PHP Class Autoloader

<?php
/**
 *      // set configuration settings
 *
 *      autoloader([[
 *          'debug' => true, // set debug mode on/off
 *          'basepath' => '/var/www/myproject', // set project base path
 *          'extensions' => ['.php'], // set allowed class extension(s) to load
 *          // 'extensions' => ['.php', '.php4', '.php5'], // example of multiple extensions
 *          // use namespace if autoloader function is in namespace for registering autoloader
 *          'namespace' => 'My\Namespace',
            'verbose' => false // will print internal messages (for debugging)
 *      ]]);
 *
 *      // add class paths to autoload
 *      autoloader([
 *          'lib', // really '/var/www/myproject/lib' when using basepath in config settings
 *          'models/data' // really '/var/www/myproject/models/data' when using basepath in config settings
 *      ]);
 *
 *      // get array registered class paths (when in debug mode any autoloaded classes will show up as 'loaded')
 *      $registered_class_paths = autoloader();
 *
 *      // or configuration settings AND class paths to autoload, example:
 *      autoloader([
 *          // set configuration settings
 *          [
 *              'debug' => true,
 *              'basepath' => '/var/www/myproject'
 *          ],
 *          // set class paths to autoload
 *          'lib',
 *          'models/data'
 *      ]);
 */

function Autoloader($class_paths = NULL, $use_base_dir = true){
    static $is_init = false;

    static $conf = [
        'basepath' => '',
        'debug' => false,
        'extensions' => ['.php'], // multiple extensions ex: ['.php', '.class.php']
        'namespace' => '',
        'verbose' => false
    ];

    static $paths = [];

    // autoloader(); returns paths (for debugging)
    if(\is_null($class_paths)){
        return $paths;
    }

    if(\is_array($class_paths) && isset($class_paths[0]) && \is_array($class_paths[0])) // conf settings
    {
        foreach($class_paths[0] as $k => $v)
        {
            if(isset($conf[$k]) || \array_key_exists($k, $conf))
            {
                $conf[$k] = $v; // set conf setting
            }
        }

        unset($class_paths[0]); // rm conf from class paths
    }

    // init autoloader
    if(!$is_init){
        \spl_autoload_extensions(implode(',', $conf['extensions']));
        \spl_autoload_register(NULL, false); // flush existing autoloads
        $is_init = true;
    }

    if($conf['debug']){
        $paths['conf'] = $conf; // add conf for debugging
    }
    // autoload class
    if(!\is_array($class_paths)){
        // class with namespaces, ex: 'MyPack\MyClass' => 'MyPack/MyClass' (directories)
        $class_path = \str_replace('\\', \DIRECTORY_SEPARATOR, $class_paths);

        foreach($paths as $path){
            // do not allow cached 'loaded' paths
            if(!\is_array($path)){
                foreach($conf['extensions'] as &$ext){
                    $ext = \trim($ext);

                    if(\file_exists($path . $class_path . $ext)){
                        if($conf['debug']){
                            if(!isset($paths['loaded']))
                            {
                                $paths['loaded'] = [];
                            }

                            $paths['loaded'][] = $path . $class_path . $ext;
                        }

                        require $path . $class_path . $ext;

                        if($conf['verbose']){
                            echo '<div>' . __METHOD__ . ': autoloaded class "' . $path
                                . $class_path . $ext . '"</div>';
                        }

                        return true;
                    }
                }

                if($conf['verbose']){
                    echo '<div>' . __METHOD__ . ': failed to autoload class "' . $path
                        . $class_path . $ext . '"</div>';
                }
            }
        }

        return false; // failed to autoload class
    } else {
        // register class path
        $is_unregistered = true;

        if(count($class_paths) > 0){
            foreach($class_paths as $path){
                $tmp_path = ( $use_base_dir ? \rtrim($conf['basepath'], \DIRECTORY_SEPARATOR)
                    . \DIRECTORY_SEPARATOR : '' ) . \trim(\rtrim($path, \DIRECTORY_SEPARATOR))
                    . \DIRECTORY_SEPARATOR;

                if(!\in_array($tmp_path, $paths)){
                    $paths[] = $tmp_path;

                    if($conf['verbose']){
                        echo '<div>' . __METHOD__ . ': registered path "' . $tmp_path . '"</div>';
                    }
                }
            }

            if(\spl_autoload_register(( strlen($conf['namespace']) > 0 // add namespace
                ? rtrim($conf['namespace'], '\\') . '\\' : '' ) . 'autoloader', (bool)$conf['debug'])){
                if($conf['verbose']){
                    echo '<div>' . __METHOD__ . ': autoload registered</div>';
                }

                $is_unregistered = false; // flag unable to register
            } else if($conf['verbose']){
                echo '<div>' . __METHOD__ . ': autoload register failed</div>';
            }
        }

        return !$conf['debug'] ? !$is_unregistered : $paths;
    }
}