<?php
/************************************************************************
 * MXChange v0.2.1                                    Start: 12/16/2008 *
 * ===============                              Last change: 12/16/2008 *
 *                                                                      *
 * -------------------------------------------------------------------- *
 * File              : filters.php                                      *
 * -------------------------------------------------------------------- *
 * Short description : Functions for filter system                      *
 * -------------------------------------------------------------------- *
 * Kurzbeschreibung  : Funktionen fuer Filter-System                    *
 * -------------------------------------------------------------------- *
 *                                                                      *
 * -------------------------------------------------------------------- *
 * Copyright (c) 2003 - 2008 by Roland Haeder                           *
 * For more information visit: http://www.mxchange.org                  *
 *                                                                      *
 * This program is free software; you can redistribute it and/or modify *
 * it under the terms of the GNU General Public License as published by *
 * the Free Software Foundation; either version 2 of the License, or    *
 * (at your option) any later version.                                  *
 *                                                                      *
 * This program is distributed in the hope that it will be useful,      *
 * but WITHOUT ANY WARRANTY; without even the implied warranty of       *
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the        *
 * GNU General Public License for more details.                         *
 *                                                                      *
 * You should have received a copy of the GNU General Public License    *
 * along with this program; if not, write to the Free Software          *
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,               *
 * MA  02110-1301  USA                                                  *
 ************************************************************************/

// Some security stuff...
if (!defined('__SECURITY')) {
	$INC = substr(dirname(__FILE__), 0, strpos(dirname(__FILE__), "/inc") + 4)."/security.php";
	require($INC);
}

// Init "generic filter system"
function INIT_FILTER_SYSTEM() {
	global $filters, $loadedFilters;

	// Is the filter already initialized?
	if ((isset($filters)) && (is_array($filters))) {
		// Then abort here
		ADD_FATAL(FILTER_FAILED_ALREADY_INIT);
		return false;
	} // END - if

	// Init the filter system (just some ideas)
	$filters = array(
		// Filters for pre-init phase
		'preinit'   => array(),
		// Filters for post-init phase
		'postinit'  => array(),
		// Filters for shutdown phase
		'shutdown'  => array()
	);

	// Init loaded filters
	$loadedFilters =  array();

	// Load all saved filers if sql_patches is updated
	if (GET_EXT_VERSION("sql_patches") >= "0.5.9") {
		// Load all active filers
		$result = SQL_QUERY("SELECT `filter_name`, `filter_function`, `filter_active`
FROM `"._MYSQL_PREFIX."_filters`
ORDER BY `filter_id` ASC", __FILE__, __LINE__);

		// Are there entries?
		if (SQL_NUMROWS($result) > 0) {
			// Load all filters
			while ($filterArray = SQL_FETCHARRAY($result)) {
				// Mark this filter as loaded (from database)
				$loadedFilters[$filterArray['filter_name']][$filterArray['filter_function']] = true;

				// Set this filter
				$filters[$filterArray['filter_name']][$filterArray['filter_function']] = $filterArray['filter_active'];
			} // END - while
		} // END - if
	
		// Free result
		SQL_FREERESULT($result);
	} // END - if

	// @TODO Find some more init/shutdown filter functions

	// Register shutdown filters
	REGISTER_FILTER('shutdown', 'FLUSH_FILTERS');
	REGISTER_FILTER('shutdown', 'SHUTDOWN_DATABASE');
}

// "Registers" a new filter function
function REGISTER_FILTER ($filterName, $filterFunction, $silentAbort = true, $force = false) {
	global $filters;

	// Extend the filter function name
	$filterFunction = sprintf("FILTER_%s", strtoupper($filterFunction));

	// Is that filter already there?
	if ((isset($filters[$filterName][$filterFunction])) && (!$force)) {
		// Then abort here
		if (!$silentAbort) {
			ADD_FATAL(sprintf(FILTER_FAILED_ALREADY_ADDED, $filterFunction, $filterName));
		} // END - if

		// Abort here
		return false;
	} // END - if

	// Is the function there?
	if (!function_exists($filterFunction)) {
		// Then abort here
		ADD_FATAL(sprintf(FILTER_FAILED_NOT_FOUND, $filterFunction, $filterName));
		return false;
	} // END - if

	// Simply add it to the array
	$filters[$filterName][$filterFunction] = "Y";
}

// "Unregisters" a filter from the given chain
function UNREGISTER_FILTER ($filterName, $filterFunction, $force = false, $remove = true) {
	global $filters;

	// Extend the filter function name
	$filterFunction = sprintf("FILTER_%s", strtoupper($filterFunction));

	// Is that filter there?
	if ((!isset($filters[$filterName][$filterFunction])) && (!$force)) {
		// Not found, so abort here
		ADD_FATAL(sprintf(FILTER_FAILED_NOT_REMOVED, $filterFunction, $filterName));
		return false;
	} // END - if

	// Shall we remove? (default, not while just showing an extension removal)
	if ($remove) {
		// Mark for filter removal
		$filters[$filterName][$filterFunction] = "R";
	} // END  - if
}

// "Runs" the given filters, data is optional and can be any type of data
function RUN_FILTER ($filterName, $data = null, $silentAbort = true) {
	global $filters;

	// Is that filter chain there?
	if (!isset($filters[$filterName])) {
		// Then abort here (quick'N'dirty hack)
		if ((!$silentAbort) && (defined('FILTER_FAILED_NO_FILTER_FOUND'))) {
			// Add fatal message
			ADD_FATAL(sprintf(FILTER_FAILED_NO_FILTER_FOUND, $filterName));
		} // END - if

		// Abort here
		return false;
	} // END - if

	// Default return value
	$returnValue = $data;

	// Then run all filters
	foreach ($filters[$filterName] as $filterFunction=>$active) {
		// Debug message
		/* DEBUG: */ echo __FUNCTION__."(<font color=\"#0000aa\">".__LINE__."</font>): name={$filterName}, func={$filterFunction}, active={$active}<br />\n";

		// Is the filter active?
		if ($active == "Y") {
			// Call the filter chain
			$returnValue = call_user_func_array($filterFunction, array($returnValue));
		} // END - if
	} // END - foreach

	// Return the filtered content
	return $returnValue;
}

// -----------------------------------------------------------------------------
// Generic filter functions we always need
// -----------------------------------------------------------------------------

// Filter for flushing all new filters to the database
function FILTER_FLUSH_FILTERS () {
	global $filters, $link, $loadedFilters;

	// Is a database link here and not in installation mode?
	if ((!is_resource($link)) && (!isBooleanConstantAndTrue('mxchange_installing'))) {
		// Abort here
		ADD_FATAL(sprintf(FILTER_FLUSH_FAILED_NO_DATABASE, $filterFunction, $filterName));
		return false;
	} // END - if

	// Is the extension sql_patches updated?
	if (EXT_VERSION_IS_OLDER("sql_patches", "0.5.9")) {
		// Abort silently here
		return false;
	} // END - if

	// Nothing is added/remove by default
	$inserted = 0; $removed = 0;

	// Prepare SQL queries
	$insertSQL = "INSERT INTO `"._MYSQL_PREFIX."_filters` (`filter_name`,`filter_function`,`filter_active`) VALUES";
	$removeSQL = "DELETE LOW_PRIORITY FROM `"._MYSQL_PREFIX."_filters` WHERE";

	// Write all filters to database
	foreach ($filters as $filterName => $filterArray) {
		// Walk through all filters
		foreach ($filterArray as $filterFunction => $active) {
			// Is this filter loaded?
			if (!isset($loadedFilters[$filterName][$filterFunction])) {
				// Add this filter (all filters are active by default)
				$insertSQL .= sprintf("('%s','%s','Y'),", $filterName, $filterFunction);
				$inserted++;
			} elseif ($active == "R") {
				// Remove this filter
				$removeSQL .= sprintf(" (`filter_name`='%s' AND `filter_function`='%s') OR", $filterName, $filterFunction);
				$removed++;
			}
		} // END - foreach
	} // END - foreach

	// Something has been added?
	if ($inserted > 0) {
		// Finish SQL command
		$insertSQL = substr($insertSQL, 0, -1);

		// And run it
		SQL_QUERY($insertSQL, __FILE__, __LINE__);
	} // END - if

	// Something has been removed?
	if ($removed > 0) {
		// Finish SQL command
		$removeSQL = substr($removeSQL, 0, -2) . "LIMIT ".$removed;

		// And run it
		SQL_QUERY($removeSQL, __FILE__, __LINE__);
	} // END - if
}

// Filter for shutting down the database link
function FILTER_SHUTDOWN_DATABASE () {
	global $link;

	if (is_resource($link)) {
		// Close link
		SQL_CLOSE($link, __FILE__, __LINE__);
	} else {
		// No database link
		ADD_FATAL(NO_DB_LINK);
	}
}

//
?>