using System;
using System.Collections.Generic;
using System.Threading;

namespace Steamware.Scheduler
{
  /// <summary>
  /// Classe di gestione Scheduler scadenziabili
  /// 
  /// rif https://codinginfinite.com/creating-scheduler-task-seconds-minutes-hours-days/
  /// </summary>
  public class SchedulerService
  {
    private static SchedulerService _instance;
    private List<Timer> timers = new List<Timer>();

    private SchedulerService() { }

    public static SchedulerService Instance => _instance ?? (_instance = new SchedulerService());

    public void ScheduleTask(int hour, int min, double intervalInHour, Action task)
    {
      DateTime now = DateTime.Now;
      DateTime firstRun = new DateTime(now.Year, now.Month, now.Day, hour, min, 0, 0);
      if (now > firstRun)
      {
        firstRun = firstRun.AddDays(1);
      }

      TimeSpan timeToGo = firstRun - now;
      if (timeToGo <= TimeSpan.Zero)
      {
        timeToGo = TimeSpan.Zero;
      }

      var timer = new Timer(x =>
      {
        task.Invoke();
      }, null, timeToGo, TimeSpan.FromHours(intervalInHour));

      timers.Add(timer);
    }
  } 
}