darkcolonist/Kohana.php

## Kohana.php
<?php defined('SYSPATH') OR die('No direct access allowed.');
/**
 * Provides Kohana-specific helper functions. This is where the magic happens!
 *
 * $Id: Kohana.php 4372 2009-05-28 17:00:34Z ixmatus $
 *
 * @package    Core
 * @author     Kohana Team
 * @copyright  (c) 2007-2008 Kohana Team
 * @license    http://kohanaphp.com/license.html
 */
final class Kohana {

  // The singleton instance of the controller
  public static $instance;

  // Output buffering level
  private static $buffer_level;

  // Will be set to TRUE when an exception is caught
  public static $has_error = FALSE;

  // The final output that will displayed by Kohana
  public static $output = '';

  // The current user agent
  public static $user_agent;

  // The current locale
  public static $locale;

  // Configuration
  private static $configuration;

  // Include paths
  private static $include_paths;

  // Logged messages
  private static $log;

  // Cache lifetime
  private static $cache_lifetime;

  // Log levels
  private static $log_levels = array
  (
    'error' => 1,
    'alert' => 2,
    'info'  => 3,
    'debug' => 4,
  );

  // Internal caches and write status
  private static $internal_cache = array();
  private static $write_cache;
  private static $internal_cache_path;
  private static $internal_cache_key;
  private static $internal_cache_encrypt;

  /**
   * Sets up the PHP environment. Adds error/exception handling, output
   * buffering, and adds an auto-loading method for loading classes.
   *
   * This method is run immediately when this file is loaded, and is
   * benchmarked as environment_setup.
   *
   * For security, this function also destroys the $_REQUEST global variable.
   * Using the proper global (GET, POST, COOKIE, etc) is inherently more secure.
   * The recommended way to fetch a global variable is using the Input library.
   * @see http://www.php.net/globals
   *
   * @return  void
   */
  public static function setup()
  {
    static $run;

    // This function can only be run once
    if ($run === TRUE)
      return;

    // Start the environment setup benchmark
    Benchmark::start(SYSTEM_BENCHMARK.'_environment_setup');

    // Define Kohana error constant
    define('E_KOHANA', 42);

    // Define 404 error constant
    define('E_PAGE_NOT_FOUND', 43);

    // Define database error constant
    define('E_DATABASE_ERROR', 44);

    if (self::$cache_lifetime = self::config('core.internal_cache'))
    {
      // Are we using encryption for caches?
      self::$internal_cache_encrypt = self::config('core.internal_cache_encrypt');

      if(self::$internal_cache_encrypt===TRUE)
      {
        self::$internal_cache_key = self::config('core.internal_cache_key');

        // Be sure the key is of acceptable length for the mcrypt algorithm used
        self::$internal_cache_key = substr(self::$internal_cache_key, 0, 24);
      }

      // Set the directory to be used for the internal cache
      if ( ! self::$internal_cache_path = self::config('core.internal_cache_path'))
      {
        self::$internal_cache_path = APPPATH.'cache/';
      }

      // Load cached configuration and language files
      self::$internal_cache['configuration'] = self::cache('configuration', self::$cache_lifetime);
      self::$internal_cache['language']      = self::cache('language', self::$cache_lifetime);

      // Load cached file paths
      self::$internal_cache['find_file_paths'] = self::cache('find_file_paths', self::$cache_lifetime);

      // Enable cache saving
      Event::add('system.shutdown', array(__CLASS__, 'internal_cache_save'));
    }

    // Disable notices and "strict" errors
    $ER = error_reporting(~E_NOTICE & ~E_STRICT);

    // Set the user agent
    self::$user_agent = ( ! empty($_SERVER['HTTP_USER_AGENT']) ? trim($_SERVER['HTTP_USER_AGENT']) : '');

    if (function_exists('date_default_timezone_set'))
    {
      $timezone = self::config('locale.timezone');

      // Set default timezone, due to increased validation of date settings
      // which cause massive amounts of E_NOTICEs to be generated in PHP 5.2+
      date_default_timezone_set(empty($timezone) ? date_default_timezone_get() : $timezone);
    }

    // Restore error reporting
    error_reporting($ER);

    // Start output buffering
    ob_start(array(__CLASS__, 'output_buffer'));

    // Save buffering level
    self::$buffer_level = ob_get_level();

    // Set autoloader
    spl_autoload_register(array('Kohana', 'auto_load'));

    // Set error handler
    set_error_handler(array('Kohana', 'exception_handler'));

    // Set exception handler
    set_exception_handler(array('Kohana', 'exception_handler'));

    // Send default text/html UTF-8 header
    header('Content-Type: text/html; charset=UTF-8');

    // Load locales
    $locales = self::config('locale.language');

    // Make first locale UTF-8
    $locales[0] .= '.UTF-8';

    // Set locale information
    self::$locale = setlocale(LC_ALL, $locales);

    if (self::$configuration['core']['log_threshold'] > 0)
    {
      // Set the log directory
      self::log_directory(self::$configuration['core']['log_directory']);

      // Enable log writing at shutdown
      register_shutdown_function(array(__CLASS__, 'log_save'));
    }

    // Enable Kohana routing
    Event::add('system.routing', array('Router', 'find_uri'));
    Event::add('system.routing', array('Router', 'setup'));

    // Enable Kohana controller initialization
    Event::add('system.execute', array('Kohana', 'instance'));

    // Enable Kohana 404 pages
    Event::add('system.404', array('Kohana', 'show_404'));

    // Enable Kohana output handling
    Event::add('system.shutdown', array('Kohana', 'shutdown'));

    if (self::config('core.enable_hooks') === TRUE)
    {
      // Find all the hook files
      $hooks = self::list_files('hooks', TRUE);

      foreach ($hooks as $file)
      {
        // Load the hook
        include $file;
      }
    }

    // Setup is complete, prevent it from being run again
    $run = TRUE;

    // Stop the environment setup routine
    Benchmark::stop(SYSTEM_BENCHMARK.'_environment_setup');
  }

  /**
   * Loads the controller and initializes it. Runs the pre_controller,
   * post_controller_constructor, and post_controller events. Triggers
   * a system.404 event when the route cannot be mapped to a controller.
   *
   * This method is benchmarked as controller_setup and controller_execution.
   *
   * @return  object  instance of controller
   */
  public static function & instance()
  {
    if (self::$instance === NULL)
    {
      Benchmark::start(SYSTEM_BENCHMARK.'_controller_setup');

      // Include the Controller file
      require Router::$controller_path;

      try
      {
        // Start validation of the controller
        $class = new ReflectionClass(ucfirst(Router::$controller).'_Controller');
      }
      catch (ReflectionException $e)
      {
        // Controller does not exist
        Event::run('system.404');
      }

      if ($class->isAbstract() OR (IN_PRODUCTION AND $class->getConstant('ALLOW_PRODUCTION') == FALSE))
      {
        // Controller is not allowed to run in production
        Event::run('system.404');
      }

      // Run system.pre_controller
      Event::run('system.pre_controller');

      // Create a new controller instance
      $controller = $class->newInstance();

      // Controller constructor has been executed
      Event::run('system.post_controller_constructor');

      try
      {
        // Load the controller method
        $method = $class->getMethod(Router::$method);

        // Method exists
        if (Router::$method[0] === '_')
        {
          // Do not allow access to hidden methods
          Event::run('system.404');
        }

        if ($method->isProtected() or $method->isPrivate())
        {
          // Do not attempt to invoke protected methods
          throw new ReflectionException('protected controller method');
        }

        // Default arguments
        $arguments = Router::$arguments;
      }
      catch (ReflectionException $e)
      {
        // Use __call instead
        $method = $class->getMethod('__call');

        // Use arguments in __call format
        $arguments = array(Router::$method, Router::$arguments);
      }

      // Stop the controller setup benchmark
      Benchmark::stop(SYSTEM_BENCHMARK.'_controller_setup');

      // Start the controller execution benchmark
      Benchmark::start(SYSTEM_BENCHMARK.'_controller_execution');

      // Execute the controller method
      $method->invokeArgs($controller, $arguments);

      // Controller method has been executed
      Event::run('system.post_controller');

      // Stop the controller execution benchmark
      Benchmark::stop(SYSTEM_BENCHMARK.'_controller_execution');
    }

    return self::$instance;
  }

  /**
   * Get all include paths. APPPATH is the first path, followed by module
   * paths in the order they are configured, follow by the SYSPATH.
   *
   * @param   boolean  re-process the include paths
   * @return  array
   */
  public static function include_paths($process = FALSE)
  {
    if ($process === TRUE)
    {
      // Add APPPATH as the first path
      self::$include_paths = array(APPPATH);

      foreach (self::$configuration['core']['modules'] as $path)
      {
        if ($path = str_replace('\\', '/', realpath($path)))
        {
          // Add a valid path
          self::$include_paths[] = $path.'/';
        }
      }

      // Add SYSPATH as the last path
      self::$include_paths[] = SYSPATH;
    }

    return self::$include_paths;
  }

  /**
   * Get a config item or group.
   *
   * @param   string   item name
   * @param   boolean  force a forward slash (/) at the end of the item
   * @param   boolean  is the item required?
   * @return  mixed
   */
  public static function config($key, $slash = FALSE, $required = TRUE)
  {
    if (self::$configuration === NULL)
    {
      // Load core configuration
      self::$configuration['core'] = self::config_load('core');

      // Re-parse the include paths
      self::include_paths(TRUE);
    }

    // Get the group name from the key
    $group = explode('.', $key, 2);
    $group = $group[0];

    if ( ! isset(self::$configuration[$group]))
    {
      // Load the configuration group
      self::$configuration[$group] = self::config_load($group, $required);
    }

    // Get the value of the key string
    $value = self::key_string(self::$configuration, $key);

    if ($slash === TRUE AND is_string($value) AND $value !== '')
    {
      // Force the value to end with "/"
      $value = rtrim($value, '/').'/';
    }

    return $value;
  }

  /**
   * Sets a configuration item, if allowed.
   *
   * @param   string   config key string
   * @param   string   config value
   * @return  boolean
   */
  public static function config_set($key, $value)
  {
    // Do this to make sure that the config array is already loaded
    self::config($key);

    if (substr($key, 0, 7) === 'routes.')
    {
      // Routes cannot contain sub keys due to possible dots in regex
      $keys = explode('.', $key, 2);
    }
    else
    {
      // Convert dot-noted key string to an array
      $keys = explode('.', $key);
    }

    // Used for recursion
    $conf =& self::$configuration;
    $last = count($keys) - 1;

    foreach ($keys as $i => $k)
    {
      if ($i === $last)
      {
        $conf[$k] = $value;
      }
      else
      {
        $conf =& $conf[$k];
      }
    }

    if ($key === 'core.modules')
    {
      // Reprocess the include paths
      self::include_paths(TRUE);
    }

    return TRUE;
  }

  /**
   * Load a config file.
   *
   * @param   string   config filename, without extension
   * @param   boolean  is the file required?
   * @return  array
   */
  public static function config_load($name, $required = TRUE)
  {
    if ($name === 'core')
    {
      // Load the application configuration file
      require APPPATH.'config/config'.EXT;

      if ( ! isset($config['site_domain']))
      {
        // Invalid config file
        die('Your Kohana application configuration file is not valid.');
      }

      return $config;
    }

    if (isset(self::$internal_cache['configuration'][$name]))
      return self::$internal_cache['configuration'][$name];

    // Load matching configs
    $configuration = array();

    if ($files = self::find_file('config', $name, $required))
    {
      foreach ($files as $file)
      {
        require $file;

        if (isset($config) AND is_array($config))
        {
          // Merge in configuration
          $configuration = array_merge($configuration, $config);
        }
      }
    }

    if ( ! isset(self::$write_cache['configuration']))
    {
      // Cache has changed
      self::$write_cache['configuration'] = TRUE;
    }

    return self::$internal_cache['configuration'][$name] = $configuration;
  }

  /**
   * Clears a config group from the cached configuration.
   *
   * @param   string  config group
   * @return  void
   */
  public static function config_clear($group)
  {
    // Remove the group from config
    unset(self::$configuration[$group], self::$internal_cache['configuration'][$group]);

    if ( ! isset(self::$write_cache['configuration']))
    {
      // Cache has changed
      self::$write_cache['configuration'] = TRUE;
    }
  }

  /**
   * Add a new message to the log.
   *
   * @param   string  type of message
   * @param   string  message text
   * @return  void
   */
  public static function log($type, $message)
  {
    if (self::$log_levels[$type] <= self::$configuration['core']['log_threshold'])
    {
      $message = array(date('Y-m-d H:i:s P'), $type, $message);

      // Run the system.log event
      Event::run('system.log', $message);

      self::$log[] = $message;
    }
  }

  /**
   * Save all currently logged messages.
   *
   * @return  void
   */
  public static function log_save()
  {
    if (empty(self::$log) OR self::$configuration['core']['log_threshold'] < 1)
      return;

    // Filename of the log
    $filename = self::log_directory().date('Y-m-d').'.log'.EXT;

    if ( ! is_file($filename))
    {
      // Write the SYSPATH checking header
      file_put_contents($filename,
        '<?php defined(\'SYSPATH\') or die(\'No direct script access.\'); ?>'.PHP_EOL.PHP_EOL);

      // Prevent external writes
      chmod($filename, 0644);
    }

    // Messages to write
    $messages = array();

    do
    {
      // Load the next mess
      list ($date, $type, $text) = array_shift(self::$log);

      // Add a new message line
      $messages[] = $date.' --- '.$type.': '.$text;
    }
    while ( ! empty(self::$log));

    // Write messages to log file
    file_put_contents($filename, implode(PHP_EOL, $messages).PHP_EOL, FILE_APPEND);
  }

  /**
   * Get or set the logging directory.
   *
   * @param   string  new log directory
   * @return  string
   */
  public static function log_directory($dir = NULL)
  {
    static $directory;

    if ( ! empty($dir))
    {
      // Get the directory path
      $dir = realpath($dir);

      if (is_dir($dir) AND is_writable($dir))
      {
        // Change the log directory
        $directory = str_replace('\\', '/', $dir).'/';
      }
      else
      {
        // Log directory is invalid
        throw new Kohana_Exception('core.log_dir_unwritable', $dir);
      }
    }

    return $directory;
  }

  /**
   * Load data from a simple cache file. This should only be used internally,
   * and is NOT a replacement for the Cache library.
   *
   * @param   string   unique name of cache
   * @param   integer  expiration in seconds
   * @return  mixed
   */
  public static function cache($name, $lifetime)
  {
    if ($lifetime > 0)
    {
      $path = self::$internal_cache_path.'kohana_'.$name;

      if (is_file($path))
      {
        // Check the file modification time
        if ((time() - filemtime($path)) < $lifetime)
        {
          // Cache is valid! Now, do we need to decrypt it?
          if(self::$internal_cache_encrypt===TRUE)
          {
            $data   = file_get_contents($path);

            $iv_size  = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_ECB);
            $iv     = mcrypt_create_iv($iv_size, MCRYPT_RAND);

            $decrypted_text = mcrypt_decrypt(MCRYPT_RIJNDAEL_256, self::$internal_cache_key, $data, MCRYPT_MODE_ECB, $iv);

            $cache  = unserialize($decrypted_text);

            // If the key changed, delete the cache file
            if(!$cache)
              unlink($path);

            // If cache is false (as above) return NULL, otherwise, return the cache
            return ($cache ? $cache : NULL);
          }
          else
          {
            return unserialize(file_get_contents($path));
          }
        }
        else
        {
          // Cache is invalid, delete it
          unlink($path);
        }
      }
    }

    // No cache found
    return NULL;
  }

  /**
   * Save data to a simple cache file. This should only be used internally, and
   * is NOT a replacement for the Cache library.
   *
   * @param   string   cache name
   * @param   mixed    data to cache
   * @param   integer  expiration in seconds
   * @return  boolean
   */
  public static function cache_save($name, $data, $lifetime)
  {
    if ($lifetime < 1)
      return FALSE;

    $path = self::$internal_cache_path.'kohana_'.$name;

    if ($data === NULL)
    {
      // Delete cache
      return (is_file($path) and unlink($path));
    }
    else
    {
      // Using encryption? Encrypt the data when we write it
      if(self::$internal_cache_encrypt===TRUE)
      {
        // Encrypt and write data to cache file
        $iv_size  = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_ECB);
        $iv     = mcrypt_create_iv($iv_size, MCRYPT_RAND);

        // Serialize and encrypt!
        $encrypted_text = mcrypt_encrypt(MCRYPT_RIJNDAEL_256, self::$internal_cache_key, serialize($data), MCRYPT_MODE_ECB, $iv);

        return (bool) file_put_contents($path, $encrypted_text);
      }
      else
      {
        // Write data to cache file
        return (bool) file_put_contents($path, serialize($data));
      }
    }
  }

  /**
   * Kohana output handler. Called during ob_clean, ob_flush, and their variants.
   *
   * @param   string  current output buffer
   * @return  string
   */
  public static function output_buffer($output)
  {
    // Could be flushing, so send headers first
    if ( ! Event::has_run('system.send_headers'))
    {
      // Run the send_headers event
      Event::run('system.send_headers');
    }

    self::$output = $output;

    // Set and return the final output
    return self::$output;
  }

  /**
   * Closes all open output buffers, either by flushing or cleaning, and stores the Kohana
   * output buffer for display during shutdown.
   *
   * @param   boolean  disable to clear buffers, rather than flushing
   * @return  void
   */
  public static function close_buffers($flush = TRUE)
  {
    if (ob_get_level() >= self::$buffer_level)
    {
      // Set the close function
      $close = ($flush === TRUE) ? 'ob_end_flush' : 'ob_end_clean';

      while (ob_get_level() > self::$buffer_level)
      {
        // Flush or clean the buffer
        $close();
      }

      // Store the Kohana output buffer
      ob_end_clean();
    }
  }

  /**
   * Triggers the shutdown of Kohana by closing the output buffer, runs the system.display event.
   *
   * @return  void
   */
  public static function shutdown()
  {
    // Close output buffers
    self::close_buffers(TRUE);

    // Run the output event
    Event::run('system.display', self::$output);

    // Render the final output
    self::render(self::$output);
  }

  /**
   * Inserts global Kohana variables into the generated output and prints it.
   *
   * @param   string  final output that will displayed
   * @return  void
   */
  public static function render($output)
  {
    if (self::config('core.render_stats') === TRUE)
    {
      // Fetch memory usage in MB
      $memory = function_exists('memory_get_usage') ? (memory_get_usage() / 1024 / 1024) : 0;

      // Fetch benchmark for page execution time
      $benchmark = Benchmark::get(SYSTEM_BENCHMARK.'_total_execution');

      // Replace the global template variables
      $output = str_replace(
        array
        (
          '{kohana_version}',
          '{kohana_codename}',
          '{execution_time}',
          '{memory_usage}',
          '{included_files}',
        ),
        array
        (
          KOHANA_VERSION,
          KOHANA_CODENAME,
          $benchmark['time'],
          number_format($memory, 2).'MB',
          count(get_included_files()),
        ),
        $output
      );
    }

    if ($level = self::config('core.output_compression') AND ini_get('output_handler') !== 'ob_gzhandler' AND (int) ini_get('zlib.output_compression') === 0)
    {
      if ($level < 1 OR $level > 9)
      {
        // Normalize the level to be an integer between 1 and 9. This
        // step must be done to prevent gzencode from triggering an error
        $level = max(1, min($level, 9));
      }

      if (stripos(@$_SERVER['HTTP_ACCEPT_ENCODING'], 'gzip') !== FALSE)
      {
        $compress = 'gzip';
      }
      elseif (stripos(@$_SERVER['HTTP_ACCEPT_ENCODING'], 'deflate') !== FALSE)
      {
        $compress = 'deflate';
      }
    }

    if (isset($compress) AND $level > 0)
    {
      switch ($compress)
      {
        case 'gzip':
          // Compress output using gzip
          $output = gzencode($output, $level);
        break;
        case 'deflate':
          // Compress output using zlib (HTTP deflate)
          $output = gzdeflate($output, $level);
        break;
      }

      // This header must be sent with compressed content to prevent
      // browser caches from breaking
      header('Vary: Accept-Encoding');

      // Send the content encoding header
      header('Content-Encoding: '.$compress);

      // Sending Content-Length in CGI can result in unexpected behavior
      if (stripos(PHP_SAPI, 'cgi') === FALSE)
      {
        header('Content-Length: '.strlen($output));
      }
    }

    echo $output;
  }

  /**
   * Displays a 404 page.
   *
   * @throws  Kohana_404_Exception
   * @param   string  URI of page
   * @param   string  custom template
   * @return  void
   */
  public static function show_404($page = FALSE, $template = FALSE)
  {
    throw new Kohana_404_Exception($page, $template);
  }

  /**
   * Dual-purpose PHP error and exception handler. Uses the kohana_error_page
   * view to display the message.
   *
   * @param   integer|object  exception object or error code
   * @param   string          error message
   * @param   string          filename
   * @param   integer         line number
   * @return  void
   */
  public static function exception_handler($exception, $message = NULL, $file = NULL, $line = NULL)
  {
    try
    {
      // PHP errors have 5 args, always
      $PHP_ERROR = (func_num_args() === 5);

      // Test to see if errors should be displayed
      if ($PHP_ERROR AND (error_reporting() & $exception) === 0)
        return;

      // This is useful for hooks to determine if a page has an error
      self::$has_error = TRUE;

      // Error handling will use exactly 5 args, every time
      if ($PHP_ERROR)
      {
        $code     = $exception;
        $type     = 'PHP Error';
        $template = 'kohana_error_page';
      }
      else
      {
        $code     = $exception->getCode();
        $type     = get_class($exception);
        $message  = $exception->getMessage();
        $file     = $exception->getFile();
        $line     = $exception->getLine();
        $template = ($exception instanceof Kohana_Exception) ? $exception->getTemplate() : 'kohana_error_page';
      }

      if (is_numeric($code))
      {
        $codes = self::lang('errors');

        if ( ! empty($codes[$code]))
        {
          list($level, $error, $description) = $codes[$code];
        }
        else
        {
          $level = 1;
          $error = $PHP_ERROR ? 'Unknown Error' : get_class($exception);
          $description = '';
        }
      }
      else
      {
        // Custom error message, this will never be logged
        $level = 5;
        $error = $code;
        $description = '';
      }

      // Remove the DOCROOT from the path, as a security precaution
      $file = str_replace('\\', '/', realpath($file));
      $file = preg_replace('|^'.preg_quote(DOCROOT).'|', '', $file);

      if ($level <= self::$configuration['core']['log_threshold'])
      {
        // Log the error
        self::log('error', self::lang('core.uncaught_exception', $type, $message, $file, $line));
      }

      if ($PHP_ERROR)
      {
        $description = self::lang('errors.'.E_RECOVERABLE_ERROR);
        $description = is_array($description) ? $description[2] : '';

        if ( ! headers_sent())
        {
          // Send the 500 header
          header('HTTP/1.1 500 Internal Server Error');
        }
      }
      else
      {
        if (method_exists($exception, 'sendHeaders') AND ! headers_sent())
        {
          // Send the headers if they have not already been sent
          $exception->sendHeaders();
        }
      }

      // Close all output buffers except for Kohana
      while (ob_get_level() > self::$buffer_level)
      {
        ob_end_clean();
      }

      // Test if display_errors is on
      if (self::$configuration['core']['display_errors'] === TRUE)
      {
        if ( ! IN_PRODUCTION AND $line != FALSE)
        {
          // Remove the first entry of debug_backtrace(), it is the exception_handler call
          $trace = $PHP_ERROR ? array_slice(debug_backtrace(), 1) : $exception->getTrace();

          // Beautify backtrace
          $trace = self::backtrace($trace);
        }

        // Load the error
        require self::find_file('views', empty($template) ? 'kohana_error_page' : $template);
      }
      else
      {
        // Get the i18n messages
        $error   = self::lang('core.generic_error');
        $message = self::lang('core.errors_disabled', url::site(), url::site(Router::$current_uri));

        // Load the errors_disabled view
        require self::find_file('views', 'kohana_error_disabled');
      }

      if ( ! Event::has_run('system.shutdown'))
      {
        // Run the shutdown even to ensure a clean exit
        Event::run('system.shutdown');
      }

      // Turn off error reporting
      error_reporting(0);
      exit;
    }
    catch (Exception $e)
    {
      if (IN_PRODUCTION)
      {
        die('Fatal Error');
      }
      else
      {
        die('Fatal Error: '.$e->getMessage().' File: '.$e->getFile().' Line: '.$e->getLine());
      }
    }
  }

  /**
   * Provides class auto-loading.
   *
   * @throws  Kohana_Exception
   * @param   string  name of class
   * @return  bool
   */
  public static function auto_load($class)
  {
    if (class_exists($class, FALSE))
      return TRUE;

    if (($suffix = strrpos($class, '_')) > 0)
    {
      // Find the class suffix
      $suffix = substr($class, $suffix + 1);
    }
    else
    {
      // No suffix
      $suffix = FALSE;
    }

    if ($suffix === 'Core')
    {
      $type = 'libraries';
      $file = substr($class, 0, -5);
    }
    elseif ($suffix === 'Controller')
    {
      $type = 'controllers';
      // Lowercase filename
      $file = strtolower(substr($class, 0, -11));
    }
    elseif ($suffix === 'Model')
    {
      $type = 'models';
      // Lowercase filename
      $file = strtolower(substr($class, 0, -6));
    }
    elseif ($suffix === 'Driver')
    {
      $type = 'libraries/drivers';
      $file = str_replace('_', '/', substr($class, 0, -7));
    }
    else
    {
      // This could be either a library or a helper, but libraries must
      // always be capitalized, so we check if the first character is
      // uppercase. If it is, we are loading a library, not a helper.
      $type = ($class[0] < 'a') ? 'libraries' : 'helpers';
      $file = $class;
    }

    if ($filename = self::find_file($type, $file))
    {
      // Load the class
      require $filename;
    }
    else
    {
      // The class could not be found
      return FALSE;
    }

    if ($filename = self::find_file($type, self::$configuration['core']['extension_prefix'].$class))
    {
      // Load the class extension
      require $filename;
    }
    elseif ($suffix !== 'Core' AND class_exists($class.'_Core', FALSE))
    {
      // Class extension to be evaluated
      $extension = 'class '.$class.' extends '.$class.'_Core { }';

      // Start class analysis
      $core = new ReflectionClass($class.'_Core');

      if ($core->isAbstract())
      {
        // Make the extension abstract
        $extension = 'abstract '.$extension;
      }

      // Transparent class extensions are handled using eval. This is
      // a disgusting hack, but it gets the job done.
      eval($extension);
    }

    return TRUE;
  }

  /**
   * Find a resource file in a given directory. Files will be located according
   * to the order of the include paths. Configuration and i18n files will be
   * returned in reverse order.
   *
   * @throws  Kohana_Exception  if file is required and not found
   * @param   string   directory to search in
   * @param   string   filename to look for (without extension)
   * @param   boolean  file required
   * @param   string   file extension
   * @return  array    if the type is config, i18n or l10n
   * @return  string   if the file is found
   * @return  FALSE    if the file is not found
   */
  public static function find_file($directory, $filename, $required = FALSE, $ext = FALSE)
  {
    // NOTE: This test MUST be not be a strict comparison (===), or empty
    // extensions will be allowed!
    if ($ext == '')
    {
      // Use the default extension
      $ext = EXT;
    }
    else
    {
      // Add a period before the extension
      $ext = '.'.$ext;
    }

    // Search path
    $search = $directory.'/'.$filename.$ext;

    if (isset(self::$internal_cache['find_file_paths'][$search]))
      return self::$internal_cache['find_file_paths'][$search];

    // Load include paths
    $paths = self::$include_paths;

    // Nothing found, yet
    $found = NULL;

    if ($directory === 'config' OR $directory === 'i18n')
    {
      // Search in reverse, for merging
      $paths = array_reverse($paths);

      foreach ($paths as $path)
      {
        if (is_file($path.$search))
        {
          // A matching file has been found
          $found[] = $path.$search;
        }
      }
    }
    else
    {
      foreach ($paths as $path)
      {
        if (is_file($path.$search))
        {
          // A matching file has been found
          $found = $path.$search;

          // Stop searching
          break;
        }
      }
    }

    if ($found === NULL)
    {
      if ($required === TRUE)
      {
        // Directory i18n key
        $directory = 'core.'.inflector::singular($directory);

        // If the file is required, throw an exception
        throw new Kohana_Exception('core.resource_not_found', self::lang($directory), $filename);
      }
      else
      {
        // Nothing was found, return FALSE
        $found = FALSE;
      }
    }

    if ( ! isset(self::$write_cache['find_file_paths']))
    {
      // Write cache at shutdown
      self::$write_cache['find_file_paths'] = TRUE;
    }

    return self::$internal_cache['find_file_paths'][$search] = $found;
  }

  /**
   * Lists all files and directories in a resource path.
   *
   * @param   string   directory to search
   * @param   boolean  list all files to the maximum depth?
   * @param   string   full path to search (used for recursion, *never* set this manually)
   * @return  array    filenames and directories
   */
  public static function list_files($directory, $recursive = FALSE, $path = FALSE)
  {
    $files = array();

    if ($path === FALSE)
    {
      $paths = array_reverse(self::include_paths());

      foreach ($paths as $path)
      {
        // Recursively get and merge all files
        $files = array_merge($files, self::list_files($directory, $recursive, $path.$directory));
      }
    }
    else
    {
      $path = rtrim($path, '/').'/';

      if (is_readable($path))
      {
        $items = (array) glob($path.'*');

        if ( ! empty($items))
        {
          foreach ($items as $index => $item)
          {
            $files[] = $item = str_replace('\\', '/', $item);

            // Handle recursion
            if (is_dir($item) AND $recursive == TRUE)
            {
              // Filename should only be the basename
              $item = pathinfo($item, PATHINFO_BASENAME);

              // Append sub-directory search
              $files = array_merge($files, self::list_files($directory, TRUE, $path.$item));
            }
          }
        }
      }
    }

    return $files;
  }

  /**
   * Fetch an i18n language item.
   *
   * @param   string  language key to fetch
   * @param   array   additional information to insert into the line
   * @return  string  i18n language string, or the requested key if the i18n item is not found
   */
  public static function lang($key, $args = array())
  {
    // Extract the main group from the key
    $group = explode('.', $key, 2);
    $group = $group[0];

    // Get locale name
    $locale = self::config('locale.language.0');

    if ( ! isset(self::$internal_cache['language'][$locale][$group]))
    {
      // Messages for this group
      $messages = array();

      if ($files = self::find_file('i18n', $locale.'/'.$group))
      {
        foreach ($files as $file)
        {
          include $file;

          // Merge in configuration
          if ( ! empty($lang) AND is_array($lang))
          {
            foreach ($lang as $k => $v)
            {
              $messages[$k] = $v;
            }
          }
        }
      }

      if ( ! isset(self::$write_cache['language']))
      {
        // Write language cache
        self::$write_cache['language'] = TRUE;
      }

      self::$internal_cache['language'][$locale][$group] = $messages;
    }

    // Get the line from cache
    $line = self::key_string(self::$internal_cache['language'][$locale], $key);

    if ($line === NULL)
    {
      self::log('error', 'Missing i18n entry '.$key.' for language '.$locale);

      // Return the key string as fallback
      return $key;
    }

    if (is_string($line) AND func_num_args() > 1)
    {
      $args = array_slice(func_get_args(), 1);

      // Add the arguments into the line
      $line = vsprintf($line, is_array($args[0]) ? $args[0] : $args);
    }

    return $line;
  }

  /**
   * Returns the value of a key, defined by a 'dot-noted' string, from an array.
   *
   * @param   array   array to search
   * @param   string  dot-noted string: foo.bar.baz
   * @return  string  if the key is found
   * @return  void    if the key is not found
   */
  public static function key_string($array, $keys)
  {
    if (empty($array))
      return NULL;

    // Prepare for loop
    $keys = explode('.', $keys);

    do
    {
      // Get the next key
      $key = array_shift($keys);

      if (isset($array[$key]))
      {
        if (is_array($array[$key]) AND ! empty($keys))
        {
          // Dig down to prepare the next loop
          $array = $array[$key];
        }
        else
        {
          // Requested key was found
          return $array[$key];
        }
      }
      else
      {
        // Requested key is not set
        break;
      }
    }
    while ( ! empty($keys));

    return NULL;
  }

  /**
   * Sets values in an array by using a 'dot-noted' string.
   *
   * @param   array   array to set keys in (reference)
   * @param   string  dot-noted string: foo.bar.baz
   * @return  mixed   fill value for the key
   * @return  void
   */
  public static function key_string_set( & $array, $keys, $fill = NULL)
  {
    if (is_object($array) AND ($array instanceof ArrayObject))
    {
      // Copy the array
      $array_copy = $array->getArrayCopy();

      // Is an object
      $array_object = TRUE;
    }
    else
    {
      if ( ! is_array($array))
      {
        // Must always be an array
        $array = (array) $array;
      }

      // Copy is a reference to the array
      $array_copy =& $array;
    }

    if (empty($keys))
      return $array;

    // Create keys
    $keys = explode('.', $keys);

    // Create reference to the array
    $row =& $array_copy;

    for ($i = 0, $end = count($keys) - 1; $i <= $end; $i++)
    {
      // Get the current key
      $key = $keys[$i];

      if ( ! isset($row[$key]))
      {
        if (isset($keys[$i + 1]))
        {
          // Make the value an array
          $row[$key] = array();
        }
        else
        {
          // Add the fill key
          $row[$key] = $fill;
        }
      }
      elseif (isset($keys[$i + 1]))
      {
        // Make the value an array
        $row[$key] = (array) $row[$key];
      }

      // Go down a level, creating a new row reference
      $row =& $row[$key];
    }

    if (isset($array_object))
    {
      // Swap the array back in
      $array->exchangeArray($array_copy);
    }
  }

  /**
   * Retrieves current user agent information:
   * keys:  browser, version, platform, mobile, robot, referrer, languages, charsets
   * tests: is_browser, is_mobile, is_robot, accept_lang, accept_charset
   *
   * @param   string   key or test name
   * @param   string   used with "accept" tests: user_agent(accept_lang, en)
   * @return  array    languages and charsets
   * @return  string   all other keys
   * @return  boolean  all tests
   */
  public static function user_agent($key = 'agent', $compare = NULL)
  {
    static $info;

    // Return the raw string
    if ($key === 'agent')
      return self::$user_agent;

    if ($info === NULL)
    {
      // Parse the user agent and extract basic information
      $agents = self::config('user_agents');

      foreach ($agents as $type => $data)
      {
        foreach ($data as $agent => $name)
        {
          if (stripos(self::$user_agent, $agent) !== FALSE)
          {
            if ($type === 'browser' AND preg_match('|'.preg_quote($agent).'[^0-9.]*+([0-9.][0-9.a-z]*)|i', self::$user_agent, $match))
            {
              // Set the browser version
              $info['version'] = $match[1];
            }

            // Set the agent name
            $info[$type] = $name;
            break;
          }
        }
      }
    }

    if (empty($info[$key]))
    {
      switch ($key)
      {
        case 'is_robot':
        case 'is_browser':
        case 'is_mobile':
          // A boolean result
          $return = ! empty($info[substr($key, 3)]);
        break;
        case 'languages':
          $return = array();
          if ( ! empty($_SERVER['HTTP_ACCEPT_LANGUAGE']))
          {
            if (preg_match_all('/[-a-z]{2,}/', strtolower(trim($_SERVER['HTTP_ACCEPT_LANGUAGE'])), $matches))
            {
              // Found a result
              $return = $matches[0];
            }
          }
        break;
        case 'charsets':
          $return = array();
          if ( ! empty($_SERVER['HTTP_ACCEPT_CHARSET']))
          {
            if (preg_match_all('/[-a-z0-9]{2,}/', strtolower(trim($_SERVER['HTTP_ACCEPT_CHARSET'])), $matches))
            {
              // Found a result
              $return = $matches[0];
            }
          }
        break;
        case 'referrer':
          if ( ! empty($_SERVER['HTTP_REFERER']))
          {
            // Found a result
            $return = trim($_SERVER['HTTP_REFERER']);
          }
        break;
      }

      // Cache the return value
      isset($return) and $info[$key] = $return;
    }

    if ( ! empty($compare))
    {
      // The comparison must always be lowercase
      $compare = strtolower($compare);

      switch ($key)
      {
        case 'accept_lang':
          // Check if the lange is accepted
          return in_array($compare, self::user_agent('languages'));
        break;
        case 'accept_charset':
          // Check if the charset is accepted
          return in_array($compare, self::user_agent('charsets'));
        break;
        default:
          // Invalid comparison
          return FALSE;
        break;
      }
    }

    // Return the key, if set
    return isset($info[$key]) ? $info[$key] : NULL;
  }

  /**
   * Quick debugging of any variable. Any number of parameters can be set.
   *
   * @return  string
   */
  public static function debug()
  {
    if (func_num_args() === 0)
      return;

    // Get params
    $params = func_get_args();
    $output = array();

    foreach ($params as $var)
    {
      $output[] = '<pre>('.gettype($var).') '.html::specialchars(print_r($var, TRUE)).'</pre>';
    }

    return implode("\n", $output);
  }

  /**
   * Displays nice backtrace information.
   * @see http://php.net/debug_backtrace
   *
   * @param   array   backtrace generated by an exception or debug_backtrace
   * @return  string
   */
  public static function backtrace($trace)
  {
    if ( ! is_array($trace))
      return;

    // Final output
    $output = array();

    foreach ($trace as $entry)
    {
      $temp = '<li>';

      if (isset($entry['file']))
      {
        $temp .= self::lang('core.error_file_line', preg_replace('!^'.preg_quote(DOCROOT).'!', '', $entry['file']), $entry['line']);
      }

      $temp .= '<pre>';

      if (isset($entry['class']))
      {
        // Add class and call type
        $temp .= $entry['class'].$entry['type'];
      }

      // Add function
      $temp .= $entry['function'].'( ';

      // Add function args
      if (isset($entry['args']) AND is_array($entry['args']))
      {
        // Separator starts as nothing
        $sep = '';

        while ($arg = array_shift($entry['args']))
        {
          if (is_string($arg) AND is_file($arg))
          {
            // Remove docroot from filename
            $arg = preg_replace('!^'.preg_quote(DOCROOT).'!', '', $arg);
          }

//          $temp .= $sep.html::specialchars(print_r($arg, TRUE));

          // Change separator to a comma
          $sep = ', ';
        }
      }

      $temp .= ' )</pre></li>';

      $output[] = $temp;
    }

    return '<ul class="backtrace">'.implode("\n", $output).'</ul>';
  }

  /**
   * Saves the internal caches: configuration, include paths, etc.
   *
   * @return  boolean
   */
  public static function internal_cache_save()
  {
    if ( ! is_array(self::$write_cache))
      return FALSE;

    // Get internal cache names
    $caches = array_keys(self::$write_cache);

    // Nothing written
    $written = FALSE;

    foreach ($caches as $cache)
    {
      if (isset(self::$internal_cache[$cache]))
      {
        // Write the cache file
        self::cache_save($cache, self::$internal_cache[$cache], self::$configuration['core']['internal_cache']);

        // A cache has been written
        $written = TRUE;
      }
    }

    return $written;
  }

} // End Kohana

/**
 * Creates a generic i18n exception.
 */
class Kohana_Exception extends Exception {

  // Template file
  protected $template = 'kohana_error_page';

  // Header
  protected $header = FALSE;

  // Error code
  protected $code = E_KOHANA;

  /**
   * Set exception message.
   *
   * @param  string  i18n language key for the message
   * @param  array   addition line parameters
   */
  public function __construct($error)
  {
    $args = array_slice(func_get_args(), 1);

    // Fetch the error message
    $message = Kohana::lang($error, $args);

    if ($message === $error OR empty($message))
    {
      // Unable to locate the message for the error
      $message = 'Unknown Exception: '.$error;
    }

    // Sets $this->message the proper way
    parent::__construct($message);
  }

  /**
   * Magic method for converting an object to a string.
   *
   * @return  string  i18n message
   */
  public function __toString()
  {
    return (string) $this->message;
  }

  /**
   * Fetch the template name.
   *
   * @return  string
   */
  public function getTemplate()
  {
    return $this->template;
  }

  /**
   * Sends an Internal Server Error header.
   *
   * @return  void
   */
  public function sendHeaders()
  {
    // Send the 500 header
    header('HTTP/1.1 500 Internal Server Error');
  }

} // End Kohana Exception

/**
 * Creates a custom exception.
 */
class Kohana_User_Exception extends Kohana_Exception {

  /**
   * Set exception title and message.
   *
   * @param   string  exception title string
   * @param   string  exception message string
   * @param   string  custom error template
   */
  public function __construct($title, $message, $template = FALSE)
  {
    Exception::__construct($message);

    $this->code = $title;

    if ($template !== FALSE)
    {
      $this->template = $template;
    }
  }

} // End Kohana PHP Exception

/**
 * Creates a Page Not Found exception.
 */
class Kohana_404_Exception extends Kohana_Exception {

  protected $code = E_PAGE_NOT_FOUND;

  /**
   * Set internal properties.
   *
   * @param  string  URL of page
   * @param  string  custom error template
   */
  public function __construct($page = FALSE, $template = FALSE)
  {
    if ($page === FALSE)
    {
      // Construct the page URI using Router properties
      $page = Router::$current_uri.Router::$url_suffix.Router::$query_string;
    }

    Exception::__construct(Kohana::lang('core.page_not_found', $page));

    $this->template = $template;
  }

  /**
   * Sends "File Not Found" headers, to emulate server behavior.
   *
   * @return void
   */
  public function sendHeaders()
  {
    // Send the 404 header
    header('HTTP/1.1 404 File Not Found');
  }

} // End Kohana 404 Exception