<?php

namespace phpnotify;

/**
 * That class represents subject, also known as topic in library.
 * 
 * That represents single topic, also known as subject in the library. It
 * would be build by notifier, but could also being builded manually without
 * it. Subject would be used to generating new notifications, which could be
 * personalized and sended to notifications server
 */
class subject extends authorization_store {
    /** 
     * URL of the subject.
     * @var string
     */
    private string $url;

    /**
     * This create new subject.
     *
     * This create new topic from the server URL, subject name and also
     * authentication method. It would being used by notifier class, for
     * generating subjects manually use {@see subject::create} static 
     * function. When subject is incorrect or url generated from that is
     * not valid URL, raises TypeError.
     *
     * @throws TypeError When subject is not correct
     * @throws TypeError When final subject URL is not valid.
     *
     * @param string $server Server URL.
     * @param string $subject Subject name.
     * @param authorization_method $authorization Authorization method to use.
     */ 
    public function __construct(
        string $server, 
        string $subject,
        authorization_method $authorization
    ) {
        parent::__construct($authorization);

        $subject = trim($subject);

        if (strlen($subject) === 0 || strpos($subject, ' ') !== false) {
            throw new TypeError(
                'Subject could not being empty and contains space.'
            );
        }

        $this->url = $this->get_topic_url($server, $subject);

        if (!filter_var($this->url, FILTER_VALIDATE_URL)) {
            throw new TypeError('"'.$subject.'" is not property topic name.');
        }
    }

    /**
     * That function create new subject directly from server name and
     * subject name. It use empty authorization method by default, but it
     * could be changed. When server URL is invalid throws TypeError.
     *
     * @throws TypeError When server URL is invalid.
     * 
     * @param string $server URL of the server.
     * @param string $subject Name of the subject.
     *
     * @return subject New created subject.
     */
    public static function create(string $server, string $subject): subject {
        if (!filter_var($server, FILTER_VALIDATE_URL)) {
            throw new TypeError('"'.$server.'" is not property URL.');
        }

        return new self($server, $subject, new empty_authorization());
    }

    /**
     * This return full subject url.
     *
     * This function return full URL to the subject. It require server 
     * URL and subject name. 
     *
     * @param string $server Server URL.
     * @param string $subject Subject to use.
     *
     * @return string Full subject URL.
     */
    private function get_topic_url(
        string $server, 
        string $subject
    ): string {
        if ($server[strlen($server) - 1] === '/') {
            return $server.$subject;
        }

        return $server.'/'.$subject;
    }

    /**
     * This function generate new notification to publish in subject.
     *
     * This create new notification, to publish in that subject. Content 
     * given as parameter is content of the notofication. Notification
     * could be infill with more data before send, that function not sending 
     * notification, but only create it.
     *
     * @param string $content Content of the new notification.
     *
     * @return notification New notification to infill with data and send.
     */
    public function new_notification(string $content): notification {
        return new notification(
            $this->url, 
            $content,
            $this->get_access_method()
        );
    }
}