using System;

using System.Linq;

using NCrontab;

using ParseOptions = NCrontab.CrontabSchedule.ParseOptions;

public class Program

{

    public static void Main()

    {   

        // Library documentation: https://github.com/atifaziz/NCrontab

​

        /* 

        Five part rules:

        * * * * *

        - - - - -

        | | | | |

        | | | | +----- day of week (0 - 6) (Sunday=0)

        | | | +------- month (1 - 12)

        | | +--------- day of month (1 - 31)

        | +----------- hour (0 - 23)

        +------------- min (0 - 59)

        Six part rules:

        * * * * * *

        - - - - - -

        | | | | | |

        | | | | | +--- day of week(0 - 6) (Sunday=0)

        | | | | +----- month(1 - 12)

        | | | +------- day of month(1 - 31)

        | | +--------- hour(0 - 23)

        | +----------- min(0 - 59)

        +------------- sec(0 - 59)

        */

        var options = new ParseOptions()

        {

            IncludingSeconds = true

        };

        var expression = "0 10 * * *";

        var schedule = CrontabSchedule.Parse(

            expression: expression, 

            options: DetermineCronOptions(expression));

        var utcNow = DateTime.UtcNow;

        var occurences = schedule.GetNextOccurrences(utcNow, utcNow.AddDays(31));

        foreach (var occurrence in occurences.Take(20))

        {

            var utcOcc = DateTime.SpecifyKind(occurrence, DateTimeKind.Utc);

            Console.WriteLine("UTC: " + utcOcc.ToString() + ", PST: " + TimeZoneInfo.ConvertTimeBySystemTimeZoneId(utcOcc, "America/Los_Angeles"));

        }

    }

    // Code based on: https://github.com/Azure/azure-webjobs-sdk-extensions/blob/9feb4f2ad6f70e443a036a135b58121c70dbdaf3/src/WebJobs.Extensions/Extensions/Timers/Scheduling/CronSchedule.cs

    private static ParseOptions DetermineCronOptions(string expression)

    {

        var options = new CrontabSchedule.ParseOptions()

        {

            IncludingSeconds = expression.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries).Length != 5

        };

​

        return options;

    }

}