// Decompiled with JetBrains decompiler
// Type: Microsoft.Iris.Queues.QueueItem
// Assembly: UIX, Version=4.8.0.0, Culture=neutral, PublicKeyToken=ddd0da4d3e678217
// MVID: A56C6C9D-B7F6-46A9-8BDE-B3D9B8D60B11
// Assembly location: C:\Program Files\Zune\UIX.dll

using System.Diagnostics;

namespace Microsoft.Iris.Queues
{
    internal abstract class QueueItem
    {
        protected QueueItem _prev;
        protected QueueItem _next;
        protected QueueItem.Chain _owner;

        public bool IsPending => _owner != null;

        public abstract void Dispatch();

        public override string ToString() => GetType().Name;

        public virtual string ToDebugPacketString() => ToString();

        internal class Chain
        {
            public virtual void Dispose()
            {
            }

            protected static void ValidateAdd(QueueItem item)
            {
            }

            protected void ValidateRemove(QueueItem item)
            {
            }

            protected void Link(QueueItem item, QueueItem anchor, bool before)
            {
                UpdateOwners(item, item, null, this);
                LinkItems(item, item, anchor, before);
            }

            protected void Unlink(QueueItem item)
            {
                UnlinkItems(item, item);
                UpdateOwners(item, item, this, null);
            }

            protected void TransferFromChain(
              QueueItem.Chain oldOwner,
              QueueItem first,
              QueueItem last,
              QueueItem anchor,
              bool before)
            {
                UnlinkItems(first, last);
                UpdateOwners(first, last, oldOwner, this);
                LinkItems(first, last, anchor, before);
            }

            protected static bool IsOnlyChild(QueueItem item) => item._next == item;

            protected static QueueItem NextItem(QueueItem item) => item._next;

            protected static QueueItem PrevItem(QueueItem item) => item._prev;

            private void LinkItems(QueueItem first, QueueItem last, QueueItem anchor, bool before)
            {
                QueueItem queueItem1 = last;
                QueueItem queueItem2 = first;
                if (anchor != null)
                {
                    if (before)
                    {
                        queueItem1 = anchor._prev;
                        queueItem2 = anchor;
                    }
                    else
                    {
                        queueItem1 = anchor;
                        queueItem2 = anchor._next;
                    }
                    queueItem1._next = first;
                    queueItem2._prev = last;
                }
                first._prev = queueItem1;
                last._next = queueItem2;
            }

            private void UnlinkItems(QueueItem first, QueueItem last)
            {
                if (first._prev != last)
                {
                    first._prev._next = last._next;
                    last._next._prev = first._prev;
                }
                first._prev = null;
                last._next = null;
            }

            private void UpdateOwners(
              QueueItem first,
              QueueItem last,
              QueueItem.Chain oldOwner,
              QueueItem.Chain newOwner)
            {
                QueueItem queueItem = first;
                while (true)
                {
                    queueItem._owner = newOwner;
                    if (queueItem != last)
                        queueItem = queueItem._next;
                    else
                        break;
                }
            }

            [Conditional("DEBUG")]
            protected internal static void DEBUG_AssertLinked(QueueItem item)
            {
            }

            public struct ChainEnumerator
            {
                private QueueItem _currentItem;
                private QueueItem _stopItem;

                public ChainEnumerator(QueueItem tail)
                {
                    _currentItem = null;
                    _stopItem = tail;
                }

                public QueueItem Current => _currentItem;

                public bool MoveNext()
                {
                    if (_stopItem == null)
                    {
                        _currentItem = null;
                        return false;
                    }
                    if (_currentItem != null)
                    {
                        if (_currentItem == _stopItem)
                        {
                            _currentItem = _stopItem = null;
                            return false;
                        }
                        _currentItem = _currentItem._next;
                    }
                    else
                        _currentItem = _stopItem._next;
                    return true;
                }
            }
        }

        internal sealed class FIFO : QueueItem.Chain
        {
            private QueueItem _tail;

            public QueueItem Head
            {
                get
                {
                    QueueItem queueItem = null;
                    if (_tail != null)
                        queueItem = _tail._next;
                    return queueItem;
                }
            }

            public override void Dispose()
            {
                while (_tail != null)
                    Remove(_tail);
                base.Dispose();
            }

            public bool Append(QueueItem item)
            {
                ValidateAdd(item);
                bool flag = _tail == null;
                Link(item, _tail, false);
                _tail = item;
                return flag;
            }

            public bool Append(QueueItem.FIFO items)
            {
                bool flag = _tail == null;
                QueueItem tail = items._tail;
                if (tail == null)
                    return false;
                TransferFromChain(items, items.Head, tail, _tail, false);
                items._tail = null;
                _tail = tail;
                return flag;
            }

            public void Remove(QueueItem item)
            {
                ValidateRemove(item);
                if (item == _tail)
                    _tail = IsOnlyChild(_tail) ? null : PrevItem(_tail);
                Unlink(item);
            }

            public void Advance()
            {
                if (_tail == null)
                    return;
                _tail = NextItem(_tail);
            }
        }

        internal sealed class Stack : QueueItem.Chain
        {
            private QueueItem _top;

            public override void Dispose()
            {
                while (_top != null)
                    Pop();
                base.Dispose();
            }

            public void Push(QueueItem item)
            {
                ValidateAdd(item);
                Link(item, _top, true);
                _top = item;
            }

            public QueueItem Peek() => _top;

            public QueueItem Pop()
            {
                QueueItem top = _top;
                if (top != null)
                {
                    _top = top._next;
                    if (_top == top)
                        _top = null;
                    Unlink(top);
                }
                return top;
            }
        }
    }
}