using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using xCommons.Extensions;
using xDataService.Extensions;
using xDataService.Interfaces;
using xModels.Base;

namespace xDataService.Providers
{
    /// <summary>
    /// Default Int Key Generator ...
    /// </summary>
    /// <typeparam name="TEntity"></typeparam>
    public class XIntKeyGenerator<TEntity> : XKeyGenerator<TEntity, int>, IXKeyGenerator<TEntity, int>
    where TEntity : XBaseEntity<int>
    {
        public override async Task<int> GenerateKey(
            IXBaseRepository<TEntity, int> repository,
            CancellationToken cancellationToken = default
        )
        {
            //
            var items = (await repository.GetAllAsync())
                .OrderByDescending(nameof(XBaseEntity<int>.Id));
            var last = items
                .FirstOrDefault();

            //
            var result = last.IsNull() ? 1 : last.Id + 1;

            //
            return result;
        }

        public override bool IsEmpty(int id)
        {
            //
            var result = id <= 0;

            //
            return result;
        }
    }
}