package utils

import (
	"errors"
	"io"
	"sync"
)

var (
	blockSize = 32
)

var (
	ErrNoBuf = errors.New("no buffer can be used")

	pool = sync.Pool{
		New: func() interface{} {
			return make([]byte, blockSize*1024)
		},
	}
)

func getBuffer() []byte {
	if buffer, ok := pool.Get().([]byte); ok {
		return buffer
	}
	return nil
}

func putBuffer(buffer []byte) {
	pool.Put(buffer)
}

func Copy(dst io.Writer, src io.Reader) (int64, error) {
	if wt, ok := src.(io.WriterTo); ok {
		return wt.WriteTo(dst)
	}

	if rt, ok := dst.(io.ReaderFrom); ok {
		return rt.ReadFrom(src)
	}

	if buffer := getBuffer(); nil != buffer {
		defer putBuffer(buffer)

		return io.CopyBuffer(dst, src, buffer)
	}

	return 0, ErrNoBuf
}