using System;

namespace Umbraco.Cms.Core.Events
{
    /// <summary>
    /// Extension methods for cancellable event operations
    /// </summary>
    public static class EventExtensions
    {
        // keep these two for backward compatibility reasons but understand that
        // they are *not* part of any scope / event dispatcher / anything...

        /// <summary>
        /// Raises a cancelable event and returns a value indicating whether the event should be cancelled.
        /// </summary>
        /// <typeparam name="TSender">The type of the event source.</typeparam>
        /// <typeparam name="TArgs">The type of the event data.</typeparam>
        /// <param name="eventHandler">The event handler.</param>
        /// <param name="args">The event source.</param>
        /// <param name="sender">The event data.</param>
        /// <returns>A value indicating whether the cancelable event should be cancelled</returns>
        /// <remarks>A cancelable event is raised by a component when it is about to perform an action that can be canceled.</remarks>
        public static bool IsRaisedEventCancelled<TSender, TArgs>(this TypedEventHandler<TSender, TArgs> eventHandler, TArgs args, TSender sender)
            where TArgs : CancellableEventArgs
        {
            if (eventHandler == null) return args.Cancel;
            eventHandler(sender, args);
            return args.Cancel;
        }

        /// <summary>
        /// Raises an event.
        /// </summary>
        /// <typeparam name="TSender">The type of the event source.</typeparam>
        /// <typeparam name="TArgs">The type of the event data.</typeparam>
        /// <param name="eventHandler">The event handler.</param>
        /// <param name="args">The event source.</param>
        /// <param name="sender">The event data.</param>
        public static void RaiseEvent<TSender, TArgs>(this TypedEventHandler<TSender, TArgs> eventHandler, TArgs args, TSender sender)
            where TArgs : EventArgs
        {
            if (eventHandler == null) return;
            eventHandler(sender, args);
        }
    }
}