using System;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging;
using AyaNova.Models;

namespace AyaNova.Biz
{


    /// <summary>
    /// JobSweeper - called by Generator to clean out old jobs that are completed and their logs
    /// 
    /// </summary>
    internal static class CoreJobSweeper
    {
        private static ILogger log = AyaNova.Util.ApplicationLogging.CreateLogger("CoreJobSweeper");
        private static DateTime lastSweep = DateTime.MinValue;
        private static TimeSpan SWEEP_EVERY_INTERVAL = new TimeSpan(0, 10, 10);//every ten minutes roughly
        private static TimeSpan SUCCEEDED_JOBS_DELETE_AFTER_THIS_TIMESPAN = new TimeSpan(14, 0, 0, 0);//14 days
        private static TimeSpan FAILED_JOBS_DELETE_AFTER_THIS_TIMESPAN = new TimeSpan(14, 0, 0, 0);//14 days (gives people time to notice and look into it)
        private static TimeSpan INTERNAL_JOBS_LOGS_DELETE_AFTER_THIS_TIMESPAN = new TimeSpan(14, 0, 0, 0);//14 days

        private static TimeSpan RUNNING_JOBS_BECOME_FAILED_AFTER_THIS_TIMESPAN = new TimeSpan(24, 0, 0);//24 hours (time running jobs are allowed to sit in "running" state before considered failed)

        ////////////////////////////////////////////////////////////////////////////////////////////////
        // DoSweep
        //
        public static async Task DoWorkAsync()
        {
            //This will get triggered roughly every minute, but we don't want to sweep that frequently
            if (DateTime.UtcNow - lastSweep < SWEEP_EVERY_INTERVAL)
                return;

            log.LogDebug("Sweep starting");
            using (AyContext ct = AyaNova.Util.ServiceProviderProvider.DBContext)
            {
                //SWEEP SUCCESSFUL JOBS
                //calculate cutoff to delete 
                DateTime dtDeleteCutoff = DateTime.UtcNow - SUCCEEDED_JOBS_DELETE_AFTER_THIS_TIMESPAN;
                await sweepAsync(ct, dtDeleteCutoff, JobStatus.Completed);

                //SWEEP FAILED JOBS
                //calculate cutoff to delete 
                dtDeleteCutoff = DateTime.UtcNow - FAILED_JOBS_DELETE_AFTER_THIS_TIMESPAN;
                await sweepAsync(ct, dtDeleteCutoff, JobStatus.Failed);

                //KILL STUCK JOBS
                //calculate cutoff to delete 
                DateTime dtRunningDeadline = DateTime.UtcNow - RUNNING_JOBS_BECOME_FAILED_AFTER_THIS_TIMESPAN;
                await killStuckJobsAsync(ct, dtRunningDeadline);

                //SWEEP INTERNAL JOB LOG
                //calculate cutoff to delete 
                dtDeleteCutoff = DateTime.UtcNow - INTERNAL_JOBS_LOGS_DELETE_AFTER_THIS_TIMESPAN;
                await SweepInternalJobsLogsAsync(ct, dtDeleteCutoff);

                //Stealthy check of user count exceeded
                if (await UserBiz.ActiveCountAsync() > AyaNova.Core.License.ActiveKey.ActiveNumber)
                {
                    //WARNING: DO not change the text of this message without also 
                    //updating the authcontroller ReturnUserCredsOnSuccessfulAuthentication licenselockout check code
                    //it must match
                    var msg = $"E1020 - Active count exceeded capacity";
                    AyaNova.Util.ServiceProviderProvider.ServerState.SetSystemLock(msg);
                    log.LogCritical(msg);
                    return;
                }

            }
            lastSweep = DateTime.UtcNow;
        }


        private static async Task sweepAsync(AyContext ct, DateTime dtDeleteCutoff, JobStatus jobStatus)
        {
            //Get the deleteable succeeded jobs list
            var jobs = await ct.OpsJob
                   .AsNoTracking()
                   .Where(z => z.Created < dtDeleteCutoff && z.JobStatus == jobStatus)
                   .OrderBy(z => z.Created)
                   .ToListAsync();

            log.LogDebug($"SweepAsync processing: cutoff={dtDeleteCutoff.ToString()}, for {jobs.Count.ToString()} jobs of status {jobStatus.ToString()}");

            foreach (OpsJob j in jobs)
            {
                try
                {

                    await JobsBiz.RemoveJobAndLogsAsync(j.GId);
                }
                catch (Exception ex)
                {
                    log.LogError(ex, "sweepAsync exception calling JobsBiz.RemoveJobAndLogsAsync");
                    //for now just throw it but this needs to be removed when logging added and better handling 
                    throw;
                }
            }
        }


        /// <summary>
        /// Kill jobs that have been stuck in "running" state for too long
        /// </summary>        
        private static async Task killStuckJobsAsync(AyContext ct, DateTime dtRunningDeadline)
        {
            //Get the deleteable succeeded jobs list
            var jobs = await ct.OpsJob
                   .AsNoTracking()
                   .Where(z => z.Created < dtRunningDeadline && z.JobStatus == JobStatus.Running)
                   .OrderBy(z => z.Created)
                   .ToListAsync();

            log.LogDebug($"killStuckJobsAsync processing: cutoff={dtRunningDeadline.ToString()}, for {jobs.Count.ToString()} jobs of status {JobStatus.Running.ToString()}");

            foreach (OpsJob j in jobs)
            {
                //OPSMETRIC
                await JobsBiz.LogJobAsync(j.GId, "LT:JobFailed LT:TimedOut");
                log.LogError($"Job found job stuck in running status and set to failed: deadline={dtRunningDeadline.ToString()}, jobId={j.GId.ToString()}, jobname={j.Name}, jobtype={j.JobType.ToString()}, jobAType={j.AType.ToString()}, jobObjectId={j.ObjectId.ToString()}");
                await JobsBiz.UpdateJobStatusAsync(j.GId, JobStatus.Failed);
            }
        }


        private static async Task SweepInternalJobsLogsAsync(AyContext ct, DateTime dtDeleteCutoff)
        {
            //Get the deleteable list (this is for reporting, could easily just do it in one go)
            var logs = await ct.OpsJobLog
                   .AsNoTracking()
                   .Where(z => z.Created < dtDeleteCutoff)
                   .OrderBy(z => z.Created)
                   .ToListAsync();

            log.LogDebug($"SweepInternalJobsLogsAsync processing: cutoff={dtDeleteCutoff.ToString()}, for {logs.Count.ToString()} log entries");

            foreach (OpsJobLog l in logs)
            {
                try
                {
                    await ct.Database.ExecuteSqlInterpolatedAsync($"delete from aopsjoblog where gid = {l.GId}");
                }
                catch (Exception ex)
                {
                    log.LogError(ex, "SweepInternalJobsLogsAsync exception removed old log entries");
                    throw;
                }
            }
        }

        /////////////////////////////////////////////////////////////////////

    }//eoc


}//eons