using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
using MongoDB.Driver;

namespace xDataService.Mongo {
    public class XMongoAsyncCursor<T> : IAsyncCursor<T> {
        public IEnumerable<T> Current { get; }
        private IEnumerator<T> CurrentEnumerator { get; }

        public XMongoAsyncCursor (IEnumerable<T> source) {
            this.Current = source;
            this.CurrentEnumerator = source.GetEnumerator ();
        }

        public void Dispose () {
            CurrentEnumerator.Dispose ();
        }

        public bool MoveNext (CancellationToken cancellationToken = default) {
            return CurrentEnumerator.MoveNext ();
        }

        public Task<bool> MoveNextAsync (CancellationToken cancellationToken = default) {
            return Task.Run (
                () => CurrentEnumerator.MoveNext (),
                cancellationToken : cancellationToken
            );
        }
    }
}