koel/app/Services/iTunes.php

<?php

namespace App\Services;

use GuzzleHttp\Client;

class iTunes
{
    /**
     * @var Client
     */
    protected $client;

    /**
     * @var string
     */
    protected $endPoint = 'https://itunes.apple.com/search';

    /**
     * iTunes constructor.
     *
     * @param Client|null $client
     */
    public function __construct(Client $client = null)
    {
        $this->client = $client ?: new Client();
    }

    /**
     * Determines whether to use iTunes services.
     *
     * @return bool
     */
    public function used()
    {
        return (bool) config('koel.itunes.enabled');
    }

    /**
     * Search for a track on iTunes Store with the given information and get its URL.
     *
     * @param $term string The main query string (should be the track's name)
     * @param $album string The album's name, if available
     * @param $artist string The artist's name, if available
     *
     * @return string|false
     */
    public function getTrackUrl($term, $album = '', $artist = '')
    {
        $params = [
            'term' => $term.($album ? ' '.$album : '').($artist ? ' '.$artist : ''),
            'media' => 'music',
            'entity' => 'song',
            'limit' => 1,
        ];

        $response = (string) $this->client->get($this->endPoint, ['query' => $params])->getBody();
        $response = json_decode($response);

        if (!$response->resultCount) {
            return false;
        }

        $trackUrl = $response->results[0]->trackViewUrl;

        // Returns a string if the URL has parameters or NULL if not
        if (parse_url($trackUrl, PHP_URL_QUERY)) {
            $trackUrl .= '&at='.config('koel.itunes.affiliate_id');
        } else {
            $trackUrl .= '?at='.config('koel.itunes.affiliate_id');
        }

        return $trackUrl;
    }
}