laatzen/Common/OMNIPruefung/ViewModels/OptionVM.cs

namespace OMNIPruefung.ViewModels
{
    using OMNIPruefung.ViewModels.Base;

    using System;
    using System.Collections.ObjectModel;
    using System.ComponentModel;
    using System.Windows.Input;

    public class OptionVM : NodeVM
    {
        const int INDENT = 13;

        private readonly NodeVM parent;

        public OptionVM(NodeVM parent)
        {
            this.parent = parent;
            this.parent.PropertyChanged += this.Parent_PropertyChanged;
        }

        public event Action OptionSelected;

        private int indent = INDENT;
        public int Indent
        {
            get => this.indent;
            set
            {
                this.indent = value;

                this.NotifyPropertyChanged(nameof(this.Indent));
            }
        }

        public override string Header 
        { 
            get => this.parent?.Header; 
            set => this.NotifyPropertyChanged(this.Header); 
        }

        private bool expanded;
        public bool IsExpanded
        {
            get => this.expanded;
            set
            {
                this.expanded = value;

                this.NotifyPropertyChanged(nameof(this.IsExpanded));
            }
        }

        private bool selected;
        public bool IsSelected
        {
            get => this.selected;
            set
            {
                if (!this.selected && value)
                {
                    this.OptionSelected?.Invoke();
                }

                this.selected = value;

                this.NotifyPropertyChanged(nameof(this.IsSelected));
            }
        }

        public ICommand ToggleNodes => new Command(() =>
        {
            this.IsExpanded = !this.IsExpanded;
        });

        public ObservableCollection<OptionVM> Options { get; }
            = new ObservableCollection<OptionVM>();

        internal void Add(OptionVM option)
        {
            App.Invoke(() => this.Options.Add(option));
        }

        internal void Clear()
        {
            App.Invoke(() => this.Options.Clear());
        }

        internal void SetIndentation(int indent = INDENT)
        {
            this.indent = indent;

            foreach (var option in this.Options)
            {
                option.SetIndentation(this.indent + INDENT);
            }
        }

        protected virtual void Parent_PropertyChanged(object sender, PropertyChangedEventArgs args)
        {
            this.NotifyPropertyChanged(nameof(this.Header));
            this.NotifyPropertyChanged(nameof(this.Indent));
            this.NotifyPropertyChanged(nameof(this.IsExpanded));
            this.NotifyPropertyChanged(nameof(this.IsSelected));
        }
    }
}