CourseWork_GradeBook_Backend/GradeBookServer.Application/Services/FacultyService.cs

using GradeBookServer.Application.Common.Specifications;
using GradeBookServer.Application.DTOs.Direction;
using GradeBookServer.Application.DTOs.Faculty;
using GradeBookServer.Application.DTOs.Student;
using GradeBookServer.Application.Interfaces;
using GradeBookServer.Domain.Entities;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace GradeBookServer.Application.Services
{
    public class FacultyService
    {
        private readonly IBaseRepository<Faculty> _baseRepository;

        public FacultyService(IBaseRepository<Faculty> baseRepository)
        {
            _baseRepository = baseRepository;
        }

        public async Task<FacultyReadDto?> GetFacultyByIdAsync(int id)
        {
            var faculty = await _baseRepository.GetByIdWithIncludeAsync(
                f => f.ID == id,
                new IncludeSpecification<Faculty>(f => f.Directions!)
            );

            if (faculty == null)
                return null;

            return new FacultyReadDto
            {
                ID = faculty.ID,
                Name = faculty.Name,
                Directions = faculty.Directions.Select(
                    d => new DirectionNameDto { ID = d.ID, Name = d.Name}
                    ).ToList()
            };
        }

        public async Task<IEnumerable<FacultyReadDto>?> GetAllFacultiesAsync()
        {
            var faculties = await _baseRepository.GetAllAsync(
                new IncludeSpecification<Faculty>(f => f.Directions!)
            );

            if (faculties == null)
                return null;

            return faculties.Select(f => new FacultyReadDto
            {
                ID = f.ID,
                Name = f.Name,
                Directions = f.Directions.Select(d => new DirectionNameDto { ID = d.ID, Name = d.Name }
                    ).ToList()
            });
        }

        public async Task AddFacultyAsync(FacultyCreateDto facultyDto)
        {
            var directions = await _baseRepository.GetManyByIdsAsync<Direction>(facultyDto.DirectionIds);

            var faculty = new Faculty
            {
                Name = facultyDto.Name,
                Directions = directions.ToList()
            };

            await _baseRepository.AddAsync(faculty);
        }

        public async Task<bool> UpdateFacultyAsync(int id, FacultyCreateDto facultyDto)
        {
            var faculty = await _baseRepository.GetByIdWithIncludeAsync(
                f => f.ID == id,
                new IncludeSpecification<Faculty>(f => f.Directions!)
            );

            if (faculty == null)
                return false;

            faculty.Name = facultyDto.Name;

            var directions = await _baseRepository.GetManyByIdsAsync<Direction>(facultyDto.DirectionIds);

            faculty.Directions.Clear();
            foreach (var dir in directions)
                faculty.Directions.Add(dir);

            await _baseRepository.UpdateAsync(faculty);
            return true;
        }

        public async Task<bool> DeleteFacultyAsync(int id)
        {
            var faculty = await _baseRepository.GetByIdAsync(id);
            if (faculty == null)
                return false;

            await _baseRepository.DeleteAsync(id);
            return true;
        }
    }
}