package apiserver

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

	"github.com/google/uuid"
	"github.com/gorilla/mux"
	"github.com/sirupsen/logrus"
)

const (
	ctxKeyRequestID = iota
)

type server struct {
	router *mux.Router
	logger *logrus.Logger
}

func (s *server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	s.router.ServeHTTP(w, r)
}

func newServer() *server {
	s := &server{
		router: mux.NewRouter(),
		logger: logrus.New(),
	}
	s.configureRouter()
	return s
}

func (s *server) configureRouter() {
	s.router.Use(s.setRequestID)
	s.router.Use(s.logRequest)
	s.router.HandleFunc("/", s.handleHome())
}

func (s *server) handleHome() http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		w.Write([]byte("ok"))
	}
}

func (s *server) logRequest(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		logger := logrus.WithFields(logrus.Fields{
			"remote_addr": r.RemoteAddr,
			"request_id":  r.Context().Value(ctxKeyRequestID),
		})
		logger.Infof("started %s %s", r.Method, r.RequestURI)
		start := time.Now()
		rw := newResponseWriter(w)
		rw.code = http.StatusOK
		next.ServeHTTP(rw, r)
		logger.Infof("completed with %d %s in %v", rw.code, http.StatusText(rw.code), time.Since(start))
	})
}

func (s *server) setRequestID(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		id := uuid.New().String()
		w.Header().Set("X-Request-ID", id)
		next.ServeHTTP(w, r.WithContext(context.WithValue(r.Context(), ctxKeyRequestID, id)))
	})
}

// Helpers
func (s *server) error(w http.ResponseWriter, r *http.Request, status int, err error) {
	s.respond(w, r, status, map[string]string{"error": err.Error()})
}

func (s *server) respond(w http.ResponseWriter, r *http.Request, status int, data interface{}) {
	w.WriteHeader(status)
	if data != nil {
		json.NewEncoder(w).Encode(data)
	}
}