SUBD_SchoolSchedule/SchoolSchedule/SchoolScheduleBusinessLogic/GradeLogic.cs

using SchoolScheduleContracts.BindingModels;
using SchoolScheduleContracts.BusinessLogicsContracts;
using SchoolScheduleContracts.SearchModels;
using SchoolScheduleContracts.StoragesContracts;
using SchoolScheduleContracts.ViewModels;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace SchoolScheduleBusinessLogic
{
	public class GradeLogic : IGradeLogic
	{
		private readonly IGradeStorage _gradeStorage;
		private readonly IStudentStorage _studentStorage;
		public GradeLogic(IGradeStorage gradeStorage, IStudentStorage studentStorage)
		{
			_gradeStorage = gradeStorage;
			_studentStorage = studentStorage;
		}

		public List<GradeViewModel> ReadList(GradeSearchModel? model)
		{
			var list = model == null ? _gradeStorage.GetFullList() :
_gradeStorage.GetFilteredList(model);
			return list;
		}

		public GradeViewModel? ReadElement(GradeSearchModel model)
		{
			if (model == null)
			{
				throw new ArgumentNullException(nameof(model));
			}
			var element = _gradeStorage.GetElement(model);
			return element;
		}

		public List<StudentViewModel> GetStudents(GradeSearchModel model)
		{
			var list = _studentStorage.GetFilteredList(new StudentSearchModel { GradeId = model.Id });
			return list;
		}

		public bool Create(GradeBindingModel model)
		{
			CheckModel(model);
			if (_gradeStorage.Insert(model) == null)
			{
				return false;
			}
			return true;
		}
		public bool Update(GradeBindingModel model)
		{
			CheckModel(model);
			if (_gradeStorage.Update(model) == null)
			{
				return false;
			}
			return true;
		}
		public bool Delete(GradeBindingModel model)
		{
			CheckModel(model, false);
			if (_gradeStorage.Delete(model) == null)
			{
				return false;
			}
			return true;
		}

		private void CheckModel(GradeBindingModel model, bool withParams =
	   true)
		{
			if (model == null)
			{
				throw new ArgumentNullException(nameof(model));
			}
			if (!withParams)
			{
				return;
			}
			if (!(model.Letter >= 'A' && model.Letter <= 'Z'))
			{
				throw new ArgumentNullException("Буква класса не является заглавной буквой",
			   nameof(model.Letter));
			}
			if (!(model.Year >= 1 && model.Year <= 11))
			{
				throw new ArgumentNullException("Год класса не является числом от 1 до 11",
			   nameof(model.Letter));

			}

			var element = _gradeStorage.GetElement(new GradeSearchModel
			{
				Letter = model.Letter,
				Year = model.Year
			});
			if (element != null && element.Id != model.Id)
			{
				throw new InvalidOperationException("Такой класс уже есть");

			}
		}


	}
}