using System.Diagnostics;
using System.Threading;
using System.Threading.Tasks;

namespace PodNoms.Api.Utils.Extensions {
    public static class ProcessExtensions {
        /// <summary>
        /// Waits asynchronously for the process to exit.
        /// </summary>
        /// <param name="process">The process to wait for cancellation.</param>
        /// <param name="cancellationToken">A cancellation token. If invoked, the task will return 
        /// immediately as canceled.</param>
        /// <returns>A Task representing waiting for the process to end.</returns>
        public static Task WaitForExitAsync (this Process process,
            CancellationToken cancellationToken = default (CancellationToken)) {
            var tcs = new TaskCompletionSource<object> ();
            process.EnableRaisingEvents = true;
            process.Exited += (sender, args) => tcs.TrySetResult (null);
            if (cancellationToken != default (CancellationToken))
                cancellationToken.Register (tcs.SetCanceled);

            return tcs.Task;
        }
    }
}