namespace Chernobyl.Creation
{
    /// <summary>
    /// A implementation of <see cref="IBuilder"/> to help in the creation
    /// of <see cref="IBuilder"/> types.
    /// </summary>
    public abstract class Builder : IBuilder
    {
        /// <summary>
        /// An event that is raised when this <see cref="IBuilder" /> creates
        /// an instance.
        /// </summary>
        public event CreationCompletedEventHandler Created
        {
            add { CreatedMethod += value; }
            // ReSharper disable DelegateSubtraction
            // Delegate subtraction is fine here since we are simply forwarding
            // the operation to the CreatedMethod. Client must be aware of their
            // actions in this case.
            remove { CreatedMethod -= value; }
            // ReSharper restore DelegateSubtraction
        }

        /// <summary>
        /// Raises the <see cref="Created"/> event with <paramref name="e"/> as its args.
        /// </summary>
        protected void ReportCreation(CreationEventArgs e) => CreatedMethod?.Invoke(this, e);

        /// <summary>
        /// Raises the <see cref="Created"/> event with <paramref name="created"/> the creation to
        /// report.
        /// </summary>
        protected void ReportCreation(object created) => ReportCreation(new CreationEventArgs(created));

        /// <summary>
        /// The <see cref="Created"/> event in the form of a method.
        /// </summary>
        protected CreationCompletedEventHandler CreatedMethod { get; private set; }
    }

    /// <summary>
    /// A implementation of <see cref="IBuilder{T}"/> to help in the creation
    /// of <see cref="IBuilder{T}"/> types.
    /// </summary>
    /// <typeparam name="TResult">The type that is being constructed and/or
    /// configured.</typeparam>
    public abstract class Builder<TResult> : Builder, IBuilder<TResult>
    {
        /// <summary>
        /// Initializes a new instance of the <see cref="Builder{TResult}"/> class.
        /// </summary>
        protected Builder()
        {
            // Any creation events raised from this type should also be raised
            // from the base class.
            Created += (sender, args) =>
            {
                base.CreatedMethod?.Invoke(this, args);
            };
        }

        /// <summary>
        /// An event that is raised when this <see cref="IBuilder{T}" /> creates
        /// an instance.
        /// </summary>
        public new event CreationCompletedEventHandler<TResult> Created
        {
            add { CreatedMethod += value; }
            // ReSharper disable DelegateSubtraction
            // Delegate subtraction is fine here since we are simply forwarding
            // the operation to the CreatedMethod. Client must be aware of their
            // actions in this case.
            remove { CreatedMethod -= value; }
            // ReSharper restore DelegateSubtraction
        }

        /// <summary>
        /// Raises the <see cref="Created"/> event with <paramref name="e"/> as its args.
        /// </summary>
        protected void ReportCreation(CreationEventArgs<TResult> e) => CreatedMethod?.Invoke(this, e);

        /// <summary>
        /// Raises the <see cref="Created"/> event with <paramref name="created"/> the creation to
        /// report.
        /// </summary>
        protected void ReportCreation(TResult created) => ReportCreation(new CreationEventArgs<TResult>(created));

        /// <summary>
        /// The <see cref="Created"/> event in the form of a method.
        /// </summary>
        protected new CreationCompletedEventHandler<TResult> CreatedMethod { get; private set; }
    }
}