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


namespace AyaNova.Biz
{


    internal static class JobsBiz
    {
        private static ILogger log = AyaNova.Util.ApplicationLogging.CreateLogger("JobsBiz");

        #region JOB OPS


        /// <summary>
        /// Get a non tracked list of jobs that are ready to process and exclusive only
        /// </summary>       
        /// <returns></returns>
        internal static async Task<List<OpsJob>> GetReadyJobsExclusiveOnlyAsync()
        {
            return await GetReadyJobsAsync(true);
        }


        /// <summary>
        /// Get a non tracked list of jobs that are ready to process and exclusive only
        /// </summary>       
        /// <returns></returns>
        internal static async Task<List<OpsJob>> GetReadyJobsNotExlusiveOnlyAsync()
        {
            return await GetReadyJobsAsync(false);
        }


        /// <summary>
        /// Get a non tracked list of jobs filtered by exclusivity
        /// </summary>       
        /// <returns></returns>
        private static async Task<List<OpsJob>> GetReadyJobsAsync(bool exclusiveOnly)
        {
            using (AyContext ct = ServiceProviderProvider.DBContext)
            {
                var ret = await ct.OpsJob
                        .AsNoTracking()
                        .Where(z => z.StartAfter < System.DateTime.UtcNow && z.Exclusive == exclusiveOnly && z.JobStatus == JobStatus.Sleeping)
                        .OrderBy(z => z.Created)
                        .ToListAsync();
                return ret;
            }
        }


        /// <summary>
        /// Add a new job to the database
        /// </summary>      
        /// <param name="newJob"></param>
        internal static async Task AddJobAsync(OpsJob newJob)
        {
            using (AyContext ct = ServiceProviderProvider.DBContext)
            {
                await ct.OpsJob.AddAsync(newJob);
                await ct.SaveChangesAsync();
            }
        }


        /// <summary>
        /// Remove the job and it's logs
        /// </summary>       
        /// <param name="jobIdToBeDeleted"></param>
        internal static async Task RemoveJobAndLogsAsync(Guid jobIdToBeDeleted)
        {
            using (AyContext ct = ServiceProviderProvider.DBContext)
            using (var transaction = await ct.Database.BeginTransactionAsync())
            {
                try
                {
                    //delete logs
                    await ct.Database.ExecuteSqlInterpolatedAsync($"delete from aopsjoblog where jobid = {jobIdToBeDeleted}");
                    //delete the job
                    await ct.Database.ExecuteSqlInterpolatedAsync($"delete from aopsjob where gid = {jobIdToBeDeleted}");
                    // Commit transaction if all commands succeed, transaction will auto-rollback
                    // when disposed if either commands fails
                    await transaction.CommitAsync();
                }
                catch (Exception ex)
                {
                    throw ex;
                }
            }
        }



        /// <summary>
        /// Make a log entry for a job
        /// </summary>
        /// <param name="jobId">(NOTE: Guid.empty indicates internal job)</param>
        /// <param name="statusText"></param>
        internal static async Task LogJobAsync(Guid jobId, string statusText)
        {
            using (AyContext ct = ServiceProviderProvider.DBContext)
            {
                if (string.IsNullOrWhiteSpace(statusText))
                    statusText = "No status provided";
                OpsJobLog newObj = new OpsJobLog();
                newObj.JobId = jobId;
                newObj.StatusText = statusText;
                await ct.OpsJobLog.AddAsync(newObj);
                await ct.SaveChangesAsync();
            }
        }


        /// <summary>
        /// Update the status of a job
        /// </summary>
        /// <param name="jobId"></param>
        /// <param name="newStatus"></param>     
        internal static async Task UpdateJobStatusAsync(Guid jobId, JobStatus newStatus)
        {
            using (AyContext ct = ServiceProviderProvider.DBContext)
            {
                var oFromDb = await ct.OpsJob.SingleOrDefaultAsync(z => z.GId == jobId);
                if (oFromDb == null) return;
                oFromDb.JobStatus = newStatus;
                await ct.SaveChangesAsync();
            }
        }
        #endregion Job ops

        #region PROCESSOR

        static bool ActivelyProcessing = false;
        /// <summary>
        /// Process all jobs (stock jobs and those found in operations table)
        /// </summary>
        /// <returns></returns>
        internal static async Task ProcessJobsAsync()
        {
            if (ActivelyProcessing)
            {
                //System.Diagnostics.Debug.WriteLine("ProcessJobs called but actively processing other jobs so returning");
                log.LogTrace("ProcessJobs called but actively processing other jobs so returning");
                return;
            }
            ActivelyProcessing = true;
            try
            {
                //Sweep jobs table
                //System.Diagnostics.Debug.WriteLine($"JobsBiz processing sweeper");
                await CoreJobSweeper.DoSweepAsync();//run exclusively

                //BIZOBJECT DYNAMIC JOBS
                //get a list of exclusive jobs that are due to happen
                //Call into each item in turn 
                List<OpsJob> exclusiveJobs = await GetReadyJobsExclusiveOnlyAsync();
                foreach (OpsJob j in exclusiveJobs)
                {
                    try
                    {
                        //System.Diagnostics.Debug.WriteLine($"JobsBiz processing exclusive biz job {j.Name}");
                        await ProcessJobAsync(j);
                        //Capture metrics  
                        CoreJobMetricsSnapshot.DoJob();
                    }
                    catch (Exception ex)
                    {
                        log.LogError(ex, $"ProcessJobs::Exclusive -> job {j.Name} failed with exception");
                        await LogJobAsync(j.GId, "Job failed with errors:");
                        await LogJobAsync(j.GId, ExceptionUtil.ExtractAllExceptionMessages(ex));
                        await UpdateJobStatusAsync(j.GId, JobStatus.Failed);
                    }
                }

                //System.Diagnostics.Debug.WriteLine($"JobsBiz processing exclusive license check");
                //License check
                long CurrentActiveCount = await UserBiz.ActiveCountAsync();
                long LicensedUserCount = AyaNova.Core.License.ActiveKey.ActiveNumber;
                // log.LogInformation("JobsBiz::Checking license active count");
                if (CurrentActiveCount > LicensedUserCount)
                {
                    var msg = $"E1020 - Active count exceeded capacity";
                    ServiceProviderProvider.ServerState.SetSystemLock(msg);
                    log.LogCritical(msg);
                    return;
                }
                //backup
                //System.Diagnostics.Debug.WriteLine($"JobsBiz processing backup");
                await CoreJobBackup.DoWorkAsync();//sb exclusive
                                                  //System.Diagnostics.Debug.WriteLine($"JobsBiz processing metrics snapshotter");

                //Capture metrics  
                CoreJobMetricsSnapshot.DoJob();


                ///////////////////////////////////////
                //NON-EXCLUSIVE JOBS
                //

                //These fire and forget but use a technique to bubble up exceptions anyway
                List<OpsJob> sharedJobs = await GetReadyJobsNotExlusiveOnlyAsync();
                foreach (OpsJob j in sharedJobs)
                {
                    try
                    {
                        //System.Diagnostics.Debug.WriteLine($"JobsBiz processing NON-exclusive biz job {j.Name}");                        
                        TaskUtil.Forget(Task.Run(() => ProcessJobAsync(j)));
                    }
                    catch (Exception ex)
                    {
                        log.LogError(ex, $"ProcessJobs::Shared -> job {j.Name} failed with exception");
                        await LogJobAsync(j.GId, "Job failed with errors:");
                        await LogJobAsync(j.GId, ExceptionUtil.ExtractAllExceptionMessages(ex));
                        await UpdateJobStatusAsync(j.GId, JobStatus.Failed);
                    }
                }


                //Capture metrics  
                CoreJobMetricsSnapshot.DoJob();


                //TODO: NOTIFICATIONS

            }
            catch (Exception ex)
            {
                log.LogError(ex, "JobsBiz::ProcessJobsAsync unexpected error during processing");
                //TODO:OPSNOTIFY
            }
            finally
            {
                ActivelyProcessing = false;
                //System.Diagnostics.Debug.WriteLine($"JobsBiz in Finally - completed run");
            }

        }

        /// <summary>
        /// Process a job by calling into it's biz object
        /// </summary>       
        /// <param name="job"></param>      
        /// <returns></returns>
        internal static async Task ProcessJobAsync(OpsJob job)
        {
            var JobDescription = $"{job.Name} {job.JobType.ToString()}";
            if (job.SubType != JobSubType.NotSet)
                JobDescription += $":{job.SubType}";
            await LogJobAsync(job.GId, $"Process job \"{JobDescription}\"");
            log.LogDebug($"ProcessJobAsync -> Processing job {JobDescription}");
            IJobObject o = null;

            switch (job.JobType)
            {
                case JobType.Backup:
                    //This is called when on demand only, normal backups are processed above with normal system jobs
                    await CoreJobBackup.DoWorkAsync(true);
                    await UpdateJobStatusAsync(job.GId, JobStatus.Completed);
                    break;
                case JobType.TestJob:
                    o = (IJobObject)BizObjectFactory.GetBizObject(AyaType.ServerJob);
                    break;
                case JobType.SeedTestData:
                    o = (IJobObject)BizObjectFactory.GetBizObject(AyaType.TrialSeeder);
                    break;
                case JobType.BulkCoreBizObjectOperation:
                    //bulk op, hand off to biz object to deal with
                    //note, convention is that there is an idList in job.jobinfo json if preselected else it's all objects of type
                    o = (IJobObject)BizObjectFactory.GetBizObject(job.ObjectType);
                    break;
                default:
                    throw new System.NotSupportedException($"ProcessJobAsync type {job.JobType.ToString()} is not supported");
            }

            if (o != null)
                await o.HandleJobAsync(job);
            log.LogDebug($"ProcessJobAsync -> Job completed {JobDescription}");
        }


        #endregion process jobs

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

    }//eoc


}//eons