using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Xml;
using System.Xml.Linq;
using System.IO;

namespace WorkmatesInfoSystem
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            AddInfo addInfoForm = new AddInfo();
            addInfoForm.ShowDialog();
        }

        private void button2_Click(object sender, EventArgs e)
        {
            SearchInfo searchInfoForm = new SearchInfo();
            searchInfoForm.ShowDialog();
        }
    }
}

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Text.RegularExpressions;
using System.Xml;
using System.Xml.Linq;
using System.IO;

namespace WorkmatesInfoSystem
{
    public partial class AddInfo : Form
    {
        public AddInfo()
        {
            InitializeComponent();
        }

        private void textBox1_Click(object sender, EventArgs e)
        {
            if(WorkerNumber.Text == "The worker's nubmer must be a number(not a string or etc).") 
            {
                WorkerNumber.Text = "";
            }
        }

        private void textBox2_Click(object sender, EventArgs e)
        {
            if (WorkerName.Text == "Herry(For example)") 
            {
                WorkerName.Text = "";
            }
        }

        private void textBox3_Click(object sender, EventArgs e)
        {
           
            if (WorkerEmail.Text == "The format should like \"tylan@Avpoint.com\"") 
            {
                WorkerEmail.Text = "";
            }
        }

        private void textBox4_Click(object sender, EventArgs e)
        {
            if (WorkerDepartment.Text == "CC_CIQA(For example)") 
            {
                WorkerDepartment.Text = "";
            }         
        }

        private void button1_Click(object sender, EventArgs e)
        {
            //Check the format of the worker's number.
            if (Regex.IsMatch(WorkerNumber.Text, "^[0-9]*$") == false)
            {
                MessageBox.Show("Worker's number is in a wrong format, please type in again.");
            }
            //Check the Email's format of the worker.
            else if (Regex.IsMatch(WorkerEmail.Text,@"^\w+@\w+$") == false)
            {
                MessageBox.Show("Worker's Email is in a wrong format, please type in again.");
            }
            //Check the end format of the Email Address.
            else if (Regex.IsMatch(EmailEndFormat.Text, "^(com|net)$") == false)
            {
                MessageBox.Show("The end format of the Email is wrong, please type in again. You can type in 'com' or 'net'.");
            }
            //Add the worker's info into the xml.
            else
            {
                saveToXml(SavePath.Text.ToString());
                MessageBox.Show("Save the worker's info successfully.");
            }
        }

        //Save to XML method.
        private void saveToXml(string xmlPath)
        {
            string filePath = xmlPath + "WorkersInfo.xml";
            FileInfo file = new FileInfo(@filePath);
            if (file.Exists == false)
            {
                File.Create(@filePath).Close();
                StreamWriter sw = new StreamWriter(@filePath);
                string content = "<?xml version=\"1.0\" encoding=\"utf-8\"?>" +
                                    "<System xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\" xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\">" +
                                      "<SystemName>WorkersInfo</SystemName>" +
                                      "<Workers>" +
                                      "</Workers>" +
                                    "</System>";
                sw.WriteLine(content);
                sw.Close();
            }
            //Load XML file.
            XElement xe = XElement.Load(@filePath);
            //Create a node info.
            XElement Worker = new XElement("Worker",   
                new XElement("WorkerNumber", WorkerNumber.Text),
                new XElement("WorkerName", WorkerName.Text),
                new XElement("WorkerEmail", WorkerEmail.Text + "." + EmailEndFormat.Text),
                new XElement("WorkerDepartment", WorkerDepartment.Text)
            );
            //Add the node under the specific node.
            xe.Element("Workers").Add(Worker);
            //Save the XML file.
            xe.Save(filePath);
        }

        private void SavePath_Click(object sender, EventArgs e)
        {
            if(SavePath.Text==@"C:\Tylan\Workers(For example)")
            {
                SavePath.Text = "";
            }
        }
    }
}

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Xml;
using System.Xml.Linq;
using System.IO;

namespace WorkmatesInfoSystem
{
    public partial class SearchInfo : Form
    {
        public SearchInfo()
        {
            InitializeComponent();
        }

        private void SearchDepartmentButton_Click(object sender, EventArgs e)
        {
            XDocument workersInfo = XDocument.Load(@SearchPath.Text.ToString());
            var results = from worker in workersInfo.Element("System").Element("Workers").Elements() where worker.Element("WorkerDepartment").Value == SearchWorkerDepartment.Text.ToString() select worker;
            foreach (var result in results)
            {
                MessageBox.Show(result.Element("WorkerNumber").Value + "\n" + result.Element("WorkerName").Value + "\n" + result.Element("WorkerEmail").Value + "\n" + result.Element("WorkerDepartment").Value);
            }
        }

        private void SearchNumberButton_Click(object sender, EventArgs e)
        {
            XDocument workersInfo = XDocument.Load(@SearchPath.Text.ToString());
            var results = from worker in workersInfo.Element("System").Element("Workers").Elements() where int.Parse(worker.Element("WorkerNumber").Value) == int.Parse(SearchWokerNumber.Text.ToString()) select worker;
            foreach (var result in results)
            {
                MessageBox.Show(result.Element("WorkerNumber").Value + "\n" + result.Element("WorkerName").Value + "\n" + result.Element("WorkerEmail").Value + "\n" + result.Element("WorkerDepartment").Value);
            }
        }
    }
}