[FA-misc] Initial MassTransit implementation seems to work

FictionArchive.Service.Shared/Extensions/MassTransitExtensions.cs

@@ -0,0 +1,118 @@
+using System.Text.RegularExpressions;
+using FictionArchive.Service.Shared.Services.Filters;
+using MassTransit;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace FictionArchive.Service.Shared.Extensions;
+
+public static class MassTransitExtensions
+{
+    public static IServiceCollection AddFictionArchiveMassTransit(
+        this IServiceCollection services,
+        IConfiguration configuration,
+        Action<IBusRegistrationConfigurator>? configureConsumers = null)
+    {
+        services.AddMassTransit(x =>
+        {
+            configureConsumers?.Invoke(x);
+
+            x.UsingRabbitMq((context, cfg) =>
+            {
+                var (host, username, password) = ParseRabbitMqConfiguration(configuration);
+
+                cfg.Host(host, h =>
+                {
+                    h.Username(username);
+                    h.Password(password);
+                });
+
+                cfg.UseMessageRetry(r => r.Exponential(
+                    retryLimit: 5,
+                    minInterval: TimeSpan.FromSeconds(1),
+                    maxInterval: TimeSpan.FromMinutes(1),
+                    intervalDelta: TimeSpan.FromSeconds(2)));
+
+                cfg.UseConsumeFilter(typeof(LoggingConsumeFilter<>), context);
+
+                // Process one message at a time per consumer (matches old EventBus behavior)
+                cfg.PrefetchCount = 1;
+
+                cfg.ConfigureEndpoints(context);
+            });
+        });
+
+        return services;
+    }
+
+    /// <summary>
+    /// Parses RabbitMQ configuration from either ConnectionString format or separate Host/Username/Password keys.
+    /// ConnectionString format: amqp://[username:password@]host[:port]
+    /// </summary>
+    private static (string Host, string Username, string Password) ParseRabbitMqConfiguration(IConfiguration configuration)
+    {
+        var connectionString = configuration["RabbitMQ:ConnectionString"];
+
+        if (!string.IsNullOrEmpty(connectionString))
+        {
+            return ParseConnectionString(connectionString);
+        }
+
+        // Fallback to separate configuration keys
+        var host = configuration["RabbitMQ:Host"] ?? "localhost";
+        var username = configuration["RabbitMQ:Username"] ?? "guest";
+        var password = configuration["RabbitMQ:Password"] ?? "guest";
+
+        return (host, username, password);
+    }
+
+    /// <summary>
+    /// Parses an AMQP connection string into host, username, and password components.
+    /// Supports formats:
+    /// - amqp://host
+    /// - amqp://host:port
+    /// - amqp://username:password@host
+    /// - amqp://username:password@host:port
+    /// </summary>
+    private static (string Host, string Username, string Password) ParseConnectionString(string connectionString)
+    {
+        var username = "guest";
+        var password = "guest";
+        var host = "localhost";
+
+        // Try to parse as URI first
+        if (Uri.TryCreate(connectionString, UriKind.Absolute, out var uri))
+        {
+            host = uri.Host;
+
+            if (!string.IsNullOrEmpty(uri.UserInfo))
+            {
+                var userInfoParts = uri.UserInfo.Split(':', 2);
+                username = Uri.UnescapeDataString(userInfoParts[0]);
+                if (userInfoParts.Length > 1)
+                {
+                    password = Uri.UnescapeDataString(userInfoParts[1]);
+                }
+            }
+        }
+        else
+        {
+            // Fallback regex parsing for edge cases
+            var match = Regex.Match(connectionString, @"amqp://(?:([^:]+):([^@]+)@)?([^:/]+)");
+            if (match.Success)
+            {
+                if (match.Groups[1].Success && match.Groups[2].Success)
+                {
+                    username = match.Groups[1].Value;
+                    password = match.Groups[2].Value;
+                }
+                if (match.Groups[3].Success)
+                {
+                    host = match.Groups[3].Value;
+                }
+            }
+        }
+
+        return (host, username, password);
+    }
+}