using System;
using System.Collections.Generic;
using System.Reflection;
using JD.Collections;
using JD.Kernel.Classes;
using JD.LogService;

namespace JD.TeaBoxAddinSystem.Addins.MEF
{
    public static class AddinService
    {
        #region Variables

        private static IAddinService ms_instance = new EmptyAddinService();

        #endregion

        #region Properties

        private static IAddinService Instance
        {
            get
            {
                return ms_instance;
            }
        }

        public static IEnumerable<IAddin> Addins
        {
            get { return Instance.Addins; }
        }

        public static ObservableList<Assembly> DynamicAssemblies
        {
            get { return Instance.DynamicAssemblies; }
        }

        #endregion

        #region Methods

        public static IDisposable Use(IAddinService instance)
        {
            var oldInstance = ms_instance;
            ms_instance = instance;

            return new DisposableHelper(() => ms_instance = oldInstance);
        }

        #region Facade

        /// <summary>
        /// Satisfies all imports on the given <paramref name="part"/>.
        /// </summary>
        /// <param name="part"></param>
        public static void Compose(object part)
        {
            Instance.Compose(part);
        }

        /// <summary>
        /// Creates and composes a new object of type <typeparamref name="T"/>.
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <returns></returns>
        public static T Compose<T>()
            where T: new()
        {
            T instance = new T();
            Compose(instance);
            return instance;
        }

        /// <summary>
        /// Validates the addin ecosystem for common errors/problems.
        /// </summary>
        /// <param name="logger"></param>
        public static bool Validate(ILogger logger)
        {
            return Instance.Validate(logger);
        }

        #endregion

        #endregion
    }
}