using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using System.Reflection;

namespace SharpLib.Utils

{

    public class Reflection

    {

        /// <summary>

        /// Get a list of all the concrete types derived from the given type in all loaded assembly.

        /// That includes the given type itself if it's intanciable.

        /// </summary>

        /// <typeparam name="T"></typeparam>

        /// <returns></returns>

        public static IEnumerable<Type> GetConcreteClassesDerivedFrom<T>() where T : class

        {

            List<Type> objects = new List<Type>();

            foreach (Assembly asm in AppDomain.CurrentDomain.GetAssemblies())

            {

                foreach (Type type in asm.GetTypes()                        

                        .Where(myType => myType.IsClass && !myType.IsAbstract && (myType.IsSubclassOf(typeof(T)) || myType == typeof(T))))

                {

                    objects.Add(type);

                }

            }

            return objects;

        }

        /// <summary>

        /// Get a dictionary of all the concrete types derived from the given type in all loaded assembly.

        /// </summary>

        /// <typeparam name="T"></typeparam>

        /// <returns></returns>

        public static IDictionary<string, Type> GetConcreteClassesDerivedFromByName<T>() where T : class

        {

            Dictionary<string, Type> objects = new Dictionary<string, Type>();

            foreach (Assembly asm in AppDomain.CurrentDomain.GetAssemblies())

            {

                foreach (Type type in asm.GetTypes()

                .Where(myType => myType.IsClass && !myType.IsAbstract && myType.IsSubclassOf(typeof(T))))

                {

                    objects.Add(type.Name, type);

                }

            }

            return objects;

        }

        /// <summary>

        /// Get a list of an instance of all the types derived from the given type in all loaded assembly.

        /// </summary>

        /// <typeparam name="T"></typeparam>

        /// <returns></returns>

        public static IEnumerable<T> GetConcreteClassesInstanceDerivedFrom<T>() where T : class

        {

            List<T> objects = new List<T>();

            foreach (Assembly asm in AppDomain.CurrentDomain.GetAssemblies())

            {

                foreach (Type type in asm.GetTypes()

                .Where(myType => myType.IsClass && !myType.IsAbstract && myType.IsSubclassOf(typeof(T))))

                {

                    objects.Add((T)Activator.CreateInstance(type));

                }

            }

            if (objects.Count>0

                && objects[0] is IComparable)

            {

                objects.Sort();

            }

            return objects;

        }

        /// <summary>

        /// Get a dictionary of an instance of all the types derived from the given type in all loaded assembly.

        /// </summary>

        /// <typeparam name="T"></typeparam>

        /// <returns></returns>

        public static IDictionary<string, T> GetConcreteClassesInstanceDerivedFromByName<T>() where T : class

        {

            Dictionary<string, T> objects = new Dictionary<string, T>();

            foreach (Assembly asm in AppDomain.CurrentDomain.GetAssemblies())

            {

                foreach (Type type in asm.GetTypes()

                .Where(myType => myType.IsClass && !myType.IsAbstract && myType.IsSubclassOf(typeof(T))))

                {

                    objects.Add(type.Name, (T)Activator.CreateInstance(type));

                }

            }

            return objects;

        }

        /// <summary>

        /// Get the attribute instance matching the given attribute type from the specified type.

        /// </summary>

        /// <typeparam name="T"></typeparam>

        /// <param name="aType"></param>

        /// <returns></returns>

        public static T GetAttribute<T>(Type aType) where T : class

        {

            object[] attrs = aType.GetCustomAttributes(true);

            foreach (object attr in attrs)

            {

                T attribute = attr as T;

                if (attribute != null)

                {

                    return attribute;

                }

            }

            return null;

        }

        /// <summary>

        /// Get a list of all the types derived from the given type in all loaded assembly.

        /// </summary>

        /// <param name="baseType"></param>

        /// <param name="assembly"></param>

        /// <returns></returns>

        public static IEnumerable<Type> GetDerivedTypes<T>() where T: class

        {

            List<Type> types = new List<Type>();

            foreach (Assembly asm in AppDomain.CurrentDomain.GetAssemblies())

            {

                foreach (Type type in asm.GetTypes()

                .Where(myType => myType.IsClass && myType.IsSubclassOf(typeof(T))))

                {

                    types.Add(type);

                }

            }

            return types;

        }

    }

}