<?php
require_once("Util.php");

class TopicData
{
    public string $id;
    public string $subjectId;
    public string $displayName;
    public string $icon;
    public string $description;
    public array $relatedTopics;
    public array $files;
    public string $article;

    public static function getAll($subjectName) : array
    {
        $result = array();

        $topicDirectory = "config/subjects/$subjectName/topics";
        $topicNames = scandir($topicDirectory);
        foreach ($topicNames as $topicName) {
            if ($topicName == "." || $topicName == "..") {
                continue;
            }
            $topicData = TopicData::fromName($subjectName, $topicName);
            if(!isset($topicData)) {
                continue;
            }

            $result[] = $topicData;
        }

        return $result;
    }

    public static function fromName($subjectName, $topicName): TopicData|null
    {
        $result = new TopicData();

        $subjectName = Util::removeIllegalCharacters($subjectName);
        $topicName = Util::removeIllegalCharacters($topicName);

        $topicDirectory = "config/subjects/$subjectName/topics";
        $filename = "$topicDirectory/$topicName/properties.json";
        $data = Util::parseJsonFromFile($filename);

        $result->id = $topicName;
        $result->subjectId = $subjectName;

        if(isset($data->displayName)) {
            $result->displayName = $data->displayName;
        } else {
            return null;
        }

        if(isset($data->icon)) {
            $result->icon = $data->icon;
        } else {
            return null;
        }

        if(isset($data->description)) {
            $result->description = $data->description;
        } else {
            return null;
        }

        if(isset($data->relatedTopics)) {
            $result->relatedTopics = $data->relatedTopics;
        } else {
            $result->relatedTopics = array();
        }
        if(isset($data->files)) {
            $result->files = $data->files;
        } else {
            $result->files = array();
        }

        if(isset($data->article)) {
            $result->article = $data->article;
        } else {
            return null;
        }

        return $result;
    }

}