<?php

/*
 * FecShop file.
 *
 * @link http://www.fecshop.com/
 * @copyright Copyright (c) 2016 FecShop Software LLC
 * @license http://www.fecshop.com/license/
 */

namespace fecshop\services;

use Yii;
use yii\base\InvalidConfigException;

/**
 * 此对象就是Yii::$service,通过魔术方法__get ， 得到服务对象，服务对象是单例模式。
 * @see http://www.fecshop.com/doc/fecshop-guide/develop/cn-1.0/guide-fecshop-service-abc.html
 *
 * @property \fecshop\services\Admin $admin admin service
 * @property \fecshop\services\AdminUser $adminUser adminUser service
 * @property \fecshop\services\Cache $cache cache service
 * @property \fecshop\services\Cart $cart cart service
 * @property \fecshop\services\Category $category category service
 * @property \fecshop\services\Cms $cms cms service
 * @property \fecshop\services\Coupon $coupon coupon service
 * @property \fecshop\services\Customer $customer customer service
 * @property \fecshop\services\Email $email email service
 * @property \fecshop\services\Event $event event service
 * @property \fecshop\services\Fecshoplang $fecshopLang fecshopLang service
 * @property \fecshop\services\Helper $helper helper service
 * @property \fecshop\services\Image $image image service
 * @property \fecshop\services\Order $order order service
 * @property \fecshop\services\Page $page page service
 * @property \fecshop\services\Payment $payment payment service
 * @property \fecshop\services\Point $point point service
 * @property \fecshop\services\Product $product product service
 * @property \fecshop\services\Request $request request service
 * @property \fecshop\services\Search $search search service
 * @property \fecshop\services\Session $session session service
 * @property \fecshop\services\Shipping $shipping shipping service
 * @property \fecshop\services\Sitemap $sitemap sitemap service
 * @property \fecshop\services\Store $store store service
 * @property \fecshop\services\Url $url url service
 *
 * @author Terry Zhao <2358269014@qq.com>
 * @since 1.0
 */
class Application
{
    /**
     * @var array 服务的配置数组
     */
    public $childService;

    /**
     * @var array 实例化过的服务数组
     */
    public $_childService;
    
    /**
     * @var array $config 注入的配置数组
     * 在 @app/web/index.php 入口文件处。会调用 new fecshop\services\Application($config['services']);
     * Yii::$service 就是该类实例化的对象，注入的配置保存到 $this->childService 中
     */
    public function __construct($config = [])
    {
        Yii::$service = $this;
        $this->childService = $config;
    }

    /**
     * 根据服务名字获取服务实例
     * Get service instance by service name.
     *
     * 用类似于 Yii2 的 component 原理，采用单例模式实现的服务功能，
     * 服务的配置文件位于 config/services 目录
     *
     * @var string $childServiceName
     * @return \fecshop\services\Service
     * @throws \yii\base\InvalidConfigException if the service is not found or the service is disabled
     */
    public function getChildService($childServiceName)
    {
        if (!isset($this->_childService[$childServiceName]) || !$this->_childService[$childServiceName]) {
            $childService = $this->childService;
            if (isset($childService[$childServiceName])) {
                $service = $childService[$childServiceName];
                if (!isset($service['enableService']) || $service['enableService']) {
                    $this->_childService[$childServiceName] = Yii::createObject($service);
                } else {
                    throw new InvalidConfigException('Child Service ['.$childServiceName.'] is disabled in '.get_called_class().', you must enable it! ');
                }
            } else {
                throw new InvalidConfigException('Child Service ['.$childServiceName.'] does not exist in '.get_called_class().', you must config it! ');
            }
        }

        return isset($this->_childService[$childServiceName]) ? $this->_childService[$childServiceName] : null;
    }

    /**
     * 魔术方法，当调用一个属性，对象不存在的时候就会执行该方法，然后
     * 根据构造方法注入的配置，实例化service对象。
     * @var string $serviceName service name
     * @return \fecshop\services\Service
     * @throws \yii\base\InvalidConfigException if the service does not exist or the service is disabled
     */
    public function __get($serviceName)
    {
        return $this->getChildService($serviceName);
    }
}