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

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

        private void btnSendEmail_Click(object sender, EventArgs e)
        {
            DateTime start = Convert.ToDateTime(txt_start.Value);
            DateTime end = Convert.ToDateTime(txt_end.Value);
            var userName = "youremail@laptrinhvb.net";
            var passWord = "BanAnhThao";
            var isSuccess = SendEmailMetting(userName, passWord, txtToEmail.Text, "Demo Send Test Email", "Send email with event Metting", "Phòng họp văn phòng công ty", start, end);
            if (isSuccess)
            {
                MessageBox.Show("send mail is success");
            }
            else {
                MessageBox.Show("send mail is fail");
            }
        }

        private static string MeetingRequestString(string from, List<string> toUsers, string subject, string desc, string location, DateTime startTime, DateTime endTime, int? eventID = null, bool isCancel = false)
        {
            StringBuilder str = new StringBuilder();

            str.AppendLine("BEGIN:VCALENDAR");
            str.AppendLine("PRODID:-//Microsoft Corporation//Outlook 12.0 MIMEDIR//EN");
            str.AppendLine("VERSION:2.0");
            str.AppendLine(string.Format("METHOD:{0}", (isCancel ? "CANCEL" : "REQUEST")));
            str.AppendLine("BEGIN:VEVENT");

            str.AppendLine(string.Format("DTSTART:{0:yyyyMMddTHHmmssZ}", startTime.ToUniversalTime()));
            str.AppendLine(string.Format("DTSTAMP:{0:yyyyMMddTHHmmss}", DateTime.Now));
            str.AppendLine(string.Format("DTEND:{0:yyyyMMddTHHmmssZ}", endTime.ToUniversalTime()));
            str.AppendLine(string.Format("LOCATION: {0}", location));
            str.AppendLine(string.Format("UID:{0}", (eventID.HasValue ? "laptrinhvb_" + eventID : Guid.NewGuid().ToString())));
            str.AppendLine(string.Format("DESCRIPTION:{0}", desc.Replace("\n", "<br>")));
            str.AppendLine(string.Format("X-ALT-DESC;FMTTYPE=text/html:{0}", desc.Replace("\n", "<br>")));
            str.AppendLine(string.Format("SUMMARY:{0}", subject));

            str.AppendLine(string.Format("ORGANIZER;CN=\"{0}\":MAILTO:{1}", from, from));
            str.AppendLine(string.Format("ATTENDEE;CN=\"{0}\";RSVP=TRUE:mailto:{1}", string.Join(",", toUsers), string.Join(",", toUsers)));

            str.AppendLine("BEGIN:VALARM");
            str.AppendLine("TRIGGER:-PT20M");
            str.AppendLine("ACTION:DISPLAY");
            str.AppendLine("DESCRIPTION:Reminder");
            str.AppendLine("END:VALARM");
            str.AppendLine("END:VEVENT");
            str.AppendLine("END:VCALENDAR");

            return str.ToString();
        }
        public static bool SendEmailMetting( string fromEmail, string password, string toEmail, string Sub, string body, string location,  DateTime start, DateTime end)
        {

            string CalendarContent = MeetingRequestString(fromEmail, new List<string>() { toEmail }, Sub , body, location,start, end);

            MailMessage mailMessage = new MailMessage();
            mailMessage.From = new MailAddress(fromEmail); 
            mailMessage.Subject = Sub; 
            mailMessage.Body = body; 
            mailMessage.IsBodyHtml = true;
            mailMessage.To.Add(new MailAddress(toEmail)); 

            AlternateView calendarView = AlternateView.CreateAlternateViewFromString(CalendarContent, new System.Net.Mime.ContentType("text/calendar"));
            calendarView.TransferEncoding = System.Net.Mime.TransferEncoding.SevenBit;
            mailMessage.AlternateViews.Add(calendarView);



            try
            {
                var smtp = new System.Net.Mail.SmtpClient();
                {
                    smtp.Host = "smtp.gmail.com";
                    smtp.Port = 587;
                    smtp.EnableSsl = false;
                    smtp.DeliveryMethod = System.Net.Mail.SmtpDeliveryMethod.Network;
                    smtp.Credentials = new NetworkCredential(fromEmail, password);
                    smtp.Timeout = 20000;
                    smtp.Send(mailMessage);
                }
                return true;
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);

            }
            return false;

        }

        private void Form1_Load(object sender, EventArgs e)
        {
            txt_start.Format = DateTimePickerFormat.Custom;
            txt_start.CustomFormat = "dd-MM-yyyy HH:mm";
            txt_end.Format = DateTimePickerFormat.Custom;
            txt_end.CustomFormat = "dd-MM-yyyy HH:mm";
        }
    }
}