ISEbd-22_CourseWork_School/School/SchoolDataBaseImplement/Models/Discipline.cs

using SchoolContracts.BindingModels;
using SchoolContracts.Extensions;
using SchoolContracts.ViewModels;
using SchoolDataModels;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using System.Linq.Expressions;
using SchoolDataModels.Models;

namespace SchoolDatabaseImplement.Models
{
    public class Discipline : IDisciplineModel
    {
        public int ImplementerId { get; private set; }
        public string Name { get; private set; } = string.Empty;
        public double Price { get; set; }

        public DateOnly DateOfReceipt { get; private set; }

        public DateOnly DateOfPassage { get; private set; }


        private Dictionary<int, StudentByDisciplineModel>? _cachedClients = null;
        [NotMapped]
        public Dictionary<int, StudentByDisciplineModel> StudentsModel => 
            _cachedClients ??= Students.Select(x => (StudentByDisciplineModel)x).ToDictionary(x => x.StudentId, x => x);

        public int Id { get; private set; }

        [Required] 
        public Implementer? Student { get; private set; }
        [Required] 
        public List<StudentByDiscipline> Students { get; private set; } = new();

        [Required] 
        public List<RequirementByDiscipline> Requirements { get; private set; } = new();

        public static Discipline Create(DisciplineBindingModel model) =>
            model.CastWithCommonProperties<Discipline, DisciplineBindingModel>();

        public static implicit operator DisciplineViewModel?(Discipline? model)
        {
            if (model == null)
            {
                return null;
            }

            model._cachedClients = null;
            var res = model.CastWithCommonProperties<DisciplineViewModel, Discipline>();
            res.DirectorLogin = model.Student?.Login ?? string.Empty;
            res.RequirementViewModels = model.Requirements?
                .Select(x => (RequirementViewModel)x.Requirement)
                .ToList() ?? new();
            foreach (var studentByDiscipline in model.Students)
            {
                if (studentByDiscipline.Student != null)
                {
                    res.StudenttViewModels.Add(studentByDiscipline.Student.GetViewModel());
                }
                else
                {
                    res.StudentViewModels = new();
                    break;
                }
            }
            return res;
        }

        public void Update(DisciplineBindingModel model)
        {
            Price = model.Price;
            DateOfPassage = model.DateOfPassage;
        }

        public void UpdateClients(SchoolDB context, DisciplineBindingModel model)
        {
            var oldStudents = context.StudentsByDisciplines.Where(x => x.DisciplineId == model.Id).ToDictionary(x => x.StudentId, x => x);
            var newStudents = model.StudentsModel.ToDictionary(
                x => x.Key, 
                x =>
                {
                    var res = x.Value.CastWithCommonProperties<StudentByDiscipline, StudentByDisciplineModel>();
                    res.StudentId = x.Key;
                    res.DisciplineId = Id;
                    return res;
                });
            context.RemoveRange(oldStudents.Where(x => !newStudents.ContainsKey(x.Key)).Select(x => x.Value));
            context.SaveChanges();
            context.AddRange   (newStudents.Where(x => !oldStudents.ContainsKey(x.Key)).Select(x => x.Value));
            oldStudents
                .Where(x => newStudents.ContainsKey(x.Key))
                .Select(x => x.Value).ToList()
                .ForEach(x => x.DateOfClient = newStudents[x.StudentId].DateOfStudent);
            context.SaveChanges();
            _cachedClients = null;
        }
    }
}