Tp4_Punto5_List

using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;



namespace ConsoleApp5
{
    class List<E> : IEnumerable where E : IComparable
    {
        private Node head;
        private int count;
        private Node tail;
        public int getCount()
        {
            return this.count;
        }
        public List()
        {
            this.head = null;
            this.count = 0;
            this.tail = null;
        }
        public void AddFirst(E item)
        {
            if (this.count == 0)
            {
                this.head = this.tail = new Node(item, null, null);
                ++this.count;
            }
            else
            {
                Node temp = new Node(item, null, null);
                temp.next = this.head;
                this.head.prev = temp;
                this.head = temp;
                ++this.count;
            }
        }

        public void BetterAddFirst(E item)
        {
            Node temp = new Node(item, this.head, null);
            if (this.count == 0)
            {
                this.tail = temp;
            }
            else
            {
                this.head.prev = temp;
            }
            this.head = temp;
            ++this.count;
        }
        public void AddLast(E item)
        {
            if (this.count == 0)
            {
                this.head = this.tail = new Node(item, null, null);
                ++this.count;
            }
            else
            {
                Node temp = new Node(item, null, null);
                temp.prev = this.tail;
                this.tail.next = temp;
                this.tail = temp;
                ++this.count;

            }

        }

        public void BetterAddLast(E item)
        {
            Node temp = new Node(item, null, this.tail);
            if (this.count == 0)
            {
                this.head = temp;
            }
            else
            {
                this.tail.next = temp;
            }
            this.tail = temp;
            ++this.count;
        }
        public void AddInOrder(E item)
        {
            if (this.count == 0)
            {
                this.head = this.tail = new Node(item, null, null);
                ++this.count;
            }
            else
            {
                if (item.CompareTo(this.head.item) <= 0)
                {
                    this.AddFirst(item);
                }
                else
                {
                    if (item.CompareTo(this.tail.item) > 0)
                    {
                        this.AddLast(item);
                    }
                    else
                    {
                        Node skip = this.head;
                        for (; (skip != null) && (item.CompareTo(skip.item) > 0); skip = skip.next) { }
                        if (skip == null)
                        {
                            throw new Exception("fallo en el orden de los elementos");
                        }
                        else
                        {
                            Node temp = new Node(item, skip, skip.prev);
                            skip.prev.next = temp;
                            skip.prev = temp;
                            ++this.count;
                        }
                    }
                }
            }
        }
        public E RemoveFirst()
        {
            if (this.count == 0)
            {
                throw new Exception("LA LISTA ESTA VACIA!");
            }
            E item = this.head.item;
            this.head = this.head.next;
            if (this.head == null)
            {
                this.tail = null;
            }
            else
            {
                this.head.prev = null;
            }
            --this.count;
            return item;
        }
        public E RemoveLast()
        {
            if (this.count == 0)
            {
                throw new Exception("LA LISTA ESTA VACIA");
            }
            E item = this.tail.item;
            if (this.head.next == null)
            {
                this.head = this.tail = null;
            }
            else
            {
                this.tail = this.tail.prev;
                this.tail.next = null;
            }
            --this.count;
            return item;
        }
        public bool FindAndRemove(E item)
        {
            if (this.count == 0)
            {
                return false;
            }
            Node skip = this.head;
            for (; (skip != null) && !(item.CompareTo(skip.item) == 0); skip = skip.next) { }
            if (skip == null)
            {
                return false;
            }
            else
            {
                if (skip.prev == null)
                {
                    this.RemoveFirst();
                    return true;
                }
                else
                {
                    if (skip.next == null)
                    {
                        this.RemoveLast();
                        return true;
                    }
                    else
                    {
                        skip.prev.next = skip.next;
                        skip.next.prev = skip.prev;
                        skip.prev = skip.next = null;
                        return true;
                    }
                }
            }
        }
        private class Node
        {
            public E item;
            public Node next;
            public Node prev;
            public Node()
            {
                this.item = default(E);
                this.next = null;
                this.prev = null;
            }
            public Node(E item)
            {
                this.item = item;
                this.next = null;
                this.prev = null;
            }
            public Node(E item, Node next)
            {
                this.item = item;
                this.next = next;
                this.prev = null;
            }
            public Node(E item, Node next, Node prev)
            {
                this.item = item;
                this.next = next;
                this.prev = prev;
            }
            public override string ToString()
            {
                return this.item.ToString();
            }
        }
        public IEnumerator GetEnumerator()
        {
            return MyEnumerator();
        }
        private IEnumerator MyEnumerator()
        {
            for (Node skip = head; skip != null; skip = skip.next)
            {
                yield return skip.item;

            }
        }
    }

}