// Copyright © 2025 StellaOps Contributors
// Licensed under AGPL-3.0-or-later

using FluentAssertions;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Logging.Abstractions;
using StellaOps.Policy.Determinization;
using StellaOps.Policy.Determinization.Models;
using StellaOps.Policy.Determinization.Scoring;
using Xunit;

namespace StellaOps.Policy.Determinization.Tests.Integration;

[Trait("Category", "Unit")]
public sealed class ServiceRegistrationIntegrationTests
{
    [Fact]
    public void AddDeterminization_WithConfiguration_RegistersAllServices()
    {
        // Arrange
        var configuration = new ConfigurationBuilder()
            .AddInMemoryCollection(new Dictionary<string, string?>
            {
                ["Determinization:ConfidenceHalfLifeDays"] = "21",
                ["Determinization:ConfidenceFloor"] = "0.15",
                ["Determinization:ManualReviewEntropyThreshold"] = "0.65",
                ["Determinization:SignalWeights:VexWeight"] = "0.30",
                ["Determinization:SignalWeights:EpssWeight"] = "0.15"
            })
            .Build();

        var services = new ServiceCollection();
        services.AddSingleton(TimeProvider.System);
        services.AddLogging();

        // Act
        services.AddDeterminization(configuration);
        var provider = services.BuildServiceProvider();

        // Assert - verify all services are registered
        provider.GetService<IUncertaintyScoreCalculator>().Should().NotBeNull();
        provider.GetService<IDecayedConfidenceCalculator>().Should().NotBeNull();
        provider.GetService<TrustScoreAggregator>().Should().NotBeNull();
    }

    [Fact]
    public void AddDeterminization_WithConfigureAction_RegistersAllServices()
    {
        // Arrange
        var services = new ServiceCollection();
        services.AddSingleton(TimeProvider.System);
        services.AddLogging();

        // Act
        services.AddDeterminization(options =>
        {
            // Options are immutable records, so can't mutate
            // This tests that the configure action is called
        });
        var provider = services.BuildServiceProvider();

        // Assert
        provider.GetService<IUncertaintyScoreCalculator>().Should().NotBeNull();
        provider.GetService<IDecayedConfidenceCalculator>().Should().NotBeNull();
        provider.GetService<TrustScoreAggregator>().Should().NotBeNull();
    }

    [Fact]
    public void RegisteredServices_AreResolvableAndFunctional()
    {
        // Arrange
        var configuration = new ConfigurationBuilder()
            .AddInMemoryCollection(new Dictionary<string, string?>())
            .Build();

        var services = new ServiceCollection();
        services.AddSingleton(TimeProvider.System);
        services.AddLogging(b => b.AddProvider(NullLoggerProvider.Instance));
        services.AddDeterminization(configuration);
        var provider = services.BuildServiceProvider();

        // Act - resolve and use services
        var uncertaintyCalc = provider.GetRequiredService<IUncertaintyScoreCalculator>();
        var decayCalc = provider.GetRequiredService<IDecayedConfidenceCalculator>();
        var trustAgg = provider.GetRequiredService<TrustScoreAggregator>();

        // Test uncertainty calculator
        var snapshot = SignalSnapshot.Empty("CVE-2024-1234", "pkg:maven/test@1.0", DateTimeOffset.UtcNow);
        
        // Assert - verify they work
        var score = uncertaintyCalc.Calculate(snapshot);
        score.Entropy.Should().Be(1.0); // All signals missing = maximum entropy

        var decayed = decayCalc.Calculate(baseConfidence: 0.9, ageDays: 14.0, halfLifeDays: 14.0);
        decayed.Should().BeApproximately(0.45, 0.01); // Half-life decay

        // Trust aggregator requires an uncertainty score
        var trust = trustAgg.Aggregate(snapshot, score);
        trust.Should().BeInRange(0.0, 1.0);
    }

    [Fact]
    public void RegisteredServices_AreSingletons()
    {
        // Arrange
        var configuration = new ConfigurationBuilder().AddInMemoryCollection(new Dictionary<string, string?>()).Build();
        var services = new ServiceCollection();
        services.AddSingleton(TimeProvider.System);
        services.AddLogging();
        services.AddDeterminization(configuration);
        var provider = services.BuildServiceProvider();

        // Act - resolve same service multiple times
        var calc1 = provider.GetService<IUncertaintyScoreCalculator>();
        var calc2 = provider.GetService<IUncertaintyScoreCalculator>();

        // Assert - should be same instance (singleton)
        calc1.Should().BeSameAs(calc2);
    }
}