using domain.UseCase;
using Presence.Desktop.Models;
using Presence.Desktop.Helpers;
using System;
using System.Reactive.Linq;
using System.Reactive;
using System.Linq;
using ReactiveUI;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Diagnostics;
using System.IO;
using System.Windows.Input;
using System.Threading.Tasks;
using Avalonia.Controls.Selection;
using domain.Request;
using System.Text;

namespace Presence.Desktop.ViewModels
{
    public class MainWindowViewModel : ViewModelBase
    {
        private readonly IGroupUseCase _groupService;
        private List<GroupPresenter> groupPresenters = new List<GroupPresenter>();
        private ObservableCollection<GroupPresenter> _groups;
        public ObservableCollection<GroupPresenter> Groups
        {
            get => _groups;
            set => this.RaiseAndSetIfChanged(ref _groups, value);
        }

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

        private ObservableCollection<StudentPresenter> _students;
        public ObservableCollection<StudentPresenter> Students
        {
            get => _students;
            set => this.RaiseAndSetIfChanged(ref _students, value);
        }

        public Interaction<Unit, string?> ShowOpenFileDialog;
        private string? _selectedFile;
        public string? SelectedFile
        {
            get => _selectedFile;
            set => this.RaiseAndSetIfChanged(ref _selectedFile, value);
        }

        private bool _MultipleSelected = false;
        public bool MultipleSelected { get => _MultipleSelected; set => this.RaiseAndSetIfChanged(ref _MultipleSelected, value); }
        public SelectionModel<StudentPresenter> Selection { get; }

        private string _selectedSort = "Релевантность";

        public string SelectedSort
        {
            get => _selectedSort;
            set => this.RaiseAndSetIfChanged(ref _selectedSort, value);
        }

        public List<string> Sorting { get; set; } =
        [
            "Релевантность",
            "А-Я",
            "Я-А"
        ];

        public ICommand OpenFileDialog { get; }

        public ICommand EditCommand { get; }
        public ICommand DeleteCommand { get; }
        public ICommand DeleteSelectedCommand { get; }
        public ICommand DeleteAllCommand { get; }

        public MainWindowViewModel()
        {
            _groupService = null;
            _groups = new();
            _students = new();
            OpenFileDialog = ReactiveCommand.CreateFromTask(SelectFile);
        }

        public MainWindowViewModel(IGroupUseCase gService)
        {
            _groupService = gService;
            ShowOpenFileDialog = new Interaction<Unit, string?>();
            OpenFileDialog = ReactiveCommand.CreateFromTask(SelectFile);

            _students = new();

            this.WhenAnyValue(vm => vm.SelectedGroupItem,
                    x => x.SelectedSort)
                .Subscribe(_ =>
                {
                    RefreshGroups();
                    SetStudents(SelectedSort);
                });

            Selection = new SelectionModel<StudentPresenter>();
            Selection.SingleSelect = false;
            Selection.SelectionChanged += (sender, args) =>
            {
                MultipleSelected = Selection.SelectedItems.Count > 1;
            };

            DeleteCommand = ReactiveCommand.Create(DeleteStudent);
            DeleteSelectedCommand = ReactiveCommand.Create(DeleteStudent);
            DeleteAllCommand = ReactiveCommand.Create(DeleteAllStudents);

        }

        private void RefreshGroups()
        {
            groupPresenters.Clear();
            foreach (var item in _groupService.GetGroupsWithStudents())
            {
                GroupPresenter groupPresenter = new GroupPresenter
                {
                    Id = item.Id,
                    Name = item.Name,
                    students = item.Users?.Select(u => new StudentPresenter
                    {
                        Id = u.Id,
                        FirstName = u.FirstName,
                        LastName = u.LastName,
                        Patronymic = u.Patronymic,
                        Group = new GroupPresenter
                        {
                            Id = item.Id,
                            Name = item.Name
                        }
                    }).ToList()
                };
                groupPresenters.Add(groupPresenter);
            }

            _groups = new(groupPresenters);
        }

        private void SetStudents(string selectedSort)
        {
            if (SelectedGroupItem == null) return;
            if (SelectedGroupItem.students == null) return;

            Students.Clear();

            List<StudentPresenter> students = new(_groupService.GetGroupsWithStudents()
                .Single(g => g.Id == SelectedGroupItem.Id)
                .Users
                .Select(u => new StudentPresenter
                {
                    Id = u.Id,
                    FirstName = u.FirstName,
                    LastName = u.LastName,
                    Patronymic = u.Patronymic,
                    Group = new GroupPresenter()
                    {
                        Id = SelectedGroupItem.Id,
                        Name = SelectedGroupItem.Name
                    }
                })
            );

            students = selectedSort switch
            {
                "Релевантность" => students.OrderBy(s => s.Id).ToList(),
                "А-Я" => students.OrderBy(s => s.LastName).ToList(),
                "Я-А" => students.OrderByDescending(s => s.LastName).ToList(),
                _ => students
            };

            foreach (var student in students)
                Students.Add(student);
        }

        private async Task SelectFile()
        {
            try
            {
                SelectedFile = await ShowOpenFileDialog.Handle(Unit.Default);
            }
            catch (Exception)
            {
                return;
            }

            if (SelectedGroupItem == null) return;

            try
            {
                var studentsToAdd = CsvHelper.ReadCsvStudents(SelectedFile);

                if (studentsToAdd.Any())
                {
                    _groupService.AddStudentsToGroup(SelectedGroupItem.Id, studentsToAdd);

                    foreach (var studentRequest in studentsToAdd)
                    {
                        var studentPresenter = new StudentPresenter
                        {
                            LastName = studentRequest.LastName,
                            FirstName = studentRequest.FirstName,
                            Patronymic = studentRequest.Patronymic,
                            Group = SelectedGroupItem
                        };

                        SelectedGroupItem.students.Add(studentPresenter);
                        Students.Add(studentPresenter);
                    }

                    RefreshGroups();
                    SetStudents(SelectedSort);
                }
            }
            catch (Exception ex)
            {
                Debug.WriteLine(ex.Message);
            }

        }

        private void DeleteStudent()
        {
            if (Selection.SelectedItems == null || Selection.SelectedItems.Count == 0) return;

            var studentIds = Selection.SelectedItems.Select(s => s.Id).ToList();
            _groupService.RemoveStudentsFromGroupByIds(SelectedGroupItem.Id, studentIds);

            foreach (var student in Selection.SelectedItems.ToList())
            {
                SelectedGroupItem.students.Remove(student);
                Students.Remove(student);
            }

            SetStudents(SelectedSort);
            RefreshGroups();
        }

        private void DeleteAllStudents()
        {
            if (Students.Count == 0 && SelectedGroupItem == null) return;

            _groupService.RemoveStudentsFromGroup(SelectedGroupItem.Id);

            SelectedGroupItem.students.Clear();
            Students.Clear();

            RefreshGroups();
            SetStudents(SelectedSort);

        }

    }
}