// backend/MotoresArgentinosV2.Infrastructure/Services/AdExpirationService.cs
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using MotoresArgentinosV2.Infrastructure.Data;
using MotoresArgentinosV2.Core.Entities;
using MotoresArgentinosV2.Core.Interfaces;
using Microsoft.Extensions.Configuration;

namespace MotoresArgentinosV2.Infrastructure.Services;

public class AdExpirationService : BackgroundService
{
  private readonly IServiceProvider _serviceProvider;
  private readonly ILogger<AdExpirationService> _logger;

  public AdExpirationService(IServiceProvider serviceProvider, ILogger<AdExpirationService> logger)
  {
    _serviceProvider = serviceProvider;
    _logger = logger;
  }

  protected override async Task ExecuteAsync(CancellationToken stoppingToken)
  {
    _logger.LogInformation("Servicio de Mantenimiento Integral iniciado.");

    while (!stoppingToken.IsCancellationRequested)
    {
      try
      {
        // 1. Vencimientos
        await CheckExpiredAdsAsync();
        await ProcessExpirationWarningsAsync();

        // 2. Limpiezas
        await CleanupUnpaidDraftsAsync();
        await PermanentDeleteOldDeletedAdsAsync();
        await CleanupOldRefreshTokensAsync();
        await CleanupAdViewLogsAsync();

        // 3. Marketing y Retención
        await ProcessWeeklyStatsAsync();
        await ProcessPaymentRemindersAsync();
        await ProcessUnreadMessagesRemindersAsync();

        // Ejecutar cada 1 hora
        await Task.Delay(TimeSpan.FromHours(1), stoppingToken);
      }
      catch (OperationCanceledException)
      {
        break;
      }
      catch (Exception ex)
      {
        _logger.LogError(ex, "Error CRÍTICO en ciclo de mantenimiento.");
        await Task.Delay(TimeSpan.FromMinutes(5), stoppingToken);
      }
    }
  }

  private async Task CleanupAdViewLogsAsync()
  {
    using (var scope = _serviceProvider.CreateScope())
    {
      var context = scope.ServiceProvider.GetRequiredService<MotoresV2DbContext>();
      var logger = scope.ServiceProvider.GetRequiredService<ILogger<AdExpirationService>>();

      // Borrar logs de visitas de más de 30 días de antigüedad
      var cutoffDate = DateTime.UtcNow.AddDays(-30);

      var deletedCount = await context.AdViewLogs
          .Where(l => l.ViewDate < cutoffDate)
          .ExecuteDeleteAsync();

      if (deletedCount > 0)
      {
        logger.LogInformation("Mantenimiento: Se eliminaron {Count} registros de visitas antiguos.", deletedCount);
      }
    }
  }

  private async Task CheckExpiredAdsAsync()
  {
    using (var scope = _serviceProvider.CreateScope())
    {
      var context = scope.ServiceProvider.GetRequiredService<MotoresV2DbContext>();
      var notifService = scope.ServiceProvider.GetRequiredService<INotificationService>();

      var cutoffDate = DateTime.UtcNow.AddDays(-30);

      var expiredAds = await context.Ads
          .Include(a => a.User)
          .Include(a => a.Brand)
          .Where(a =>
              // Regla 1: Aviso activo
              a.StatusID == (int)AdStatusEnum.Active &&
              // Regla 2: Publicado hace más de 30 días
              a.PublishedAt.HasValue && a.PublishedAt.Value < cutoffDate &&
              // --- CAMBIO AQUÍ: Excluimos avisos de administradores ---
              a.User != null && a.User.UserType != 3
          )
          .ToListAsync();

      foreach (var ad in expiredAds)
      {
        ad.StatusID = (int)AdStatusEnum.Expired;

        if (ad.User != null && !string.IsNullOrEmpty(ad.User.Email))
        {
          var title = $"{ad.Brand?.Name} {ad.VersionName}";
          await notifService.SendAdExpiredEmailAsync(ad.User.Email, ad.User.FirstName ?? "Usuario", title);
        }

        context.AuditLogs.Add(new AuditLog
        {
          Action = "SYSTEM_AD_EXPIRED",
          Entity = "Ad",
          EntityID = ad.AdID,
          UserID = 0,
          Details = $"Aviso ID {ad.AdID} vencido. Email enviado a usuario no-admin."
        });
      }
      if (expiredAds.Any()) await context.SaveChangesAsync();
    }
  }

  private async Task ProcessExpirationWarningsAsync()
  {
    using (var scope = _serviceProvider.CreateScope())
    {
      var context = scope.ServiceProvider.GetRequiredService<MotoresV2DbContext>();
      var notifService = scope.ServiceProvider.GetRequiredService<INotificationService>();

      var warningThreshold = DateTime.UtcNow.AddDays(-25);

      var adsToWarn = await context.Ads
          .Include(a => a.User)
          .Include(a => a.Brand)
          .Where(a =>
              a.StatusID == (int)AdStatusEnum.Active &&
              a.PublishedAt.HasValue && a.PublishedAt.Value <= warningThreshold &&
              !a.ExpirationWarningSent &&
              // --- CAMBIO AQUÍ: Excluimos avisos de administradores ---
              a.User != null && a.User.UserType != 3
          )
          .ToListAsync();

      foreach (var ad in adsToWarn)
      {
        if (ad.User == null || string.IsNullOrEmpty(ad.User.Email)) continue;

        var title = $"{ad.Brand?.Name} {ad.VersionName}";
        var expDate = ad.PublishedAt!.Value.AddDays(30);

        try
        {
          await notifService.SendExpirationWarningEmailAsync(ad.User.Email, ad.User.FirstName ?? "Usuario", title, expDate);
          ad.ExpirationWarningSent = true;
        }
        catch { /* Log error pero continuar */ }
      }

      if (adsToWarn.Any()) await context.SaveChangesAsync();
    }
  }

  private async Task ProcessWeeklyStatsAsync()
  {
    using (var scope = _serviceProvider.CreateScope())
    {
      var context = scope.ServiceProvider.GetRequiredService<MotoresV2DbContext>();
      var notifService = scope.ServiceProvider.GetRequiredService<INotificationService>();

      var sevenDaysAgo = DateTime.UtcNow.AddDays(-7);

      var adsForStats = await context.Ads
          .Include(a => a.User)
          .Include(a => a.Brand)
          .Where(a =>
              a.StatusID == (int)AdStatusEnum.Active &&
              a.User != null && a.User.UserType != 3 && // Ya estaba excluido aquí
              a.PublishedAt.HasValue && a.PublishedAt.Value <= sevenDaysAgo &&
              (a.LastPerformanceEmailSentAt == null || a.LastPerformanceEmailSentAt <= sevenDaysAgo)
          )
          .Take(50)
          .ToListAsync();

      foreach (var ad in adsForStats)
      {
        if (ad.User == null || string.IsNullOrEmpty(ad.User.Email)) continue;

        var favCount = await context.Favorites.CountAsync(f => f.AdID == ad.AdID);
        var title = $"{ad.Brand?.Name} {ad.VersionName}";

        await notifService.SendWeeklyPerformanceEmailAsync(
            ad.User.Email,
            ad.User.FirstName ?? "Usuario",
            title,
            ad.ViewsCounter,
            favCount
        );

        ad.LastPerformanceEmailSentAt = DateTime.UtcNow;
      }

      if (adsForStats.Any()) await context.SaveChangesAsync();
    }
  }

  private async Task ProcessPaymentRemindersAsync()
  {
    using (var scope = _serviceProvider.CreateScope())
    {
      var context = scope.ServiceProvider.GetRequiredService<MotoresV2DbContext>();
      var notifService = scope.ServiceProvider.GetRequiredService<INotificationService>();

      var config = scope.ServiceProvider.GetRequiredService<IConfiguration>();
      var frontendUrl = config["AppSettings:FrontendUrl"] ?? "http://localhost:5173";

      var cutoff = DateTime.UtcNow.AddHours(-24);

      var abandonedCarts = await context.Ads
          .Include(a => a.User)
          .Include(a => a.Brand)
          .Where(a =>
              (a.StatusID == 1 || a.StatusID == 2) &&
              a.CreatedAt < cutoff &&
              a.PaymentReminderSentAt == null &&
              a.User != null && a.User.UserType != 3
          )
          .Take(20)
          .ToListAsync();

      foreach (var ad in abandonedCarts)
      {
        if (ad.User == null || string.IsNullOrEmpty(ad.User.Email)) continue;

        var title = $"{ad.Brand?.Name} {ad.VersionName}";
        var link = $"{frontendUrl}/publicar?edit={ad.AdID}";

        await notifService.SendPaymentReminderEmailAsync(ad.User.Email, ad.User.FirstName ?? "Usuario", title, link);

        ad.PaymentReminderSentAt = DateTime.UtcNow;
      }

      if (abandonedCarts.Any()) await context.SaveChangesAsync();
    }
  }

  private async Task ProcessUnreadMessagesRemindersAsync()
  {
    using (var scope = _serviceProvider.CreateScope())
    {
      var context = scope.ServiceProvider.GetRequiredService<MotoresV2DbContext>();
      var notifService = scope.ServiceProvider.GetRequiredService<INotificationService>();

      // Buscar usuarios que tengan mensajes no leídos viejos (> 4 horas) 
      // y que no hayan sido notificados en las últimas 24 horas.

      var messageThreshold = DateTime.UtcNow.AddHours(-4);
      var notificationThreshold = DateTime.UtcNow.AddHours(-24);

      // 1. Obtener IDs de usuarios con mensajes sin leer viejos
      var usersWithUnread = await context.ChatMessages
          .Where(m => !m.IsRead && m.SentAt < messageThreshold)
          .Select(m => m.ReceiverID)
          .Distinct()
          .ToListAsync();

      foreach (var userId in usersWithUnread)
      {
        var user = await context.Users.FindAsync(userId);

        // Verificar si ya le avisamos hoy
        if (user == null || string.IsNullOrEmpty(user.Email) ||
            (user.LastUnreadMessageReminderSentAt != null && user.LastUnreadMessageReminderSentAt > notificationThreshold))
        {
          continue;
        }

        // Contar total no leídos
        var totalUnread = await context.ChatMessages.CountAsync(m => m.ReceiverID == userId && !m.IsRead);

        await notifService.SendUnreadMessagesReminderEmailAsync(user.Email, user.FirstName ?? "Usuario", totalUnread);

        user.LastUnreadMessageReminderSentAt = DateTime.UtcNow;
      }

      if (usersWithUnread.Any()) await context.SaveChangesAsync();
    }
  }

  private async Task CleanupUnpaidDraftsAsync()
  {
    using (var scope = _serviceProvider.CreateScope())
    {
      var context = scope.ServiceProvider.GetRequiredService<MotoresV2DbContext>();
      var imageService = scope.ServiceProvider.GetRequiredService<IImageStorageService>();
      var logger = scope.ServiceProvider.GetRequiredService<ILogger<AdExpirationService>>();

      // Regla: Eliminar avisos IMPAGOS (Borrador = 1) con más de 30 días de antigüedad (CreatedAt).
      // No se tocan los que están en Moderación (3) ni los Rechazados (5) a menos que se especifique.

      var cutoffDate = DateTime.UtcNow.AddDays(-30);

      var oldDrafts = await context.Ads
          .Include(a => a.Photos)
          .Where(a => a.StatusID == 1 && a.CreatedAt < cutoffDate) // 1 = Borrador/Impago
          .ToListAsync();

      if (oldDrafts.Any())
      {
        logger.LogInformation("Eliminando {Count} avisos impagos (borradores) de más de 30 días de antigüedad...", oldDrafts.Count);

        foreach (var draft in oldDrafts)
        {
          try
          {
            // 1. Borrar fotos del disco físico
            if (draft.Photos != null)
            {
              foreach (var photo in draft.Photos)
              {
                if (!string.IsNullOrEmpty(photo.FilePath))
                  imageService.DeleteAdImage(photo.FilePath);
              }
            }

            // 2. Eliminar registro de la DB
            context.Ads.Remove(draft);

            // 📝 AUDITORÍA
            context.AuditLogs.Add(new AuditLog
            {
              Action = "SYSTEM_DRAFT_CLEANED",
              Entity = "Ad",
              EntityID = draft.AdID,
              UserID = 0, // Sistema
              Details = $"Borrador impago ID {draft.AdID} eliminado por antigüedad."
            });
          }
          catch (Exception ex)
          {
            logger.LogError(ex, "Error eliminando borrador ID {AdId}", draft.AdID);
          }
        }

        await context.SaveChangesAsync();
        logger.LogInformation("Limpieza de borradores antiguos completada.");
      }
    }
  }

  private async Task PermanentDeleteOldDeletedAdsAsync()
  {
    using (var scope = _serviceProvider.CreateScope())
    {
      var context = scope.ServiceProvider.GetRequiredService<MotoresV2DbContext>();
      var imageService = scope.ServiceProvider.GetRequiredService<IImageStorageService>();
      var logger = scope.ServiceProvider.GetRequiredService<ILogger<AdExpirationService>>();

      var cutoffDate = DateTime.UtcNow.AddDays(-60);

      var adsToRemove = await context.Ads
          .Include(a => a.Photos)
          .Include(a => a.Features)
          .Include(a => a.Messages)
          .Where(a => a.StatusID == (int)AdStatusEnum.Deleted
                      && a.DeletedAt.HasValue
                      && a.DeletedAt.Value < cutoffDate)
          .ToListAsync();

      if (adsToRemove.Any())
      {
        logger.LogInformation("Eliminando permanentemente {Count} avisos...", adsToRemove.Count);

        foreach (var ad in adsToRemove)
        {
          try
          {
            // 1. Borrar fotos del disco físico
            if (ad.Photos != null)
            {
              foreach (var photo in ad.Photos)
              {
                if (!string.IsNullOrEmpty(photo.FilePath))
                  imageService.DeleteAdImage(photo.FilePath);
              }
            }

            // 2. Info para el log antes de borrar
            int msgCount = ad.Messages?.Count ?? 0;

            // 3. Eliminar registro de la DB
            // Al tener Cascade configurado en EF y SQL, esto borrará:
            // - El Aviso (Ad)
            // - Sus Fotos (AdPhotos)
            // - Sus Características (AdFeatures)
            // - Sus Mensajes (ChatMessages)
            context.Ads.Remove(ad);

            // 📝 AUDITORÍA
            context.AuditLogs.Add(new AuditLog
            {
              Action = "SYSTEM_HARD_DELETE",
              Entity = "Ad",
              EntityID = ad.AdID,
              UserID = 0, // Sistema
              Details = $"Aviso ID {ad.AdID} eliminado permanentemente. Se eliminaron {msgCount} mensajes de chat asociados."
            });

            logger.LogInformation("Hard Delete AdID {AdId} completado. Mensajes eliminados: {MsgCount}", ad.AdID, msgCount);
          }
          catch (Exception ex)
          {
            logger.LogError(ex, "Error en Hard Delete del aviso ID {AdId}", ad.AdID);
          }
        }

        await context.SaveChangesAsync();
      }
    }
  }
  private async Task CleanupOldRefreshTokensAsync()
  {
    using (var scope = _serviceProvider.CreateScope())
    {
      var context = scope.ServiceProvider.GetRequiredService<MotoresV2DbContext>();
      var logger = scope.ServiceProvider.GetRequiredService<ILogger<AdExpirationService>>();

      // Política: Eliminar tokens que:
      // 1. Ya expiraron hace más de 30 días OR
      // 2. Fueron revocados hace más de 30 días
      // (Mantenemos un historial de 30 días por seguridad/auditoría, luego se borra)

      var cutoffDate = DateTime.UtcNow.AddDays(-30);

      // Usamos ExecuteDeleteAsync para borrado masivo eficiente (EF Core 7+)
      var deletedCount = await context.RefreshTokens
          .Where(t => t.Expires < cutoffDate || (t.Revoked != null && t.Revoked < cutoffDate))
          .ExecuteDeleteAsync();

      if (deletedCount > 0)
      {
        logger.LogInformation("Limpieza de Tokens: Se eliminaron {Count} refresh tokens obsoletos.", deletedCount);

        // No hace falta guardar AuditLog para esto, es mantenimiento técnico puro,
        // pero se podría agregar.
      }
    }
  }
}