// -----------------------------------------------------------------------------
// ValidationServiceCollectionExtensions.cs
// Sprint: SPRINT_20260118_031_LIB_input_pinning_trusted_vex_keys
// Task: TASK-031-006 - Implement Adversarial Input Validation
// Description: DI registration for adversarial validation services
// -----------------------------------------------------------------------------

using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;

namespace StellaOps.DeltaVerdict.Validation;

/// <summary>
/// Extension methods for registering adversarial validation services.
/// </summary>
public static class ValidationServiceCollectionExtensions
{
    /// <summary>
    /// Adds adversarial input validation to the service collection.
    /// </summary>
    /// <param name="services">The service collection.</param>
    /// <param name="configuration">Optional configuration.</param>
    /// <returns>The service collection for chaining.</returns>
    public static IServiceCollection AddAdversarialInputValidation(
        this IServiceCollection services,
        IConfiguration? configuration = null)
    {
        if (configuration != null)
        {
            services.Configure<AdversarialValidationPolicy>(
                configuration.GetSection(AdversarialValidationPolicy.SectionName));
        }

        services.AddSingleton<IAdversarialInputValidator, AdversarialInputValidator>();

        return services;
    }

    /// <summary>
    /// Adds adversarial input validation with custom policy.
    /// </summary>
    /// <param name="services">The service collection.</param>
    /// <param name="configurePolicy">Policy configuration delegate.</param>
    /// <returns>The service collection for chaining.</returns>
    public static IServiceCollection AddAdversarialInputValidation(
        this IServiceCollection services,
        Action<AdversarialValidationPolicy> configurePolicy)
    {
        services.Configure(configurePolicy);
        services.AddSingleton<IAdversarialInputValidator, AdversarialInputValidator>();

        return services;
    }

    /// <summary>
    /// Adds adversarial input validation with a predefined policy.
    /// </summary>
    /// <param name="services">The service collection.</param>
    /// <param name="policy">The validation policy to use.</param>
    /// <returns>The service collection for chaining.</returns>
    public static IServiceCollection AddAdversarialInputValidation(
        this IServiceCollection services,
        AdversarialValidationPolicy policy)
    {
        services.AddSingleton(Microsoft.Extensions.Options.Options.Create(policy));
        services.AddSingleton<IAdversarialInputValidator, AdversarialInputValidator>();

        return services;
    }
}