<?php
/** Custom-made funky-caching for HB!: save it as wp-content/advanced-cache.php */

/** Where all the static pages will be stored, each site in a sub-folder */
define('HBCACHE_STORAGE', __DIR__ . '/hb-cache');

/** The magic happens here */
class HB_Cache {

	/**
	* Start output buffering
	*/
	Public Static Function process() {
		ob_start(array( __CLASS__, 'ob_callback'));
		}	

	/**
	* Output buffering callback
	*
	* @param string $buffer
	* @return string
	*/
	Public Static Function ob_callback(&$buffer) {

		if ($buffer != '' ) {

			$file = HBCACHE_STORAGE  . '/'
				. $_SERVER['HTTP_HOST'] 
				. $_SERVER['REQUEST_URI']
				. 'hb.html';

			mkdir(dirname($file), 0755, true);
			file_put_contents($file, $buffer 
				. '<!-- HB! Cache ' . date('r') . ' -->');
			}
		
		return $buffer;
		}
	
	// -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
	    
	/**
	* Disk cache cleanup
	*
	* @param string $path
	* @param boolean $remove
	*/
	Public Static Function cleanup($path = HBCACHE_STORAGE, $remove = false) {
        
		if ($dir = @opendir($path)) {
			while (($entry = @readdir($dir)) !== false) {
				if ($entry != '.' && $entry != '..') {
					$full_path = $path . '/' . $entry;
		
					if (@is_dir($full_path)) {
						self::cleanup($full_path, true);
						} else
					if (!self::is_valid($full_path)) {
						echo $full_path, "\r\n";
						@unlink($full_path);
						}
					}
				}
		
			@closedir($dir);
		
			if ($remove) {
				echo $path, "\r\n";
				@rmdir($path);
				}
			}
		}

	/**
	* Check if a file is due to be garbage-collected
	*
	* @param string $file
	* @return boolean
	*/
	Public Static Function is_valid($file) {
        
		if (file_exists($file)) {
			$ftime = @filemtime($file);
		
			/* cache the pages for 24hrs */
			if ($ftime && $ftime > (time() - 86400)) { 
				return true;
				}
			}
		
		return false;
		}

	////-end-of-class-- 
	}

/////////////////////////////////////////////////////////////////////////////

/**
* Skip caching for some pages
*/
switch (true) {
	case defined('DOING_AJAX'):
	case defined('DOING_CRON'):
	case defined('APP_REQUEST'):
	case defined('XMLRPC_REQUEST'):
	case defined('WP_ADMIN'):
	case (defined('SHORTINIT') && SHORTINIT):
	    return;
	}

/** 
* If included from WordPress will process the buffered output, otherwise 
* if called from console\cron will execute the garbage-collection 
*/
defined('WP_CACHE') 
	? HB_Cache::process() 
	: HB_Cache::cleanup();

/////////////////////////////////////////////////////////////////////////////

/* Include this in your nginx conf:

location / {

        # file exist, push it
        if (-f $request_filename) {
                break;
        	}

        set $hb_file '';

        # compose the path to the static file form the cache
	if ($request_uri ~ ^.+$) {
		set $hb_file /wp-content/hb-cache/$http_host/$request_uri/hb.html;
        	}

        if ($request_method = POST) {
		set $hb_file '';
        	}

        # query string found, do not push then
        if ($query_string) {
		set $hb_file '';
        	}

	# admin, comment troll or whetever -- do not push either
        if ($http_cookie ~* "comment_author_|wordpress|wp-postpass_" ) {
		set $hb_file '';
        	}

        # only rewrite to the static cache file if it actually exists
        if (-f $document_root$hb_file) {
		rewrite ^(.*)$ $hb_file break;
        	}

        # all other requests go to WordPress
        if (!-e $request_filename) {
                rewrite . /index.php last;
        	}
	}

*/