SushiBarBase/SushiBar/SushiBarFileImplement/Implements/ImplementerStorage.cs

using SushiBarContracts.BindingModels;
using SushiBarContracts.SearchModels;
using SushiBarContracts.StoragesContracts;
using SushiBarContracts.ViewModels;
using SushiBarFileImplement.Models;

namespace SushiBarFileImplement.Implements
{
    public class ImplementerStorage : IImplementerStorage
    {
        private readonly DataFileSingleton source;
        public ImplementerStorage()
        {
            source = DataFileSingleton.GetInstance();
        }
        public List<ImplementerViewModel> GetFullList()
        {
            return source.Implementers
            .Select(x => x.GetViewModel)
           .ToList();
        }
        public List<ImplementerViewModel> GetFilteredList(ImplementerSearchModel model)
        {
            if (string.IsNullOrEmpty(model.ImplementerFIO) && string.IsNullOrEmpty(model.Password))
            {
                return new();
            }
            return source.Implementers
                .Where(x => 
                    (string.IsNullOrEmpty(model.ImplementerFIO) || x.ImplementerFIO.Contains(model.ImplementerFIO)) &&
                    (string.IsNullOrEmpty(model.Password) || x.Password.Contains(model.Password)))
                .Select(x => x.GetViewModel)
                .ToList();
        }
        public ImplementerViewModel? GetElement(ImplementerSearchModel model)
        {
            return source.Implementers
                .FirstOrDefault(x =>
                    (string.IsNullOrEmpty(model.ImplementerFIO) || x.ImplementerFIO == model.ImplementerFIO) &&
                    (!model.Id.HasValue || x.Id == model.Id) &&
                    (string.IsNullOrEmpty(model.Password) || x.Password == model.Password))
                ?.GetViewModel;
        }
        public ImplementerViewModel? Insert(ImplementerBindingModel model)
        {
            model.Id = source.Implementers.Count > 0 ? source.Implementers.Max(x => x.Id) + 1 : 1;
            var newImplementer = Implementer.Create(model);
            if (newImplementer == null)
            {
                return null;
            }
            source.Implementers.Add(newImplementer);
            source.SaveImplementers();
            return newImplementer.GetViewModel;
        }
        public ImplementerViewModel? Update(ImplementerBindingModel model)
        {
            var implementer = source.Implementers.FirstOrDefault(x => x.Id == model.Id);
            if (implementer == null)
            {
                return null;
            }
            implementer.Update(model);
            source.SaveImplementers();
            return implementer.GetViewModel;
        }
        public ImplementerViewModel? Delete(ImplementerBindingModel model)
        {
            var element = source.Implementers.FirstOrDefault(rec => rec.Id == model.Id);
            if (element != null)
            {
                source.Implementers.Remove(element);
                source.SaveImplementers();
                return element.GetViewModel;
            }
            return null;
        }
    }
}