using System;
using System.IO;

namespace ln.http;

public class HttpRequestStream : Stream
{
    public int MemoryLimit { get; set; } = 1024 * 1024 * 10;

    private Stream _stream;
    private string _tempFileName;
    
    public HttpRequestStream(Stream connectionStream, int length)
    {
        byte[] transferBuffer;
        // if (length <= MemoryLimit)
        // {
        //     transferBuffer = new byte[length];
        //     if (connectionStream.ReadExactly(transferBuffer, 0, transferBuffer.Length) != length)
        //         throw new IOException();
        //     
        //     _stream = new MemoryStream(transferBuffer);   
        // }
        // else
        // {
            _tempFileName = Path.GetTempFileName();
            _stream = new FileStream(_tempFileName, FileMode.Open, FileAccess.ReadWrite);
            
            transferBuffer = new byte[MemoryLimit];
            while (length > 0)
            {
                int size = length > transferBuffer.Length ? transferBuffer.Length : length;
                int nread = connectionStream.Read(transferBuffer, 0, size);
                _stream.Write(transferBuffer, 0, nread);
                length -= nread;
            }

            _stream.Position = 0;
        // }
    }
    
    public override int Read(byte[] buffer, int offset, int count) => _stream.Read(buffer, offset, count);
    public override long Seek(long offset, SeekOrigin origin) => _stream.Seek(offset, origin);
    public override void SetLength(long value) => throw new System.NotImplementedException();
    public override void Write(byte[] buffer, int offset, int count) => throw new System.NotImplementedException();
    public override void Flush() => throw new System.NotImplementedException();
    
    public override bool CanRead { get; } = true;
    public override bool CanSeek { get; } = true;
    public override bool CanWrite { get; } = false;
    public override long Length => _stream.Length;
    public override long Position { get => _stream.Position; set => _stream.Position = value; }

    public override int Read(Span<byte> buffer) => _stream.Read(buffer);
    public override void Close() => _stream.Close();

    protected override void Dispose(bool disposing)
    {
        _stream.Dispose();
        if (_tempFileName is not null)
            File.Delete(_tempFileName);
    }
}