using System;

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

using NodaTime;

namespace MfGames.Nitride.Temporal.Schedules;

/// <summary>
/// A schedule that goes against all entities it is applied to.
/// </summary>
[WithProperties]
public partial class SimplePathSchedule : ISchedule
{
    /// <summary>
    /// Gets or sets when the first item is scheduled.
    /// </summary>
    public DateTime? ScheduleStart { get; set; }

    /// <inheritdoc />
    public virtual Entity Apply(
        Entity entity,
        TimeService timeService)
    {
        DateTime start = this.ScheduleStart
            ?? throw new NullReferenceException(
                "Cannot use a schedule without a start date.");
        Instant instant = timeService.CreateInstant(start);

        // If the time hasn't past, then we don't apply it.
        Instant now = timeService.Clock.GetCurrentInstant();

        return instant > now
            ? entity
            : this.Apply(entity, instant);
    }

    /// <inheritdoc />
    public virtual bool CanApply(Entity entity)
    {
        return true;
    }

    protected virtual Entity Apply(
        Entity entity,
        Instant instant)
    {
        return entity.Set(instant);
    }
}