package main

import (
	"encoding/json"
	"errors"
	"fmt"
	"net/http"
	"sync"

	"github.com/google/uuid"
)

type UserData struct {
	Username string `json:"username"`
	Nickname string `json:"nickname"`
	Admin    bool   `json:"admin"`
}

var (
	sessions = make(map[string]UserData)
	mu       sync.Mutex
)

func checkSessionID(r *http.Request) (string, error) {
	cookie, err := r.Cookie("session_id")
	if err != nil {
		return "", errors.New("keine session-ID")
	}
	return cookie.Value, nil
}

func getSessionID(w http.ResponseWriter, r *http.Request) string {
	sessionID, err := checkSessionID(r)
	if err != nil {
		newID := uuid.New().String()
		newCookie := http.Cookie{
			Name:  "session_id",
			Value: newID,
		}
		http.SetCookie(w, &newCookie)

		mu.Lock()
		sessions[newID] = UserData{}
		mu.Unlock()

		return newID
	}
	return sessionID
}

func signup(w http.ResponseWriter, r *http.Request) {
	sessionID := getSessionID(w, r)
	var user UserData
	err := json.NewDecoder(r.Body).Decode(&user)
	if err != nil {
		http.Error(w, "Daten konnten nicht verarbeitet werden.", http.StatusBadRequest)
		return
	}
	if user.Nickname == "" || user.Username == "" {
		http.Error(w, "Daten unvollständig.", http.StatusBadRequest)
		return
	}
	sessions[sessionID] = user
}

func whoami(w http.ResponseWriter, r *http.Request) {
	sessionID, err := checkSessionID(r)
	if err != nil {
		fmt.Fprintf(w, "Du bist noch niemand.")
	} else {
		user := sessions[sessionID]
		fmt.Fprintf(w, "Hallo %s!\n", user.Nickname)
		if user.Admin {
			fmt.Fprintln(w, "Du bist als Admin registriert.")
		} else {
			fmt.Fprintln(w, "Du bist nicht als Admin registriert.")
		}
	}
}

func main() {
	http.HandleFunc("/signup", signup)
	http.HandleFunc("/whoami", whoami)
	http.ListenAndServe("localhost:8080", nil)
}