Zadatak 2 - Generic

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

namespace Vezba_04_2017
{
    class GenericStack<T>
    {
       class GenericStackNode<T>
        {
            public GenericStackNode(T t)
            {
                Content = t;
                Next = null;
            }

            public T Content { get; set; }
            public GenericStackNode<T> Next { get; set; }
        }



        private GenericStackNode<T> _head;

        public int Lenght
        {
            get
            {
                int lenght = 0;

                GenericStackNode<T> current = _head;
                while(current != null)
                {
                    current = current.Next;
                    lenght++;
                }
                return lenght;
            }
        }

        public bool IsEmpty
        {
            get { return _head == null; }
        }

        public T this[int index]
        {
            get
            {
                return GetNode(index).Content;
            }
            set
            {
                GetNode(index).Content = value;
            }
        }

        private GenericStackNode<T> GetNode(int index)
        {
            if (index < 0 || index >= Lenght)
                throw new IndexOutOfRangeException();

            GenericStackNode<T> current = _head;
            for (int i = 0; i < index; i++)
                current = current.Next;

            return current;
        }

        public void AddFirst(T content)
        {
            GenericStackNode<T> newNode = new GenericStackNode<T>(content);
            newNode.Next = _head;
            _head = newNode;
        }

        public void AddLast(T content)
        {
            if (IsEmpty)
                AddFirst(content);
            else
            {
                GenericStackNode<T> newNode = new GenericStackNode<T>(content);
                GenericStackNode<T> currentNode = _head;
                while (currentNode.Next != null)
                {
                    currentNode = currentNode.Next;
                }
                currentNode.Next = newNode;
            }
        }

        public void RemoveFirst()
        {
            if (!IsEmpty)
                _head = _head.Next;
            else
                throw new InvalidOperationException();
        }

        public void RemoveLast()
        {
            if(!IsEmpty)
            {
                if (_head.Next == null)
                    _head = null;
                else
                {
                    GenericStackNode<T> node = _head;
                    while (node.Next.Next != null)
                        node = node.Next;
                    node.Next = null;
                }
            }
        }
        public void InsertAt(T content, int index)
        {
            if (index < 0 || index >= Lenght)
                throw new IndexOutOfRangeException();

            if (index == 0)
                AddFirst(content);
            else if (index == Lenght)
                AddLast(content);
            else
            {
                GenericStackNode<T> newNode = new GenericStackNode<T>(content);
                GenericStackNode<T> previousNode = GetNode(index - 1);
                newNode.Next = previousNode.Next;
                previousNode.Next = newNode;
            }


        }

        public void Clear()
        {
            _head = null;
        }

        public int IndexOf(T content)
        {
            GenericStackNode<T> newNode = new GenericStackNode<T>(content);

            for (int i = 0; i < Lenght; i++)
            {
                if (_head == newNode)
                    return i;
                _head = _head.Next;
            }
            return -1;
        }
        public override string ToString()
        {
            StringBuilder sb = new StringBuilder();

            GenericStackNode<T> node = _head;
            while (node != null)
            {
                sb.Append(node.Content);
                sb.Append(" -> ");
                node = node.Next;
            }
            sb.Append("*");

            return sb.ToString();
        }
    }
}