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

namespace AyaNova.Biz
{

    /// <summary>
    /// Notification processor
    /// turn notifyEvent records into inappnotification records for in app viewing and / or deliver smtp notifications seperately
    /// 
    /// </summary>
    internal static class CoreJobNotify
    {
        private static bool NotifyIsRunning = false;
        private static ILogger log = AyaNova.Util.ApplicationLogging.CreateLogger("CoreJobNotify");
        private static DateTime lastRun = DateTime.MinValue;
        private static DateTime lastNotifyHealthCheckSentLocal = DateTime.MinValue;
        private static TimeSpan TS_24_HOURS = new TimeSpan(24, 0, 0);//used to ensure daily ops happen no more than that

#if (DEBUG)      
        private static TimeSpan RUN_EVERY_INTERVAL = new TimeSpan(0, 0, 21);//no more frequently than once every 20 seconds
#else 
        private static TimeSpan RUN_EVERY_INTERVAL = new TimeSpan(0, 1, 1);//no more frequently than once every 1 minute
#endif

        ////////////////////////////////////////////////////////////////////////////////////////////////
        // DoSweep
        //
        public static async Task DoWorkAsync()
        {
            log.LogDebug("Checking if Notify should run");
            if (NotifyIsRunning)
            {
                log.LogDebug("Notify is running already exiting this cycle");
                return;
            }
            //This will get triggered roughly every minute, but we don't want to deliver that frequently
            if (DateTime.UtcNow - lastRun < RUN_EVERY_INTERVAL)
            {
                log.LogDebug($"Notify ran less than {RUN_EVERY_INTERVAL} ago, exiting this cycle");
                return;
            }
            try
            {
                NotifyIsRunning = true;
                log.LogDebug("Notify set to RUNNING state and starting now");

                //NotifyHealthCheck processing
                //Note this deliberately uses LOCAL time in effort to deliver the health check first thing in the morning for workers
                //However if server is on UTC already then that's what is used, there is no adjustment
                DateTime dtNowLocal = DateTime.Now;
                if (dtNowLocal - lastNotifyHealthCheckSentLocal > TS_24_HOURS)
                {
                    //are we in the 7th to 9th hour?
                    if (dtNowLocal.Hour > 6 && dtNowLocal.Hour < 10)
                    {
                        log.LogDebug("Notify health check submitted to subscribers");
                        await NotifyEventHelper.AddGeneralNotifyEvent(NotifyEventType.NotifyHealthCheck, "OK", "");
                        lastNotifyHealthCheckSentLocal = dtNowLocal;
                    }
                }

                using (AyContext ct = AyaNova.Util.ServiceProviderProvider.DBContext)
                {
                    var events = await ct.NotifyEvent.AsNoTracking().ToListAsync();
                    log.LogDebug($"Found {events.Count} NotifyEvents to examine for potential delivery");

                    //iterate and deliver
                    foreach (var notifyevent in events)
                    {
                        //no notifications for inactive users, just delete it as if it was delivered                      
                        var UserInfo = await ct.User.AsNoTracking().Where(x => x.Id == notifyevent.UserId).Select(x => new { Active = x.Active, Name = x.Name }).FirstOrDefaultAsync();
                        if (!UserInfo.Active)
                        {
                            log.LogDebug($"Inactive user {UserInfo.Name}, removing notify rather than delivering it: {notifyevent}");
                            ct.NotifyEvent.Remove(notifyevent);
                            await ct.SaveChangesAsync();
                            continue;
                        }

                        //Get subscription for delivery
                        var Subscription = await ct.NotifySubscription.AsNoTracking().FirstOrDefaultAsync(x => x.Id == notifyevent.NotifySubscriptionId);

                        //NOTE: There is no need to separate out future delivery and immediate delivery because
                        // All events have an event date, it's either immediate upon creation or it's future
                        // but not all events have an age value including ones with future event dates,   
                        // and the default agevalue and advancenotice are both zero regardless so the block below works for either future or immediate deliveries                   

                        var deliverAfter = notifyevent.EventDate + Subscription.AgeValue - Subscription.AdvanceNotice;
                        if (deliverAfter < DateTime.UtcNow)
                        {
                            //Check "circuit breaker" for notification types that could
                            //repeat rapidly 
                            //(e.g. pm notification error for a fucked up PM that is attempted every few minutes or a 
                            //system exception for something that pops up every few minutes or a thousand times in a hour etc)
                            //Don't check for ones that are regular object based
                            //which can and will properly send out the same notification regularly
                            //(e.g. workorder status change into out of and back into the same staus)          
                            switch (notifyevent.EventType)
                            {
                                case NotifyEventType.BackupStatus:
                                case NotifyEventType.GeneralNotification:
                                case NotifyEventType.ServerOperationsProblem:
                                case NotifyEventType.PMGenerationFailed:
                                    {
                                        //check if we've just delivered this same thing in the last 12 hours which is the hard limit (case 3917)
                                        var twelvehoursago = DateTime.UtcNow - new TimeSpan(12, 0, 0);

                                        //look for same delivery less than last12hours ago
                                        if (await ct.NotifyDeliveryLog.AnyAsync(z => z.Processed > twelvehoursago && z.NotifySubscriptionId == notifyevent.NotifySubscriptionId && z.ObjectId == notifyevent.ObjectId))
                                        {
                                            log.LogDebug($"Notification event will not be delivered: repetitive (server system event type and delivered at least once in the last 12 hours to this subscriber: {notifyevent})");
                                            ct.NotifyEvent.Remove(notifyevent);
                                            await ct.SaveChangesAsync();
#if (DEBUG)
                                            log.LogInformation($"DeliverInApp event will not be delivered: repetitive (server system event type and delivered at least once in the last 12 hours to this subscriber: {notifyevent})");
#endif
                                            continue;
                                        }
                                    }
                                    break;
                            }

                            //Do the delivery, it's kosher
                            if (Subscription.DeliveryMethod == NotifyDeliveryMethod.App)
                                await DeliverInApp(notifyevent, Subscription.AgeValue, ct);
                            else if (Subscription.DeliveryMethod == NotifyDeliveryMethod.SMTP)
                                await DeliverSMTP(notifyevent, Subscription.AgeValue, Subscription.AdvanceNotice, Subscription.DeliveryAddress, ct);
                        }
                    }
                }
            }
            catch (Exception ex)
            {
                log.LogError(ex, $"Error processing notification event");
            }
            finally
            {
                log.LogDebug("Notify is done setting to not running state and tagging lastRun timestamp");
                lastRun = DateTime.UtcNow;
                NotifyIsRunning = false;

            }

        }

        private static async Task DeliverInApp(NotifyEvent ne, TimeSpan ageValue, AyContext ct)
        {
            log.LogDebug($"DeliverInApp notify event: {ne}");

            //Place in the In-app notification table for user to view
            await ct.InAppNotification.AddAsync(
                new InAppNotification()
                {
                    UserId = ne.UserId,
                    AyaType = ne.AyaType,
                    ObjectId = ne.ObjectId,
                    EventType = ne.EventType,
                    NotifySubscriptionId = ne.NotifySubscriptionId,
                    Message = ne.Message,
                    Name = ne.Name,
                    AgeValue = ageValue,
                    DecValue = ne.DecValue
                });

            ct.NotifyEvent.Remove(ne);
            //add delivery log item
            await ct.NotifyDeliveryLog.AddAsync(new NotifyDeliveryLog()
            {
                Processed = DateTime.UtcNow,
                ObjectId = ne.ObjectId,
                NotifySubscriptionId = ne.NotifySubscriptionId,
                Fail = false
            });
            await ct.SaveChangesAsync();
        }



        private static async Task DeliverSMTP(NotifyEvent ne, TimeSpan ageValue, TimeSpan advanceNotice, string deliveryAddress, AyContext ct)
        {
            var DeliveryLogItem = new NotifyDeliveryLog()
            {
                Processed = DateTime.UtcNow,
                ObjectId = ne.ObjectId,
                NotifySubscriptionId = ne.NotifySubscriptionId,
                Fail = false
            };

            try
            {
                log.LogDebug($"DeliverSMTP delivering notify event: {ne}");
                if (string.IsNullOrWhiteSpace(deliveryAddress))
                {
                    await NotifyEventHelper.AddGeneralNotifyEvent(NotifyEventType.GeneralNotification, $"No email address is set in subscription to deliver email notification.  This event will be removed from the delivery queue as undeliverable: {ne}", "Error", null, ne.UserId);
                    DeliveryLogItem.Fail = true;
                    DeliveryLogItem.Error = $"No email address provided for smtp delivery; event: {ne}";
                }
                else
                {
                    //Email notification requires pre-translated values
                    List<string> TranslationKeysToFetch = new List<string>();
                    TranslationKeysToFetch.Add(ne.AyaType.ToString());
                    TranslationKeysToFetch.Add("NotifySubscription");
                    TranslationKeysToFetch.Add("NotifySubscriptionLinkText");
                    if (ne.Name == "~SERVER~")
                        TranslationKeysToFetch.Add("Server");
                    var EventTypeTranslationKey = "NotifyEvent" + ne.EventType.ToString();
                    TranslationKeysToFetch.Add(EventTypeTranslationKey);
                    if (ageValue != TimeSpan.Zero || ne.EventType == NotifyEventType.CustomerServiceImminent)
                    {
                        TranslationKeysToFetch.Add("TimeSpanDays");
                        TranslationKeysToFetch.Add("TimeSpanHours");
                        TranslationKeysToFetch.Add("TimeSpanMinutes");
                        TranslationKeysToFetch.Add("TimeSpanSeconds");
                    }
                    if (ne.EventType == NotifyEventType.CustomerServiceImminent)
                        TranslationKeysToFetch.Add("NotifyEventCustomerServiceImminentMessage");

                    if (ne.DecValue != 0 && ne.EventType == NotifyEventType.WorkorderTotalExceedsThreshold)
                    {
                        TranslationKeysToFetch.Add("Total");
                    }

                    //get translations
                    var transid = await ct.UserOptions.AsNoTracking().Where(x => x.UserId == ne.UserId).Select(x => x.TranslationId).FirstOrDefaultAsync();
                    var LT = await TranslationBiz.GetSubsetStaticAsync(TranslationKeysToFetch, transid);

                    var NotifySubscriptionLinkText = LT["NotifySubscriptionLinkText"];
                    var name = ne.Name;
                    if (name == "~SERVER~")
                        name = LT["Server"];

                    //AyaType translation
                    var AyaTypeTranslated = "-";
                    if (ne.AyaType != AyaType.NoType)
                        AyaTypeTranslated = $"{LT[ne.AyaType.ToString()]}";

                    //subscription name translation
                    var SubscriptionTypeName = LT[EventTypeTranslationKey];



                    //Age relevant notification
                    string AgeDisplay = "";
                    if (ageValue != TimeSpan.Zero)
                        AgeDisplay = $"({AyaNova.Util.DateUtil.FormatTimeSpan(ageValue, LT["TimeSpanDays"], LT["TimeSpanHours"], LT["TimeSpanMinutes"], LT["TimeSpanSeconds"])})\n";


                    //DecValue
                    string DecDisplay = "";
                    //could be money or integer depending on typ
                    if (ne.DecValue != 0)
                    {
                        if (ne.EventType == NotifyEventType.WorkorderTotalExceedsThreshold)
                            DecDisplay = $"{LT["Total"]}: {ne.DecValue.ToString("N2", System.Globalization.CultureInfo.InvariantCulture)}\n";
                        else if (ne.EventType == NotifyEventType.UnitMeterReadingMultipleExceeded)
                            DecDisplay = $"{System.Convert.ToInt64(ne.DecValue).ToString()}\n";
                    }

                    string subject = "";


                    IMailer m = AyaNova.Util.ServiceProviderProvider.Mailer;
                    var body = "";

                    //Special notification handling
                    switch (ne.EventType)
                    {
                        case NotifyEventType.CustomerServiceImminent:
                            subject = SubscriptionTypeName;
                            body = LT["NotifyEventCustomerServiceImminentMessage"].Replace("{0}", AyaNova.Util.DateUtil.FormatTimeSpan(advanceNotice, LT["TimeSpanDays"], LT["TimeSpanHours"], LT["TimeSpanMinutes"], LT["TimeSpanSeconds"]));
                            body += $"\n{OpenObjectUrlBuilder(ne.AyaType, ne.ObjectId, ne.EventType)}\n";
                            break;
                        default:
                            subject = $"AY:{AyaTypeTranslated}:{name}:{SubscriptionTypeName}";
                            if (ne.ObjectId != 0 || ne.EventType == NotifyEventType.BackupStatus)
                            {
                                body = $"{AgeDisplay}{DecDisplay}{AyaTypeTranslated}\n{OpenObjectUrlBuilder(ne.AyaType, ne.ObjectId, ne.EventType)}\n";
                            }
                            body += ne.Message;
                            break;
                    }


                    //Add link to subscription, all messages have this regardless of content
                    //http://localhost:8080/open/51/1 //add subscription link, notifysub is object type 51
                    if (!body.EndsWith('\n'))
                        body += "\n";

                    body += $"-----\n{NotifySubscriptionLinkText}\n{OpenSubscriptionUrlBuilder(ne.NotifySubscriptionId)}\n";

                    if (!ServerGlobalOpsSettingsCache.Notify.SmtpDeliveryActive)
                    {
                        await NotifyEventHelper.AddGeneralNotifyEvent(NotifyEventType.GeneralNotification, $"Email notifications are set to OFF at server, unable to send email notification for this event:{ne}", "Error", null, ne.UserId);
                        log.LogInformation($"** WARNING: SMTP notification is currently set to Active=False; unable to deliver email notification, re-routed to in-app notification instead [UserId={ne.UserId}, Notify subscription={ne.NotifySubscriptionId}].  Change this setting or have users remove email delivery notifications if this is permanent **");
                        DeliveryLogItem.Fail = true;
                        DeliveryLogItem.Error = $"Email notifications are set to OFF at server, unable to send email notification for this event: {ne}";
                    }
                    else
                        await m.SendEmailAsync(deliveryAddress, subject, body, ServerGlobalOpsSettingsCache.Notify);

                }
            }
            catch (Exception ex)
            {
                await NotifyEventHelper.AddOpsProblemEvent("SMTP Notification failed", ex);
                await NotifyEventHelper.AddGeneralNotifyEvent(NotifyEventType.GeneralNotification, $"An error prevented delivering the following notification via email. System operator users have been notified:{ne}", "Error", null, ne.UserId);
                DeliveryLogItem.Fail = true;
                DeliveryLogItem.Error = $"SMTP Notification failed to deliver for this event: {ne}, message: {ex.Message}";
                log.LogDebug(ex, $"DeliverSMTP Failure delivering notify event: {ne}");
            }
            finally
            {
                //remove event no matter what
                ct.NotifyEvent.Remove(ne);

                //add delivery log item
                await ct.NotifyDeliveryLog.AddAsync(DeliveryLogItem);
                await ct.SaveChangesAsync();
            }
        }

        //Called from ops notification settings to test smtp setup by delivering to address of choosing
        public static async Task<string> TestSMTPDelivery(string toAddress)
        {
            //DO TEST DELIVERY HERE USING EXACT SAME SETTINGS AS FOR DeliverSMTP above
            //todo: abstract out email sending to it's own class maybe or whatever method I choose supports the best
            //https://jasonwatmore.com/post/2020/07/15/aspnet-core-3-send-emails-via-smtp-with-mailkit
            //https://medium.com/@ffimnsr/sending-email-using-mailkit-in-asp-net-core-web-api-71b946380442

            IMailer m = AyaNova.Util.ServiceProviderProvider.Mailer;
            try
            {
                await m.SendEmailAsync(toAddress, "Test from Notification system", "This is a test to confirm notification system is working", ServerGlobalOpsSettingsCache.Notify);
                return "ok";
            }
            catch (Exception ex)
            {
                await NotifyEventHelper.AddOpsProblemEvent("SMTP (TEST) Notification failed", ex);
                return ExceptionUtil.ExtractAllExceptionMessages(ex);
            }

        }


        //Open object url
        //### NOTE: If this is required anywhere else, move it to a central BizUtils class in Biz folder callable from here and there 
        private static string OpenObjectUrlBuilder(AyaType aType, long id, NotifyEventType net)
        {
            var ServerUrl = ServerGlobalOpsSettingsCache.Notify.AyaNovaServerURL;
            if (string.IsNullOrWhiteSpace(ServerUrl))
            {
                NotifyEventHelper.AddOpsProblemEvent("Notification system: The OPS Notification setting is empty for AyaNova Server URL.  This prevents Notification system from linking events to openable objects.").Wait();
                return "OPS ERROR NO SERVER URL CONFIGURED";
            }
            ServerUrl = ServerUrl.Trim().TrimEnd('/');

            //HANDLE ITEMS WITHOUT TYPE OR ID
            if (net == NotifyEventType.BackupStatus)
            {
                return $"{ServerUrl}/ops-backup";
            }


            //Might not have a type or id in which case nothing directly to open
            if (aType == AyaType.NoType || id == 0)
            {
                return ServerUrl;
            }

            if (NotifyEventType.ObjectDeleted == net)
            {
                //goto event log for item
                // path: "/history/:ayatype/:recordid/:userlog?",
                return $"{ServerUrl}/history/{(int)aType}/{id}";
            }

            //default is to open the object in question directly            
            return $"{ServerUrl}/open/{(int)aType}/{id}";
        }


        // //Used to directly open a report at client
        // private static string OpenReportUrlBuilder(long objectId, long reportId)
        // {
        //     //CLIENT EXPECTS: open report links to have a query string [CLIENTAPPURL]/viewreport?oid=[objectid]&rid=[reportid]
        //     var ServerUrl = ServerGlobalOpsSettingsCache.Notify.AyaNovaServerURL;
        //     if (string.IsNullOrWhiteSpace(ServerUrl))
        //     {
        //         NotifyEventHelper.AddOpsProblemEvent("Notification system: The OPS Notification setting is empty for AyaNova Server URL.  This prevents Notification system from linking events to openable objects.").Wait();
        //         return "OPS ERROR NO SERVER URL CONFIGURED";
        //     }
        //     ServerUrl = ServerUrl.Trim().TrimEnd('/');
        //     return $"{ServerUrl}/viewreport?oid={objectId}&rid={reportId}";
        // }



        //url to open subscription for editing
        private static string OpenSubscriptionUrlBuilder(long id)
        {
            var ServerUrl = ServerGlobalOpsSettingsCache.Notify.AyaNovaServerURL;
            if (string.IsNullOrWhiteSpace(ServerUrl))
            {
                NotifyEventHelper.AddOpsProblemEvent("Notification system: The OPS Notification setting is empty for AyaNova Server URL.  This prevents Notification system from linking events to openable objects.").Wait();
                return "OPS ERROR NO SERVER URL CONFIGURED";
            }
            ServerUrl = ServerUrl.Trim().TrimEnd('/');

            //default is to open the object in question directly            
            return $"{ServerUrl}/open/{(int)AyaType.NotifySubscription}/{id}";
        }


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

    }//eoc


}//eons