package main

import (
	"flag"
	"fmt"
	"html/template"
	"log"
	"net/http"
	"sync"
)

// User struktura za uporabniške podatke
type User struct {
	ID       int
	Username string
	Password string
	Email    string
	FullName string
}

// In-memory shranjevanje uporabnikov
var (
	users    = make(map[string]*User)
	usersMux = &sync.RWMutex{}
	lastID   = 0
)

// Template cache
var templates *template.Template

func init() {
	// Privzeti uporabniki
	addUser("jnovak", "secure123", "janez.novak@securebank.si", "Janez Novak")
	addUser("mpetric", "banking456", "maja.petric@securebank.si", "Maja Petrič")
}

func addUser(username, password, email, fullName string) {
	usersMux.Lock()
	defer usersMux.Unlock()
	lastID++
	users[username] = &User{
		ID:       lastID,
		Username: username,
		Password: password,
		Email:    email,
		FullName: fullName,
	}
}

func main() {
	// Nastavimo port preko command line argumenta
	var port = flag.String("port", "8080", "Port na katerem se bo zagnal server")
	flag.Parse()

	// Naložimo HTML predloge
	var err error
	templates, err = template.ParseGlob("templates/*.html")
	if err != nil {
		log.Fatal("Napaka pri nalaganju predlog:", err)
	}

	// Statične datoteke (CSS)
	http.Handle("/static/", http.StripPrefix("/static/", http.FileServer(http.Dir("static/"))))

	// Routes
	http.HandleFunc("/", homeHandler)
	http.HandleFunc("/register", registerHandler)
	http.HandleFunc("/login", loginHandler)
	http.HandleFunc("/dashboard", dashboardHandler)
	http.HandleFunc("/logout", logoutHandler)

	// Zagon strežnika
	fmt.Printf("SecureBank aplikacija se zaganja na portu %s\n", *port)
	fmt.Printf("Dostop: http://localhost:%s\n", *port)

	serverAddr := ":" + *port
	log.Fatal(http.ListenAndServe(serverAddr, nil))
}

func homeHandler(w http.ResponseWriter, r *http.Request) {
	templates.ExecuteTemplate(w, "home.html", nil)
}

func registerHandler(w http.ResponseWriter, r *http.Request) {
	if r.Method == "GET" {
		templates.ExecuteTemplate(w, "register.html", nil)
		return
	}

	if r.Method == "POST" {
		username := r.FormValue("username")
		password := r.FormValue("password")
		email := r.FormValue("email")
		fullName := r.FormValue("fullName")

		//Validacija
		if username == "" || password == "" || email == "" || fullName == "" {
			templates.ExecuteTemplate(w, "register.html", map[string]string{
				"Error": "Vsa polja so obvezna!",
			})
			return
		}

		// Preverimo če uporabnik že obstaja
		usersMux.RLock()
		_, exists := users[username]
		usersMux.RUnlock()

		if exists {
			templates.ExecuteTemplate(w, "register.html", map[string]string{
				"Error": "Uporabniško ime že obstaja!",
			})
			return
		}

		// Dodamo novega uporabnika
		addUser(username, password, email, fullName)

		// Preusmeri na prijavo
		http.Redirect(w, r, "/login?registered=1", http.StatusSeeOther)
		return
	}
}

func loginHandler(w http.ResponseWriter, r *http.Request) {
	if r.Method == "GET" {
		data := map[string]string{}
		if r.URL.Query().Get("registered") == "1" {
			data["Success"] = "Registracija je bila uspešna! Sedaj se lahko prijavite."
		}
		templates.ExecuteTemplate(w, "login.html", data)
		return
	}

	if r.Method == "POST" {
		username := r.FormValue("username")
		password := r.FormValue("password")

		// Preverimo podatke
		usersMux.RLock()
		user, exists := users[username]
		usersMux.RUnlock()

		if !exists || user.Password != password {
			templates.ExecuteTemplate(w, "login.html", map[string]string{
				"Error": "Napačno uporabniško ime ali geslo!",
			})
			return
		}

		// Uspešna prijava - preusmeri na dashboard
		// POZOR: Brez session management za demo!
		http.Redirect(w, r, "/dashboard?user="+username, http.StatusSeeOther)
		return
	}
}

func dashboardHandler(w http.ResponseWriter, r *http.Request) {
	username := r.URL.Query().Get("user")
	if username == "" {
		http.Redirect(w, r, "/login", http.StatusSeeOther)
		return
	}

	usersMux.RLock()
	user, exists := users[username]
	usersMux.RUnlock()

	if !exists {
		http.Redirect(w, r, "/login", http.StatusSeeOther)
		return
	}

	// Simuliramo "bančne" podatke
	accounts := []map[string]interface{}{
		{
			"Name":    "Glavni račun",
			"Number":  "SI56 1234 5678 9012 345",
			"Balance": "€2,456.78",
		},
		{
			"Name":    "Varčevalni račun",
			"Number":  "SI56 1234 5678 9012 999",
			"Balance": "€15,230.45",
		},
	}

	data := map[string]interface{}{
		"User":     user,
		"Accounts": accounts,
	}

	templates.ExecuteTemplate(w, "dashboard.html", data)
}

func logoutHandler(w http.ResponseWriter, r *http.Request) {
	http.Redirect(w, r, "/", http.StatusSeeOther)
}