package gifts

import (
	"encoding/json"
	"errors"
	"net/http"
	"strings"
)

type Handler struct {
	service *Service
}

func NewHandler(service *Service) *Handler {
	return &Handler{service: service}
}

func (h *Handler) Routes() http.Handler {
	mux := http.NewServeMux()
	mux.HandleFunc("GET /health", h.Health)
	mux.HandleFunc("GET /api/gifts/{slug}", h.GetGift)
	return mux
}

func (h *Handler) Health(w http.ResponseWriter, _ *http.Request) {
	writeJSON(w, http.StatusOK, map[string]string{"status": "ok"})
}

func (h *Handler) GetGift(w http.ResponseWriter, r *http.Request) {
	slug := strings.TrimSpace(r.PathValue("slug"))
	if !validSlug(slug) {
		writeError(w, http.StatusBadRequest, "invalid gift slug")
		return
	}

	gift, err := h.service.GetPublicGift(r.Context(), slug)
	if err != nil {
		if errors.Is(err, ErrNotFound) {
			writeError(w, http.StatusNotFound, "gift not found")
			return
		}
		writeError(w, http.StatusInternalServerError, "could not load gift")
		return
	}

	writeJSON(w, http.StatusOK, gift)
}

func validSlug(slug string) bool {
	if len(slug) == 0 || len(slug) > 100 {
		return false
	}
	for index, character := range slug {
		if (character >= 'a' && character <= 'z') ||
			(character >= 'A' && character <= 'Z') ||
			(character >= '0' && character <= '9') ||
			(character == '-' && index > 0 && index < len(slug)-1) {
			continue
		}
		return false
	}
	return true
}

func writeError(w http.ResponseWriter, status int, message string) {
	writeJSON(w, status, map[string]string{"error": message})
}

func writeJSON(w http.ResponseWriter, status int, value any) {
	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	w.WriteHeader(status)
	_ = json.NewEncoder(w).Encode(value)
}