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

namespace xDataService.Providers
{
    /// <summary>
    /// Default Guid Key Generator ...
    /// </summary>
    /// <typeparam name="TEntity"></typeparam>
    public class XGuidKeyGenerator<TEntity> : XKeyGenerator<TEntity, Guid>, IXKeyGenerator<TEntity, Guid>
    where TEntity : XBaseEntity<Guid>
    {
        private readonly IXSequentialGuid sequentialGuid;

        public XGuidKeyGenerator(
            IXSequentialGuid sequentialGuid = null
        )
        {
            this.sequentialGuid = sequentialGuid;
        }

        public override async Task<Guid> GenerateKey(
            IXBaseRepository<TEntity, Guid> repository,
            CancellationToken cancellationToken = default
        )
        {
            //
            return await Task.Run(() =>
            {
                //
                // Check if provided SequentialGuid ...
                if (sequentialGuid.IsNull())
                {
                    return Guid.NewGuid();
                }
                else
                {
                    return sequentialGuid.Next();
                }
            }, cancellationToken: cancellationToken);
        }

        public override bool IsEmpty(Guid id)
        {
            //
            var result = id.IsNull() || id.IsDefaultGuid();

            //
            return result;
        }
    }
}