// Copyright (c) 2017 Kastellanos Nikolaos

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

namespace FarseerPhysics.Dynamics.Contacts
{
    /// <summary>
    /// Head of a circular doubly linked list.
    /// </summary>
    public class ContactListHead : Contact , IEnumerable<Contact>
    {
        internal ContactListHead(): base(null, 0, null, 0)
        {
            this.Prev = this;
            this.Next = this;
        }
        
        IEnumerator<Contact> IEnumerable<Contact>.GetEnumerator()
        {
            return new ContactEnumerator(this);
        }

        IEnumerator IEnumerable.GetEnumerator()
        {
            return new ContactEnumerator(this);
        }

        
        #region Nested type: ContactEnumerator

        private struct ContactEnumerator : IEnumerator<Contact>
        {
            private ContactListHead _head;
            private Contact _current;

            public Contact Current { get { return _current; } }
            object IEnumerator.Current { get { return _current; } }


            public ContactEnumerator(ContactListHead contact)
            {
                _head = contact;
                 _current = _head;
            }

            public void Reset()
            {
                _current = _head;
            }

            public bool MoveNext()
            {
                _current = _current.Next;
                return (_current != _head);
            }

            public void Dispose()
            {
                _head = null;
                _current = null;
            }
        }

        #endregion

    }
}