using Microsoft.Extensions.DependencyInjection;
using System.Threading;
using NCrontab;
using LCU.API.Internal.Operations.IncentiveApiLib.Persistence;
using LCU.Library.Internal.LCUHostedService.LCUBackgroundService;
using LCU.API.Internal.Operations.IncentiveApi.Configuration;
using LCU.API.Internal.Operations.IncentiveApi.Utilities;

namespace LCU.API.Internal.Operations.IncentiveApi.HostedServices;

public class ApplicationDbIntegrityHostedService : LCUBackgroundService, IApplicationDbIntegrityHostedService
{
    private readonly ApiConfiguration _apiConfiguration;
    private readonly IServiceScopeFactory _scopeFactory;
    private readonly CrontabSchedule _applicationDbIntegritySchedule;
    private DateTime _nextScheduleRun;
    public const string DefaultErrorMonitoringCronPattern = "0 0 * * *";
    private CancellationToken _cancellationToken;

    public ApplicationDbIntegrityHostedService(IServiceScopeFactory scopeFactory, ApiConfiguration apiConfiguration)
    {
        _scopeFactory = scopeFactory;
        _apiConfiguration = apiConfiguration;
        _applicationDbIntegritySchedule = CronHelpers.SetCronSchedule(_apiConfiguration.ApplicationDbIntegrityCronSchedule,
                                                                                        DefaultErrorMonitoringCronPattern);

        _nextScheduleRun = _applicationDbIntegritySchedule.GetNextOccurrence(DateTime.Now);
        _cancellationToken = new CancellationToken();
    }

    protected override async Task ExecuteAsync(CancellationToken cancellationToken)
    {
        Log.Debug("ApplicationDbIntegrity Hosted Service is starting.");
        try
        {
            while (!cancellationToken.IsCancellationRequested)
            {
                await Task.Delay(UntilNextExecution(), cancellationToken);

                using (var scope = _scopeFactory.CreateScope())
                {
                    Log.Debug("Running ApplicationDbIntegrity Service");
                    await scope.ServiceProvider.GetRequiredService<IApplicationDbIntegrityService>().AppUserIdIntegrityMaintenanceSucceeded(_cancellationToken);
                }

                _nextScheduleRun = _applicationDbIntegritySchedule.GetNextOccurrence(DateTime.Now);
            }
        }
        catch (OperationCanceledException taskCanceledEx)
        {
            Log.Error(taskCanceledEx, $"Manual start/stop of ApplicationDbIntegrity Hosted Service was initiated.");
        }
        catch (Exception exception)
        {
            Log.Error(exception,
                "Error trying to startup main thread for ApplicationDbIntegrity Hosted Service");
        }

        Log.Debug("ApplicationDbIntegrity Hosted Service is stopping.");
    }

    private int UntilNextExecution() => Math.Max(0, (int)_nextScheduleRun.Subtract(DateTime.Now).TotalMilliseconds);
}