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

namespace Menu
{
    internal class Program
    {
        private static readonly Random random = new Random();

        private static void Main(string[] args)
        {
            var mujList = new List();
            mujList.Add("Boháč");
            mujList.Add("kokot");
            var count = 2;


            var root = new MenuItem("Hlavní menu");
            var item1 = new MenuItem("Fronta");
            var item2 = new MenuItem("Zásobník");
            var item3 = new MenuItem("Přidat");
            var item4 = new MenuItem("Odebrat");
            var item5 = new MenuItem("Počet");
            var item6 = new MenuItem("Peek");
            var item7 = new MenuItem("Vypiš");


            root.Items.Add(item1);
            root.Items.Add(item2);

            item1.Items.Add(item3);
            item1.Items.Add(item4);
            item1.Items.Add(item5);
            item1.Items.Add(item6);
            item1.Items.Add(item7);
            var current = root;
            while (true)
            {
                current.Draw();
                var key = Console.ReadKey(true);
                switch (key.Key)
                {
                    case ConsoleKey.UpArrow:
                        if (current.SelectedItemIndex - 1 >= 0)
                            current.SelectedItemIndex--;
                        break;
                    case ConsoleKey.DownArrow:
                        if (current.SelectedItemIndex + 1 < current.Items.Count)
                            current.SelectedItemIndex++;
                        break;
                    case ConsoleKey.Enter:
                        var selected = current.Items[current.SelectedItemIndex];
                        if (selected == item3)
                        {
                            mujList.Add(RandomString(7));
                            count++;
                        }
                        else if (selected == item4)
                        {
                            mujList.RemoveAt(0);
                            count--;
                        }
                        else if (selected == item5)
                        {
                            Console.WriteLine(count);
                            Console.ReadLine();
                        }
                        else if (selected == item6)
                        {

                        }
                        else if (selected == item7)
                        {
                            foreach (var item in mujList)
                                Console.WriteLine(item);
                            Console.ReadLine();
                        }
                        else
                        {
                            current = selected;
                        }
                        break;
                    case ConsoleKey.Escape:
                        current = root;
                        break;
                }
            }
        }

        public static string RandomString(int length)
        {
            const string chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
            return new string(Enumerable.Repeat(chars, length)
                .Select(s => s[random.Next(s.Length)]).ToArray());
        }
    }


    internal class MenuItem
    {
        private int _selectedItemIndex;


        public MenuItem(string title)
        {
            Title = title;
        }

        public string Title { get; set; } = "Titulek";
        public List<MenuItem> Items { get; set; } = new List<MenuItem>();

        public int SelectedItemIndex
        {
            get => _selectedItemIndex;
            set
            {
                if (value < 0) throw new Exception("Vybraná položka menu nemůže být záporná");
                if (value >= Items.Count)
                    throw new Exception("Vybraná položka menu musí být v rozsahu 0-počet položek");
                _selectedItemIndex = value;
            }
        }

        public int Width
        {
            get
            {
                var width = Title.Length;
                for (var j = 0; j < Items.Count; j++)
                    if (width < Items[j].Title.Length)
                        width = Items[j].Title.Length;
                return width;
            }
        }

        public void Draw()
        {
            Console.Clear();
            Console.OutputEncoding = Encoding.UTF8;

            var w = Width;

            var centerX = Console.WindowWidth / 2 - w / 2;

            Console.CursorTop = Console.WindowHeight / 2 - (Items.Count + 4) / 2;
            Console.CursorLeft = centerX - w / 2 - 1;

            Console.Write("┌");
            for (var i = 0; i < w; i++)
                Console.Write("─");
            Console.WriteLine("┐");

            Console.CursorLeft = centerX - w / 2 - 1;
            Console.WriteLine($"│{Title.PadLeft(w)}│");
            Console.CursorLeft = centerX - w / 2 - 1;

            Console.Write("├");
            for (var i = 0; i < w; i++)
                Console.Write("─");
            Console.WriteLine("┤");

            for (var index = 0; index < Items.Count; index++)
            {
                var menuItem = Items[index];
                Console.CursorLeft = centerX - w / 2 - 1;
                Console.Write($"│");
                if (index == _selectedItemIndex)
                {
                    var tmp = Console.BackgroundColor;
                    Console.BackgroundColor = Console.ForegroundColor;
                    Console.ForegroundColor = tmp;
                }
                Console.Write($"{menuItem.Title.PadLeft(w)}");
                if (index == _selectedItemIndex)
                {
                    var tmp = Console.BackgroundColor;
                    Console.BackgroundColor = Console.ForegroundColor;
                    Console.ForegroundColor = tmp;
                }
                Console.WriteLine("│");
            }

            Console.CursorLeft = centerX - w / 2 - 1;

            Console.Write("└");
            for (var i = 0; i < w; i++)
                Console.Write("─");
            Console.WriteLine("┘");
        }
    }

    internal class ListItem
    {
        public string Data;
        public ListItem Next;
    }

    internal class List : IEnumerable
    {
        private ListItem first;
        private ListItem last;

        public IEnumerator GetEnumerator()
        {
            return new MyEnumerator(first);
        }

        public void Add(string data)
        {
            var tmp = new ListItem();
            tmp.Data = data;
            if (last == null)
            {
                first = last = tmp;
            }
            else
            {
                last.Next = tmp;
                last = tmp;
            }
        }


        public void RemoveAt(int index)
        {
            if (index == 0)
            {
                var tmp = first.Next;
                first = tmp;
            }
            else
            {
                var tmp = first;
                for (var i = 0; i < index - 1; i++)
                    tmp = tmp.Next;
                tmp.Next = tmp.Next.Next;
            }
        }

        private class MyEnumerator : IEnumerator
        {
            private ListItem curr;
            private readonly ListItem first;

            public MyEnumerator(ListItem first)
            {
                this.first = curr = first;
            }

            public bool MoveNext()
            {
                curr = curr.Next;
                return curr != null;
            }

            public void Reset()
            {
                curr = first;
            }

            public object Current => curr.Data;
        }
    }
}