using LinFu.IoC.Interfaces;

namespace LinFu.IoC
{
    /// <summary>
    ///     An adapter that converts strongly-typed IFactory&lt;T&gt;
    ///     instances into an equivalent IFactory instance.
    /// </summary>
    /// <typeparam name="T">The service type to create.</typeparam>
    public class FactoryAdapter<T> : IFactory, IFactory<T>
    {
        private readonly object _factory;

        /// <summary>
        ///     Creates the factory adapter using the given
        ///     IFactory&lt;T&gt; instance.
        /// </summary>
        /// <param name="factory">
        ///     The factory instance that
        ///     will be called every time the <see cref="IFactory.CreateInstance" /> method
        ///     is called.
        /// </param>
        public FactoryAdapter(object factory)
        {
            _factory = factory;
        }

        /// <summary>
        ///     The factory that will create the service instance.
        /// </summary>
        public IFactory<T> Factory => _factory as IFactory<T>;


        /// <summary>
        ///     Overridden. Uses the strongly-typed factory
        ///     to create the service instance every time
        ///     the <see cref="IFactory.CreateInstance" /> method
        ///     is called.
        /// </summary>
        /// <param name="request">The <see cref="IFactoryRequest" /> instance that describes the requested service.</param>
        /// <returns>An object instance that represents the service to be created. This cannot be <c>null</c>.</returns>
        public object CreateInstance(IFactoryRequest request)
        {
            if (_factory == null)
                return default(T);

            var factory = _factory as IFactory<T>;
            if (factory == null)
                return default(T);

            return factory.CreateInstance(request);
        }


        T IFactory<T>.CreateInstance(IFactoryRequest request)
        {
            var factory = _factory as IFactory<T>;
            if (factory == null)
                return default(T);

            return factory.CreateInstance(request);
        }
    }
}