presence/Presence.Desktop/ViewModels/GroupViewModel.cs

using Demo.Domain.UseCase;
using DynamicData;
using DynamicData.Binding;
using Presence.Desktop.Models;
using ReactiveUI;
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Reactive;
using System.Reactive.Linq;
using Tmds.DBus.Protocol;

namespace Presence.Desktop.ViewModels
{
    public class GroupViewModel : ViewModelBase, IRoutableViewModel
    {
        private readonly List<GroupPresenter> _groupPresentersDataSource = new List<GroupPresenter>();
        private ObservableCollection<GroupPresenter> _groups;
        public ObservableCollection<GroupPresenter> Groups => _groups;
        private GroupPresenter? _selectedGroupItem;

        public ReactiveCommand<Unit, Unit> ButtonRemoveUsersByGroup {get; }
        // public ReactiveCommand<Unit, Unit> ButtonAddUser { get; }

        public GroupPresenter? SelectedGroupItem 
        { 
            get => _selectedGroupItem; 
            set => this.RaiseAndSetIfChanged(ref _selectedGroupItem, value); 
        }


        public ObservableCollection<UserPresenter> Users { get => _users;}
        public ObservableCollection<UserPresenter> _users;
        public GroupViewModel(IGroupUseCase groupUseCase, IUserUseCase userUseCase)
        {
            foreach (var item in groupUseCase.GetAllGroupsWithUsers())
            {
                GroupPresenter groupPresenter = new GroupPresenter
                {
                    Id = item.ID,
                    Name = item.Name,
                    users = item.Users?.Select(user => new UserPresenter
                    {
                        Name = user.FIO,
                        Guid = user.Guid,
                        Group = new GroupPresenter { Id = item.ID, Name = item.Name }
                    }
                    ).ToList()
                };
                _groupPresentersDataSource.Add(groupPresenter);
            }

            _groups = new ObservableCollection<GroupPresenter>(_groupPresentersDataSource);
            
            _users = new ObservableCollection<UserPresenter>();

            this.WhenAnyValue(vm => vm.SelectedGroupItem)
                .Subscribe(_ => SetUsers());
            
            ButtonRemoveUsersByGroup = ReactiveCommand.Create(() => RemoveUsersByGroup(groupUseCase));
        }

        private void SetUsers()
        {
            if(SelectedGroupItem == null) return;
            if (SelectedGroupItem.users == null) return;
            Users.Clear();
            foreach (var item in SelectedGroupItem.users)
            {
                Users.Add(item);
            }
        }

        private void RemoveUsersByGroup(IGroupUseCase groupUseCase)
        {
            if (_selectedGroupItem != null){
                groupUseCase.RemoveUsersByGroup(_selectedGroupItem.Id);
            }

            var usersToRemove = Users.Where(user => user.Group.Id == _selectedGroupItem.Id).ToList();
            foreach (var user in usersToRemove)
            {
                Users.Remove(user);
            }
        }

        public string? UrlPathSegment { get; }
        public IScreen HostScreen { get; }
    }
}