<?php

// +---------------------------------------------------------------------------+
// | This file is part of the core package.                                    |
// | Copyright (c) laiketui.com                                                |
// |                                                                           |
// | For the full copyright and license information, please view the LICENSE   |
// | file that was distributed with this source code. You can also view the    |
// | LICENSE file online at http://www.laiketui.com                            |
// +---------------------------------------------------------------------------+

/**
 * ConfigCache allows you to customize the format of a configuration file to
 * make it easy-to-use, yet still provide a PHP formatted result for direct
 * inclusion into your modules.
 *
 * @package    laiketui
 * @subpackage config
 *
 * @author ketter (ketter@laiketui.com)
 * @since  3.0.0
 */
class ConfigCache extends MojaviObject
{

    // +-----------------------------------------------------------------------+
    // | PRIVATE VARIABLES                                                     |
    // +-----------------------------------------------------------------------+

    private static
        $handlers = array();

    // +-----------------------------------------------------------------------+
    // | METHODS                                                               |
    // +-----------------------------------------------------------------------+

    /**
     * Load a configuration handler.
     *
     * @param string The handler to use when parsing a configuration file.
     * @param string An absolute filesystem path to a configuration file.
     * @param string An absolute filesystem path to the cache file that will be
     *               written.
     *
     * @return void
     *
     * @throws <b>ConfigurationException</b> If a requested configuration file
     *                                       does not have an associated
     *                                       configuration handler.
     *
     * @author ketter (ketter@laiketui.com)
     * @since  3.0.0
     */
    private static function callHandler ($handler, $config, $cache)
    {

        if (count(self::$handlers) == 0)
        {

            // we need to load the handlers first
            self::loadConfigHandlers();

        }

        // grab the base name of the handler
        $basename = basename($handler);

        if (isset(self::$handlers[$handler]))
        {

            // we have a handler associated with the full configuration path

            // call the handler and retrieve the cache data
            $data =& self::$handlers[$handler]->execute($config);

            self::writeCacheFile($config, $cache, $data, false);

            return;

        } else if (isset(self::$handlers[$basename]))
        {

            // we have a handler associated with the configuration base name

            // call the handler and retrieve the cache data
            $data =& self::$handlers[$basename]->execute($config);

            self::writeCacheFile($config, $cache, $data, false);

            return;

        } else
        {

            // let's see if we have any wildcard handlers registered that match
            // this basename
            foreach (self::$handlers as $key => $handlerInstance)
            {

                // replace wildcard chars in the configuration
                $pattern = str_replace('.', '\.', $key);
                $pattern = str_replace('*', '.*?', $pattern);

                // create pattern from config
                $pattern = '#' . $pattern . '#';

                if (preg_match($pattern, $handler))
                {

                    // we found a match!

                    // call the handler and retrieve the cache data
                    $data =& self::$handlers[$key]->execute($config);

                    self::writeCacheFile($config, $cache, $data, false);

                    return;

                }

            }

        }

        // we do not have a registered handler for this file
        $error = 'Configuration file "%s" does not have a ' .
                 'registered handler';
        $error = sprintf($error, $config);

        throw new ConfigurationException($error);

    }

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

    /**
     * Check to see if a configuration file has been modified and if so
     * recompile the cache file associated with it.
     *
     * If the configuration file path is relative, the path itself is relative
     * to the Mojavi MO_WEBAPP_DIR application setting.
     *
     * @param string A filesystem path to a configuration file.
     *
     * @return string An absolute filesystem path to the cache filename
     *                associated with this specified configuration file.
     *
     * @throws <b>ConfigurationException</b> If a requested configuration file
     *                                       does not exist.
     *
     * @author ketter (ketter@laiketui.com)
     * @since  3.0.0
     */
    public static function checkConfig ($config)
    {

        // the full filename path to the config
        $filename = $config;

        if (!Toolkit::isPathAbsolute($filename))
        {

            $filename = MO_WEBAPP_DIR . '/' . $filename;

        }

        if (!is_readable($filename))
        {

            // configuration file does not exist
            $error = 'Configuration file "%s" does not exist or is unreadable';
            $error = sprintf($error, $filename);

            throw new ConfigurationException($error);

        }

        // the cache filename we'll be using
        $cache = self::getCacheName($config);

        if (!is_readable($cache) || filemtime($filename) > filemtime($cache))
        {

            // configuration file has changed so we need to reparse it
            self::callHandler($config, $filename, $cache);

        }

        return $cache;

    }

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

    /**
     * Clear all configuration cache files.
     *
     * @return void
     *
     * @author ketter (ketter@laiketui.com)
     * @since  3.0.0
     */
    public static function clear ()
    {

        self::clearCache(MO_CACHE_DIR);

    }

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

    /**
     * Clear all configuration cache files.
     *
     * This method exists to prevent accidental deletion of non-cache directory
     * files.
     *
     * @param string An absolute filesystem path to a cache directory.
     *
     * @return void
     *
     * @author ketter (ketter@laiketui.com)
     * @since  3.0.0
     */
    private static function clearCache ($directory)
    {

        // open a file point to the cache dir
        $fp = opendir($directory);

        // ignore names
        $ignore = array('.', '..', 'CVS', '.svn');

        while (($file = readdir($fp)) !== false)
        {

            if (!in_array($file, $ignore))
            {

                if (is_dir($file))
                {

                    // recurse through directory
                    self::clearCache($file);

                    // delete the directory
                    rmdir($file);

                } else
                {

                    // delete the file
                    unlink($directory . '/' . $file);

                }

            }

        }

        // close file pointer
        closedir($fp);

    }

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

    /**
     * Convert a normal filename into a cache filename.
     *
     * @param string A normal filename.
     *
     * @return string An absolute filesystem path to a cache filename.
     *
     * @author ketter (ketter@laiketui.com)
     * @since  3.0.0
     */
    public static function getCacheName ($config)
    {

        if (strlen($config) > 3 && ctype_alpha($config[0]) &&
            $config[1] == ':' && $config[2] == '\\')
        {

            // file is a windows absolute path, strip off the drive letter
            $config = substr($config, 3);

        }

        // replace unfriendly filename characters with an underscore
        $config  = str_replace(array('\\', '/'), '_', $config);
        $config .= '.php';

        return MO_CACHE_DIR . '/' . $config;

    }

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

    /**
     * Import a configuration file.
     *
     * If the configuration file path is relative, the path itself is relative
     * to the Mojavi MO_WEBAPP_DIR application setting.
     *
     * @param string A filesystem path to a configuration file.
     * @param bool   Only allow this configuration file to be included once per
     *               request?
     *
     * @return void
     *
     * @author ketter (ketter@laiketui.com)
     * @since  3.0.0
     */
    public static function import ($config, $once = true)
    {

        // check the config file
        $cache = self::checkConfig($config);

        // include cache file
        if ($once)
        {

            include_once($cache);

        } else
        {

            include($cache);

        }

    }

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

    /**
     * Load all configuration application and module level handlers.
     *
     * @return void
     *
     * @throws <b>ConfigurationException</b> If a configuration related error
     *                                       occurs.
     *
     * @author ketter (ketter@laiketui.com)
     * @since  3.0.0
     */
    private static function loadConfigHandlers ()
    {

        // manually create our config_handlers.ini handler
        self::$handlers['config_handlers.ini'] = new RootConfigHandler();
        self::$handlers['config_handlers.ini']->initialize();

        // application configuration handlers

        require_once(ConfigCache::checkConfig('config/config_handlers.ini'));

        // module level configuration handlers

        // make sure our modules directory exists
        if (is_readable(MO_MODULE_DIR))
        {

            // ignore names
            $ignore = array('.', '..', 'CVS', '.svn');

            // create a file pointer to the module dir
            $fp = opendir(MO_MODULE_DIR);

            // loop through the directory and grab the modules
            while (($directory = readdir($fp)) !== false)
            {

                if (!in_array($directory, $ignore))
                {

                    $config = MO_MODULE_DIR . '/' . $directory .
                              '/config/config_handlers.ini';

                    if (is_readable($config))
                    {

                        // initialize the root configuration handler with this
                        // module name
                        $params = array('module_level' => true,
                                        'module_name'  => $directory);

                        self::$handlers['config_handlers.ini']->initialize($params);

                        // replace module dir path with a special keyword that
                        // checkConfig knows how to use
                        $config = 'modules/' . $directory .
                                  '/config/config_handlers.ini';

                        require_once(ConfigCache::checkConfig($config));

                    }

                }

            }

            // close file pointer
            closedir($fp);

        } else
        {

            // module directory doesn't exist or isn't readable
            $error = 'Module directory "%s" does not exist or is not readable';
            $error = sprintf($error, MO_MODULE_DIR);

            throw new ConfigurationException($error);

        }

    }

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

    /**
     * Write a cache file.
     *
     * @param string An absolute filesystem path to a configuration file.
     * @param string An absolute filesystem path to the cache file that will
     *               be written.
     * @param string Data to be written to the cache file.
     * @param string Should we append the data?
     *
     * @throws <b>CacheException</b> If the cache file cannot be written.
     *
     * @author ketter (ketter@laiketui.com)
     * @since  3.0.0
     */
    private static function writeCacheFile ($config, $cache, &$data, $append)
    {

        $flags = ($append) ? FILE_APPEND : 0;

        if (@file_put_contents($cache, $data, $flags) === false)
        {

            // cannot write cache file
            $error = 'Failed to write cache file "%s" generated from ' .
                     'configuration file "%s"';
            $error = sprintf($error, $cache, $config);

            throw new CacheException($error);

        }

    }

}

?>