package transformers

import (
	"context"
	"encoding/xml"
	"io"
	"net/textproto"
	"reflect"

	"gitee.com/go-genie/httptransport/httpx"
	typesutil "gitee.com/go-genie/xx/types"
)

func init() {
	TransformerMgrDefault.Register(&XMLTransformer{})
}

type XMLTransformer struct {
}

func (XMLTransformer) Names() []string {
	return []string{"application/xml", "xml"}
}

func (t *XMLTransformer) String() string {
	return t.Names()[0]
}

func (XMLTransformer) NamedByTag() string {
	return "xml"
}

func (XMLTransformer) New(context.Context, typesutil.Type) (Transformer, error) {
	return &XMLTransformer{}, nil
}

func (t *XMLTransformer) EncodeTo(ctx context.Context, w io.Writer, v interface{}) error {
	if rv, ok := v.(reflect.Value); ok {
		v = rv.Interface()
	}

	httpx.MaybeWriteHeader(
		ctx, w, t.String(), map[string]string{
			"charset": "utf-8",
		},
	)

	return xml.NewEncoder(w).Encode(v)
}

func (XMLTransformer) DecodeFrom(
	ctx context.Context,
	r io.Reader,
	v interface{},
	headers ...textproto.MIMEHeader,
) error {
	if rv, ok := v.(reflect.Value); ok {
		if rv.Kind() != reflect.Ptr && rv.CanAddr() {
			rv = rv.Addr()
		}
		v = rv.Interface()
	}
	d := xml.NewDecoder(r)
	err := d.Decode(v)
	if err != nil {
		// todo resolve field path by InputOffset()
		return err
	}
	return nil
}