using Serilog;
using Serilog.Core;
using Serilog.Events;
using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Commons.Messages.Logging;

namespace ZB.MOM.WW.OtOpcUa.Core.Scripting.Tests;

/// <summary>
///     Verifies the root script-logger fan-out: events flowing through the composed
///     pipeline (rolling file + companion mirror + topic sink) reach the
///     <see cref="IScriptLogPublisher"/> topic sink only when they meet the configured
///     minimum level, carrying their <c>ScriptId</c> identity property.
/// </summary>
/// <remarks>
///     Builds the identical <see cref="LoggerConfiguration"/> that the Host's
///     <c>ScriptRootLoggerFactory.Build</c> composes (file + <see cref="ScriptLogCompanionSink"/>
///     + <see cref="ScriptLogTopicSink"/>). The factory itself is a thin shell over this
///     exact wiring; testing the composition here keeps the suite a pure unit test with no
///     dependency on the Host's Web SDK executable.
/// </remarks>
[Trait("Category", "Unit")]
public sealed class ScriptRootLoggerFanoutTests : IDisposable
{
    private readonly string _tempFile = Path.Combine(
        Path.GetTempPath(), $"scripts-fanout-{Guid.NewGuid():N}-.log");

    private sealed class FakePublisher : IScriptLogPublisher
    {
        /// <summary>Gets the entries that have been published to the topic.</summary>
        public List<ScriptLogEntry> Published { get; } = [];

        /// <inheritdoc/>
        public void Publish(ScriptLogEntry entry) => Published.Add(entry);
    }

    /// <summary>
    ///     Builds the same pipeline the Host's <c>ScriptRootLoggerFactory.Build</c> composes,
    ///     so this test exercises the real production sink fan-out.
    /// </summary>
    private Logger BuildRootLogger(FakePublisher publisher, LogEventLevel topicMinLevel) =>
        new LoggerConfiguration()
            .MinimumLevel.Verbose()
            .WriteTo.File(_tempFile, rollingInterval: RollingInterval.Day)
            .WriteTo.Sink(new ScriptLogCompanionSink(Serilog.Log.Logger))
            .WriteTo.Sink(new ScriptLogTopicSink(publisher, topicMinLevel))
            .CreateLogger();

    /// <summary>
    ///     An Information event flows to the topic sink as a single <see cref="ScriptLogEntry"/>
    ///     carrying the bound <c>ScriptId</c>.
    /// </summary>
    [Fact]
    public void Information_event_reaches_the_topic_sink_with_its_ScriptId()
    {
        var publisher = new FakePublisher();
        using var root = BuildRootLogger(publisher, LogEventLevel.Information);

        root.ForContext(ScriptLoggerFactory.ScriptIdProperty, "S1")
            .Information("virtual tag recomputed");

        publisher.Published.Count.ShouldBe(1);
        publisher.Published[0].ScriptId.ShouldBe("S1");
        publisher.Published[0].Level.ShouldBe("Information");
        publisher.Published[0].Message.ShouldBe("virtual tag recomputed");
    }

    /// <summary>
    ///     A Debug event is gated out by the topic sink's Information minimum level, so the
    ///     publisher receives nothing (it still lands in the file sink, which we don't assert).
    /// </summary>
    [Fact]
    public void Debug_event_is_gated_out_by_the_topic_minimum_level()
    {
        var publisher = new FakePublisher();
        using var root = BuildRootLogger(publisher, LogEventLevel.Information);

        root.ForContext(ScriptLoggerFactory.ScriptIdProperty, "S1")
            .Debug("verbose diagnostic noise");

        publisher.Published.ShouldBeEmpty();
    }

    /// <summary>Disposes the temp log file created by the rolling file sink.</summary>
    public void Dispose()
    {
        // Serilog appends a date stamp where the trailing '-' sits; clean any matching file.
        var dir = Path.GetDirectoryName(_tempFile)!;
        var prefix = Path.GetFileNameWithoutExtension(_tempFile);
        try
        {
            foreach (var f in Directory.EnumerateFiles(dir, prefix + "*"))
                File.Delete(f);
        }
        catch (IOException)
        {
            // Best-effort cleanup — a locked file on a flaky CI box must not fail the test.
        }
    }
}