// Licensed under AGPL-3.0-or-later. Copyright (C) 2026 StellaOps Contributors.

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

namespace StellaOps.BinaryIndex.Analysis;

/// <summary>
/// Extension methods for registering analysis services.
/// </summary>
public static class ServiceCollectionExtensions
{
    /// <summary>
    /// Adds golden set analysis pipeline services.
    /// </summary>
    /// <param name="services">Service collection.</param>
    /// <param name="configuration">Configuration for options binding.</param>
    /// <returns>Service collection for chaining.</returns>
    public static IServiceCollection AddGoldenSetAnalysis(
        this IServiceCollection services,
        IConfiguration? configuration = null)
    {
        // Register options
        if (configuration is not null)
        {
            services.Configure<FingerprintExtractionOptions>(
                configuration.GetSection("BinaryIndex:Analysis:Fingerprinting"));
            services.Configure<SignatureMatchOptions>(
                configuration.GetSection("BinaryIndex:Analysis:Matching"));
            services.Configure<ReachabilityOptions>(
                configuration.GetSection("BinaryIndex:Analysis:Reachability"));
            services.Configure<AnalysisPipelineOptions>(
                configuration.GetSection("BinaryIndex:Analysis"));
        }
        else
        {
            // Register default options
            services.Configure<FingerprintExtractionOptions>(_ => { });
            services.Configure<SignatureMatchOptions>(_ => { });
            services.Configure<ReachabilityOptions>(_ => { });
            services.Configure<AnalysisPipelineOptions>(_ => { });
        }

        // Register core services
        services.AddSingleton<ISignatureIndexFactory, SignatureIndexFactory>();
        services.AddSingleton<ISignatureMatcher, SignatureMatcher>();
        services.AddSingleton<ITaintGateExtractor, TaintGateExtractor>();

        // Register stub implementations (to be replaced with real implementations)
        services.AddSingleton<IFingerprintExtractor, FingerprintExtractor>();
        services.AddSingleton<IReachabilityAnalyzer, ReachabilityAnalyzer>();

        // Register null reachability service (for testing/standalone use)
        // Real implementation should be registered via AddReachGraphIntegration
        services.TryAddSingleton<IBinaryReachabilityService, NullBinaryReachabilityService>();

        // Register pipeline
        services.AddSingleton<IGoldenSetAnalysisPipeline, GoldenSetAnalysisPipeline>();

        return services;
    }

    /// <summary>
    /// Registers a custom IBinaryReachabilityService implementation.
    /// Use this to provide real ReachGraph integration.
    /// </summary>
    /// <typeparam name="TImplementation">Implementation type.</typeparam>
    /// <param name="services">Service collection.</param>
    /// <returns>Service collection for chaining.</returns>
    public static IServiceCollection AddBinaryReachabilityService<TImplementation>(
        this IServiceCollection services)
        where TImplementation : class, IBinaryReachabilityService
    {
        // Remove any existing registration
        var descriptor = services.FirstOrDefault(d => d.ServiceType == typeof(IBinaryReachabilityService));
        if (descriptor is not null)
        {
            services.Remove(descriptor);
        }

        services.AddSingleton<IBinaryReachabilityService, TImplementation>();
        return services;
    }

    /// <summary>
    /// Registers a custom IBinaryReachabilityService instance.
    /// Use this to provide real ReachGraph integration via factory.
    /// </summary>
    /// <param name="services">Service collection.</param>
    /// <param name="factory">Factory to create the service.</param>
    /// <returns>Service collection for chaining.</returns>
    public static IServiceCollection AddBinaryReachabilityService(
        this IServiceCollection services,
        Func<IServiceProvider, IBinaryReachabilityService> factory)
    {
        // Remove any existing registration
        var descriptor = services.FirstOrDefault(d => d.ServiceType == typeof(IBinaryReachabilityService));
        if (descriptor is not null)
        {
            services.Remove(descriptor);
        }

        services.AddSingleton(factory);
        return services;
    }
}