<?php

/*
|--------------------------------------------------------------------------
| Register AutoLoader
|--------------------------------------------------------------------------
| Vafpress Framework has separated app and core directories, developers can
| put their extension code and configuration at app folder, as everything
| inside app will be loaded first and will override class with the same
| name with core classes.
*/
VP_AutoLoader::add_namespaces(VP_NAMESPACE);
VP_AutoLoader::add_directories(VP_CLASSES_DIR, VP_NAMESPACE);
VP_AutoLoader::register();

class VP_AutoLoader
{

	/**
	 * Indicates if VP_AutoLoader has been registered.
	 * 
	 * @var boolean
	 */
	protected static $registered = false;

	/**
	 * The registered directories
	 * 
	 * @var array
	 */
	protected static $directories = array();

	/**
	 * THe registered namespaces
	 * 
	 * @var array
	 */
	protected static $namespaces = array();

	/**
	 * Autoloading logic
	 * 
	 * @param  String  $class Class name
	 * @return Boolean        Whether the loading succeded.
	 */
	public static function load($class)
	{
		clearstatcache();

		// figure out namespace and halt process if not in our namespace
		$namespace = self::discover_namespace($class);
		if($namespace === '')
			return;

		$class = self::normalize_class($class, $namespace);

		foreach (self::$directories[$namespace] as $dir)
		{
			$file = $dir . DIRECTORY_SEPARATOR . $class;

			if (is_link($file))
			{
				$file = readlink($file);
			}

			if(is_file($file))
			{
				require $file;
				return true;
			}
		}
	}

	/**
	 * Discover namespace from a string
	 * 
	 * @param  String $key A class name or namespaced key
	 * @return String      Namespace
	 */
	public static function discover_namespace($key)
	{
		$namespace = '';
		foreach (self::$namespaces as $ns)
		{
			if (strpos($key, $ns) === 0)
			{
				$namespace = $ns;
				break;
			}
		}
		return $namespace;
	}

	/**
	 * Register autoloader
	 * 
	 * @return void
	 */
	public static function register()
	{
		if(self::$registered !== TRUE)
		{
			spl_autoload_register(array('VP_AutoLoader', 'load'));
		}
		self::$registered = TRUE;
	}

	/**
	 * Add a namespace
	 *
	 * @return void
	 */
	public static function add_namespaces($namespaces)
	{
		self::$namespaces = array_merge(self::$namespaces, (array) $namespaces);
		self::$namespaces = array_unique(self::$namespaces);
		usort(self::$namespaces, array('self', 'sort'));
	}

	/**
	 * Sort by length
	 */
	private static function sort($a, $b)
	{
    	return strlen($b) - strlen($a);
	}


	/**
	 * Add directories to the autoloader, loading process will be run in orderly fashion
	 * of directory addition.
	 * 
	 * @param  String|Array $directories
	 * @param  String       $namespace
	 * @return void
	 */
	public static function add_directories($directories, $namespace)
	{
		if(in_array($namespace, self::$namespaces))
		{
			if(!isset(self::$directories[$namespace]))
				self::$directories[$namespace] = array();
			self::$directories[$namespace] = array_merge(self::$directories[$namespace], (array) $directories);
			self::$directories[$namespace] = array_unique(self::$directories[$namespace]);
		}
	}

	/**
	 * Remove directories.
	 * 
	 * @param  String|Array $directories
	 * @return void
	 */
	public static function remove_directories($directories = null, $namespace = null)
	{
		// check if namespace existed
		if(!in_array($namespace, self::$namespaces))
			return;

		// annihilate everything if none / null passed
		if(is_null($directories))
		{
			self::$directories[$namespace] = array();
		}
		else
		{
			// prepare directories to be filtered
			$directories = (array) $directories;

			// do the filtering
			foreach (self::$directories[$namespace] as $key => $dir)
			{
				if(in_array($dir, $directories))
				{
					unset(self::$directories[$namespace][$key]);
				}
			}
		}
	}

	/**
	 * Normalize class to be loaded
	 * 
	 * @param  String $class Class name
	 * @return String        Normalized class name
	 */
	public static function normalize_class($class, $namespace)
	{
		$class = ltrim($class, '\\');
		$class = str_replace($namespace, '', $class);
		$class = ltrim($class, '_');
		$class = strtolower($class);
		return str_replace('_', DIRECTORY_SEPARATOR, $class) . '.php';
	}

	/**
	 * Get all directories
	 * 
	 * @return Array
	 */
	public static function get_directories()
	{
		return self::$directories;
	}

}

/**
 * EOF
 */