using System.Security.Cryptography;

namespace EnvelopeGenerator.Infrastructure.Crypt.Services;

internal static class Pkcs11DigestInfoBuilder
{
    public static byte[] Build(byte[] hash, HashAlgorithmName hashAlgorithm)
    {
        byte[] prefix = hashAlgorithm.Name switch
        {
            "SHA256" =>
            [
                0x30, 0x31,
                0x30, 0x0d,
                0x06, 0x09, 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01,
                0x05, 0x00,
                0x04, 0x20
            ],
            "SHA384" =>
            [
                0x30, 0x41,
                0x30, 0x0d,
                0x06, 0x09, 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x02,
                0x05, 0x00,
                0x04, 0x30
            ],
            "SHA512" =>
            [
                0x30, 0x51,
                0x30, 0x0d,
                0x06, 0x09, 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x03,
                0x05, 0x00,
                0x04, 0x40
            ],
            _ => throw new NotSupportedException($"Hash algorithm '{hashAlgorithm.Name}' is not supported.")
        };

        var digestInfo = new byte[prefix.Length + hash.Length];
        Buffer.BlockCopy(prefix, 0, digestInfo, 0, prefix.Length);
        Buffer.BlockCopy(hash, 0, digestInfo, prefix.Length, hash.Length);
        return digestInfo;
    }
}