using System;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using Svrnty.CQRS.Sagas.Abstractions;
using Svrnty.CQRS.Sagas.Abstractions.Messaging;

namespace Svrnty.CQRS.Sagas.RabbitMQ;

/// <summary>
/// Hosted service that manages RabbitMQ saga connections and subscriptions.
/// </summary>
public class RabbitMqSagaHostedService : BackgroundService
{
    private readonly IServiceProvider _serviceProvider;
    private readonly ISagaMessageBus _messageBus;
    private readonly ILogger<RabbitMqSagaHostedService> _logger;

    /// <summary>
    /// Creates a new RabbitMQ saga hosted service.
    /// </summary>
    public RabbitMqSagaHostedService(
        IServiceProvider serviceProvider,
        ISagaMessageBus messageBus,
        ILogger<RabbitMqSagaHostedService> logger)
    {
        _serviceProvider = serviceProvider;
        _messageBus = messageBus;
        _logger = logger;
    }

    /// <inheritdoc />
    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        _logger.LogInformation("Starting RabbitMQ saga hosted service");

        try
        {
            // Subscribe to saga responses so the orchestrator can process them
            await _messageBus.SubscribeToResponsesAsync(
                async (response, ct) =>
                {
                    using var scope = _serviceProvider.CreateScope();
                    var orchestrator = scope.ServiceProvider.GetRequiredService<ISagaOrchestrator>();

                    // The orchestrator needs to handle responses
                    // This is a simplified approach - in production you'd want to handle this more robustly
                    _logger.LogDebug(
                        "Received response for saga {SagaId}, step {StepName}, success: {Success}",
                        response.SagaId, response.StepName, response.Success);

                    // For now, we just log the response
                    // The orchestrator's HandleResponseAsync method would be called here
                    // but it requires knowing the saga data type, which we don't have in this context
                },
                stoppingToken);

            _logger.LogInformation("RabbitMQ saga hosted service started successfully");

            // Keep the service running
            await Task.Delay(Timeout.Infinite, stoppingToken);
        }
        catch (OperationCanceledException) when (stoppingToken.IsCancellationRequested)
        {
            _logger.LogInformation("RabbitMQ saga hosted service is stopping");
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error in RabbitMQ saga hosted service");
            throw;
        }
    }

    /// <inheritdoc />
    public override async Task StopAsync(CancellationToken cancellationToken)
    {
        _logger.LogInformation("Stopping RabbitMQ saga hosted service");

        if (_messageBus is IAsyncDisposable disposable)
        {
            await disposable.DisposeAsync();
        }

        await base.StopAsync(cancellationToken);
    }
}