using NCrontab;
using ReserveManagementSystemApi.Services;

namespace ReserveManagementSystemApi.HostedService
{
    public class HostedImportExportActive : BackgroundService
    {
        private readonly IConfiguration _config;
        private readonly IServiceScopeFactory _scopeFactory; 
        private readonly CrontabSchedule _schedule;
        private DateTime _nextRun;
        public const string DefaultCronPattern = "0 19 * * 0-6"; 

        private CancellationToken _cancellationToken;

        public HostedImportExportActive(IConfiguration config, IServiceScopeFactory scopeFactory)
        {
            _config = config;
            _scopeFactory = scopeFactory;
            try
            {
                _schedule = CrontabSchedule.Parse(_config.GetSection("HostedServices").GetSection("ImportExportActiveCronSchedule").Value);
            }
            catch (Exception ex)
            {
                Log.Error(ex, "Failure parsing crontab in appsettings.");
                _schedule = CrontabSchedule.Parse(DefaultCronPattern);
            }
            _nextRun = _schedule.GetNextOccurrence(DateTime.Now);         
        }

        protected override async Task ExecuteAsync(CancellationToken cancellationToken)
        {
            Log.Information("Hosted ImportExportActive is starting.");
            Log.Information($"The import export active job will run at {_nextRun:M/d/yyyy HH:mm:ss tt}");

            _cancellationToken = cancellationToken;
            try
            {
                await ImportExportScheduler(cancellationToken);
              }
            catch (TaskCanceledException ex) when (_cancellationToken.IsCancellationRequested)
            {
                Log.Information(ex, "Hosted ImportExportActive shut down normally.");
            }
            catch (Exception ex)
            {
                Log.Error(ex, "Error trying to startup main thread for Hosted ImportExportActive");
            }

            Log.Information("Hosted ImportExportActive is stopping.");
        }

        private async Task ImportExportScheduler(CancellationToken cancellationToken)
        {
            do
            {
                if (DateTime.Now > _nextRun)
                {
                    using (var scope = _scopeFactory.CreateScope())
                    {
                        await scope.ServiceProvider.GetRequiredService<IScheduleService>().RunImportExportActive(_cancellationToken);
                    }

                    _nextRun = _schedule.GetNextOccurrence(DateTime.Now);
                }

                await Task.Delay(5000, cancellationToken); //5 seconds delay
            } while (!cancellationToken.IsCancellationRequested);
        }
    }
}