using System.Text;
using System.Text.RegularExpressions;
using InnovEnergy.App.Backend.Database;
using InnovEnergy.App.Backend.DataTypes;
using InnovEnergy.App.Backend.DataTypes.Methods;
using InnovEnergy.App.Backend.Websockets;
using InnovEnergy.Lib.Utils;

namespace InnovEnergy.App.Backend.Services;

public static class AutoTicketService
{
    private const String NicoLappName    = "Nico Lapp";
    private const String AtefSarrajName  = "Atef Sarraj";

    private const String TagAlarm   = "auto:alarm";
    private const String TagOffline = "auto:offline";

    private const Int32 AlarmStatus   = (Int32)StatusType.Alarm;
    private const Int32 OfflineStatus = (Int32)StatusType.Offline;

    public static async Task MaybeCreateForAlarmAsync(
        Installation installation,
        Int32 prevStatus,
        IReadOnlyList<AlarmOrWarning> alarms)
    {
        if (!IsSodistore(installation.Product)) return;
        if (prevStatus == AlarmStatus) return;
        // Edit/testing mode: alarms during commissioning shouldn't open tickets.
        if (installation.TestingMode) return;

        var assignee = FindAdminByName(NicoLappName);
        if (assignee is null)
        {
            Console.WriteLine($"[AutoTicket] assignee \"{NicoLappName}\" not found, skipping alarm ticket for installation {installation.Id}");
            return;
        }

        if (alarms.Count == 0)
        {
            Console.WriteLine($"[AutoTicket] alarm transition for installation {installation.Id} carried no alarm payload, skipping (likely transient)");
            return;
        }

        if (HasOpenAutoTicket(installation.Id, TagAlarm)) return;

        var lang = String.IsNullOrWhiteSpace(assignee.Language) ? "en" : assignee.Language;
        var firstName = SplitCamelCase(alarms[0].Description);
        var suffix    = alarms.Count > 1 ? $" (+{alarms.Count - 1} more)" : "";
        var subject   = $"[Auto] {installation.Name} entered error state [{firstName}]{suffix}";

        var description = await BuildAlarmDescriptionAsync(installation, prevStatus, alarms, lang);

        CreateTicket(installation, assignee, subject, description, TagAlarm);
    }

    public static Task MaybeCreateForOfflineAsync(
        Installation installation,
        Int32 prevStatus,
        DateTime lastSeen)
    {
        if (!IsSodistore(installation.Product)) return Task.CompletedTask;
        if (prevStatus == OfflineStatus) return Task.CompletedTask;
        // Edit/testing mode: offline transitions during commissioning shouldn't open tickets.
        if (installation.TestingMode) return Task.CompletedTask;

        var assignee = FindAdminByName(AtefSarrajName);
        if (assignee is null)
        {
            Console.WriteLine($"[AutoTicket] assignee \"{AtefSarrajName}\" not found, skipping offline ticket for installation {installation.Id}");
            return Task.CompletedTask;
        }

        if (HasOpenAutoTicket(installation.Id, TagOffline)) return Task.CompletedTask;

        var subject     = $"[Auto] {installation.Name} went offline";
        var description = BuildOfflineDescription(installation, prevStatus, lastSeen);

        CreateTicket(installation, assignee, subject, description, TagOffline);
        return Task.CompletedTask;
    }

    private static void CreateTicket(
        Installation installation,
        User assignee,
        String subject,
        String description,
        String tag)
    {
        var ticket = new Ticket
        {
            Subject         = subject,
            Description     = description,
            Status          = (Int32)TicketStatus.Open,
            Priority        = (Int32)TicketPriority.Critical,
            Category        = (Int32)TicketCategory.Other,
            SubCategory     = 0,
            Source          = (Int32)TicketSource.AutoAlert,
            InstallationId  = installation.Id,
            AssigneeId      = assignee.Id,
            CreatedByUserId = assignee.Id,
            Tags            = tag,
            CreatedAt       = DateTime.UtcNow,
            UpdatedAt       = DateTime.UtcNow
        };

        if (!Db.Create(ticket))
        {
            Console.WriteLine($"[AutoTicket] Db.Create failed for installation {installation.Id} ({tag})");
            return;
        }

        var timelineOk = Db.Create(new TicketTimelineEvent
        {
            TicketId    = ticket.Id,
            EventType   = (Int32)TimelineEventType.Created,
            Description = $"Ticket auto-created by status monitor ({tag}).",
            ActorType   = (Int32)TimelineActorType.System,
            ActorId     = null,
            CreatedAt   = DateTime.UtcNow
        });
        if (!timelineOk)
            Console.WriteLine($"[AutoTicket] timeline event insert failed for ticket {ticket.Id} (informational only — ticket itself is fine)");

        _ = Task.Run(async () =>
        {
            try { await assignee.SendTicketAssignedEmail(ticket); }
            catch (Exception ex) { Console.WriteLine($"[AutoTicket] assignment email failed for ticket {ticket.Id}: {ex.Message}"); }
        });

        var lang = String.IsNullOrWhiteSpace(assignee.Language) ? "en" : assignee.Language;
        TicketDiagnosticService.DiagnoseTicketAsync(ticket.Id, lang).SupressAwaitWarning();
    }

    private static Boolean HasOpenAutoTicket(Int64 installationId, String tag)
    {
        return Db.GetTicketsForInstallation(installationId).Any(t =>
            t.Source == (Int32)TicketSource.AutoAlert
            && (t.Status == (Int32)TicketStatus.Open || t.Status == (Int32)TicketStatus.InProgress)
            && t.Tags == tag);
    }

    private static User? FindAdminByName(String name) =>
        Db.Users.FirstOrDefault(u => u.UserType == 2 && u.Name == name);

    private static Boolean IsSodistore(Int32 product) => product is 2 or 3 or 4 or 5;

    private static String SplitCamelCase(String name) =>
        Regex.Replace(name ?? "", @"(?<=[a-z])(?=[A-Z])|(?<=[A-Z])(?=[A-Z][a-z])", " ").Trim();

    private static async Task<String> BuildAlarmDescriptionAsync(
        Installation installation,
        Int32 prevStatus,
        IReadOnlyList<AlarmOrWarning> alarms,
        String lang)
    {
        var sb = new StringBuilder();
        sb.AppendLine("Auto-created by status monitor.");
        sb.AppendLine($"Installation: {installation.Name} (id {installation.Id})");
        sb.AppendLine($"Location: {installation.Location}");
        sb.AppendLine($"Transition: {StatusLabel(prevStatus)} → Alarm");
        sb.AppendLine($"Detected at: {DateTime.UtcNow:O} UTC");
        sb.AppendLine();
        sb.AppendLine($"—— Alarms ({alarms.Count}) ——");

        foreach (var alarm in alarms)
        {
            var displayName = SplitCamelCase(alarm.Description);
            sb.AppendLine();
            sb.AppendLine($"[{displayName}] (raw: {alarm.Description}) — {alarm.Date} {alarm.Time} from {alarm.CreatedBy}");

            DiagnosticResponse? diag = null;
            try
            {
                diag = await DiagnosticService.DiagnoseAsync(installation.Id, alarm.Description, lang);
            }
            catch (Exception ex)
            {
                Console.WriteLine($"[AutoTicket] DiagnoseAsync failed for {alarm.Description}: {ex.Message}");
            }

            if (diag is null)
            {
                sb.AppendLine("  (no diagnosis available)");
                continue;
            }

            sb.AppendLine($"  Explanation: {diag.Explanation}");

            if (diag.Causes is { Count: > 0 })
            {
                sb.AppendLine("  Likely causes:");
                foreach (var cause in diag.Causes) sb.AppendLine($"    - {cause}");
            }

            if (diag.NextSteps is { Count: > 0 })
            {
                sb.AppendLine("  Suggested next steps:");
                var i = 1;
                foreach (var step in diag.NextSteps) sb.AppendLine($"    {i++}. {step}");
            }
        }

        return sb.ToString();
    }

    private static String BuildOfflineDescription(Installation installation, Int32 prevStatus, DateTime lastSeen)
    {
        // lastSeen is captured from WebsocketManager which uses DateTime.Now (server local time);
        // normalise to UTC so the rendered timestamps + "min ago" delta are consistent and unambiguous.
        var lastSeenUtc = lastSeen.Kind == DateTimeKind.Utc ? lastSeen : lastSeen.ToUniversalTime();
        var minutesAgo  = (DateTime.UtcNow - lastSeenUtc).TotalMinutes;
        var (productLabel, timeoutMin) = OfflineProfile(installation.Product);

        var sb = new StringBuilder();
        sb.AppendLine("Auto-created by status monitor.");
        sb.AppendLine($"Installation: {installation.Name} (id {installation.Id})");
        sb.AppendLine($"Location: {installation.Location}");
        sb.AppendLine($"Transition: {StatusLabel(prevStatus)} → Offline");
        sb.AppendLine($"Detected at: {DateTime.UtcNow:O} UTC");
        sb.AppendLine();
        sb.AppendLine($"Last heartbeat received: {lastSeenUtc:O} UTC ({minutesAgo:F1} min ago)");
        sb.AppendLine($"Expected heartbeat interval for {productLabel}: {timeoutMin} min");
        sb.AppendLine();
        sb.AppendLine("This ticket was auto-created because no message was received from the");
        sb.AppendLine("installation within the expected interval. Please verify network/VPN");
        sb.AppendLine("connectivity, then check the device side.");

        return sb.ToString();
    }

    private static String StatusLabel(Int32 status) => status switch
    {
        (Int32)StatusType.Offline => "Offline",
        (Int32)StatusType.Green   => "Green",
        (Int32)StatusType.Warning => "Warning",
        (Int32)StatusType.Alarm   => "Alarm",
        -2                        => "Unknown",
        _                         => $"Status({status})"
    };

    private static (String label, Int32 timeoutMinutes) OfflineProfile(Int32 product) => product switch
    {
        (Int32)ProductType.SodioHome     => ("Sodistore Home", 4),
        (Int32)ProductType.SodiStoreMax  => ("Sodistore Max", 2),
        (Int32)ProductType.SodistoreGrid => ("Sodistore Grid", 2),
        (Int32)ProductType.SodistorePro  => ("Sodistore Pro", 4),
        _                                => ($"Product {product}", 0)
    };
}