marechai/Marechai/Services/ScreensByMachineService.cs

using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Marechai.Database.Models;
using Marechai.ViewModels;
using Microsoft.EntityFrameworkCore;

namespace Marechai.Services
{
    public class ScreensByMachineService
    {
        readonly MarechaiContext _context;

        public ScreensByMachineService(MarechaiContext context) => _context = context;

        public async Task<List<ScreenByMachineViewModel>> GetByMachine(int machineId) =>
            await _context.ScreensByMachine.Where(s => s.MachineId == machineId).
                           Select(s => new ScreenByMachineViewModel
                           {
                               Id = s.Id, ScreenId = s.ScreenId, MachineId = s.MachineId, Screen = new ScreenViewModel
                               {
                                   Diagonal = s.Screen.Diagonal, EffectiveColors = s.Screen.EffectiveColors,
                                   Height   = s.Screen.Height, Id                = s.Screen.Id, NativeResolution =
                                       new ResolutionViewModel
                                       {
                                           Chars = s.Screen.NativeResolution.Chars,
                                           Colors = s.Screen.NativeResolution.Colors,
                                           Grayscale = s.Screen.NativeResolution.Grayscale,
                                           Height = s.Screen.NativeResolution.Height, Id = s.Screen.NativeResolutionId,
                                           Palette = s.Screen.NativeResolution.Palette,
                                           Width = s.Screen.NativeResolution.Width
                                       },
                                   NativeResolutionId = s.Screen.NativeResolutionId, Type = s.Screen.Type,
                                   Width              = s.Screen.Width
                               }
                           }).ToListAsync();

        public async Task DeleteAsync(long id)
        {
            ScreensByMachine item = await _context.ScreensByMachine.FindAsync(id);

            if(item is null)
                return;

            _context.ScreensByMachine.Remove(item);

            await _context.SaveChangesAsync();
        }

        public async Task<long> CreateAsync(int machineId, int screenId)
        {
            if(_context.ScreensByMachine.Any(s => s.MachineId == machineId && s.ScreenId == screenId))
                return 0;

            var item = new ScreensByMachine
            {
                ScreenId = screenId, MachineId = machineId
            };

            await _context.ScreensByMachine.AddAsync(item);
            await _context.SaveChangesAsync();

            return item.Id;
        }
    }
}