using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Xml.Linq;

namespace xml
{
    class Program
    {
        static XDocument Betoltes()
        {
            //XDocument.Load("workers.xml"); //local bin/debug
            return XDocument.Load("http://users.nik.uni-obuda.hu/siposm/db/workers.xml");
        }

        static void Main(string[] args)
        {
            XDocument allomany = Betoltes();
            var mailok = from x in allomany.Root.Descendants("person")
                         select x.Element("email").Value;

            var tamasok = from x in allomany.Root.Descendants("person")
                          where x.Element("name").Value.ToUpper().Contains("TAMÁS")
                          select x.Element("name").Value;

            var polihisztorok = from x in allomany.Root.Descendants("person")
                                where x.Element("rank").Value.Equals("polihisztor")
                                select new
                                {
                                    NEV = x.Element("name").Value,
                                    MAIL = x.Element("email").Value
                                };
            var intezetek = from x in allomany.Root.Descendants("person")
                            group x by x.Element("dept").Value into g
                            select new
                            {
                                LETSZAM = g.Count(),
                                INTEZET = g.Key
                            };
            XElement uj = new XElement("person",
                new XElement("name","ULTRON"),
                new XElement("email", "U@MAIL.HU"),
                new XElement("dept", "AII")
                //----
                );
            allomany.Root.Add(uj);

        }
    }
}