using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace Project
{
    class CountDayInDate
    {
        public string DayInDate(string FirstDate,string EndDate)
        {
            FirstDate = UpdateDateFormat(FirstDate);
            EndDate = UpdateDateFormat(EndDate);
            //******
            System.Globalization.PersianCalendar persia = new System.Globalization.PersianCalendar();

            Int16 StartYear = Convert.ToInt16(FirstDate.Substring(0, 4));
            Int16 StartMonth = Convert.ToInt16(FirstDate.Substring(5, 2));
            Int16 StartDay = Convert.ToInt16(FirstDate.Substring(8, 2));

            Int16 EndYear = Convert.ToInt16(EndDate.Substring(0, 4));
            Int16 EndMonth = Convert.ToInt16(EndDate.Substring(5, 2));
            Int16 EndDay = Convert.ToInt16(EndDate.Substring(8, 2));

            DateTime StartDateTime = persia.ToDateTime(StartYear, StartMonth, StartDay, 0, 0, 0, 0);
            DateTime EndDateTime = persia.ToDateTime(EndYear, EndMonth, EndDay, 0, 0, 0, 0);

            TimeSpan Difference = EndDateTime - StartDateTime;

            int Days = Difference.Days;
            return Days.ToString();
        }

        private string UpdateDateFormat(string Command)
        {
            try
            {
                if (Command != string.Empty)
                {
                    string year, month, day;
                    string Sub_date;//holde sub date for example 12/5 or 86/12
                    year = Command.Substring(Command.LastIndexOf("/") + 1);//read day or year
                    Sub_date = Command.Substring(0, Command.LastIndexOf("/"));
                    month = Sub_date.Substring(Sub_date.LastIndexOf("/") + 1);//read month
                    day = Sub_date.Substring(0, Sub_date.LastIndexOf("/"));
                    //now bild normal date
                    if (Convert.ToInt32(year) < Convert.ToInt32(day))//if year value saved in day
                    {
                        string value = day;
                        day = year;
                        year = value;
                    }
                    if (day.Length == 1)//bild normal day
                        day = "0" + day;
                    if (month.Length == 1)//bild normal month
                        month = "0" + month;
                    if (year.Length == 2)//bild normal year
                        year = "13" + year;
                    //
                    Command = year + "/" + month + "/" + day;
                }
                return Command;
            }
            catch (Exception)
            {
                MessageBox.Show("تاریخ را درست وارد نمایید");
                return "";
            }
        }
    }
}