country-geo-locations/api/v1/server.go

package api_v1

import (
	"context"
	"net/http"

	"git.ar21.de/tom/country-geo-locations/pkg/geoloc"
	"github.com/go-chi/chi/v5"
	"github.com/go-chi/render"
)

func ApiRouter() chi.Router {
	r := chi.NewRouter()

	r.Use(render.SetContentType(render.ContentTypeJSON))

	r.Get("/ping", func(w http.ResponseWriter, r *http.Request) {
		w.Write([]byte("pong"))
	})

	r.Route("/location", func(r chi.Router) {
		r.Route("/{ipAddress}", func(r chi.Router) {
			r.Use(searchIPCtx)
			r.Get("/", searchIP)
		})
	})

	return r
}

func searchIP(w http.ResponseWriter, r *http.Request) {
	ipinfo := r.Context().Value(keyIPInfo).(*geoloc.IPInfo)

	if err := render.Render(w, r, newIPInfoResponse(ipinfo)); err != nil {
		render.Render(w, r, errRender(err))
		return
	}
}

func searchIPCtx(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		var ipinfo *geoloc.IPInfo
		var ipnetnum uint
		var err error

		if ipAddress := chi.URLParam(r, "ipAddress"); ipAddress != "" {
			ipnetnum, err = geoloc.GetIPInfo(ipAddress)
			if err != nil {
				render.Render(w, r, errInvalidRequest(err))
				return
			}
			for {
				ipinfo, err = geoloc.SearchIPNet(ipnetnum)
				if err != nil {
					render.Render(w, r, errNotFound)
					return
				}
				if ipinfo != nil {
					break
				}
				ipnetnum = ipnetnum - 8
			}
		}
		ctx := context.WithValue(r.Context(), keyIPInfo, ipinfo)
		next.ServeHTTP(w, r.WithContext(ctx))
	})
}

type errResponse struct {
	Err            error `json:"-"`
	HTTPStatusCode int   `json:"-"`

	StatusText string `json:"status"`
	AppCode    int64  `json:"code,omitempty"`
	ErrorText  string `json:"error,omitempty"`
}

func (e *errResponse) Render(w http.ResponseWriter, r *http.Request) error {
	render.Status(r, e.HTTPStatusCode)
	return nil
}

func errInvalidRequest(err error) render.Renderer {
	return &errResponse{
		Err:            err,
		HTTPStatusCode: 400,
		StatusText:     "Invalid request",
		ErrorText:      err.Error(),
	}
}

func errRender(err error) render.Renderer {
	return &errResponse{
		Err:            err,
		HTTPStatusCode: 422,
		StatusText:     "Error rendering response",
		ErrorText:      err.Error(),
	}
}

var errNotFound = &errResponse{HTTPStatusCode: 404, StatusText: "Resource not found"}

type key int

const keyIPInfo key = iota

type ipInfoResponse struct {
	*geoloc.IPInfo

	Elapsed int64 `json:"elapsed"`
}

func (ir *ipInfoResponse) Render(w http.ResponseWriter, r *http.Request) error {
	ir.Elapsed = 10
	return nil
}

func newIPInfoResponse(ipinfo *geoloc.IPInfo) *ipInfoResponse {
	return &ipInfoResponse{IPInfo: ipinfo}
}