using System;
using System.Collections;
using System.Collections.Specialized;
using System.Linq;
using System.Windows.Input;
using Xamarin.Forms;
using Xamarin.Forms.Xaml;
using XF.Material.Forms.UI.Dialogs;

namespace InABox.Mobile
{

    public class MobileListRefreshEventArgs : EventArgs
    {
    }
    
    public delegate void MobileListRefreshEvent(object sender, MobileListRefreshEventArgs args);
    
    [XamlCompilation(XamlCompilationOptions.Compile)]
    public partial class MobileList
    {

        public bool PullToRefresh
        {
            get => _refresher.IsEnabled == true;
            set => _refresher.IsEnabled = value;
        }

        // public int RowHeight
        // {
        //     get => _viewmodel.RowHeight;
        //     set => _viewmodel.RowHeight = value;
        // }
        
        public DataTemplate ItemTemplate
        {
            get => _list.ItemTemplate;
            set => _list.ItemTemplate = value;
        }
        
        public IEnumerable ItemsSource
        {
            get => _list.ItemsSource;
            set
            {
                if (_list.ItemsSource is INotifyCollectionChanged old)
                    old.CollectionChanged -= ItemsSourceChanged;
                _list.ItemsSource = value;
                CheckChanged();
                if (value is INotifyCollectionChanged observable)
                    observable.CollectionChanged += ItemsSourceChanged;
            }
        }

        private void ItemsSourceChanged(object sender, NotifyCollectionChangedEventArgs e)
        {
            CheckChanged();
        }

        private void CheckChanged()
        {
            _list.IsVisible = ItemsSource?.GetEnumerator().MoveNext() == true;
            _nodata.IsVisible = !_list.IsVisible;
        }

        private double _spacing;
        public double Spacing
        {
            get => _spacing;
            set
            {
                _spacing = value;
                var layout = _list?.ItemsLayout as LinearItemsLayout;
                if (layout != null)
                    layout.ItemSpacing = _spacing;
            }
        }


        private bool _unevenrows;
        public bool HasUnevenRows
        {
            get => _unevenrows;
            set
            {
                _unevenrows = value;
                if (_list != null)
                    _list.ItemSizingStrategy =
                        value 
                            ? ItemSizingStrategy.MeasureAllItems 
                            : ItemSizingStrategy.MeasureFirstItem;
            }
        }
        
        public event MobileListRefreshEvent RefreshRequested;

        public MobileList()
        {
            InitializeComponent();
            _refresher.Command = new Command(DoRefresh);
            Spacing = 5;
            HasUnevenRows = true;
        }
        
        private void DoRefresh(object sender)
        {
            if (_refresher != null)
            {
                //var src = _list.ItemsSource;
                //_list.ItemsSource = null;
                _refresher.IsRefreshing = true;
                RefreshRequested?.Invoke(sender, new MobileListRefreshEventArgs());
                _refresher.IsRefreshing = false;
                //_list.ItemsSource = src;
            }
        }
        
    }
}