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

namespace Delegates.TreeTraversal
{
    public static class Traversal
    {
        private static IEnumerable<TResult> Travers<TData,TResult>(
            TData data,
            Func<TData, IEnumerable<TResult>> getResults,
            Func<TData, IEnumerable<TData>> updateStack)
        {
            var stack = new Stack<TData>();
            stack.Push(data);
            while (stack.Count > 0)
            {
                var temp = stack.Pop();
                foreach (var res in getResults(temp))
                    yield return res;
                foreach (var res in updateStack(temp))
                    stack.Push(res);
            }
        }
        public static IEnumerable<TParameters> GetBinaryTreeValues<TParameters>(BinaryTree<TParameters> data)
        {
            return Travers(
                data,
                x => new List<TParameters> {x.Value},
                tree => new[] {tree.Left, tree.Right}.Where(x => x != null));
        }
        public static IEnumerable<Job> GetEndJobs(Job data)
        {
            return Travers(
                data,
                x => x.Subjobs.Count == 0 ? new[] {x} : new Job[0],
                tree => tree.Subjobs);
        }
        public static IEnumerable<Product> GetProducts(ProductCategory data)
        {
            return Travers(
                data,
                x => x.Products,
                tree => tree.Categories);
        }
    }
}