using System;
using System.IO;
using System.Runtime.CompilerServices;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace Tools
{
    public static class ExStreamTools
    {
        public static void CopyTo(this Stream input, Stream output, int buffersize, long bytes)
        {
            byte[] buffer = new byte[buffersize];
            int count;
            while (bytes > 0L && (count = input.Read(buffer, 0, (int)Math.Min((long)buffer.Length, bytes))) > 0)
            {
                output.Write(buffer, 0, count);
                bytes -= (long)count;
            }
        }
        public static async Task CopyToAsync(this Stream input, Stream output, int buffersize, long bytes, CancellationToken token =default)
        {
            byte[] buffer = new byte[buffersize];
            int count;
            while (bytes > 0L && (count = await input.ReadAsync(buffer, 0, (int)Math.Min((long)buffer.Length, bytes), token)) > 0)
            {
                await output.WriteAsync(buffer, 0, count, token);
                bytes -= (long)count;
            }
        }
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static unsafe void WriteValueUnmanaged<T>(this Stream s, T t) where T : unmanaged
        {
            byte[] buffer = new byte[sizeof(T)];
            fixed (byte* ptr = buffer)
            {
                *(T*)ptr = t;
            }
            s.Write(buffer, 0, buffer.Length);
        }
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static unsafe Task WriteValueUnmanagedAsync<T>(this Stream s, T t, CancellationToken token = default) where T : unmanaged
        {
            byte[] buffer = new byte[sizeof(T)];
            fixed (byte* ptr = buffer)
            {
                *(T*)ptr = t;
            }
            return s.WriteAsync(buffer, 0, buffer.Length, token);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static void WriteAll(this Stream s, byte[] buffer)
        {
            s.Write(buffer, 0, buffer.Length);
        }
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static Task WriteAllAsync(this Stream s, byte[] buffer, CancellationToken token=default)
        {
            return s.WriteAsync(buffer, 0, buffer.Length,token);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static int ReadAll(this Stream s, byte[] buffer)
        {
            return s.Read(buffer, 0, buffer.Length);
        }
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static Task<int> ReadAllAsync(this Stream s, byte[] buffer, CancellationToken token = default)
        {
            return s.ReadAsync(buffer, 0, buffer.Length, token);
        }
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static int ReadAllBlocking(this Stream s, byte[] buffer)
        {
            return s.BlockingRead(buffer, 0, buffer.Length);
        }
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static Task<int> ReadAllBlockingAsync(this Stream s, byte[] buffer, CancellationToken token = default)
        {
            return s.BlockingReadAsync(buffer, 0, buffer.Length, token);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static byte[] ReadNew(this Stream s, int len)
        {
            byte[] buffer = new byte[len];
            s.Read(buffer, 0, len);
            return buffer;
        }
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static async Task<byte[]> ReadNewAsync(this Stream s, int len, CancellationToken token = default)
        {
            byte[] buffer = new byte[len];
            await s.ReadAsync(buffer, 0, len, token);
            return buffer;
        }
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static byte[] ReadNewBlocking(this Stream s, int len)
        {
            byte[] buffer = new byte[len];
            s.BlockingRead(buffer, 0, len);
            return buffer;
        }
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static async Task<byte[]> ReadNewBlockingAsync(this Stream s, int len, CancellationToken token = default)
        {
            byte[] buffer = new byte[len];
            await s.BlockingReadAsync(buffer, 0, len, token);
            return buffer;
        }

        public static int BlockingRead(this Stream s, byte[] buffer, int offset, int count)
        {
            int read;
            int rlen = 0;

            while ((rlen += (read = s.Read(buffer, offset + rlen, count - rlen))) < count) if (read <= 0) break;

            return rlen;
        }
        public static async Task<int> BlockingReadAsync(this Stream s, byte[] buffer, int offset, int count, CancellationToken token=default)
        {
            int read;
            int rlen = 0;

            while ((rlen += (read = await s.ReadAsync(buffer, offset + rlen, count - rlen, token))) < count) if (read <= 0) break;

            return rlen;
        }

        public static void WriteString(this Stream s, string str, Encoding encoding = null)
        {
            if (encoding == null) encoding = Encoding.UTF8;

            int code = encoding.CodePage;
            byte[] buf = encoding.GetBytes(str);

            s.WriteValueUnmanaged(buf.Length);
            s.WriteValueUnmanaged(code);
            s.WriteAll(buf);
        }
        public static Task WriteStringAsync(this Stream s, string str, CancellationToken token = default)
            => WriteStringAsync(s, str, Encoding.UTF8, token);
        public static async Task WriteStringAsync(this Stream s, string str, Encoding encoding, CancellationToken token=default)
        {
            int code = encoding.CodePage;
            byte[] buf = encoding.GetBytes(str);

            await s.WriteValueUnmanagedAsync(buf.Length, token);
            await s.WriteValueUnmanagedAsync(code,token);
            await s.WriteAllAsync(buf,token);
        }

        public static string ReadString(this Stream s, Encoding encoding = null)
        {
            int len = s.ReadValueUnmanaged<int>();
            int code = s.ReadValueUnmanaged<int>();
            byte[] buf = s.ReadNew(len);

            if (encoding == null)
                encoding = Encoding.GetEncoding(code);

            return encoding.GetString(buf);
        }
        public static async Task<string> ReadStringAsync(this Stream s, CancellationToken token = default)
        {
            int len = await s.ReadValueUnmanagedAsync<int>(token);
            int code = await s.ReadValueUnmanagedAsync<int>(token);
            byte[] buf = await s.ReadNewAsync(len, token);

            var encoding = Encoding.GetEncoding(code);

            return encoding.GetString(buf);
        }
        public static async Task<string> ReadStringAsync(this Stream s, Encoding encoding, CancellationToken token = default)
        {
            int len = await s.ReadValueUnmanagedAsync<int>(token);
            await s.ReadValueUnmanagedAsync<int>(token);
            byte[] buf = await s.ReadNewAsync(len, token);

            return encoding.GetString(buf);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static unsafe T ReadValueUnmanaged<T>(this Stream s) where T : unmanaged
        {
            T output;
            byte[] buffer = new byte[sizeof(T)];
            s.Read(buffer, 0, buffer.Length);

            fixed (byte* ptr = buffer)
            {
                output = *(T*)ptr;
            }

            return output;
        }
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static async Task<T> ReadValueUnmanagedAsync<T>(this Stream s, CancellationToken token=default) where T : unmanaged
        {
            T output;
            int len;
            unsafe
            {
                len = sizeof(T);
            }
            byte[] buffer = new byte[len];
            await s.ReadAsync(buffer, 0, buffer.Length, token);
            unsafe
            {
                fixed (byte* ptr = buffer)
                {
                    output = *(T*)ptr;
                }
            }
            return output;
        }
    }
}