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

namespace WarcViewerBlazorWinForm.Backend.IO
{
    internal static class StreamExtension
    {
        public static void SeekForwardStupid(this Stream stream, long bytes)
        {
            if (stream == null) throw new ArgumentNullException(nameof(stream));
            if (bytes < 0) throw new ArgumentOutOfRangeException(nameof(bytes));
            if (bytes == 0) return;

            if (stream.CanSeek)
            {
                var newPosition = stream.Position + bytes;

                if (newPosition < 0 || newPosition > stream.Length) throw new ArgumentOutOfRangeException(nameof(bytes), "Attempted to move the stream pointer beyond its limits.");

                stream.Seek(bytes, SeekOrigin.Current);
            }
            else
            {
                var buffer = new byte[4096];
                var remainingBytes = bytes;

                while (remainingBytes > 0)
                {
                    var bytesRead = stream.Read(buffer, 0, (int)Math.Min(buffer.Length, remainingBytes));

                    // Reached the end of the stream
                    if (bytesRead == 0) throw new EndOfStreamException("Attempted to move the stream pointer beyond its limits.");

                    remainingBytes -= bytesRead;
                }
            }
        }

        public static long GetLengthStupid(this Stream stream, int readAndDiscardBufferSize = 4096)
        {
            if (stream == null)
            {
                throw new ArgumentNullException(nameof(stream));
            }

            try
            {
                return stream.Length;
            }
            catch (NotSupportedException)
            {
                // Ignore if getting length is not supported
            }

            try
            {
                if (stream.Position != 0) throw new InvalidOperationException("The stream position must be 0 when getting length.");
            }
            catch (NotSupportedException)
            {
                // Ignore if getting position is not supported
            }

            var buf = new byte[readAndDiscardBufferSize];
            var totalRead = 0;
            do
            {
                var read = stream.Read(buf, 0, readAndDiscardBufferSize);
                if (read == 0) break;
                totalRead += read;
            } while (true);

            return totalRead;
        }
    }
}