Tango - Twine softwares

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Tango.BL.Entities;
using Tango.MachineStudio.Common.Notifications;
using SimpleValidator.Extensions;

namespace Tango.MachineStudio.DB.ViewModels
{
    public class UsersViewVM : DbTableViewModel<User>
    {
        public UsersViewVM(INotificationProvider notification) : base(notification)
        {
            SelectedRoles = new ObservableCollection<MultiComboVM<Role>>();
        }

        private ObservableCollection<MultiComboVM<Role>> _selectedRoles;
        public ObservableCollection<MultiComboVM<Role>> SelectedRoles
        {
            get { return _selectedRoles; }
            set { _selectedRoles = value; RaisePropertyChangedAuto(); }
        }

        protected override void OnEdit()
        {
            SelectedRoles = Adapter.Roles.Select(x => new MultiComboVM<Role>(x, () => RaisePropertyChanged(nameof(SelectedRoles)))).ToObservableCollection();

            foreach (var role in SelectedRoles)
            {
                if (SelectedEntity.UsersRoles.ToList().Exists(x => x.Role == role.Entity))
                {
                    role.IsSelected = true;
                }
            }

            base.OnEdit();
        }

        protected override void OnAdd()
        {
            SelectedRoles = Adapter.Roles.Select(x => new MultiComboVM<Role>(x, () => RaisePropertyChanged(nameof(SelectedRoles)))).ToObservableCollection();

            base.OnAdd();
        }

        protected override void OnBeforeEntitySave(DialogOpenMode mode, User user)
        {
            base.OnBeforeEntitySave(mode, user);

            Adapter.Context.UsersRoles.RemoveRange(user.UsersRoles);

            foreach (var role in SelectedRoles)
            {
                if (role.IsSelected)
                {
                    user.UsersRoles.Add(new UsersRole()
                    {
                        Role = role.Entity,
                        User = user,
                        RoleGuid = role.Entity.Guid,
                        UserGuid = user.Guid
                    });
                }
            }
        }

        protected override void OnValidating()
        {
            base.OnValidating();

            if (EditEntity.Email != null)
            {
                if (Adapter.Users.ToList().Exists(x => x.Guid != EditEntity.Guid && x.Email.ToLower() == EditEntity.Email.ToLower()))
                {
                    ValidationErrors.Add("Email already exist");
                }
            }

            if (!EditEntity.Email.IsEmail())
            {
                ValidationErrors.Add("Email address is invalid");
            }

            if (!EditEntity.Password.IsMinLength(4))
            {
                ValidationErrors.Add("Password must have at least 4 characters");
            }
        }
    }
}