package xmlutils

import (
	"bytes"
	"encoding/base64"
	"encoding/xml"
	"io"
)

type nopCloseWriter struct {
	io.Writer
}

func (b nopCloseWriter) Close() error {
	return nil
}

const (
	nonXML  = "nonXML"
	typeXML = "application/xml"
)

func DetectXML(data []byte) string {
	token, err := xml.NewDecoder(bytes.NewReader(data)).RawToken()
	if err != nil {
		return nonXML
	}

	switch token.(type) {
	case xml.StartElement, xml.ProcInst:
		return typeXML
	}
	return nonXML
}

func ChooseWriter(dataType string, bodyWriter io.Writer) io.WriteCloser {
	if dataType == typeXML {
		return nopCloseWriter{bodyWriter}
	}
	return base64.NewEncoder(base64.StdEncoding, bodyWriter)
}

func ChooseReader(dataType string, bodyReader io.Reader) io.Reader {
	if dataType == typeXML {
		return bodyReader
	}
	return base64.NewDecoder(base64.StdEncoding, bodyReader)
}