using System;
using System.Security.Cryptography;

namespace StellaOps.Cryptography;

/// <summary>
/// Default implementation of <see cref="ICryptoHasher"/> using BCL cryptographic primitives.
/// </summary>
public sealed class DefaultCryptoHasher : ICryptoHasher
{
    public DefaultCryptoHasher(string algorithmId)
    {
        if (string.IsNullOrWhiteSpace(algorithmId))
        {
            throw new ArgumentException("Algorithm identifier is required.", nameof(algorithmId));
        }

        AlgorithmId = algorithmId.ToUpperInvariant();
    }

    public string AlgorithmId { get; }

    public byte[] ComputeHash(ReadOnlySpan<byte> data)
    {
        return AlgorithmId switch
        {
            HashAlgorithms.Sha256 => SHA256.HashData(data),
            HashAlgorithms.Sha384 => SHA384.HashData(data),
            HashAlgorithms.Sha512 => SHA512.HashData(data),
            _ => throw new InvalidOperationException($"Unsupported hash algorithm '{AlgorithmId}'.")
        };
    }

    public string ComputeHashHex(ReadOnlySpan<byte> data)
    {
        var hash = ComputeHash(data);
        return Convert.ToHexStringLower(hash);
    }
}