<?php

namespace NoccyLabs\Dataset;

/**
 * DatasetManager is the central class of noccylabs/dataset.
 * 
 * @author Christopher Vagnetoft <cvagnetoft@gmail.com>
 * @copyright (c) 2022, NoccyLabs
 * @package noccylabs/dataset
 */
class DatasetManager
{


    private static $datasets = [];

    public function __construct()
    {
        if (count(self::$datasets) == 0) {
            $this->scanForDatasets();
        }
    }

    private function scanForDatasets()
    {
        $root = $this->determineVendorPath();
        if (!$root) {
            // Skip loading if we couldn't determine the root
            return;
        }

        $glob = glob($root."/*/*/dataset.json");
    }

    private function determineVendorPath(): ?string
    {
        if (file_exists(__DIR__."/../../../autoload.php")) {
            // we are installed as a composer package
            return dirname(__DIR__, 3);
        }
        return null;
    }

    public function registerDataset(Dataset $dataset)
    {
        $id = $dataset->getIdentifier();
        if (array_key_exists($id, self::$datasets)) {
            // Don't overwrite previously registered datasets. Investigate how
            // this can be handled better in the future.
            return;
        }

        self::$datasets[$id] = $dataset;
    }


    /**
     * 
     * 
     * @throws InvalidDatasetException if the dataset can not be opened
     * @throws UnknownDatasetExcception if the dataset does not exist
     */
    public function getDataset(string $identifier): Dataset
    {

        return self::$datasets[$identifier];
    }
}