// <copyright file="DefaultCryptoHash.cs" company="StellaOps">
// Copyright (c) StellaOps. Licensed under AGPL-3.0-or-later.
// </copyright>

using System.Security.Cryptography;

namespace StellaOps.Facet;

/// <summary>
/// Default implementation of <see cref="ICryptoHash"/> using .NET built-in algorithms.
/// </summary>
public sealed class DefaultCryptoHash : ICryptoHash
{
    /// <summary>
    /// Gets the singleton instance.
    /// </summary>
    public static DefaultCryptoHash Instance { get; } = new();

    /// <inheritdoc/>
    public byte[] ComputeHash(byte[] data, string algorithm)
    {
        ArgumentNullException.ThrowIfNull(data);
        ArgumentException.ThrowIfNullOrWhiteSpace(algorithm);

        return algorithm.ToUpperInvariant() switch
        {
            "SHA256" => SHA256.HashData(data),
            "SHA384" => SHA384.HashData(data),
            "SHA512" => SHA512.HashData(data),
            "SHA1" => SHA1.HashData(data),
            "MD5" => MD5.HashData(data),
            _ => throw new NotSupportedException($"Hash algorithm '{algorithm}' is not supported")
        };
    }

    /// <inheritdoc/>
    public async Task<byte[]> ComputeHashAsync(
        Stream stream,
        string algorithm,
        CancellationToken ct = default)
    {
        ArgumentNullException.ThrowIfNull(stream);
        ArgumentException.ThrowIfNullOrWhiteSpace(algorithm);

        return algorithm.ToUpperInvariant() switch
        {
            "SHA256" => await SHA256.HashDataAsync(stream, ct).ConfigureAwait(false),
            "SHA384" => await SHA384.HashDataAsync(stream, ct).ConfigureAwait(false),
            "SHA512" => await SHA512.HashDataAsync(stream, ct).ConfigureAwait(false),
            _ => throw new NotSupportedException($"Hash algorithm '{algorithm}' is not supported for async")
        };
    }
}