presence/data/Repository/SQLGroupRepository.cs

using data.DAO;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Microsoft.EntityFrameworkCore;

namespace data.Repository
{
    public class SQLGroupRepository : IGroupRepository
    {
        private readonly DatabaseContext _dbContext;
        public SQLGroupRepository(DatabaseContext dbContext)
        {
            _dbContext = dbContext;
        }

        public bool AddGroupWithStudents(Group group, IEnumerable<Student> students)
        {
            using var transaction = _dbContext.Database.BeginTransaction();
            try
            {
                _dbContext.Groups.Add(group);
                _dbContext.SaveChanges();
                foreach (var item in students)
                {
                    item.Group = group;
                    _dbContext.Students.Add(item);
                }
                _dbContext.SaveChanges();
                transaction.Commit();
                return true;
            }
            catch (Exception ex)
            {
                Debug.WriteLine("Во время добавления группы со студентами произошла ошибка: ", ex.Message);
                transaction.Rollback();
            } 
            return false;
        }

        public bool AddStudentsToGroup(int id, IEnumerable<Student> students)
        {
            using var transaction = _dbContext.Database.BeginTransaction();
            try
            {
                Group group = _dbContext.Groups.Find(id);
                foreach (var student in students)
                {
                    student.Group = group;
                    student.GroupId = id;
                    _dbContext.Students.Add(student);
                }

                _dbContext.SaveChanges();
                transaction.Commit();
                return true;
            }
            catch (Exception ex)
            {
                Console.WriteLine("Во время добавления студентов в группу произошла ошибка: ", ex.Message);
                transaction.Rollback();
            }

            return false;
        }

        public bool CreateGroup(Group group)
        {
            _dbContext.Groups.Add(group);
            return _dbContext.SaveChanges() > 0;
        }

        public bool DeleteGroup(int id)
        {
            Group group = _dbContext.Groups.Single(g => g.Id == id);
            _dbContext.Groups.Remove(group);
            return _dbContext.SaveChanges() > 0;
        }

        public IEnumerable<Group> GetAllGroups()
            => _dbContext.Groups
            .Include(g => g.Students)
            .Include(g => g.StudentGroupsSubjects)
                .ThenInclude(sgs => sgs.Subject)
            .ToList();

        public bool UpdateGroup(int id, string name)
        {
            Group group = _dbContext.Groups.Single(g => g.Id == id);
            group.Name = name;
            return _dbContext.SaveChanges() > 0;
        }

        public bool RemoveStudentsFromGroup(int id)
        {
            var students = _dbContext.Students.Where(s => s.GroupId == id).ToList();
            _dbContext.Students.RemoveRange(students);
            return _dbContext.SaveChanges() > 0;
        }

        public bool RemoveStudentsFromGroupByIds(int id, IEnumerable<int> studentIds)
        {
            var studentsToRemove = _dbContext.Students
                .Where(s => s.GroupId == id && studentIds.Contains(s.Id))
                .ToList();

            if (studentsToRemove.Any())
            {
                _dbContext.Students.RemoveRange(studentsToRemove);
                return _dbContext.SaveChanges() > 0;
            }

            return false;
        }
    }
}