feat: add support for validator resolution from dependency injection

src/request.validation/DispatchingValidator.cs

@@ -0,0 +1,69 @@
+// Copyright (c) The Geekeey Authors
+// SPDX-License-Identifier: EUPL-1.2
+
+using System.Collections.Concurrent;
+using System.Reflection.Metadata;
+
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Options;
+
+[assembly: MetadataUpdateHandler(typeof(Geekeey.Request.Validation.DispatchingValidator))]
+
+namespace Geekeey.Request.Validation;
+
+internal sealed class DispatchingValidator : IValidator
+{
+	private static readonly ConcurrentDictionary<Type, ValidatorInvoker> ValidatorsHandlers = new();
+
+	private readonly IServiceProvider _serviceProvider;
+
+	public DispatchingValidator(IServiceProvider serviceProvider)
+	{
+		_serviceProvider = serviceProvider;
+	}
+
+	public Validation Validate(ValidationContext context)
+	{
+		ArgumentNullException.ThrowIfNull(context);
+
+		if (context.Instance is null)
+		{
+			return new Validation([]);
+		}
+
+		var handler = ValidatorsHandlers.GetOrAdd(context.Instance.GetType(), static key =>
+		{
+			var type = typeof(ValidatorInvoker<>).MakeGenericType(key);
+			return (ValidatorInvoker)Activator.CreateInstance(type)!;
+		});
+
+		return handler.Validate(context, _serviceProvider);
+	}
+
+	private abstract class ValidatorInvoker
+	{
+		public abstract Validation Validate(ValidationContext context, IServiceProvider serviceProvider);
+	}
+
+	private sealed class ValidatorInvoker<T> : ValidatorInvoker
+	{
+		public override Validation Validate(ValidationContext context, IServiceProvider serviceProvider)
+		{
+			var options = serviceProvider.GetRequiredService<IOptions<ValidationOptions>>().Value;
+
+			var validators = options.GetValidators<T>(serviceProvider);
+
+			var problems = new List<Problem>();
+
+			foreach (var validator in validators)
+			{
+				if (validator.Validate(context) is { IsValid: false, Problems: { } result })
+				{
+					problems.AddRange(result);
+				}
+			}
+
+			return new Validation(problems);
+		}
+	}
+}