using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace Remotely.Shared.Utilities;

public class AppendableStream : Stream
{
    private readonly byte[] _bytesToAppend;
    private readonly Stream _underlyingStream;
    private bool _bytesAppended;

    public AppendableStream(Stream underlyingStream, byte[] bytesToAppend)
    {
        _underlyingStream = underlyingStream;
        _bytesToAppend = bytesToAppend;
    }

    public override bool CanRead => _underlyingStream.CanRead;

    public override bool CanSeek => _underlyingStream.CanSeek;

    public override bool CanTimeout => _underlyingStream.CanTimeout;

    public override bool CanWrite => _underlyingStream.CanWrite;

    public override long Length => _underlyingStream.Length + _bytesToAppend.Length;

    public override long Position
    {
        get => _underlyingStream.Position;
        set => _underlyingStream.Position = value;
    }

    public override int ReadTimeout
    {
        get => _underlyingStream.ReadTimeout;
        set => _underlyingStream.ReadTimeout = value;
    }

    public override int WriteTimeout
    {
        get => _underlyingStream.WriteTimeout;
        set => _underlyingStream.WriteTimeout = value;
    }

    public override void Close()
    {
        _underlyingStream.Close();
        base.Close();
    }


    public override ValueTask DisposeAsync()
    {
        GC.SuppressFinalize(this);
        return _underlyingStream.DisposeAsync();
    }

    public override void Flush()
    {
        _underlyingStream.Flush();
    }

    public override int Read(byte[] buffer, int offset, int count)
    {
        if (_underlyingStream.Position == _underlyingStream.Length && !_bytesAppended)
        {
            _bytesToAppend.CopyTo(buffer, 0);
            _bytesAppended = true;
            return _bytesToAppend.Length;
        }
        return _underlyingStream.Read(buffer, offset, count);
    }

    public override long Seek(long offset, SeekOrigin origin)
    {
        return _underlyingStream.Seek(offset, origin);
    }

    public override void SetLength(long value)
    {
        _underlyingStream.SetLength(value);
    }

    public override void Write(byte[] buffer, int offset, int count)
    {
        _underlyingStream.Write(buffer, offset, count);
    }

    protected override void Dispose(bool disposing)
    {
        _underlyingStream.Dispose();
        base.Dispose(disposing);
    }
}