using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.Extensions.Logging;
using StellaOps.Determinism;
using StellaOps.Signals.Models;
using StellaOps.Signals.Options;
using StellaOps.Signals.Services;
using Xunit;

using StellaOps.TestKit;
namespace StellaOps.Signals.Tests;

public class InMemoryEventsPublisherTests
{
    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public async Task PublishFactUpdatedAsync_EmitsStructuredEvent()
    {
        var logger = new TestLogger<InMemoryEventsPublisher>();
        var options = new SignalsOptions();
        options.Events.Driver = "inmemory";
        options.Events.Stream = "signals.fact.updated.v1";
        options.Events.DefaultTenant = "tenant-default";

        var builder = new ReachabilityFactEventBuilder(options, TimeProvider.System, SystemGuidProvider.Instance);
        var publisher = new InMemoryEventsPublisher(logger, builder);

        var fact = new ReachabilityFactDocument
        {
            SubjectKey = "tenant:image@sha256:abc",
            CallgraphId = "cg-123",
            ComputedAt = System.DateTimeOffset.Parse("2025-11-18T12:00:00Z"),
            States = new List<ReachabilityStateDocument>
            {
                new() { Target = "pkg:pypi/django", Reachable = true, Confidence = 0.9, Bucket = "runtime", Weight = 0.45 },
                new() { Target = "pkg:pypi/requests", Reachable = false, Confidence = 0.2, Bucket = "runtime", Weight = 0.45 }
            },
            RuntimeFacts = new List<RuntimeFactDocument>
            {
                new() { SymbolId = "funcA", HitCount = 3 }
            }
        };

        var envelope = builder.Build(fact);
        await publisher.PublishFactUpdatedAsync(fact, CancellationToken.None);

        Assert.Equal("signals.fact.updated.v1", envelope.Topic);
        Assert.Equal("signals.fact.updated@v1", envelope.Version);
        Assert.False(string.IsNullOrWhiteSpace(envelope.EventId));
        Assert.Equal("tenant-default", envelope.Tenant);
        Assert.Equal("tenant:image@sha256:abc", envelope.SubjectKey);
        Assert.Equal("cg-123", envelope.CallgraphId);
        Assert.Equal(1, envelope.Summary.ReachableCount);
        Assert.Equal(1, envelope.Summary.UnreachableCount);
        Assert.Equal(1, envelope.Summary.RuntimeFactsCount);
        Assert.Equal("runtime", envelope.Summary.Bucket);
        Assert.Equal(2, envelope.Summary.StateCount);
        Assert.Contains("pkg:pypi/django", envelope.Summary.Targets);
        Assert.Contains("pkg:pypi/requests", envelope.Summary.Targets);
        Assert.Contains("signals.fact.updated.v1", logger.LastMessage);
    }

    private sealed class TestLogger<T> : ILogger<T>
    {
        public string LastMessage { get; private set; } = string.Empty;

        public IDisposable BeginScope<TState>(TState state) where TState : notnull => NullScope.Instance;

        public bool IsEnabled(LogLevel logLevel) => true;

        public void Log<TState>(LogLevel logLevel, EventId eventId, TState state, System.Exception? exception, Func<TState, System.Exception?, string> formatter)
        {
            LastMessage = formatter(state, exception);
        }

        private sealed class NullScope : IDisposable
        {
            public static readonly NullScope Instance = new();
            public void Dispose() { }
        }
    }
}