using System;
using System.IO;
using System.Xml;
using System.Xml.XPath;
using System.Collections;

public class Task {
  private DateTime start, end;
  private string descr;

  public Task(DateTime s, DateTime e, string d) {
    this.start = s;
    this.end = e;
    this.descr = d;
  }

  public DateTime StartTime {
    get { return start; }
    set { start = value; }
  }

  public DateTime EndTime {
    get { return end; }
    set { end = value; }
  }

  public string Description {
    get { return descr; }
    set { descr = value; }
  }
}

public class Organizer {
  private ArrayList tl;

  public Organizer() {
    tl = new ArrayList();
  }

  public void AddTask(Task t) {
    tl.Add(t);
  }

  public void Store(string file) {
    XmlDocument doc = new XmlDocument();
    XmlDeclaration decl = doc.CreateXmlDeclaration("1.0", null, null);
    doc.AppendChild(decl);
    //----- create the root element �organizer�
    XmlElement rootElem = doc.CreateElement("organizer");
    doc.AppendChild(rootElem);
    foreach(Task t in tl) {
      XmlElement tNode = doc.CreateElement("task");
      XmlElement sNode = doc.CreateElement("start");
      sNode.AppendChild(doc.CreateTextNode(t.StartTime.ToString()));
      XmlElement eNode = doc.CreateElement("end");
      eNode.AppendChild(doc.CreateTextNode(t.EndTime.ToString()));
      XmlElement dNode = doc.CreateElement("description");
      dNode.AppendChild(doc.CreateTextNode(t.Description));
      tNode.AppendChild(sNode);
      tNode.AppendChild(eNode);
      tNode.AppendChild(dNode);
      rootElem.AppendChild(tNode);
    }
    FileStream fs = new FileStream(file,FileMode.OpenOrCreate);
    doc.Save(fs);
    fs.Close();
  }

  public bool Load(string file) {
    tl.Clear();
    XmlDocument doc = new XmlDocument();
    FileStream fs = new FileStream(file,FileMode.Open);
    doc.Load(fs);
    XPathNavigator nav = doc.CreateNavigator();
    XPathNodeIterator iterator = nav.Select("/organizer/*/*");
    // iterate through all elements of every task element
    try {
      while (iterator.MoveNext()) {
        //Console.WriteLine(iterator.Current.Value);
        DateTime s = DateTime.Parse(iterator.Current.Value);
        iterator.MoveNext();
        DateTime e = DateTime.Parse(iterator.Current.Value);
        iterator.MoveNext();
        tl.Add(new Task(s, e, iterator.Current.Value));
          
      }
    } catch(Exception e) {
      Console.WriteLine(e.Message);
      fs.Close();
      return false;
    }
    fs.Close();
    return true;
  }
}

public class Cap4_Ex29_Test {

  public static void Main(string[] args) {
    Organizer o = new Organizer();
    o.AddTask(new Task(new DateTime(2004,12,1,1,1,1,1), new DateTime(2004,12,1,1,2,1,1),"Shopping with friends"));
    o.AddTask(new Task(new DateTime(2004,12,1,1,2,1,1), new DateTime(2004,12,1,1,3,1,1),"Working for the DotNet-book"));
    o.AddTask(new Task(new DateTime(2004,12,1,1,3,1,1), new DateTime(2004,12,1,1,4,1,1),"Teaching Programming for Students"));
    o.Store("organizer.xml");
    o.Load("organizer.xml");
  }
}