using BCards.Web.Models;
using BCards.Web.Repositories;
using BCards.Web.ViewModels;
using MongoDB.Driver;

namespace BCards.Web.Services;

public class TrialExpirationService : BackgroundService
{
    private readonly IServiceProvider _serviceProvider;
    private readonly ILogger<TrialExpirationService> _logger;
    private readonly TimeSpan _checkInterval = TimeSpan.FromHours(1); // Check every hour

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

    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        _logger.LogInformation("TrialExpirationService started");
        
        while (!stoppingToken.IsCancellationRequested)
        {
            try
            {
                await ProcessTrialExpirationsAsync();
                
                // Verificar cancelamento antes de fazer delay
                if (stoppingToken.IsCancellationRequested)
                    break;
                
                await Task.Delay(_checkInterval, stoppingToken);
            }
            catch (OperationCanceledException)
            {
                // Cancelamento normal - não é erro
                _logger.LogInformation("TrialExpirationService is being cancelled");
                break;
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error processing trial expirations");
                
                // Verificar cancelamento antes de fazer delay de erro
                if (stoppingToken.IsCancellationRequested)
                    break;
                
                try
                {
                    await Task.Delay(TimeSpan.FromMinutes(5), stoppingToken); // Wait 5 minutes on error
                }
                catch (OperationCanceledException)
                {
                    // Cancelamento durante delay de erro - também é normal
                    _logger.LogInformation("TrialExpirationService cancelled during error delay");
                    break;
                }
            }
        }
        
        _logger.LogInformation("TrialExpirationService stopped");
    }

    private async Task ProcessTrialExpirationsAsync()
    {
        try
        {
            using var scope = _serviceProvider.CreateScope();
            var subscriptionRepository = scope.ServiceProvider.GetRequiredService<ISubscriptionRepository>();
            var userPageRepository = scope.ServiceProvider.GetRequiredService<IUserPageRepository>();
            var userRepository = scope.ServiceProvider.GetRequiredService<IUserRepository>();

            _logger.LogInformation("Checking for expired trials...");

            // Process trial expirations
            var trialSubscriptions = await subscriptionRepository.GetTrialSubscriptionsAsync();
            var now = DateTime.UtcNow;

            _logger.LogInformation($"Found {trialSubscriptions.Count} trial subscriptions to process");

            foreach (var subscription in trialSubscriptions)
            {
                try
                {
                    var user = await userRepository.GetByIdAsync(subscription.UserId);
                    if (user == null) 
                    {
                        _logger.LogWarning($"User not found for subscription {subscription.Id}");
                        continue;
                    }

                    var daysUntilExpiration = (subscription.CurrentPeriodEnd - now).TotalDays;

                    if (daysUntilExpiration <= 0)
                    {
                        // Trial expired - deactivate page
                        _logger.LogInformation($"Trial expired for user {user.Email}");
                        await HandleTrialExpiredAsync(user, subscription, userPageRepository);
                    }
                    else if (daysUntilExpiration <= 2 && !user.NotifiedOfExpiration)
                    {
                        // Trial expiring soon - send notification
                        _logger.LogInformation($"Trial expiring in {daysUntilExpiration:F1} days for user {user.Email}");
                        await SendExpirationWarningAsync(user, subscription, daysUntilExpiration);
                        
                        // Mark as notified
                        user.NotifiedOfExpiration = true;
                        await userRepository.UpdateAsync(user);
                    }
                }
                catch (Exception ex)
                {
                    _logger.LogError(ex, $"Error processing trial for subscription {subscription.Id}");
                }
            }

            _logger.LogInformation("Finished checking trial expirations");

            // Process permanent deletions (pages deleted for more than 30 days)
            await ProcessPermanentDeletionsAsync(userPageRepository);
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Critical error in ProcessTrialExpirationsAsync");
            throw; // Re-throw para ser tratado pelo ExecuteAsync
        }
    }

    private async Task HandleTrialExpiredAsync(
        User user,
        Subscription subscription,
        IUserPageRepository userPageRepository)
    {
        // Mark user page as expired (logical deletion)
        var userPage = await userPageRepository.GetByUserIdAsync(user.Id);
        if (userPage != null)
        {
            userPage.Status = PageStatus.Expired;
            userPage.DeletedAt = DateTime.UtcNow;
            userPage.DeletionReason = "trial_expired";
            userPage.UpdatedAt = DateTime.UtcNow;
            await userPageRepository.UpdateAsync(userPage);
        }

        // Update subscription status
        subscription.Status = "expired";
        subscription.UpdatedAt = DateTime.UtcNow;
        
        using var scope = _serviceProvider.CreateScope();
        var subscriptionRepository = scope.ServiceProvider.GetRequiredService<ISubscriptionRepository>();
        await subscriptionRepository.UpdateAsync(subscription);

        // Send expiration email
        await SendTrialExpiredEmailAsync(user);

        _logger.LogInformation($"Deactivated trial page for user {user.Email}");
    }

    private async Task SendExpirationWarningAsync(
        User user, 
        Subscription subscription, 
        double daysRemaining)
    {
        // TODO: Implement email service
        // For now, just log
        _logger.LogInformation($"Should send expiration warning to {user.Email} - {daysRemaining:F1} days remaining");
        
        // Example email content:
        var subject = "Seu trial do BCards expira em breve!";
        var message = $@"
            Olá {user.Name},
            
            Seu trial gratuito do BCards expira em {Math.Ceiling(daysRemaining)} dia(s).
            
            Para continuar usando sua página de links, escolha um de nossos planos:
            
            • Básico - R$ 12,90/mês
            • Profissional - R$ 25,90/mês  
            • Premium - R$ 29,90/mês
            
            Acesse: {GetUpgradeUrl()}
            
            Equipe BCards
        ";

        // TODO: Send actual email when email service is implemented
        await Task.CompletedTask;
    }

    private async Task SendTrialExpiredEmailAsync(User user)
    {
        // TODO: Implement email service
        _logger.LogInformation($"Should send trial expired email to {user.Email}");
        
        var subject = "Seu trial do BCards expirou";
        var message = $@"
            Olá {user.Name},
            
            Seu trial gratuito do BCards expirou e sua página foi temporariamente desativada.
            
            Para reativar sua página, escolha um de nossos planos:
            
            • Básico - R$ 12,90/mês - 5 links, analytics básicos
            • Profissional - R$ 25,90/mês - 15 links, todos os temas, analytics avançados
            • Premium - R$ 29,90/mês - Links ilimitados, temas premium, analytics completos, upload de PDFs
            
            Seus dados estão seguros e serão restaurados assim que você escolher um plano.
            
            Acesse: {GetUpgradeUrl()}
            
            Equipe BCards
        ";

        // TODO: Send actual email when email service is implemented
        await Task.CompletedTask;
    }

    private string GetUpgradeUrl()
    {
        // TODO: Get from configuration
        return "https://bcards.com.br/pricing";
    }

    private async Task ProcessPermanentDeletionsAsync(IUserPageRepository userPageRepository)
    {
        try
        {
            _logger.LogInformation("Checking for pages to permanently delete...");

            // Find pages that have been logically deleted for more than 30 days
            var cutoffDate = DateTime.UtcNow.AddDays(-30);

            // Get all expired pages older than 30 days
            var filter = MongoDB.Driver.Builders<UserPage>.Filter.And(
                MongoDB.Driver.Builders<UserPage>.Filter.Eq(p => p.Status, PageStatus.Expired),
                MongoDB.Driver.Builders<UserPage>.Filter.Ne(p => p.DeletedAt, null),
                MongoDB.Driver.Builders<UserPage>.Filter.Lt(p => p.DeletedAt, cutoffDate)
            );

            var pagesToDelete = await userPageRepository.GetManyAsync(filter);

            _logger.LogInformation($"Found {pagesToDelete.Count} pages to permanently delete");

            foreach (var page in pagesToDelete)
            {
                try
                {
                    _logger.LogInformation($"Permanently deleting page {page.Id} ({page.DisplayName}) - deleted at {page.DeletedAt}");
                    await userPageRepository.DeleteAsync(page.Id);
                }
                catch (Exception ex)
                {
                    _logger.LogError(ex, $"Error permanently deleting page {page.Id}");
                }
            }

            if (pagesToDelete.Count > 0)
            {
                _logger.LogInformation($"Permanently deleted {pagesToDelete.Count} pages");
            }
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error processing permanent deletions");
        }
    }
}