using System;
using System.Threading.Tasks;

namespace Sony.Filtr.ScheduledTask
{
    public static class TaskExtensions
    {
        public static Task<R1> Select<R, R1>(this Task<R> task, Func<R, R1> selector)
        {
            return task.ContinueWith(t => selector(t.Result));
        }

        public static Task<R1> Bind<R, R1>(this Task<R> task, Func<R, Task<R1>> binder)
        {
            var tcs = new TaskCompletionSource<R1>();

            task.ContinueWith(t => {
                if (t.IsFaulted) tcs.SetException(t.Exception);
                else if (t.IsCanceled) tcs.SetCanceled();
                else {
                    try
                    {
                        binder(t.Result).ContinueWith(b => tcs.SetResult(b.Result));
                    }
                    catch (Exception ex)
                    {
                        tcs.SetException(ex);
                    }
                }
            });

            return tcs.Task;
        }

        public static Task<T> OnSuccess<T>(this Task<T> task, Action<T> action)
        {
            task.ContinueWith(t => action(t.Result), TaskContinuationOptions.ExecuteSynchronously | TaskContinuationOptions.OnlyOnRanToCompletion);

            return task;
        }

        public static Task<T> OnFail<T>(this Task<T> task, Action<Exception> action)
        {
            task.ContinueWith(t => action(t.Exception), TaskContinuationOptions.ExecuteSynchronously | TaskContinuationOptions.OnlyOnFaulted);

            return task;
        }
    }
}