<?php

declare(strict_types=1);

/*
 * The MIT License (MIT)
 *
 * Copyright (c) 2014-2020 Spomky-Labs
 *
 * This software may be modified and distributed under the terms
 * of the MIT license.  See the LICENSE file for details.
 */

namespace Base64Url;

use function base64_decode;
use function base64_encode;
use InvalidArgumentException;
use function rtrim;
use function strtr;

/**
 * Encode and decode data into Base64 Url Safe.
 */
final class Base64Url
{
    /**
     * @param string $data       The data to encode
     * @param bool   $usePadding If true, the "=" padding at end of the encoded value are kept, else it is removed
     *
     * @return string The data encoded
     */
    public static function encode(string $data, bool $usePadding = false): string
    {
        $encoded = strtr(base64_encode($data), '+/', '-_');

        return true === $usePadding ? $encoded : rtrim($encoded, '=');
    }

    /**
     * @param string $data The data to decode
     *
     * @throws InvalidArgumentException
     *
     * @return string The data decoded
     */
    public static function decode(string $data): string
    {
        $data = strtr($data, '-_', '+/');

        // Base64Url values are often provided without '=' padding.
        // Newer PHP versions can be stricter with base64_decode(..., true).
        $remainder = strlen($data) % 4;
        if (1 === $remainder) {
            throw new InvalidArgumentException('Invalid data provided');
        }
        if (0 !== $remainder) {
            $data .= str_repeat('=', 4 - $remainder);
        }

        $decoded = base64_decode($data, true);
        if (false === $decoded) {
            throw new InvalidArgumentException('Invalid data provided');
        }

        return $decoded;
    }
}
