using System.Threading;
using System;
using System.Threading.Tasks;
using Microsoft.Extensions.Logging;
using AyaNova.Api.ControllerHelpers;
using AyaNova.Biz;
using AyaNova.Util;

namespace AyaNova.Generator
{
    //Implemented from a example here
    //https://docs.microsoft.com/en-us/dotnet/standard/microservices-architecture/multi-container-microservice-net-applications/background-tasks-with-ihostedservice

    /*
    LOOKAT: Generator tasks that should happen:
    - Periodically erase any temp files written to userfiles root (attachments temp files) that are older than a day
        - These files should be normally erased within seconds after uploading and processing into their permanent folder but shit will go wrong
     */

    public class GeneratorService : BackgroundService
    {
        private readonly ILogger<GeneratorService> log;
        // private const int MAXIMUM_MS_ALLOWED_FOR_PROCESSING_ALL_JOBS = 1 * 60 * 1000;//1 minutes TEST TEST TEST #####
#if (DEBUG)
        private const int GENERATE_SECONDS = 5;
#else
        private const int GENERATE_SECONDS = 20;
#endif      
        public GeneratorService(ILogger<GeneratorService> logger)
        {
            log = logger;
        }

        /*
        todo: improve this 
            it should timeout: https://stackoverflow.com/questions/23476576/cancellationtoken-timeout-vs-task-delay-and-timeout
            it should never stop running no matter what unless teh server shuts down
        */

        protected override async Task ExecuteAsync(CancellationToken stoppingToken)
        {
            //don't immediately run the generator stuff on boot
            bool justStarted = true;
            log.LogDebug($"GeneratorService is starting.");

            stoppingToken.Register(() =>
                    log.LogDebug($" GeneratorService background task is stopping."));

            while (!stoppingToken.IsCancellationRequested)
            {
                if (!justStarted)
                {
                    log.LogDebug($"GeneratorService task doing background work.");
                    ApiServerState serverState = ServiceProviderProvider.ServerState;
                    //=================================================================
                    try
                    {
                        if (!serverState.IsOpen)
                        {
                            log.LogDebug($"GeneratorService: ServerState is closed returning without processing jobs, will try again next iteration");
                        }
                        else
                        {
                           //System.Diagnostics.Debug.WriteLine($"### GENERATE calling JobsBiz.ProcessJobs");
                            //Capture metrics  
                            CoreJobMetricsSnapshot.DoJob();
                            await JobsBiz.ProcessJobsAsync();
                            //Capture metrics again, (calling repeatedly won't increase metrics but will ensure it doesn't miss frequency of capturing)
                            CoreJobMetricsSnapshot.DoJob();
                           //System.Diagnostics.Debug.WriteLine($"### GENERATE BACK FROM calling JobsBiz.ProcessJobs");
                        }
                    }
                    catch (Exception ex)
                    {
                        log.LogError(ex, "Generate::ProcessJobs result in exception error ");
                    }
                    //=================================================================

                }
                await Task.Delay((GENERATE_SECONDS * 1000), stoppingToken);
                justStarted = false;
            }

            log.LogDebug($"GeneratorService background task is stopping.");

        }

        public override Task StopAsync(CancellationToken stoppingToken)
        {
            log.LogDebug($"GeneratorService StopAsync triggered.");
            return Task.FromResult(0);
            // Run your graceful clean-up actions
        }
    }//eoc

}//eons