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

namespace ZeroLevel.Services.Async
{
    public class TimerAsyncBatchQueue<T>
        : IAsyncBatchCollection<T>, IDisposable
    {
        private readonly Timer _flushTimer;
        private readonly IAsyncBatchCollection<T> _innerCollection;

        public TimerAsyncBatchQueue(IAsyncBatchCollection<T> innerCollection, TimeSpan flushPeriod)
        {
            _innerCollection = innerCollection;
            _flushTimer = new Timer(_ => Flush(), null, flushPeriod, flushPeriod);
        }

        public int BatchSize => _innerCollection.BatchSize;
        public int Count => _innerCollection.Count;
        public void Add(T item) => _innerCollection.Add(item);
        public ValueTask<IReadOnlyList<T>> TakeAsync(CancellationToken cancellationToken) => _innerCollection.TakeAsync(cancellationToken);
        public void Flush() => _innerCollection.Flush();
        public IEnumerator<IReadOnlyList<T>> GetEnumerator() => _innerCollection.GetEnumerator();
        IEnumerator IEnumerable.GetEnumerator() => (_innerCollection as IEnumerable).GetEnumerator();

        public void Dispose() => _flushTimer.Dispose();
    }
}