using System;
using System.Threading;
using System.Threading.Tasks;
using MQTTnet.Core.Exceptions;

namespace MQTTnet.Core.Internal
{
    public static class TaskExtensions
    {
        public static async Task TimeoutAfter( this Task task, TimeSpan timeout )
        {
            using ( var cancellationTokenSource = new CancellationTokenSource() )
            {
                try
                {
                    var timeoutTask = Task.Delay(timeout, cancellationTokenSource.Token);
                    var finishedTask = await Task.WhenAny(timeoutTask, task).ConfigureAwait(false);

                    if ( finishedTask == timeoutTask )
                    {
                        throw new MqttCommunicationTimedOutException();
                    }

                    if ( task.IsCanceled )
                    {
                        throw new TaskCanceledException();
                    }

                    if ( task.IsFaulted )
                    {
                        throw new MqttCommunicationException( task.Exception.GetBaseException() );
                    }
                }
                finally
                {
                    cancellationTokenSource.Cancel();
                }
            }
        }

        public static async Task<TResult> TimeoutAfter<TResult>( this Task<TResult> task, TimeSpan timeout )
        {
            using ( var cancellationTokenSource = new CancellationTokenSource() )
            {
                try
                {
                    var timeoutTask = Task.Delay(timeout, cancellationTokenSource.Token);
                    var finishedTask = await Task.WhenAny(timeoutTask, task).ConfigureAwait(false);

                    if ( finishedTask == timeoutTask )
                    {
                        throw new MqttCommunicationTimedOutException();
                    }

                    if ( task.IsCanceled )
                    {
                        throw new TaskCanceledException();
                    }

                    if ( task.IsFaulted )
                    {
                        throw new MqttCommunicationException( task.Exception.GetBaseException() );
                    }

                    return task.Result;
                }
                finally
                {
                    cancellationTokenSource.Cancel();
                }
            }
        }
    }
}