using System;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using FluentAssertions;
using Microsoft.Extensions.Logging;
using StellaOps.Scheduler.ImpactIndex;
using StellaOps.Scheduler.Models;
using Xunit;

namespace StellaOps.Scheduler.ImpactIndex.Tests;

public sealed class FixtureImpactIndexTests
{
    [Fact]
    public async Task ResolveByPurls_UsesEmbeddedFixtures()
    {
        var selector = new Selector(SelectorScope.AllImages);
        var (impactIndex, loggerFactory) = CreateImpactIndex();
        using var _ = loggerFactory;

        var result = await impactIndex.ResolveByPurlsAsync(
            new[] { "pkg:apk/alpine/openssl@3.2.2-r0?arch=x86_64" },
            usageOnly: false,
            selector);

        result.UsageOnly.Should().BeFalse();
        result.Images.Should().ContainSingle();

        var image = result.Images.Single();
        image.ImageDigest.Should().Be("sha256:8f47d7c6b538c0d9533b78913cba3d5e671e7c4b4e7c6a2bb9a1a1c4d4f8e123");
        image.Registry.Should().Be("docker.io");
        image.Repository.Should().Be("library/nginx");
        image.Tags.Should().ContainSingle(tag => tag == "1.25.4");
        image.UsedByEntrypoint.Should().BeTrue();

        result.GeneratedAt.Should().Be(DateTimeOffset.Parse("2025-10-19T00:00:00Z"));
        result.SchemaVersion.Should().Be(SchedulerSchemaVersions.ImpactSet);
    }

    [Fact]
    public async Task ResolveByPurls_UsageOnlyFiltersInventoryOnlyComponents()
    {
        var selector = new Selector(SelectorScope.AllImages);
        var (impactIndex, loggerFactory) = CreateImpactIndex();
        using var _ = loggerFactory;

        var inventoryOnlyPurl = "pkg:apk/alpine/pcre2@10.42-r1?arch=x86_64";

        var runtimeResult = await impactIndex.ResolveByPurlsAsync(
            new[] { inventoryOnlyPurl },
            usageOnly: true,
            selector);

        runtimeResult.Images.Should().BeEmpty();

        var inventoryResult = await impactIndex.ResolveByPurlsAsync(
            new[] { inventoryOnlyPurl },
            usageOnly: false,
            selector);

        inventoryResult.Images.Should().ContainSingle();
        inventoryResult.Images.Single().UsedByEntrypoint.Should().BeFalse();
    }

    [Fact]
    public async Task ResolveAll_ReturnsDeterministicFixtureSet()
    {
        var selector = new Selector(SelectorScope.AllImages);
        var (impactIndex, loggerFactory) = CreateImpactIndex();
        using var _ = loggerFactory;

        var first = await impactIndex.ResolveAllAsync(selector, usageOnly: false);
        first.Images.Should().HaveCount(6);

        var second = await impactIndex.ResolveAllAsync(selector, usageOnly: false);
        second.Images.Should().HaveCount(6);
        second.Images.Should().Equal(first.Images);
    }

    [Fact]
    public async Task ResolveByVulnerabilities_ReturnsEmptySet()
    {
        var selector = new Selector(SelectorScope.AllImages);
        var (impactIndex, loggerFactory) = CreateImpactIndex();
        using var _ = loggerFactory;

        var result = await impactIndex.ResolveByVulnerabilitiesAsync(
            new[] { "CVE-2025-0001" },
            usageOnly: false,
            selector);

        result.Images.Should().BeEmpty();
    }

    [Fact]
    public async Task FixtureDirectoryOption_LoadsFromFileSystem()
    {
        var selector = new Selector(SelectorScope.AllImages);
        var samplesDirectory = LocateSamplesDirectory();
        var (impactIndex, loggerFactory) = CreateImpactIndex(options =>
        {
            options.FixtureDirectory = samplesDirectory;
        });
        using var _ = loggerFactory;

        var result = await impactIndex.ResolveAllAsync(selector, usageOnly: false);

        result.Images.Should().HaveCount(6);
    }

    private static (FixtureImpactIndex ImpactIndex, ILoggerFactory LoggerFactory) CreateImpactIndex(
        Action<ImpactIndexStubOptions>? configure = null)
    {
        var options = new ImpactIndexStubOptions();
        configure?.Invoke(options);

        var loggerFactory = LoggerFactory.Create(builder => builder.SetMinimumLevel(LogLevel.Debug));
        var logger = loggerFactory.CreateLogger<FixtureImpactIndex>();

        var impactIndex = new FixtureImpactIndex(options, TimeProvider.System, logger);
        return (impactIndex, loggerFactory);
    }

    private static string LocateSamplesDirectory()
    {
        var current = AppContext.BaseDirectory;

        while (!string.IsNullOrWhiteSpace(current))
        {
            var candidate = Path.Combine(current, "samples", "scanner", "images");
            if (Directory.Exists(candidate))
            {
                return candidate;
            }

            current = Directory.GetParent(current)?.FullName;
        }

        throw new InvalidOperationException("Unable to locate 'samples/scanner/images'.");
    }
}