feat: add support for validator resolution from dependency injection

src/request.validation/ServiceCollectionExtensions.cs

@@ -0,0 +1,49 @@
+// Copyright (c) The Geekeey Authors
+// SPDX-License-Identifier: EUPL-1.2
+
+using Microsoft.Extensions.DependencyInjection;
+
+namespace Geekeey.Request.Validation;
+
+/// <summary>
+/// Provides extension methods for configuring and registering validator services in the <see cref="IServiceCollection"/>.
+/// </summary>
+public static class ServiceCollectionExtensions
+{
+	/// <summary>
+	/// Adds validator services to the specified <see cref="IServiceCollection"/>.
+	/// </summary>
+	/// <param name="services">The service collection to which the validator services will be added.</param>
+	/// <returns>An instance of <see cref="IValidatorBuilder"/> to configure the validator registrations.</returns>
+	public static IValidatorBuilder AddValidation(this IServiceCollection services)
+	{
+		ArgumentNullException.ThrowIfNull(services);
+
+		services.AddOptions<ValidationOptions>();
+		services.AddTransient<IValidator, DispatchingValidator>();
+
+		return new ValidatorBuilder(services);
+	}
+
+	/// <summary>
+	/// Adds validator services to the specified <see cref="IServiceCollection"/>
+	/// and configures them using the provided <see cref="Action{T}"/>.
+	/// </summary>
+	/// <param name="services">The service collection to which the validator services will be added.</param>
+	/// <param name="configure">A delegate to configure the validator builder.</param>
+	/// <returns>The service collection with the validator services added.</returns>
+	public static IServiceCollection AddValidation(this IServiceCollection services, Action<IValidatorBuilder> configure)
+	{
+		ArgumentNullException.ThrowIfNull(services);
+		ArgumentNullException.ThrowIfNull(configure);
+
+		configure(services.AddValidation());
+
+		return services;
+	}
+
+	private sealed class ValidatorBuilder(IServiceCollection services) : IValidatorBuilder
+	{
+		public IServiceCollection Services { get; } = services;
+	}
+}