package main

import (
	"fmt"

	"golang.org/x/text/encoding"
	"golang.org/x/text/encoding/charmap"
)

type Encoding string

const (
	EncodingUtf8    Encoding = "UTF-8"
	EncodingWin1251 Encoding = "Win-1251"
)

func (e Encoding) Encoder() (*encoding.Encoder, error) {
	switch e {
	case EncodingWin1251:
		return charmap.Windows1251.NewEncoder(), nil
	case EncodingUtf8:
		return &encoding.Encoder{Transformer: new(DummyTransformer)}, nil
	}

	return nil, fmt.Errorf("unknown encoding: %s", string(e))
}

type DummyTransformer struct{}

func (e *DummyTransformer) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
	copy(dst, src)

	return len(dst), len(src), nil
}
func (e *DummyTransformer) Reset() {}