using System;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Serilog;
using NCrontab;
using LCU.Api.Internal.MaidBotApi.Services;
using LCU.Api.Internal.MaidBotApi.Configurations;
namespace LCU.API.Internal.MaidBotApi.HostedService;

public class SchedulerHostedService : BackgroundService
{
    private readonly ApiConfiguration _apiConfiguration;
    private readonly IServiceScopeFactory _scopeFactory;

    private readonly CrontabSchedule _schedule;
    private DateTime _nextScheduleRun;
    public const string DefaultScheduleCronPattern = "*/5 * * * *";

    private CancellationToken _cancellationToken;

    public SchedulerHostedService(IServiceScopeFactory scopeFactory,
                                       ApiConfiguration apiConfiguration)
    {
        _scopeFactory = scopeFactory;
        _apiConfiguration = apiConfiguration;

        var cron = (_apiConfiguration?.BatchSchedulerCron) ?? DefaultScheduleCronPattern;
        _schedule = CrontabSchedule.Parse(cron);
        _nextScheduleRun = _schedule.GetNextOccurrence(DateTime.Now);

        _cancellationToken = new CancellationToken();
    }

    protected override async Task ExecuteAsync(CancellationToken cancellationToken)
    {
        Log.Information("MaidBot Scheduler Hosted Service is starting.");
        _cancellationToken = cancellationToken;
        try
        {
            do
            {
                if (_apiConfiguration.FeatureFlags.RunScheduler && DateTime.Now > _nextScheduleRun)
                {
                    using var scope = _scopeFactory.CreateScope();
                    await Task.Run(async () => await scope.ServiceProvider.GetRequiredService<ILogDistributionService>().HandleLogDistribution());

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

                await Task.Delay(5000, cancellationToken); //5 seconds delay
            } while (!cancellationToken.IsCancellationRequested);
        }
        catch (TaskCanceledException taskCanceledException) when (_cancellationToken.IsCancellationRequested)
        {
            Log.Information(taskCanceledException, "MaidBot Scheduler Hosted Service was shut down normally.");
        }
        catch (Exception exception)
        {
            Log.Error(exception, "Error trying to startup main thread for MaidBot Scheduler Hosted Service");
        }

        Log.Information("MaidBot Scheduler Hosted Service is stopping.");
    }
}