// Licensed under AGPL-3.0-or-later. Copyright (C) 2026 StellaOps Contributors.
// Sprint: SPRINT_20260110_012_008_POLICY
// Task: FCG-003 - Policy Engine Integration

using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.DependencyInjection.Extensions;
using StellaOps.Policy.Gates;

namespace StellaOps.Policy.Predicates.FixChain;

/// <summary>
/// Extension methods for registering FixChain gate services.
/// </summary>
public static class FixChainGateExtensions
{
    /// <summary>
    /// Adds FixChain gate predicate services to the service collection.
    /// </summary>
    /// <param name="services">Service collection.</param>
    /// <param name="configuration">Configuration section for options.</param>
    /// <returns>Service collection for chaining.</returns>
    public static IServiceCollection AddFixChainGate(
        this IServiceCollection services,
        IConfiguration? configuration = null)
    {
        ArgumentNullException.ThrowIfNull(services);

        // Register options
        if (configuration is not null)
        {
            services.AddOptions<FixChainGateOptions>()
                .Bind(configuration.GetSection("Policy:Predicates:FixChainGate"))
                .ValidateDataAnnotations()
                .ValidateOnStart();
        }
        else
        {
            services.TryAddSingleton(new FixChainGateOptions());
        }

        // Register core services
        services.TryAddSingleton<IFixChainGatePredicate, FixChainGatePredicate>();
        services.TryAddSingleton<IFixChainGateBatchService, FixChainGateBatchService>();

        // Register adapter for policy gate registry
        services.TryAddSingleton<FixChainGateAdapter>();

        return services;
    }

    /// <summary>
    /// Adds FixChain gate predicate services with custom options.
    /// </summary>
    /// <param name="services">Service collection.</param>
    /// <param name="configureOptions">Options configuration delegate.</param>
    /// <returns>Service collection for chaining.</returns>
    public static IServiceCollection AddFixChainGate(
        this IServiceCollection services,
        Action<FixChainGateOptions> configureOptions)
    {
        ArgumentNullException.ThrowIfNull(services);
        ArgumentNullException.ThrowIfNull(configureOptions);

        services.Configure(configureOptions);

        // Register core services
        services.TryAddSingleton<IFixChainGatePredicate, FixChainGatePredicate>();
        services.TryAddSingleton<IFixChainGateBatchService, FixChainGateBatchService>();

        // Register adapter for policy gate registry
        services.TryAddSingleton<FixChainGateAdapter>();

        return services;
    }

    /// <summary>
    /// Registers the FixChain gate with the policy gate registry.
    /// </summary>
    /// <param name="registry">Policy gate registry.</param>
    /// <returns>Registry for chaining.</returns>
    public static IPolicyGateRegistry RegisterFixChainGate(this IPolicyGateRegistry registry)
    {
        ArgumentNullException.ThrowIfNull(registry);

        registry.Register<FixChainGateAdapter>("fixChainRequired");
        return registry;
    }
}