using System;
using System.Collections.Generic;
using Chernobyl.Update;

namespace Chernobyl.StateMachine
{
    /// <summary>
    /// A state than can be updated
    /// </summary>
    public class UpdateableState : State, IUpdateable
    {
        /// <summary>
        /// Creates an UpdateableState that uses an <see cref="List{T}"/>
        /// to store children IUpdateables.
        /// </summary>
        public UpdateableState() : this(new List<IUpdateable>())
        {}

        /// <summary>
        /// Constructor.
        /// </summary>
        /// <param name="childCollection">The list to use to hold onto children
        /// IUpdateables.</param>
        public UpdateableState(ICollection<IUpdateable> childCollection)
        {
            UpdateableChildren = childCollection;
        }

        /// <summary>
        /// Updates this state and it's children <see cref="IUpdateable"/> 
        /// instances.
        /// </summary>
        /// <param name="deltaTime">The amount of time that has
        /// passed since the last call to this update.</param>
        public virtual void Update(TimeSpan deltaTime)
        {
            foreach (IUpdateable child in UpdateableChildren)
            {
                child.Update(deltaTime);
            }
        }

        /// <summary>
        /// The parent of this IUpdateable.
        /// </summary>
        public IUpdateable UpdateableParent { get; set; }

        /// <summary>
        /// The children of this IUpdateable.
        /// </summary>
        public ICollection<IUpdateable> UpdateableChildren { get; set; }
    }
}