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

using MfGames.Gallium;
using MfGames.Nitride.Generators;

using NodaTime;

namespace MfGames.Nitride.Temporal;

/// <summary>
/// Filters out all entities that have an instant before the current
/// NitrideClock time.
/// </summary>
[WithProperties]
public partial class FilterOutFutureInstant : OperationBase
{
    public FilterOutFutureInstant(TimeService timeService)
    {
        this.TimeService = timeService;
    }

    public TimeService TimeService { get; set; }

    /// <inheritdoc />
    public override IEnumerable<Entity> Run(
        IEnumerable<Entity> input,
        CancellationToken cancellationToken = default)
    {
        Instant now = this.TimeService.Clock.GetCurrentInstant();

        return input
            .SelectEntity<Instant>(
                (
                        entity,
                        instant) =>
                    instant.CompareTo(now) <= 0 ? entity : null);
    }
}