using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading.Tasks;

namespace Test
{
    public class GroupKeyList<T> : ObservableCollection<T>, INotifyPropertyChanged
    {
        public string Key { get; private set; }

        // Declare the event
        public new event PropertyChangedEventHandler PropertyChanged;

        // Create the OnPropertyChanged method to raise the event
        protected void OnPropertyChanged(string name)
        {
            PropertyChangedEventHandler handler = PropertyChanged;
            if (handler != null)
            {
                handler(this, new PropertyChangedEventArgs(name));
            }
        }

        public delegate string GetKeyDelegate(T item);

        public static ObservableCollection<GroupKeyList<T>> CreateGroupList(ObservableCollection<T> items, GetKeyDelegate getKey)
        {
            ObservableCollection<GroupKeyList<T>> new_group_list = new ObservableCollection<GroupKeyList<T>>();                                 // create the list

            foreach (T item in items)
            {
                string key = getKey(item);                                  // get key

                // search to see if the key has been added to the group
                GroupKeyList<T> new_item = new_group_list.FirstOrDefault(delegate(GroupKeyList<T> t) { return t.Key == key; });

                if (new_item == null)
                {
                    new_item = new GroupKeyList<T>();                       // create the group
                    new_item.Key = key;                                     // set the key
                    new_group_list.Add(new_item);                           // add the new group
                    new_item.Add(item);                                     // add the item to the new group
                }
                else
                {
                    new_item.Add(item);                                     // add the item to the existing group (matching)
                }
            }

            return new_group_list;


        }

        public T FindMatch(string pattern, GetKeyDelegate getKey)
        {
            Regex rgx = new Regex(pattern, RegexOptions.IgnoreCase);

            foreach (T item in this.Items)
            {
                string key = getKey(item);
                Match match = rgx.Match(key);
                if (match.Success)
                    return item;
            }

            return default(T);
        }

    }
}