package net

import (
	"io"

	"github.com/go-gost/core/common/bufpool"
)

const (
	bufferSize = 64 * 1024
)

// Transport copies data bidirectionally between rw1 and rw2 using two
// goroutines. It returns the first non-EOF error encountered.
func Transport(rw1, rw2 io.ReadWriter) error {
	errc := make(chan error, 2)
	go func() {
		errc <- CopyBuffer(rw1, rw2, bufferSize)
	}()

	go func() {
		errc <- CopyBuffer(rw2, rw1, bufferSize)
	}()

	if err := <-errc; err != nil && err != io.EOF {
		return err
	}

	return nil
}

// CopyBuffer copies from src to dst using a buffer of bufSize obtained from
// the buffer pool, reducing allocation overhead for repeated copies.
func CopyBuffer(dst io.Writer, src io.Reader, bufSize int) error {
	buf := bufpool.Get(bufSize)
	defer bufpool.Put(buf)

	_, err := io.CopyBuffer(dst, src, buf)
	return err
}