using System.Collections.Generic;
using System.Linq;

using FluentValidation;

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

namespace MfGames.Nitride.Temporal.Schedules;

public enum SchedulePeriod
{
    /// <summary>
    /// Indicates that all the matching schedule periods are instant (zero time).
    /// </summary>
    Instant,

    /// <summary>
    /// Indicates that the entities will be scheduled a day apart.
    /// </summary>
    Day,

    /// <summary>
    /// Indicates that the entities will be scheduled seven days apart.
    /// </summary>
    Week,
}

/// <summary>
/// Applies schedules against the list of entities.
/// </summary>
[WithProperties]
public partial class ApplySchedules : OperationBase
{
    private readonly IValidator<ApplySchedules> validator;

    public ApplySchedules(
        IValidator<ApplySchedules> validator,
        Timekeeper timekeeper)
    {
        this.Timekeeper = timekeeper;
        this.validator = validator;
        this.Schedules = new List<ISchedule>();
    }

    /// <summary>
    /// Gets or sets the ordered list of schedules to apply to the entities.
    /// </summary>
    public IList<ISchedule> Schedules { get; set; }

    /// <summary>
    /// Gets or sets the timekeeper associated with this operation.
    /// </summary>
    public Timekeeper Timekeeper { get; set; }

    /// <inheritdoc />
    public override IEnumerable<Entity> Run(IEnumerable<Entity> input)
    {
        this.validator.ValidateAndThrow(this);

        return input.Select(this.Apply);
    }

    public ApplySchedules WithSchedules<TItem>(IEnumerable<TItem> items)
        where TItem : ISchedule
    {
        this.Schedules = items.OfType<ISchedule>().ToList();
        return this;
    }

    private Entity Apply(Entity entity)
    {
        foreach (ISchedule schedule in this.Schedules)
        {
            if (!schedule.CanApply(entity))
            {
                continue;
            }

            entity = schedule.Apply(entity, this.Timekeeper);
        }

        return entity;
    }
}