using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Collections.Specialized;
using System.Linq;

namespace ChatController.Utilities.Extensions
{
    public class ObservableSortCollection<T> : ObservableCollection<T>
    {
        private readonly List<NotifyCollectionChangedEventHandler> _ChangedHandler = new List<NotifyCollectionChangedEventHandler>();

        private readonly Comparison<T> _Comparer;

        public ObservableSortCollection()
        {
        }

        public ObservableSortCollection(IEnumerable<T> pList) : base(pList.ToList())
        {
        }

        public ObservableSortCollection(Comparison<T> pComparer) : this()
        {
            _Comparer = pComparer;
            Sort();
        }

        public ObservableSortCollection(IEnumerable<T> pList, Comparison<T> pComparer) : this(pList)
        {
            _Comparer = pComparer;
            Sort();
        }

        public override event NotifyCollectionChangedEventHandler CollectionChanged
        {
            add
            {
                _ChangedHandler.Add(value);
                base.CollectionChanged += value;
            }

            remove
            {
                _ChangedHandler.Remove(value);
                base.CollectionChanged -= value;
            }
        }

        public void Sort()
        {
            if (!(_Comparer is null))
            {
                DisconnectHandler();
                var lTemp = this.ToList();
                lTemp.Sort(_Comparer);
                for (var i = 0; i < Count; i++)
                {
                    this[i] = lTemp[i];
                }

                ReconnectHandler();
                NotifyHandlerAfterSort();
            }
        }

        public void Sort(Comparison<T> pComparer)
        {
            DisconnectHandler();
            var lTemp = this.ToList();
            lTemp.Sort(pComparer);
            for (var i = 0; i < Count; i++)
            {
                this[i] = lTemp[i];
            }

            ReconnectHandler();
            NotifyHandlerAfterSort();
        }

        private void DisconnectHandler()
        {
            foreach (var iHandler in _ChangedHandler)
            {
                base.CollectionChanged -= iHandler;
            }
        }

        private void NotifyHandlerAfterSort()
        {
            foreach (var iHandler in _ChangedHandler)
            {
                iHandler(this, new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
            }
        }

        private void ReconnectHandler()
        {
            foreach (var iHandler in _ChangedHandler)
            {
                base.CollectionChanged += iHandler;
            }
        }
    }
}