Diplom_O/DataBase/ShtatDB.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using Microsoft.EntityFrameworkCore;

namespace Diplom_O.DataBase
{
	public class Shtat
	{
		[Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
		public int Id { get; set; }
		public string Doljnost { get; set; }
		public int Size { get; set; }
		public bool Active { get; set; }
		public List<Rabotnik> Rabotniky { get; set; }
	}

	public static partial class FuncDB
  {
		public static void ShtatCheckValid(Shtat obj)
		{
			try
			{
				if (obj == null)
					throw new Exception("Ошибка инициализации должности.");
				if (string.IsNullOrEmpty(obj.Doljnost))
					throw new Exception("Пустая должность.");
				if (obj.Size <= 0)
					throw new Exception("Количество мест <= 0.");
			}
			catch
			{
				throw;
			}
		}
		private static void ShtatClear()
    {
      try
      {
				using (var db = new MainDB())
				{
					var shtat = (
						from a in db.Shtat
						where !a.Active
						select a).ToArray();
					for (var i = 0; i < shtat.Length; i++)
						if(ShtatFreeSpaceByShtat(shtat[i]) == shtat[i].Size)
            {
							db.Shtat.Remove(shtat[i]);
							db.SaveChanges();
						}
				}
			}
			catch
      {
				return;
      }
    }

		public static Shtat ShtatGetById(int id)
		{
			try
			{
				using (var db = new MainDB())
				{
					var res =
						from a in db.Shtat
						where a.Id == id
						select a;
					try
					{
						return res.Single();
					}
					catch
					{
						return null;
					}
				}
			}
			catch
			{
				throw;
			}
		}
		public static Shtat ShtatGetByDoljnost(string doljnost)
    {
			try
			{
				using (var db = new MainDB())
				{
					var chkDolj =
						from a in db.Shtat
						where a.Doljnost == doljnost && a.Active
						select a;
					try
					{
						return chkDolj.Single();
					}
					catch
					{
						return null;
					}
				}
			}
			catch
			{
				throw;
			}
		}

		public static int ShtatFreeSpaceById(int id)
		{
			try
			{
				return
					ShtatFreeSpaceByShtat(
						ShtatGetById(id)
						);
			}
			catch
			{
				throw;
			}
		}
		public static int ShtatFreeSpaceByShtat(Shtat obj)
		{
			try
			{
				ShtatCheckValid(obj);
				using (var db = new MainDB())
				{
					var now = DateTime.Now;
					var res = (
						from a in db.Rabotniky
						where
							a.ShtatId == obj.Id
								&&
							(
								!a.End.HasValue
									||
								(
									now >= a.Start
										&&
									now <= a.End.Value
								)
							)
						select a).Count();
					return obj.Size - res;
				}
			}
			catch
			{
				throw;
			}
		}

		public static void ShtatAdd(Shtat obj)
		{
			try
			{
				ShtatCheckValid(obj);
				if (ShtatGetByDoljnost(obj.Doljnost) != null)
					throw new Exception("Должность существует.");
				using (var db = new MainDB())
				{
					obj.Active = true;
					db.Shtat.Add(obj);
					db.SaveChanges();
				}
			}
			catch
			{
				throw;
			}
		}
		public static void ShtatChange(Shtat obj)
		{
			try
			{
				ShtatCheckValid(obj);
				var localObjById = ShtatGetById(obj.Id);
				var localObjByDoljnost = ShtatGetByDoljnost(obj.Doljnost);
				if (localObjById == null)
					throw new Exception("Должность не существует.");
				if (localObjByDoljnost != null &&
					localObjByDoljnost != localObjById)
					throw new Exception("Должность существует.");
				if (localObjById.Size - ShtatFreeSpaceByShtat(localObjById) > obj.Size ) 
					throw new Exception("Занятых мест больше > указанных.");
				using (var db = new MainDB())
				{
					db.Shtat.Update(obj);
					db.SaveChanges();
				}
			}
			catch
			{
				throw;
			}
		}
		public static void ShtatDelete(Shtat obj)
		{
			try
			{
				if (obj == null)
					return;
				var localObj = ShtatGetById(obj.Id);
				if (localObj == null)
					throw new Exception("Должность не существует.");
				if (ShtatFreeSpaceByShtat(localObj) != localObj.Size)
					throw new Exception("Есть занятые места.");
				localObj.Active = false;
				using (var db = new MainDB())
				{
					db.Shtat.Update(localObj);
					db.SaveChanges();
				}
				ShtatClear();
			}
			catch
			{
				throw;
			}
		}

		public static (Shtat shtat, int free)[] ShtatList(string filter = null, bool isActual = false)
		{
			try
			{
				using (var db = new MainDB())
				{
					var shtat = (
						from a in db.Shtat
						where a.Active 
						select a
						).ToList();
					var res = new List<(Shtat shtat, int free)>();
					for (var i = 0; i < shtat.Count; i++)
					{
						var free = ShtatFreeSpaceByShtat(shtat[i]);
						if (isActual && free <= 0)
							continue;
						res.Add((
							shtat[i],
							free
							));
					}

					if (string.IsNullOrEmpty(filter))
						return res.ToArray();

					filter = filter.ToLower();
					for (var i = 0; i < res.Count;)
          {
						var dolj = res[i].shtat.Doljnost.ToLower();
						if (!dolj.Contains(filter))
							res.RemoveAt(i);
						else
							i++;
          }
					return res.ToArray();
				}
			}
			catch
			{
				throw;
			}
		}
		public static string[][] ShtatListTableMain(string filter = null, bool isActual = false)
    {
      try
      {
				return ShtatListTableMain(ShtatList(filter, isActual));
      }
      catch
      {
				throw;
      }
    }
		public static string[][] ShtatListTableMain((Shtat shtat, int free)[] data)
		{
			try
			{
				var result = new List<string[]>();
				foreach (var (shtat, free) in data)
					result.Add(
						new string[]
						{
							shtat.Id.ToString(),
							shtat.Doljnost,
							shtat.Size.ToString(),
							free.ToString()
						}
					);
				return result.ToArray();
			}
			catch
			{
				throw;
			}

		}


	}
}