using System.IO;
using System.Threading;
using System.Threading.Tasks;

namespace DocumentService.Client.Extensions;

/// <summary>
/// Extension methods for Stream operations.
/// </summary>
public static class StreamExtensions
{
    /// <summary>
    /// Converts a stream to a Base64-encoded string.
    /// </summary>
    /// <param name="stream">Source stream</param>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>Base64-encoded string</returns>
    public static async Task<string> ToBase64StringAsync(this Stream stream, CancellationToken cancellationToken = default)
    {
        if (stream == null)
            throw new ArgumentNullException(nameof(stream));

        byte[] bytes = await stream.ToBytesAsync(cancellationToken);
        return Convert.ToBase64String(bytes);
    }

    /// <summary>
    /// Converts a stream to a byte array.
    /// </summary>
    /// <param name="stream">Source stream</param>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>Byte array</returns>
    public static async Task<byte[]> ToBytesAsync(this Stream stream, CancellationToken cancellationToken = default)
    {
        if (stream == null)
            throw new ArgumentNullException(nameof(stream));

        if (stream is MemoryStream ms)
        {
            return ms.ToArray();
        }

        using var memoryStream = new MemoryStream();
#if NET8_0
        await stream.CopyToAsync(memoryStream, cancellationToken);
#else
        await stream.CopyToAsync(memoryStream);
#endif
        return memoryStream.ToArray();
    }

    /// <summary>
    /// Resets stream position to beginning if seekable.
    /// </summary>
    /// <param name="stream">Stream to reset</param>
    /// <returns>The same stream (for chaining)</returns>
    public static Stream Reset(this Stream stream)
    {
        if (stream != null && stream.CanSeek)
            stream.Position = 0;

        return stream!;
    }
}