package http

import (
	"io/ioutil"
	"net/http"

	"github.com/go-kratos/kratos/v2/encoding"
	"github.com/go-kratos/kratos/v2/errors"
	"github.com/go-kratos/kratos/v2/internal/httputil"
	"github.com/go-kratos/kratos/v2/transport/http/binding"
)

// SupportPackageIsVersion1 These constants should not be referenced from any other code.
const SupportPackageIsVersion1 = true

// DecodeRequestFunc is decode request func.
type DecodeRequestFunc func(*http.Request, interface{}) error

// EncodeResponseFunc is encode response func.
type EncodeResponseFunc func(http.ResponseWriter, *http.Request, interface{}) error

// EncodeErrorFunc is encode error func.
type EncodeErrorFunc func(http.ResponseWriter, *http.Request, error)

// DefaultRequestDecoder decodes the request body to object.
func DefaultRequestDecoder(r *http.Request, v interface{}) error {
	if codec, ok := CodecForRequest(r, "Content-Type"); ok {
		data, err := ioutil.ReadAll(r.Body)
		if err != nil {
			return errors.BadRequest("CODEC", err.Error())
		}
		if err := codec.Unmarshal(data, v); err != nil {
			return errors.BadRequest("CODEC", err.Error())
		}
		return nil
	}
	if err := binding.BindForm(r, v); err != nil {
		return errors.BadRequest("CODEC", err.Error())
	}
	return nil
}

// DefaultResponseEncoder encodes the object to the HTTP response.
func DefaultResponseEncoder(w http.ResponseWriter, r *http.Request, v interface{}) error {
	codec, _ := CodecForRequest(r, "Accept")
	data, err := codec.Marshal(v)
	if err != nil {
		return err
	}
	w.Header().Set("Content-Type", httputil.ContentType(codec.Name()))
	if sc, ok := v.(interface {
		StatusCode() int
	}); ok {
		w.WriteHeader(sc.StatusCode())
	}
	_, _ = w.Write(data)
	return nil
}

// DefaultErrorEncoder encodes the error to the HTTP response.
func DefaultErrorEncoder(w http.ResponseWriter, r *http.Request, se error) {
	codec, _ := CodecForRequest(r, "Accept")
	body, err := codec.Marshal(se)
	if err != nil {
		w.WriteHeader(http.StatusInternalServerError)
		return
	}
	w.Header().Set("Content-Type", httputil.ContentType(codec.Name()))
	if sc, ok := se.(interface {
		StatusCode() int
	}); ok {
		w.WriteHeader(sc.StatusCode())
	} else {
		w.WriteHeader(http.StatusInternalServerError)
	}
	w.Write(body)
}

// CodecForRequest get encoding.Codec via http.Request
func CodecForRequest(r *http.Request, name string) (encoding.Codec, bool) {
	for _, accept := range r.Header[name] {
		codec := encoding.GetCodec(httputil.ContentSubtype(accept))
		if codec != nil {
			return codec, true
		}
	}
	return encoding.GetCodec("json"), false
}