/DataBoundApp1/ViewModels/MainViewModel.cs

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Collections.ObjectModel;

using System.IO;

using System.IO.IsolatedStorage;

using System.Linq;

using System.Net;

using System.Xml.Linq;



namespace DataBoundApp1.ViewModels

{

	public class MainViewModel : INotifyPropertyChanged

	{

		public MainViewModel()

		{

			this.Sessions = new ObservableCollection<SessionViewModel>();

			this.Favorites = new ObservableCollection<SessionViewModel>();

			this.AllSessions = new List<SessionViewModel>();

		}



		/// <summary>

		/// A collection for SessionViewModel objects.

		/// </summary>

		public ObservableCollection<SessionViewModel> Sessions { get; private set; }

		public ObservableCollection<SessionViewModel> Favorites{ get; private set; }

		public List<SessionViewModel> AllSessions{ get; private set; }		



		public bool IsDataLoaded

		{

			get;

			private set;

		}



		/// <summary>

		/// Creates and adds a few SessionViewModel objects into the Sessions collection.

		/// </summary>

		public void LoadData()

		{

			using (var iso = IsolatedStorageFile.GetUserStoreForApplication())

			{

				if (iso.FileExists("sessions.xml"))

				{

					using (var file = new IsolatedStorageFileStream("sessions.xml", FileMode.Open, iso))

					{

						var sessionXml = XElement.Load(file);

						ParseXml(sessionXml);

					}

				}

				else

				{

					RefreshData();

				}

			}



			LoadFavorites();

		}



		private void LoadFavorites()

		{

			this.Favorites.Clear();



			if (IsolatedStorageSettings.ApplicationSettings.Contains("fav"))

			{

				var loadedFav = (ObservableCollection<SessionViewModel>) IsolatedStorageSettings.ApplicationSettings["fav"];

				foreach (var sessionViewModel in loadedFav)

				{

					this.Favorites.Add(sessionViewModel);

				}

			}

		}



		private void ParseXml(XElement sessionXml)

		{

			this.AllSessions = sessionXml.Descendants("Session")

				.Select(s => new SessionViewModel()

				             	{

				             		Title = s.Element("Title").Value,

				             		Abstract = s.Element("Abstract").Value,

				             		Difficulty = s.Element("Difficulty").Value,

				             		Room = s.Element("Room").Value,

				             		SpeakerName = s.Element("SpeakerName").Value,

				             		Technology = s.Element("Technology").Value,

				             		Uri = s.Element("URI").Value,

				             		Start = DateTime.Parse(s.Element("Start").Value)

				             	})

				.OrderBy(s => s.Start)

				.ToList();



			foreach (var sessionViewModel in this.AllSessions)

			{

				this.Sessions.Add(sessionViewModel);

			}

			this.IsDataLoaded = true;

		}



		public void FilterData(string searchTerm)

		{

			this.Sessions.Clear();



			if (searchTerm.Length == 0)

			{

				foreach (var sessionViewModel in AllSessions)

				{

					this.Sessions.Add(sessionViewModel);

				}	

			}

			else

			{

				foreach (var sessionViewModel in AllSessions.Where(s => s.Title.ToLower().Contains(searchTerm.ToLower())))

				{

					this.Sessions.Add(sessionViewModel);

				}

			}

		}



		private void RefreshData()

		{

			var webClient = new WebClient();

			webClient.DownloadStringCompleted += new DownloadStringCompletedEventHandler(DownloadComplete);

			webClient.DownloadStringAsync(new Uri("http://www.codemash.org/rest/sessions.xml"));

		}



		private void DownloadComplete(object sender, DownloadStringCompletedEventArgs e)

		{

			if (e.Error != null)

				return;



			var sessionXml = XElement.Parse(e.Result);

			ParseXml(sessionXml);



			using (var iso = IsolatedStorageFile.GetUserStoreForApplication())

			{

				using (var file = new IsolatedStorageFileStream("sessions.xml", FileMode.Create, iso))

				{

					sessionXml.Save(file);

				}

			}

		}



		public event PropertyChangedEventHandler PropertyChanged;

		private void NotifyPropertyChanged(String propertyName)

		{

			PropertyChangedEventHandler handler = PropertyChanged;

			if (null != handler)

			{

				handler(this, new PropertyChangedEventArgs(propertyName));

			}

		}

	}

}