ServiceProvider callback for NATS DI configuration; (#619)

* ServiceProvider callback for NATS DI configuration;

* Recursion fix;

* Build fixes

* Build fixes

* Build fixes

* dotnet format

---------

Co-authored-by: Ziya Suzen <ziya@suzen.net>

src/NATS.Extensions.Microsoft.DependencyInjection/NatsBuilder.cs

@@ -9,9 +9,10 @@ namespace NATS.Extensions.Microsoft.DependencyInjection;
 public class NatsBuilder
 {
     private readonly IServiceCollection _services;
+
     private int _poolSize = 1;
-    private Func<NatsOpts, NatsOpts>? _configureOpts;
-    private Action<NatsConnection>? _configureConnection;
+    private Func<IServiceProvider, NatsOpts, NatsOpts>? _configureOpts;
+    private Action<IServiceProvider, NatsConnection>? _configureConnection;
     private object? _diKey = null;
 
     public NatsBuilder(IServiceCollection services)
@@ -20,43 +21,59 @@ public NatsBuilder(IServiceCollection services)
     public NatsBuilder WithPoolSize(int size)
     {
         _poolSize = Math.Max(size, 1);
+
         return this;
     }
 
-    public NatsBuilder ConfigureOptions(Func<NatsOpts, NatsOpts> optsFactory)
+    public NatsBuilder ConfigureOptions(Func<NatsOpts, NatsOpts> optsFactory) =>
+        ConfigureOptions((_, opts) => optsFactory(opts));
+
+    public NatsBuilder ConfigureOptions(Func<IServiceProvider, NatsOpts, NatsOpts> optsFactory)
     {
-        var previousFactory = _configureOpts;
-        _configureOpts = opts =>
+        var configure = _configureOpts;
+        _configureOpts = (serviceProvider, opts) =>
         {
-            // Apply the previous configurator if it exists.
-            if (previousFactory != null)
-            {
-                opts = previousFactory(opts);
-            }
+            opts = configure?.Invoke(serviceProvider, opts) ?? opts;
 
-            // Then apply the new configurator.
-            return optsFactory(opts);
+            return optsFactory(serviceProvider, opts);
         };
+
         return this;
     }
 
-    public NatsBuilder ConfigureConnection(Action<NatsConnection> connectionOpts)
+    public NatsBuilder ConfigureConnection(Action<NatsConnection> configureConnection) =>
+        ConfigureConnection((_, con) => configureConnection(con));
+
+    public NatsBuilder ConfigureConnection(Action<IServiceProvider, NatsConnection> configureConnection)
     {
-        _configureConnection = connectionOpts;
+        var configure = _configureConnection;
+        _configureConnection = (serviceProvider, connection) =>
+        {
+            configure?.Invoke(serviceProvider, connection);
+
+            configureConnection(serviceProvider, connection);
+        };
+
         return this;
     }
 
-    public NatsBuilder AddJsonSerialization(JsonSerializerContext context)
-        => ConfigureOptions(opts =>
+    public NatsBuilder AddJsonSerialization(JsonSerializerContext context) =>
+        AddJsonSerialization(_ => context);
+
+    public NatsBuilder AddJsonSerialization(Func<IServiceProvider, JsonSerializerContext> contextFactory)
+        => ConfigureOptions((serviceProvider, opts) =>
         {
-            var jsonRegistry = new NatsJsonContextSerializerRegistry(context);
+            var context = contextFactory(serviceProvider);
+            NatsJsonContextSerializerRegistry jsonRegistry = new(context);
+
             return opts with { SerializerRegistry = jsonRegistry };
         });
 
 #if NET8_0_OR_GREATER
     public NatsBuilder WithKey(object key)
     {
         _diKey = key;
+
         return this;
     }
 #endif
@@ -117,18 +134,18 @@ private static NatsConnection PooledConnectionFactory(IServiceProvider provider,
     private NatsConnectionPool PoolFactory(IServiceProvider provider, object? diKey = null)
     {
         var options = NatsOpts.Default with { LoggerFactory = provider.GetRequiredService<ILoggerFactory>() };
-        options = _configureOpts?.Invoke(options) ?? options;
+        options = _configureOpts?.Invoke(provider, options) ?? options;
 
-        return new NatsConnectionPool(_poolSize, options, _configureConnection ?? (_ => { }));
+        return new NatsConnectionPool(_poolSize, options, con => _configureConnection?.Invoke(provider, con));
     }
 
     private NatsConnection SingleConnectionFactory(IServiceProvider provider, object? diKey = null)
     {
         var options = NatsOpts.Default with { LoggerFactory = provider.GetRequiredService<ILoggerFactory>() };
-        options = _configureOpts?.Invoke(options) ?? options;
+        options = _configureOpts?.Invoke(provider, options) ?? options;
 
         var conn = new NatsConnection(options);
-        _configureConnection?.Invoke(conn);
+        _configureConnection?.Invoke(provider, conn);
 
         return conn;
     }

tests/NATS.Extensions.Microsoft.DependencyInjection.Tests/MyResolvedService.cs

@@ -0,0 +1,11 @@
+namespace NATS.Extensions.Microsoft.DependencyInjection.Tests;
+
+internal interface IMyResolvedService
+{
+    string GetValue();
+}
+
+internal class MyResolvedService(string value) : IMyResolvedService
+{
+    public string GetValue() => value;
+}

tests/NATS.Extensions.Microsoft.DependencyInjection.Tests/NatsHostingExtensionsTests.cs

@@ -80,6 +80,57 @@ public Task AddNatsClient_ConfigureOptionsSetsUrl()
         return Task.CompletedTask;
     }
 
+    [Fact]
+    public Task AddNatsClient_ConfigureOptionsSetsUrlResolvesServices()
+    {
+        var services = new ServiceCollection();
+        services.AddSingleton<ILoggerFactory, NullLoggerFactory>();
+        services.AddSingleton<IMyResolvedService>(new MyResolvedService("url-set"));
+        services.AddNatsClient(nats => nats
+            .ConfigureOptions((_, opts) => opts) // Add multiple to test chaining
+            .ConfigureOptions((serviceProvider, opts) =>
+            {
+                opts = opts with
+                {
+                    Url = serviceProvider.GetRequiredService<IMyResolvedService>().GetValue(),
+                };
+
+                return opts;
+            }));
+
+        var provider = services.BuildServiceProvider();
+        var nats = provider.GetRequiredService<INatsConnection>();
+
+        Assert.Equal("url-set", nats.Opts.Url);
+
+        return Task.CompletedTask;
+    }
+
+    [Fact]
+    public async Task AddNatsClient_ConfigureConnectionResolvesServices()
+    {
+        var services = new ServiceCollection();
+        services.AddSingleton<ILoggerFactory, NullLoggerFactory>();
+        services.AddSingleton<IMyResolvedService>(new MyResolvedService("url-set"));
+        services.AddNatsClient(nats => nats
+            .ConfigureConnection((_, _) => { }) // Add multiple to test chaining
+            .ConfigureConnection((serviceProvider, conn) =>
+            {
+                conn.OnConnectingAsync = async instance =>
+                {
+                    var resolved = serviceProvider.GetRequiredService<IMyResolvedService>().GetValue();
+
+                    return (resolved, instance.Port);
+                };
+            }));
+
+        var provider = services.BuildServiceProvider();
+        var nats = provider.GetRequiredService<NatsConnection>();
+
+        (var host, var _) = await nats.OnConnectingAsync!((Host: "host", Port: 123));
+        Assert.Equal("url-set", host);
+    }
+
 #if NET8_0_OR_GREATER
     [Fact]
     public void AddNats_RegistersKeyedNatsConnection_WhenKeyIsProvided()