package api

import (
	"encoding/json"
	"errors"
	"net/http"
	"net/mail"

	"github.com/alchemistkay/guestguard/internal/domain"
	"github.com/alchemistkay/guestguard/internal/storage"
)

type userHandler struct {
	repo *storage.UserRepo
}

type upsertUserRequest struct {
	Email string `json:"email"`
	Name  string `json:"name"`
}

// POST /users — idempotent: returns the existing user if the email already
// exists, creates one otherwise. This keeps the demo flow simple without
// requiring real auth.
func (h *userHandler) upsert(w http.ResponseWriter, r *http.Request) {
	var req upsertUserRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid json")
		return
	}
	if _, err := mail.ParseAddress(req.Email); err != nil {
		writeError(w, http.StatusBadRequest, "email is invalid")
		return
	}
	if req.Name == "" {
		writeError(w, http.StatusBadRequest, "name is required")
		return
	}

	u, err := h.repo.Create(r.Context(), req.Email, req.Name)
	if err == nil {
		writeJSON(w, http.StatusCreated, u)
		return
	}
	if errors.Is(err, domain.ErrEmailTaken) {
		existing, getErr := h.repo.GetByEmail(r.Context(), req.Email)
		if getErr != nil {
			writeError(w, http.StatusInternalServerError, "failed to load user")
			return
		}
		writeJSON(w, http.StatusOK, existing)
		return
	}
	writeError(w, http.StatusInternalServerError, "failed to create user")
}