RKIS/Task1/ViewModel/MainWindowsVM.cs

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;


namespace Task1.ViewModel
{
    class MainWindowsVM : BaseViewModel
    {
        private ObservableCollection<User> _users;
        private User _user;
        private RelayCommand _login;
        private RelayCommand _reg;


        public RelayCommand Reg
        {
            get
            {
                return _reg ??
                    (_reg = new RelayCommand((x) =>
                    {
                        new RegWindow().Show();
                        Helper.CloseWindowsAtType<MainWindow>();
                    }));
            }

        }
        public RelayCommand Login
        {
            get
            {
                return _login ?? (_login = new RelayCommand(
                _password =>
                {
                    User.Password = ((PasswordBox)_password).Password;//
                    User user = Users.FirstOrDefault(a => a.Login == User.Login && a.Password == User.Password);//Возвращает первый элемент, который равен условию
                    if (user != null)
                    {
                        User.AUser = user;
                        new UserWindow().Show();
                        Helper.CloseWindowsAtType<MainWindow>();
                    }
                    else
                    {
                        MessageBox.Show("Ввели пароль или логин не правильно");
                    }

                }));
            }
        }

        public User User
        {
            get => _user;
            set
            {
                _user = value;
                OnPropertyChanged();
            }
        }
        public ObservableCollection<User> Users
        {
            get => _users;
            set
            {
                _users = value;
                OnPropertyChanged();
            }
        }

        public MainWindowsVM()
        {
            _user = new User();
            TaskContext taskContext = new TaskContext();
            _users = new ObservableCollection<User>(taskContext.Users);

        }


    }
}