using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using ModernShoppingList.Models;
using Windows.ApplicationModel.DataTransfer;
using Windows.Foundation;

namespace ModernShoppingList.Services
{
    public class ShareService
    {
        public List<Item> ShareData { get; set; }

        #region Constructor
        private static ShareService _instance;
        private static object _instanceSync = new Object();

        protected ShareService()
        {
            Initialize();
            ShareData = new List<Item>();
        }

        public static ShareService GetInstance()
        {
            // This implementation of the singleton design pattern prevents unnecessary locks (using the double if-test)
            if (_instance == null)
            {
                lock (_instanceSync)
                {
                    if (_instance == null)
                    {
                        _instance = new ShareService();
                    }
                }
            }
            return _instance;
        }
        #endregion

        #region Private methods
        private void Initialize()
        {
            DataTransferManager dataTransferManager;
            dataTransferManager = DataTransferManager.GetForCurrentView();
            dataTransferManager.DataRequested += new TypedEventHandler<DataTransferManager, DataRequestedEventArgs>(this.DataRequested);

        }

        private async void DataRequested(DataTransferManager sender, DataRequestedEventArgs args)
        {
            if (!ReferenceEquals(this.ShareData, null))
            {
                DataPackage data = args.Request.Data;

                // permet de pouvoir traiter un long traitement sans bloquer la request
                DataRequestDeferral deferral = args.Request.GetDeferral();

                data.Properties.Title = "Partage ModernShoppingList du " + DateTime.Now.ToString();
                // objet de l'email
                data.Properties.Description = "Partage Produit";

                StringBuilder sb = new StringBuilder();

                foreach (Item i in ShareData)
                {
                    sb.Append(i.Title);
                    sb.Append(" ; ");
                }

                data.SetText(sb.ToString());

                deferral.Complete();
            }
        }
        #endregion
    }
}