megaframework.go

type Error struct {
	Code    string            `json:"code"`
	Message string            `json:"message"`
	Meta    map[string]string `json:"meta"`
}

type Handler[I, O comparable] func(ctx context.Context, i I) (O, *handlers.Error)

func NewHandler[I, O comparable](call Handler[I, O]) http.HandlerFunc {
	hasReqBody := unsafe.Sizeof(i) != 0
	hasResBody := unsafe.Sizeof(res) != 0

	return func(w http.ResponseWriter, r *http.Request) {
		var i I

		if hasReqBody {
			if err := json.NewDecoder(r.Body).Decode(&i); err != nil {
				w.WriteHeader(http.StatusBadRequest)
				json.NewEncoder(w).Encode(handlers.Error{
					Code:    "FAILED_DECODING",
					Message: err.Error(),
				})
				return
			}
		}

		res, callErr := call(r.Context(), i)
		if callErr != nil {
			w.WriteHeader(http.StatusBadRequest)
			json.NewEncoder(w).Encode(callErr)
			return
		}

		if hasResBody {
			if err := json.NewEncoder(w).Encode(res); err != nil {
				w.WriteHeader(http.StatusBadRequest)
				json.NewEncoder(w).Encode(handlers.Error{
					Code:    "FAILED_ENCODING",
					Message: err.Error(),
				})
			}
		}
	}
}