using System;
using System.Threading;

namespace Amib.Threading.Internal
{
    public partial class WorkItem
    {
        #region WorkItemResult class

        private class WorkItemResult : IWorkItemResult, IInternalWorkItemResult, IInternalWaitableResult
        {
            /// <summary>
            /// A back reference to the work item
            /// </summary>
            private readonly WorkItem _workItem;

            public WorkItemResult(WorkItem workItem)
            {
                _workItem = workItem;
            }

            internal WorkItem GetWorkItem()
            {
                return _workItem;
            }

            #region IWorkItemResult Members

            public bool IsCompleted
            {
                get
                {
                    return _workItem.IsCompleted;
                }
            }

            public bool IsCanceled
            {
                get
                {
                    return _workItem.IsCanceled;
                }
            }

            public object GetResult()
            {
                return _workItem.GetResult(Timeout.Infinite, true, null);
            }

            public object GetResult(int millisecondsTimeout, bool exitContext)
            {
                return _workItem.GetResult(millisecondsTimeout, exitContext, null);
            }

            public object GetResult(TimeSpan timeout, bool exitContext)
            {
                return _workItem.GetResult((int)timeout.TotalMilliseconds, exitContext, null);
            }

            public object GetResult(int millisecondsTimeout, bool exitContext, WaitHandle cancelWaitHandle)
            {
                return _workItem.GetResult(millisecondsTimeout, exitContext, cancelWaitHandle);
            }

            public object GetResult(TimeSpan timeout, bool exitContext, WaitHandle cancelWaitHandle)
            {
                return _workItem.GetResult((int)timeout.TotalMilliseconds, exitContext, cancelWaitHandle);
            }

            public object GetResult(out Exception e)
            {
                return _workItem.GetResult(Timeout.Infinite, true, null, out e);
            }

            public object GetResult(int millisecondsTimeout, bool exitContext, out Exception e)
            {
                return _workItem.GetResult(millisecondsTimeout, exitContext, null, out e);
            }

            public object GetResult(TimeSpan timeout, bool exitContext, out Exception e)
            {
                return _workItem.GetResult((int)timeout.TotalMilliseconds, exitContext, null, out e);
            }

            public object GetResult(int millisecondsTimeout, bool exitContext, WaitHandle cancelWaitHandle, out Exception e)
            {
                return _workItem.GetResult(millisecondsTimeout, exitContext, cancelWaitHandle, out e);
            }

            public object GetResult(TimeSpan timeout, bool exitContext, WaitHandle cancelWaitHandle, out Exception e)
            {
                return _workItem.GetResult((int)timeout.TotalMilliseconds, exitContext, cancelWaitHandle, out e);
            }

            public bool Cancel()
            {
                return Cancel(false);
            }

            public bool Cancel(bool abortExecution)
            {
                return _workItem.Cancel(abortExecution);
            }

            public object State
            {
                get
                {
                    return _workItem.m_state;
                }
            }

            /// <summary>
            /// Return the result, same as GetResult()
            /// </summary>
            public object Result
            {
                get { return GetResult(); }
            }

            /// <summary>
            /// Returns the exception if occured otherwise returns null.
            /// This value is valid only after the work item completed,
            /// before that it is always null.
            /// </summary>
            public object Exception
            {
                get { return _workItem.m_exception; }
            }

            #endregion

            #region IInternalWorkItemResult Members

            public event WorkItemStateCallback OnWorkItemStarted
            {
                add
                {
                    _workItem.OnWorkItemStarted += value;
                }
                remove
                {
                    _workItem.OnWorkItemStarted -= value;
                }
            }


            public event WorkItemStateCallback OnWorkItemCompleted
            {
                add
                {
                    _workItem.OnWorkItemCompleted += value;
                }
                remove
                {
                    _workItem.OnWorkItemCompleted -= value;
                }
            }

            #endregion

            #region IInternalWorkItemResult Members

            public IWorkItemResult GetWorkItemResult()
            {
                return this;
            }

            public IWorkItemResult<TResult> GetWorkItemResultT<TResult>()
            {
                return new WorkItemResultTWrapper<TResult>(this);
            }

            #endregion
        }

        #endregion

    }
}