<?php
namespace Aws\S3;

use AWS\CRT\CRT;
use Aws\Exception\CommonRuntimeException;
use GuzzleHttp\Psr7;
use InvalidArgumentException;

trait CalculatesChecksumTrait
{
    /**
     * @param string $requestedAlgorithm  the algorithm to encode with
     * @param string $value               the value to be encoded
     * @return string
     */
    public static function getEncodedValue($requestedAlgorithm, $value) {
        $requestedAlgorithm = strtolower($requestedAlgorithm);
        $useCrt = extension_loaded('awscrt');
        if ($useCrt) {
            $crt = new Crt();
            switch ($requestedAlgorithm) {
                case 'crc32c':
                    return base64_encode(pack('N*',($crt->crc32c($value))));
                case 'crc32':
                    return base64_encode(pack('N*',($crt->crc32($value))));
                case 'sha256':
                case 'sha1':
                    return base64_encode(Psr7\Utils::hash($value, $requestedAlgorithm, true));
                default:
                    break;
                throw new InvalidArgumentException(
                    "Invalid checksum requested: {$requestedAlgorithm}."
                    . "  Valid algorithms are CRC32C, CRC32, SHA256, and SHA1."
                );
            }
        }  else {
            if ($requestedAlgorithm == 'crc32c') {
                throw new CommonRuntimeException("crc32c is not supported for checksums "
                    . "without use of the common runtime for php.  Please enable the CRT or choose "
                    . "a different algorithm."
                );
            }
            if ($requestedAlgorithm == "crc32") {
                $requestedAlgorithm = "crc32b";
            }
            return base64_encode(Psr7\Utils::hash($value, $requestedAlgorithm, true));
        }
    }

}