<?php

/**
 * Includes the Autoloader used.
 * @package Templately
 */

namespace Templately;

// if direct access than exit the file.
defined('ABSPATH') || exit;

class Autoloader {
    /**
     * Instance of Autoloader
     * @var Autoloader
     */
    private static $_instance = null;
    /**
     * Classes map.
     * Maps classes to file names.
     * @access private
     * @static
     * @var array Classes array use by Templately.
     */
    private static $classes_map;
    /**
     * Classes directory.
     * Maps classes to file names.
     * @access private
     * @static
     * Classes folder used for @package Templately.
     */
    private static $SOURCE_DIRECTORY = TEMPLATELY_PATH;
    /**
     * Classmap file for Autoloader
     * @access private
     * @static
     * Classes array used for @package Templately.
     */
    private static $CLASS_MAPS_FILE = __DIR__ . '/classmaps.php';

    /**
     * Get a single instace of Autoloader
     * @return Autoloader
     */
    public static function init() {
        if (is_null(self::$_instance)) {
            self::$_instance = new self();
        }
        return self::$_instance;
    }

    /**
     * Automatically get invoked when initilize the Autoloader.
     */
    public function __construct() {
        spl_autoload_register(array(&$this, 'autoload'));
    }

    /**
     * Autoload function ensure that, every class you called is loaded properly.
     * @param Object $class
     * @access private
     * @return void
     */
    private function autoload($class) {
        if (0 !== strpos($class, __NAMESPACE__ . '\\')) {
            return;
        }
        $relative_class_name = preg_match( '/.*\\\\([\\w]+)/', $class, $matches );
        if( count( $matches ) > 1 ){
            $relative_class_name = $matches[1];
        }
        if( ! class_exists( $class ) ){
            self::load_class( $relative_class_name );
        }
    }

    /**
     * Load class.
     *
     * For a given class name, require the class file.
     *
     * @access private
     * @static
     * @param string $relative_class_name Class name.
     */
    private static function load_class($relative_class_name) {
        $classes_map = self::get_classes_map();

        if (isset($classes_map[ $relative_class_name ])) {
            $filename = self::$SOURCE_DIRECTORY . $classes_map[ $relative_class_name ];
            if (is_readable($filename)) {
                require $filename;
            }
        }
    }

    /**
     * Get the class map, if its not set than load the classmap file.
     * @return void
     */
    private static function get_classes_map() {
        if (!self::$classes_map) {
            self::init_classes_map();
        }
        return self::$classes_map;
    }

    /**
     * Loader of the classmap file.
     * @return array of classes.
     */
    private static function init_classes_map() {
        self::$classes_map = require_once self::$CLASS_MAPS_FILE;
    }
}