presence/Presence.Desktop/ViewModels/GroupViewModel.cs

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 System.Threading.Tasks;
using Avalonia.Controls;
using System.IO;
using presence_client.ApiClients.Interfaces;
using Demo.Domain.Models;
using Microsoft.Extensions.DependencyInjection;
using Presence.Desktop.DI;

namespace Presence.Desktop.ViewModels
{
    public class GroupViewModel : ViewModelBase, IRoutableViewModel
    {
        private readonly IGroupApiClient _groupApiClient;
        private readonly IUserApiClient _userApiClient;
        
        private readonly List<GroupPresenter> _groupPresentersDataSource = new();
        private ObservableCollection<GroupPresenter> _groups;
        private ObservableCollection<UserPresenter> _users;
        private string? _newFIO;
        private GroupPresenter? _selectedGroupItem;
        private UserPresenter? _selectedUser;
        private string? _selectedSecondItem;

        public ObservableCollection<GroupPresenter> Groups => _groups;
        public ObservableCollection<UserPresenter> Users => _users;
        
        public ObservableCollection<string> SecondComboBoxItems { get; } = 
            new ObservableCollection<string> { "no sort", "name sort", "name sort rev" };

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

        public UserPresenter? SelectedUser
        {
            get => _selectedUser;
            set => this.RaiseAndSetIfChanged(ref _selectedUser, value);
        }

        public string? SelectedSecondItem
        {
            get => _selectedSecondItem;
            set => this.RaiseAndSetIfChanged(ref _selectedSecondItem, value);
        }

        public string? NewFIO
        {
            get => _newFIO;
            set => this.RaiseAndSetIfChanged(ref _newFIO, value);
        }

        public ReactiveCommand<Unit, Unit> DeleteUsersByGroupCommand { get; }
        public ReactiveCommand<Unit, Unit> ImportStudentsCommand { get; }
        public ReactiveCommand<UserPresenter, Unit> DeleteUserCommand { get; }
        public ReactiveCommand<UserPresenter, Unit> UpdateUserFIOCommand { get; }
        public ReactiveCommand<Unit, Unit> GoBackCommand { get; }

        public GroupViewModel(IGroupApiClient groupApiClient, IUserApiClient userApiClient, IScreen hostScreen)
        {
            _groupApiClient = groupApiClient;
            _userApiClient = userApiClient;
            
            _groups = new ObservableCollection<GroupPresenter>();
            _users = new ObservableCollection<UserPresenter>();
            
            DeleteUsersByGroupCommand = ReactiveCommand.CreateFromTask(DeleteUsersByGroupAsync);
            ImportStudentsCommand = ReactiveCommand.CreateFromTask(ImportStudentsAsync);
            DeleteUserCommand = ReactiveCommand.CreateFromTask<UserPresenter>(DeleteUserAsync);
            UpdateUserFIOCommand = ReactiveCommand.CreateFromTask<UserPresenter>(UpdateUserFIOAsync);
            HostScreen = hostScreen;
            
            GoBackCommand = ReactiveCommand.Create(() =>
            {
                HostScreen.Router.Navigate.Execute(new StartViewModel(HostScreen));
            });
            
            SelectedSecondItem = SecondComboBoxItems.First();
            
            this.WhenAnyValue(vm => vm.SelectedGroupItem)
                .WhereNotNull()
                .Subscribe(_ => SetUsers());
            
            this.WhenAnyValue(vm => vm.SelectedSecondItem)
                .WhereNotNull()
                .Subscribe(_ => SetUsers());
            
            LoadDataAsync().ConfigureAwait(false);
        }

        private async Task LoadDataAsync()
        {
            await RefreshGroupsAsync();
        }

        private async Task RefreshGroupsAsync()
        {
            var groupsFromApi = await _groupApiClient.GetGroupsWithUsersAsync();
            _groupPresentersDataSource.Clear();
        
            foreach (var group in groupsFromApi)
            {
                var groupPresenter = new GroupPresenter
                {
                    Id = group.ID,
                    Name = group.Name,
                    users = group.Users?.Select(user => new UserPresenter
                    {
                        Name = user.FIO,
                        Guid = user.Guid,
                        Group = new GroupPresenter { Id = group.ID, Name = group.Name }
                    }).ToList() ?? new List<UserPresenter>()
                };
                _groupPresentersDataSource.Add(groupPresenter);
            }

            _groups = new ObservableCollection<GroupPresenter>(_groupPresentersDataSource);
            this.RaisePropertyChanged(nameof(Groups));
                
            if (_groups.Any())
            {
                SelectedGroupItem = _groups.First();
            }
        }

        private void SetUsers()
        {
            Users.Clear();

            if (SelectedGroupItem == null) 
            {
                this.RaisePropertyChanged(nameof(Users));
                return;
            }

            var group = _groupPresentersDataSource.FirstOrDefault(it => it.Id == SelectedGroupItem.Id);
            if (group?.users == null) 
            {
                this.RaisePropertyChanged(nameof(Users));
                return;
            }

            var sortedUsers = SelectedSecondItem switch
            {
                "name sort" => group.users.OrderBy(user => user.Name),
                "name sort rev" => group.users.OrderByDescending(user => user.Name),
                _ => group.users
            };

            foreach (var user in sortedUsers)
            {
                Users.Add(user);
            }
    
            this.RaisePropertyChanged(nameof(Users));
        }

        private async Task ImportStudentsAsync()
        {
            if (SelectedGroupItem == null || SelectedGroupItem.Id == null) return;

            var openFileDialog = new OpenFileDialog
            {
                Filters = new List<FileDialogFilter>
                {
                    new() { Name = "CSV Files", Extensions = { "csv" } }
                },
                AllowMultiple = false
            };

            var result = await openFileDialog.ShowAsync(new Window());
            if (result?.Length > 0)
            {
                var filePath = result[0];
                var lines = File.ReadAllLines(filePath);
                var createdUsers = new List<ImportStudents>();

                foreach (var line in lines.Skip(1))
                {
                    var columns = line.Split(';');
                    if (columns.Length < 2) continue;

                    var fio = columns[0];
                    var groupName = columns[1];
                    var newUser = new ImportStudents
                    {
                        fio = fio,
                        groupName = groupName
                    };
                    createdUsers.Add(newUser);
                }

                foreach (var user in createdUsers)
                {
                    var success = await _userApiClient.CreateUser(user.fio, user.groupName);
                    if (!success)
                    {
                        return;
                    }
                }
                
                await RefreshGroupsAsync();
            }
        }

        private async Task DeleteUsersByGroupAsync()
        {
            if (SelectedGroupItem == null) return;

            var groupId = SelectedGroupItem.Id;
            var success = await _userApiClient.DeleteUsersByGroupIdAsync(groupId);
            
            if (success)
            {
                await RefreshGroupsAsync();
            }
        }

        private async Task DeleteUserAsync(UserPresenter user)
        {
            if (user == null) return;

            var success = await _userApiClient.DeleteUserAsync(user.Guid);
            if (success)
            {
                await RefreshGroupsAsync();
            }
        }

        private async Task UpdateUserFIOAsync(UserPresenter user)
        {
            if (user == null || string.IsNullOrWhiteSpace(NewFIO))
            {
                return;
            }

            var success = await _userApiClient.UpdateUserFioAsync(user.Guid, NewFIO);
            if (success)
            {
                user.Name = NewFIO; 
                NewFIO = string.Empty;
                this.RaisePropertyChanged(nameof(Users));
                await RefreshGroupsAsync();
            }
        }

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