<?php

/**
 * @package KantPHP
 * @author  Zhenqiang Zhang <zhenqiang.zhang@hotmail.com>
 * @copyright (c) KantPHP Studio, All rights reserved.
 * @license http://www.opensource.org/licenses/BSD-3-Clause  The BSD 3-Clause License
 */
namespace Kant\Foundation;

use Kant\Foundation\BaseObject;

/**
 * Link represents a link object as defined in [JSON Hypermedia API Language](https://tools.ietf.org/html/draft-kelly-json-hal-03).
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @since 2.0
 */
class Link extends BaseObject
{

    /**
     * The self link.
     */
    const REL_SELF = 'self';

    /**
     *
     * @var string a URI [RFC3986](https://tools.ietf.org/html/rfc3986) or
     *      URI template [RFC6570](https://tools.ietf.org/html/rfc6570). This property is required.
     */
    public $href;

    /**
     *
     * @var string a secondary key for selecting Link Objects which share the same relation type
     */
    public $name;

    /**
     *
     * @var string a hint to indicate the media type expected when dereferencing the target resource
     */
    public $type;

    /**
     *
     * @var boolean a value indicating whether [[href]] refers to a URI or URI template.
     */
    public $templated = false;

    /**
     *
     * @var string a URI that hints about the profile of the target resource.
     */
    public $profile;

    /**
     *
     * @var string a label describing the link
     */
    public $title;

    /**
     *
     * @var string the language of the target resource
     */
    public $hreflang;

    /**
     * Serializes a list of links into proper array format.
     * 
     * @param array $links
     *            the links to be serialized
     * @return array the proper array representation of the links.
     */
    public static function serialize(array $links)
    {
        foreach ($links as $rel => $link) {
            if (is_array($link)) {
                foreach ($link as $i => $l) {
                    $link[$i] = $l instanceof self ? array_filter((array) $l) : [
                        'href' => $l
                    ];
                }
                $links[$rel] = $link;
            } elseif (!$link instanceof self) {
                $links[$rel] = [
                    'href' => $link
                ];
            }
        }
        
        return $links;
    }
}
