package main

import (
	"encoding/json"
	"log"
	"net/http"
	"regexp"
	"strconv"

	"git.huntm.net/wedding/server/guests"
)

type guestHandler struct {
	store guestStore
}

type guestStore interface {
	Get() (map[int]guests.Guest, error)
	Add(id int, guest guests.Guest) error
	Update(id int, guest guests.Guest) error
}

var (
	guestRe   = regexp.MustCompile(`^/guests/*$`)
	guestIdRe = regexp.MustCompile(`^/guests/([0-9]+)$`)
)

func newGuestHandler(s guestStore) *guestHandler {
	return &guestHandler{
		store: s,
	}
}

func (h *guestHandler) getGuests(w http.ResponseWriter, _ *http.Request) {
	guests, err := h.store.Get()
	if err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
	}

	jsonBytes, err := json.Marshal(guests)
	if err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
	}

	w.WriteHeader(http.StatusOK)
	w.Write(jsonBytes)
}

func (h *guestHandler) createGuest(w http.ResponseWriter, r *http.Request) {
	var guest guests.Guest
	err := json.NewDecoder(r.Body).Decode(&guest)
	defer r.Body.Close()
	if err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}

	err = h.store.Add(guest.Id, guest)
	if err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}

	w.WriteHeader(http.StatusOK)
}

func (h *guestHandler) updateGuest(w http.ResponseWriter, r *http.Request) {
	matches := guestIdRe.FindStringSubmatch(r.URL.Path)
	if len(matches) < 2 {
		http.Error(w, "No id found", http.StatusBadRequest)
	}

	var guest guests.Guest
	err := json.NewDecoder(r.Body).Decode(&guest)
	defer r.Body.Close()
	if err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
	}

	id, err := strconv.Atoi(matches[1])
	if err != nil {
		http.Error(w, "Cannot convert string to integer", http.StatusBadRequest)
	}

	err = h.store.Update(id, guest)
	if err != nil {
		http.Error(w, "Guest not found", http.StatusBadRequest)
	}
}

func (h *guestHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	switch {
	case r.Method == http.MethodGet && guestRe.MatchString(r.URL.Path):
		h.getGuests(w, r)
	case r.Method == http.MethodPost && guestRe.MatchString(r.URL.Path):
		h.createGuest(w, r)
	case r.Method == http.MethodPut && guestIdRe.MatchString(r.URL.Path):
		h.updateGuest(w, r)
	}
}

func main() {
	store := guests.NewMemStore()
	guestHandler := newGuestHandler(store)

	mux := http.NewServeMux()
	mux.Handle("/guests/", guestHandler)
	log.Fatal(http.ListenAndServe(":8080", mux))
}