kit/http/response.go

package http

import (
	"encoding/json"
	"fmt"
	"google.golang.org/genproto/googleapis/rpc/errdetails"
	"google.golang.org/grpc/status"
	"io"
	"net/http"
	"strings"
)

type Response struct {
	Code     int         `json:"code"`
	Reason   string      `json:"reason"`
	Message  string      `json:"message"`
	Metadata interface{} `json:"metadata"`

	w  http.ResponseWriter
	ct string
}

func NewResponse(w http.ResponseWriter) *Response {
	return &Response{
		w: w,
	}
}

func (r *Response) StatusCode(code int) *Response {
	r.Code = code
	return r
}

func (r *Response) ContentType(ct string) *Response {
	r.ct = ct
	return r
}

func (r *Response) getCode(defaultCode int) int {
	if r.Code != 0 {
		return r.Code
	}
	return defaultCode
}

func (r *Response) getContentType(defaultContentType string) string {
	if r.ct != "" {
		return r.ct
	}
	return defaultContentType
}

func (r *Response) Error(err error) {
	r.buildResponseBody(err)
	r.w.Header().Set("Content-Type", r.getContentType("application/json"))
	r.w.WriteHeader(r.getCode(http.StatusInternalServerError))

	body, err := json.Marshal(r)
	if err != nil {
		r.w.Write([]byte(err.Error()))
		return
	}
	r.w.Write(body)
}

func (r *Response) Json(body []byte) {
	r.w.Header().Set("Content-Type", r.getContentType("application/json"))
	r.w.WriteHeader(r.getCode(http.StatusOK))
	r.w.Write(body)
}

func (r *Response) Raw(rc io.Reader) {
	r.w.Header().Set("Content-Type", r.getContentType("application/octet-stream"))
	r.w.WriteHeader(r.getCode(http.StatusOK))
	io.Copy(r.w, rc)
}

func (r *Response) Redirect(url string) {
	r.w.Header().Set("Location", url)
	r.w.WriteHeader(r.getCode(http.StatusOK))
	r.w.Write([]byte(""))
}

func (r *Response) JsonOk(ok bool) {
	j, _ := json.Marshal(map[string]bool{
		"ok": ok,
	})
	r.Json(j)
}

func (r *Response) Abort() {
	r.ContentType("text/plain").Raw(strings.NewReader(http.StatusText(r.getCode(http.StatusInternalServerError))))
}

func (r *Response) Download(body io.Reader, filename string) {
	r.w.Header().Set("Content-Disposition", fmt.Sprintf("attachment; filename=%s", filename))
	r.Raw(body)
}

func (r *Response) buildResponseBody(err error) {
	s := status.Convert(err)
	pb := s.Proto()
	st := httpStatusFromGrpcCode(s.Code())
	if len(s.Details()) > 0 {
		for _, detail := range s.Details() {
			switch d := detail.(type) {
			case *errdetails.ErrorInfo:
				r.Reason = d.Reason
				r.Metadata = d.Metadata
				break
			}
		}
	} else {
		r.Reason = "UNKNOWN_ERROR"
	}
	r.Message = pb.GetMessage()
	r.Code = st
}