path: root/handler.go

package mux

import (
	"context"
	"encoding/json"
	"net/http"

	"neonxp.ru/go/mux/ctxlib"
)

// Handler API handler and returns standard http.HandlerFunc function
func Handler[RQ any, RS any](handler func(ctx context.Context, request *RQ) (RS, error)) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		req := new(RQ)
		ctx := r.Context()
		ctx = context.WithValue(ctx, ctxlib.Request, r)
		ctx = context.WithValue(ctx, ctxlib.Method, r.Method)
		ctx = context.WithValue(ctx, ctxlib.Headers, r.Header)

		switch r.Method {
		case http.MethodPost, http.MethodPatch, http.MethodDelete, http.MethodPut:
			if err := Bind(r, req); err != nil {
				w.WriteHeader(http.StatusBadRequest)
				_, _ = w.Write([]byte(err.Error()))
				return
			}
		}
		resp, err := handler(ctx, req)
		if err != nil {
			w.WriteHeader(http.StatusInternalServerError)
			_, _ = w.Write([]byte(err.Error()))
			return
		}

		statusCode := http.StatusOK
		contentType := "application/json"
		var body []byte

		if v, ok := (any)(resp).(WithContentType); ok {
			contentType = v.ContentType()
		}
		if v, ok := (any)(resp).(WithHTTPStatus); ok {
			statusCode = v.Status()
		}
		if v, ok := (any)(resp).(Renderer); ok {
			err = v.Render(ctx, w)
			return
		}

		body, err = json.Marshal(resp)
		if err != nil {
			w.WriteHeader(http.StatusInternalServerError)
			_, _ = w.Write([]byte(err.Error()))
			return
		}
		w.WriteHeader(statusCode)
		w.Header().Set("Content-Type", contentType)
		w.Write(body)
	}
}

type NilRequest struct{}

// WithContentType returns custom content type for response
type WithContentType interface {
	ContentType() string
}

// WithHTTPStatus returns custom status code
type WithHTTPStatus interface {
	Status() int
}

type RedirectResponse struct {
	Code     int
	Location string
}

func (rr *RedirectResponse) Render(ctx context.Context, w http.ResponseWriter) error {
	w.Header().Add("Location", rr.Location)
	w.WriteHeader(rr.Code)
	return nil
}

func Redirect(code int, location string) *RedirectResponse {
	return &RedirectResponse{
		Code:     code,
		Location: location,
	}
}