EinmaleinsTrainer/ViewModels/MainViewModel.cs

using ReactiveUI;
using System.Reactive;
using EinmaleinsTrainer.Services;
using EinmaleinsTrainer.Models;
using System.Collections.ObjectModel;
using System.Linq;
using System.Reactive.Linq;
using System;

namespace EinmaleinsTrainer.ViewModels;

public class MainViewModel : ViewModelBase
{
    public ObservableCollection<int> SelectedRows { get; } = new();

    public event EventHandler? RedrawRequired;

    private bool _includeSquares;
    public bool IncludeSquares
    {
        get => _includeSquares;
        set => this.RaiseAndSetIfChanged(ref _includeSquares, value);
    }

    private bool _useTimer;
    public bool UseTimer
    {
        get => _useTimer;
        set
        {
            this.RaiseAndSetIfChanged(ref _useTimer, value);
            RedrawRequired?.Invoke(this, new());
        }
    }
    private int _secondsPerQuestion = 0;
    public int SecondsPerQuestion
    {
        get => _secondsPerQuestion;
        set
        {
            if (value < 2) value = 2;
            if (value > 120) value = 120;
            this.RaiseAndSetIfChanged(ref _secondsPerQuestion, value);
        }
    }
    public ReactiveCommand<Unit, QuizModel> StartCommand { get; }

    public MainViewModel()
    {
        StartCommand = ReactiveCommand.Create(
            execute: () =>
            {
                var generator = new QuestionGenerator();

                var questions = generator.Generate(SelectedRows.ToList(), IncludeSquares);

                return new QuizModel(){ Questions = questions, UseTimer = UseTimer, Seconds = SecondsPerQuestion};
            },
            canExecute: Observable.Return(true).ObserveOn(RxApp.MainThreadScheduler),
            outputScheduler: RxApp.MainThreadScheduler);
    }

    public void ToggleRow(int row, bool isChecked)
    {
        if (isChecked)
            SelectedRows.Add(row);
        else
            SelectedRows.Remove(row);
    }

    public bool IsRow1Checked
    {
        get => SelectedRows.Contains(1);
        set => ToggleRow(1, value);
    }

    public bool IsRow2Checked
    {
        get => SelectedRows.Contains(2);
        set => ToggleRow(2, value);
    }

    public bool IsRow3Checked
    {
        get => SelectedRows.Contains(3);
        set => ToggleRow(3, value);
    }

    public bool IsRow4Checked
    {
        get => SelectedRows.Contains(4);
        set => ToggleRow(4, value);
    }

    public bool IsRow5Checked
    {
        get => SelectedRows.Contains(5);
        set => ToggleRow(5, value);
    }

    public bool IsRow6Checked
    {
        get => SelectedRows.Contains(6);
        set => ToggleRow(6, value);
    }

    public bool IsRow7Checked
    {
        get => SelectedRows.Contains(7);
        set => ToggleRow(7, value);
    }

    public bool IsRow8Checked
    {
        get => SelectedRows.Contains(8);
        set => ToggleRow(8, value);
    }

    public bool IsRow9Checked
    {
        get => SelectedRows.Contains(9);
        set => ToggleRow(9, value);
    }

    public bool IsRow10Checked
    {
        get => SelectedRows.Contains(10);
        set => ToggleRow(10, value);
    }

    public void Init()
    {
        SelectedRows.Clear();
        IncludeSquares = false;
        UseTimer = false;
        SecondsPerQuestion = 30;
    }
}