using System;
using System.Collections;
using System.Collections.Generic;

    class Program
    {
        static void Main(string[] args)
        {
            //Test with classes
            string[] classesList1 = new[] {"a", "b", "c"};
            string[] classesList2 = new[] { "1", "2", "3" };
            List<string[]> classesListCombined = new List<string[]> { classesList1, classesList2 };

            Console.WriteLine("classesList1: {0}", String.Join(",", classesList1.SelectManyRecusive<string>()));
            Console.WriteLine("classesListCombined: {0}", String.Join(",", classesListCombined.SelectManyRecusive<string>()));

            //Test with structs
            int[] structList1 = new[] { 1, 2, 3 };
            int[] structList2 = new[] { 4, 5, 6 };
            List<int[]> structListCombined = new List<int[]> { structList1, structList2 };


            Console.WriteLine("structList1: {0}", String.Join(",", structList1.SelectManyRecusive<int>()));
            Console.WriteLine("structListCombined: {0}", String.Join(",", structListCombined.SelectManyRecusive<int>()));

            //Test tripple nesting

            var nest1 = new[] {1, 2, 3};
            var nest2 = new[] { 4, 5, 6 };
            var nest3 = new[] { 7, 8, 9 };
            var nest4 = new[] {10, 11, 12};

            var layer1 = new[] {nest1, nest2};
            var layer2 = new[] {nest3, nest4};
            var top = new[] {layer1, layer2};


            Console.WriteLine("top: {0}", String.Join(",", top.SelectManyRecusive<int>()));

            Console.ReadLine();

        }
    }

    internal static class ExtensionMethods
    {
        public static IEnumerable<T> SelectManyRecusive<T>(this IEnumerable enumerable)
        {
            foreach (var item in enumerable)
            {
                var castEnumerable = item as IEnumerable;
                if (castEnumerable != null 
                    && ((typeof(T) != typeof(string)) || !(castEnumerable is string))) //Don't split string to char if string is our target
                {
                    foreach (var inner in SelectManyRecusive<T>(castEnumerable))
                    {
                        yield return inner;
                    }
                }
                else
                {
                    if (item is T)
                    {
                        yield return (T) item;
                    }
                }
            }
        }
    }