<?php

/**
 * Autoloader
 *
 * @package Less
 * @subpackage autoload
 */
class Less_Autoloader {

	/**
	 * Registered flag
	 *
	 * @var boolean
	 */
	protected static $registered = false;

	/**
	 * Library directory
	 *
	 * @var string
	 */
	protected static $libDir;

	/**
	 * Register the autoloader in the spl autoloader
	 *
	 * @return void
	 * @throws Exception If there was an error in registration
	 */
	public static function register() {
		if ( self::$registered ) {
			return;
		}

		self::$libDir = dirname( __FILE__ );

		if ( false === spl_autoload_register( array( 'Less_Autoloader', 'loadClass' ) ) ) {
			throw new Exception( 'Unable to register Less_Autoloader::loadClass as an autoloading method.' );
		}

		self::$registered = true;
	}

	/**
	 * Unregisters the autoloader
	 *
	 * @return void
	 */
	public static function unregister() {
		spl_autoload_unregister( array( 'Less_Autoloader', 'loadClass' ) );
		self::$registered = false;
	}

	/**
	 * Loads the class
	 *
	 * @param string $className The class to load
	 */
	public static function loadClass( $className ) {
		// handle only package classes
		if ( strpos( $className, 'Less_' ) !== 0 ) {
			return;
		}

		$className = substr( $className, 5 );
		$fileName = self::$libDir . DIRECTORY_SEPARATOR . str_replace( '_', DIRECTORY_SEPARATOR, $className ) . '.php';

		if ( file_exists( $fileName ) ) {
			require $fileName;
			return true;
		} else {
			throw new Exception( 'file not loadable '.$fileName );
		}
	}

}
