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

namespace Chernobyl.Event
{
    /// <summary>
    /// An <see cref="EventArgs"/> used by an event when that event is reporting
    /// something that affects the items contained within an instance of this
    /// class.
    /// </summary>
    public class ItemsEventArgs : EventArgs
    {
        /// <summary>
        /// Constructor
        /// </summary>
        /// <param name="items">The items that were affected by the event.</param>
        public ItemsEventArgs(IEnumerable<object> items)
            : this(items.ToArray())
        {}

        /// <summary>
        /// Constructor
        /// </summary>
        /// <param name="items">The items that were affected by the event.</param>
        public ItemsEventArgs(object[] items)
        {
            // Note: the "items" parameter above is not a "params" argument as
            // "params" arguments can be dangerous. See here for more info:
            // http://daniel.wertheim.se/2012/01/18/c-why-params-object-should-be-forbidden/
            Items = items;
        }

        /// <summary>
        /// The items that were affected by the event.
        /// </summary>
        public object[] Items { get; protected set; }
    }

    /// <summary>
    /// An <see cref="EventArgs"/> used by an event when that event is reporting
    /// something that affects the items contained within an instance of this
    /// class. This type is the generic version of <see cref="ItemsEventArgs"/>.
    /// </summary>
    /// <typeparam name="T">The type of the items being affected.</typeparam>
    public class ItemsEventArgs<T> : ItemsEventArgs
    {
        /// <summary>
        /// Constructor
        /// </summary>
        /// <param name="items">The items that were affected by the event.</param>
        public ItemsEventArgs(IEnumerable<T> items)
            : this(items.ToArray())
        {}

        /// <summary>
        /// Constructor
        /// </summary>
        /// <param name="items">The items that were affected by the event.</param>
        public ItemsEventArgs(params T[] items)
            : base(items.Cast<object>())
        {
            Items = items;
        }

        /// <summary>
        /// The items that were affected by the event.
        /// </summary>
        public new T[] Items { get; protected set; }
    }
}