// Needed for NET40
#if !NET_4_6
using System;
using LinqInternal.Core;

namespace LinqInternal.Collections
{
    [Serializable]
    internal sealed class CustomObserver<T> : IObserver<T>
    {
        private readonly Action _onCompleted;
        private readonly Action<Exception> _onError;
        private readonly Action<T> _onNext;

        public CustomObserver(Action<T> onNext)
        {
            _onCompleted = ActionHelper.GetNoopAction();
            _onError = ActionHelper.GetNoopAction<Exception>();
            _onNext = onNext ?? ActionHelper.GetNoopAction<T>();
        }

        public CustomObserver(Action onCompleted, Action<Exception> onError, Action<T> onNext)
        {
            _onCompleted = onCompleted ?? ActionHelper.GetNoopAction();
            _onError = onError ?? ActionHelper.GetNoopAction<Exception>();
            _onNext = onNext ?? ActionHelper.GetNoopAction<T>();
        }

        public void OnCompleted()
        {
            var onCompleted = _onCompleted;
            onCompleted();
        }

        public void OnError(Exception error)
        {
            var onError = _onError;
            onError(error);
        }

        public void OnNext(T value)
        {
            var onNext = _onNext;
            onNext(value);
        }
    }
}
#endif