elsa-core/src/modules/Elsa.MassTransit.RabbitMq/Features/RabbitMqServiceBusFeature.cs

using Elsa.Extensions;
using Elsa.Features.Abstractions;
using Elsa.Features.Attributes;
using Elsa.Features.Services;
using Elsa.MassTransit.Consumers;
using Elsa.MassTransit.Features;
using Elsa.MassTransit.Options;
using Elsa.Workflows.Contracts;
using MassTransit;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Options;

namespace Elsa.MassTransit.RabbitMq.Features;

/// <summary>
/// Configures MassTransit to use the RabbitMQ transport.
/// </summary>
[DependsOn(typeof(MassTransitFeature))]
public class RabbitMqServiceBusFeature : FeatureBase
{
    /// <inheritdoc />
    public RabbitMqServiceBusFeature(IModule module) : base(module)
    {
    }

    /// A RabbitMQ connection string.
    public string? ConnectionString { get; set; }

    /// Configures the RabbitMQ transport options.
    public Action<RabbitMqTransportOptions>? TransportOptions { get; set; }
    
    /// <summary>
    /// Configures the RabbitMQ bus.
    /// </summary>
    public Action<IRabbitMqBusFactoryConfigurator>? ConfigureServiceBus { get; set; }

    /// <inheritdoc />
    public override void Configure()
    {
        Module.Configure<MassTransitFeature>(massTransitFeature =>
        {
            massTransitFeature.BusConfigurator = configure =>
            {
                var tempConsumers = massTransitFeature.GetConsumers()
                    .Where(c => c.IsTemporary)
                    .ToList();
                
                configure.AddConsumers(tempConsumers.Select(c => c.ConsumerType).ToArray());
                
                configure.UsingRabbitMq((context, serviceBus) =>
                {
                    var options = context.GetRequiredService<IOptions<MassTransitWorkflowDispatcherOptions>>().Value;
                    var instanceNameRetriever = context.GetRequiredService<IInstanceNameRetriever>();
                    
                    if (!string.IsNullOrEmpty(ConnectionString))
                        serviceBus.Host(ConnectionString);

                    ConfigureServiceBus?.Invoke(serviceBus);
                    
                    foreach (var consumer in tempConsumers)
                    {
                        serviceBus.ReceiveEndpoint($"{instanceNameRetriever.GetName()}-{consumer.Name}", configurator =>
                        {
                            configurator.QueueExpiration = options.ShortTermQueueLifetime ?? TimeSpan.FromHours(1);
                            configurator.ConcurrentMessageLimit = options.ConcurrentMessageLimit;
                            configurator.ConfigureConsumer<DispatchCancelWorkflowsRequestConsumer>(context);
                        });
                    }

                    serviceBus.ConfigureEndpoints(context, new KebabCaseEndpointNameFormatter("Elsa", false));
                });
            };
        });
    }

    /// <inheritdoc />
    public override void Apply()
    {
        if (TransportOptions != null) Services.Configure(TransportOptions);
    }
}