/' : $path;

		if ( ! is_dir($cache_path) OR ! is_really_writable($cache_path))
		{
			log_message('error', "Unable to write cache file: ".$cache_path);
			return;
		}

		$uri =	$CI->config->item('base_url').
				$CI->config->item('index_page').
				$CI->uri->uri_string();

        
		///////改成按照URL保存缓存
		//$cache_path .= md5($uri);
		//生成缓存需要把@cache@refresh标识去掉
		$origin_url=$this->get_origin_url($CI->config->item('index_page'));	
		$cache_path=$cache_path.$_SERVER['HTTP_HOST'].'/'.$origin_url;
        create_folder_by_path(dirname($cache_path));
		///////

		if ( ! $fp = @fopen($cache_path, FOPEN_WRITE_CREATE_DESTRUCTIVE))
		{
			log_message('error', "Unable to write cache file: ".$cache_path);
			return;
		}

		$expire = time() + ($this->cache_expiration * 60);

		if (flock($fp, LOCK_EX))
		{
			fwrite($fp, $expire.'TS--->'.$output);
			fseek($fp,0,SEEK_END);
			fwrite($fp, '<!-- Generated by '.$_SERVER['HTTP_HOST'].' ('.date('c').') -->');
			flock($fp, LOCK_UN);
		}
		else
		{
			log_message('error', "Unable to secure a file lock for file at: ".$cache_path);
			return;
		}
		fclose($fp);
		@chmod($cache_path, FILE_WRITE_MODE);

		log_message('debug', "Cache file written: ".$cache_path);
	}

	// --------------------------------------------------------------------

	/**
	 * Update/serve a cached file
	 *
	 * @access	public
	 * @param 	object	config class
	 * @param 	object	uri class
	 * @return	void
	 */
	function _display_cache(&$CFG, &$URI)
	{
		$cache_path = ($CFG->item('cache_path') == '') ? APPPATH.'cache/' : $CFG->item('cache_path');
		
		///////改成按照URL保存缓存
		//$filepath = $cache_path.md5($uri);
		//如果有@cache@refresh标识则返回false，不读取缓存
		$origin_url=$this->get_origin_url($CFG->item('index_page'));
		$filepath=$cache_path.$_SERVER['HTTP_HOST'].'/'.$origin_url;
		if($this->is_has_cache_mark())
		{
			@unlink($filepath);
			return false;
		}
		///////

		if ( ! @file_exists($filepath))
		{
			return FALSE;
		}

		if ( ! $fp = @fopen($filepath, FOPEN_READ))
		{
			return FALSE;
		}

		flock($fp, LOCK_SH);

		$cache = '';
		if (filesize($filepath) > 0)
		{
			$cache = fread($fp, filesize($filepath));
		}

		flock($fp, LOCK_UN);
		fclose($fp);

		// Strip out the embedded timestamp
		if ( ! preg_match("/(\d+TS--->)/", $cache, $match))
		{
			return FALSE;
		}

		// Has the file expired? If so we'll delete it.
		if (time() >= trim(str_replace('TS--->', '', $match['1'])))
		{
			if (is_really_writable($cache_path))
			{
				@unlink($filepath);
				log_message('debug', "Cache file has expired. File deleted");
				return FALSE;
			}
		}

		// Display the cache
		$this->_display(str_replace($match['0'], '', $cache));
		log_message('debug', "Cache file is current. Sending it to browser.");
		return TRUE;
	}

	 /**
	  * 获取iis rewrite之前的原始url
	  */ 
	 function get_origin_url($index_page) {
		if (isset($_SERVER['HTTP_X_REWRITE_URL'])) {
			$origin_url = str_replace($index_page,'/',$_SERVER['HTTP_X_REWRITE_URL']);
		} else {
			$origin_url = str_replace($index_page,'/',$_SERVER['REQUEST_URI']);
		}
		$origin_url=str_replace(array('///','//','@cache@refresh'),array('/','/',''),urldecode($origin_url));
		if(mb_substr($origin_url,-1,1)=='/')
		{
			$origin_url.='index.htm';
		}
		return $origin_url;
	 }
	 
	 /*
	 * 判断是否有更新标识@cache@refresh
	 */
	 function is_has_cache_mark()
	 {
		//HTTP_X_REWRITE_URL 是不会带有@cache@refresh标识的，判断的时候需要判断两种url
        if (!isset($_SERVER['HTTP_X_REWRITE_URL']))
        {
    		if(strpos($_SERVER['REQUEST_URI'],'@cache@refresh'))
    		{
    			return true;
    		}
        } 
        else 
        {
            if (strpos($_SERVER['HTTP_X_REWRITE_URL'],'@cache@refresh'))
            {
                return true;
            }
        }
        return false;
	 }

}