using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Runtime.CompilerServices;
using XSDVisualiser.Models;

namespace XSDVisualiser.Desktop.ViewModels
{
    public class MainWindowViewModel(SchemaModel model) : INotifyPropertyChanged
    {
        private SchemaModel _model = model ?? throw new ArgumentNullException(nameof(model));
        private SchemaNode? _selectedRootElement;
        private SchemaNode? _selectedNode;

        public event PropertyChangedEventHandler? PropertyChanged;

        private void OnPropertyChanged([CallerMemberName] string? name = null)
        {
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));
        }

        public SchemaModel Model
        {
            get => _model;
            set
            {
                if (ReferenceEquals(_model, value)) return;
                _model = value ?? throw new ArgumentNullException(nameof(value));
                OnPropertyChanged();
                OnPropertyChanged(nameof(RootElements));
                OnPropertyChanged(nameof(VisibleRootElements));
            }
        }

        public IEnumerable<SchemaNode> RootElements => _model?.RootElements ?? Enumerable.Empty<SchemaNode>();

        public SchemaNode? SelectedRootElement
        {
            get => _selectedRootElement;
            set
            {
                if (EqualityComparer<SchemaNode?>.Default.Equals(_selectedRootElement, value)) return;
                _selectedRootElement = value;
                OnPropertyChanged();
                OnPropertyChanged(nameof(VisibleRootElements));
            }
        }

        public SchemaNode? SelectedNode
        {
            get => _selectedNode;
            set
            {
                if (EqualityComparer<SchemaNode?>.Default.Equals(_selectedNode, value)) return;
                _selectedNode = value;
                OnPropertyChanged();
            }
        }

        public IEnumerable<SchemaNode> VisibleRootElements => SelectedRootElement != null ? [SelectedRootElement] : RootElements;
    }
}